Articial Intelligence in Medicine 56 (2012) 137156

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Articial Intelligence in Medicine

journa l homepage: www.e lsev ier .co

Smart w tu

Marie Ch hrisa Laboratory fo e du Cb University of

a r t i c l

Article history:Received 27 JuReceived in re12 SeptemberAccepted 19 S

Keywords:Smart wearabe-HealthAgeingAssistive technology

mad) forent tecs, thindivmponrt comus 24tive h

as references for researchers and provide perspectives for future research.Methods: Herein, we review the current research and development of and the challenges facing SWS forHM, focusing on multi-parameter physiological sensor systems and activity and mobility measurementsystem designs that reliably measure mobility or vital signs and integrate real-time decision supportprocessing for disease prevention, symptom detection, and diagnosis. For this literature review, we havechosen specic selection criteria to include papers in which wearable systems or devices are covered.

1. Introdu

Efforts thave beenworld popuin developehave a greagreater neeadmitted toa care hommost of whCurrently, bhomes [9]. DEconomic Ccare expendare at an ato a genera

Correspontems, NationaToulouse, Fran

E-mail add

0933-3657/$ http://dx.doi.oResults: We describe the state of the art in SWS and provide a survey of recent implementations ofwearable health-care systems. We describe current issues, challenges, and prospects of SWS.Conclusion: We conclude by identifying the future challenges facing SWS for HM.

2012 Elsevier B.V. All rights reserved.

ction

o research and develop smart wearable systems (SWS)increasing in both academia and industry [13]. Thelation is ageing, and the proportion of young workersd countries has been shrinking [4,5]. Elderly peopleter level of disability due to age-related diseases, ad for care and assistance, and are more likely to bea hospital or nursing home. Permanent admission toe is an expensive way of providing care for elderly,om would prefer to remain in their own home [68].etween 2 and 5% of elderly people reside in nursingata on health from 30 countries of the Organization forooperation and Development (OECD) show that healthitures as a proportion of gross domestic product (GDP)ll-time high, due to both increased expenditures andl economic slow-down [10]. France spent 11.8% of its

ding author at: Laboratory for Analysis and Architecture of Sys-l Center for Scientic Research, 7 avenue du Colonel Roche, F-31400ce. Tel.: +33 5 61 33 69 51; fax: +33 5 61 33 62 08.ress: chan@laas.fr (M. Chan).

GDP on healthcare delivery in 2009 according to OECD statistics.France was second among the OECD countries, behind the USA(17.4%), Germany (11.6%), Canada (11.4%), Switzerland (11.4%) andAustria (11. 0%) [11]. Telecare, telehealth and telemedicine arenew models of care already in use, bringing solutions to healthcareissues [12,13]. A large variety of laboratory prototypes, test bedsand industrial products have already been produced. The role ofSWS is to match the living environment with the physical and cog-nitive abilities and limitations of those suffering from disabilitiesor diseases, thereby enhancing performance and minimising therisk of illness, injury, and inconvenience. These systems supportindependent living for the elderly, postoperative rehabilitation forpatients to expedite recovery, and assessment or enhancement ofindividual sportive or technical abilities [14,15].

For monitoring heath, an SWS may include a wide range ofwearable or implantable devices, including sensors, actuators,smart fabrics, power supplies, wireless communication networks(WCNs), processing units,multimedia devices, user interfaces, soft-ware, and algorithms for data capture, processing, and decisionsupport. These systems are able tomeasure vital signs, such as bodyand skin temperature, heart rate, arterial blood pressure, bloodoxygen saturation (SpO2), electrocardiograms (ECGs), electroen-

see front matter 2012 Elsevier B.V. All rights reserved.rg/10.1016/j.artmed.2012.09.003earable systems: Current status and fu

ana,b,, Daniel Estvea,b, Jean-Yves Fourniolsa,b, Cr Analysis and Architecture of Systems, National Center for Scientic Research, 7 avenuToulouse, F-31400 Toulouse, France

e i n f o

ne 2011vised form2012eptember 2012

le system

a b s t r a c t

Objective: Extensive efforts have beenment of smartwearable systems (SWShealthcare costs and supported by recturisation of sensors, and smart fabrilandscape of healthcare by allowinghealth status. Consisting of various cotimedia devices, these systems supponon-invasive alternatives for continuoboth indoors and outdoors. Our objecm/locate /a i im

re challenges

tophe Escribaa,b, Eric Campoa,b

olonel Roche, F-31400 Toulouse, France

e in both academia and industry in the research and develop-healthmonitoring (HM). Primarily inuenced by skyrocketingchnological advances inmicro- and nanotechnologies, minia-e continuous advances in SWS will progressively change theidual management and continuous monitoring of a patientsents and devices, ranging from sensors and actuators to mul-plex healthcare applications and enable low-cost wearable,

-h monitoring of health, activity, mobility, and mental status,as been to examine the current research in wearable to serve

138 M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156

cephalograms (EEGs), and respiration rate. The measurements areforwarded via a wireless sensor network (WSN) either to a cen-tral connection node, such as a personal digital assistant (PDA),or directly to a medical centre. A physician can then manage thepatient bastypeofweacapable of pstaff, patiendevice duriitor the patduring a hocan even iswhen a subsent as sooelectromecclinical indpoint-of-catranscutanemotor andduring the atral nervouobstacles thincluding htion, sensorfreedom, au

This paptus of researeporting thbeing develis organisedand methodtures of wesystemsdevlaboratorysurroundinfutures pers

2. Materia

SWS hapatient andtechnologying. SWS acornerstonenetworks apersons andfrom depenbring newrapidly, deubiquitousso will wirewearable de[28]. Theseand help wabilities incSWS are ustelemedicihealth, assto connectinetwork (B(WAN), aninclude useeffectiveneand softwa

literature review, we have chosen specic selection criteria toinclude papers in which wearable systems or devices are covered.

clusi

t resintelwhicthe

llowxtenemsearatchbricobilent dghtwresuSWSectsuser. Driweagnisaviounostpervmatarchal oonalcts opeoprven; emly toanceng hems.rovi

liancsing,reakheaitalsstafffor eroceputiudednt tof sesingion oervisidity, BSNword

clusi

inclds, tees, hed on the transmitted data. An increasingly importantrable system is an intelligentmedicalmonitoringdeviceroviding real-time processing and feedback to medicalts, athletes, andhealthy subjects. A subject canwear theng normal daily life while medical professionals mon-ient in real-time for longer periods than are possiblespital stay or a visit to a physicians ofce. The systemsue alerts in the event of an emergency. For example,ject living alone suffers a stroke, an ambulance can ben as the stroke occurs. Advances in the eld of micro-hanical systems (MEMS) have addressed a number ofications, such as drug release [16] and biosensors forre testing [17]. Electrical stimulation by implantable orous electronic devices or electrodes is often used forsensory function recovery in the treatment of patientscute and subacute phase of paralysis induced by a cen-s system lesion [18]. However, there are a number ofatmust be overcome to fully implement theuse of SWS,igh costs, size and weight limitations, energy consump-implementation and connectivity, ethics, laws, privacy,tonomy, reliability, security, and service issues [1921].er provides a review of SWS, describing the current sta-rch and development of wearable systems for HM bye salient characteristics of the most promising projectsoped and the future challenges in this area. The paperas follows. Section 2 describes the common materialss used in SWS, and Section 3 describes the current fea-arable systems, the sensor technologies, the wearableeloped in academia and industry andour ownon-going

research in the eld. Section 4 presents current issuesg SWS, and Section 5 discusses the challenges and thepectives. Section 6 draws the review to a close.

ls and methods

ve the potential to monitor and respond to both thethe patients environment, and the advances in the

behind the development of SWS are steadily increas-re commonly recognised as one of the technologicals for HM. Intelligent, low-cost, ultra-low-power sensorre designed to help provide services to dependentcan collect a huge amount of biomedical informationdent individuals [22]. They offer new resources andchallenges as a result of the data that they providependably, and safely. As wireless technologies andand pervasive computing [23] continue to develop,less network sensors [24], mobile devices, intelligentvices [2527], SWS, anddata communication networkstechnologies will create an intelligent environmentith long-distance health care [26,27]. Their currentlude physiological, biochemical, and motion sensing.ed in areas ranging from telehealth, telehealthcare,ne, telecare, telehomecare, e-health, p-health, m-istive technology, or gerontechnology. Issues relatedvity have introduced terms such as WSN, body areaAN), body sensor network (BSN), wide area networkd personal area network (PAN). Important concernsr needs, user acceptance, privacy, ethics, legality,ss, cost, psychological and social issues, hardwarere, implantation site, and unobtrusiveness. For this

2.1. In

1. Mosanding,fromswaby eSyst- W- Pa- Fa- M

2. Receof lithe[3].Projthe[25]ing,recobehdiagand

3. Autoreseformperseffeforinteuserlike

4. Advputisystby papppento btakehospicalandcal pcomincl

5. Recetionon aeratsuphumBANthe

2.2. In

Wetest beoratorion criteria for wearable systems search

earch projects in SWS have focused on smart devicesligent environments that encompasswearable comput-hdisplace the interface for computational surroundingshome (the smart home) onto our bodies (implantable,

able) [29] and into our clothes (smart clothing) [30] andsion as portable accessories (jewelry), in patch form, etc.that have the following features are included:ble, portable, implantable, swallowable capsule, in vivo., biosensor, sensor., clothing, textile, bre., stationary, ambulatory, at home, at work.evelopments in micro- and nanotechnology, the useeight devices, WSNs, and data processing have led torgence of noninvasive SWS that improve HM systems

detect the state of the user in his or her vicinity.in SWS concentrate on detecting the physical state of(physiological parameters, activity, mobility, location)ven by fast progress in mobile sensing and comput-rable computing has developed powerful methods toe, classify, and label human health states, actions, andrs automatically [31]. SWS have monitoring as well asic applications. Systems that are intelligent, ubiquitous,asive or context-aware are included.ic integration of collected data and user input intodatabases can provide the medical community or ther informal caregiver with an opportunity to search forised trends, enabling insights into illness evolution, thef drug therapy, the rehabilitation process, and supportle with disabilities. Systems may either require usertion or may not rely on the active participation of thepowered patients suffering chronic disease are morefeel in control of their health [3235].s in wireless sensor networking and ubiquitous com-ave paved the way for new possibilities in health-careIn the home, pervasive networks can assist residentsding memory support, remote control of householdes, medical data look-up, automatic medication dis-and emergency communications and services. It is timethrough the physical boundaries of hospitals and to

lth-care facilities into the home. In nursing homes and, SWS and ubiquitous computing for nursing and med-constitute a solution both for reducing medical costsnhancing patient safety while better supporting clini-sses [36,37]. Projects that involve SWS and ubiquitousng in the home, in nursing homes, or in hospitals are.echnological advances in integration and miniaturisa-nsors, embeddedmicrocontrollers, and radio interfacesle chip and in wireless networks have led to a new gen-f WSNs for HM. A number of physiological sensors thate vital signs, environmental sensors (temperature, light,), and a location sensor can all be inserted into a WSN,, WAN, or PAN. Descriptions of networks that includes WSN, BAN, BSN, WAN, or PAN are included.

on criteria for study area search

uded projects, pilot studies, case studies, prototypes,st sites, and research conducted in nursing homes, lab-ealth care settings, e-health care settings, or systems

M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156 139

Table 1Keywords used for the literature search.

Assistive technology Smart homeE-health Smart textileHome healthImplantableIn vivo devicM-health PaObtrusivenePatchPortableSmart clothiSmart fabric

involving husers.

2.3. Search

This litereport an exreports areOur studyreview. Ourperiodicals2012. Someprojects weadequate pwere conduPubMed, Pu

2.4. Results

Scopusginitial searcwith the keyin combinatof the systeand the issters, WSN,number of pinclude onlyexhaustiveonly some ror products

The num

3. Current

Non-invcal functionHM systemimplantableiological paECGs, EEGsprovide reacommunicaproviders thThe aim ofmonitoringsuffering fro

3.1. Assessa

3.1.1. WhenThere is

to provide

Table 2Number of hits in the smart wearable systems research area.

Scopus PubMed PubMedCentral

SWSedicinalthreonitorlthlthedicineedseeds aine sktablefabricclothicceptacceptancy wive wilitatiocal stieconoss senss senrea nerea ne

earabal areal aremic an

ere aolutis.

are uoutdoitorinuredd. Thotionlifehabits suddenly change, suchas thepropensity to remainme or reduction of mobility, appetite, and social activities,dangerous conditions can be foreseen based on analysis of

ctivities of daily living. During extreme climatic conditionsssively cold or hot weather), elderly people are more proneg infections, dehydration, or other diseases [38]. This can beed if the changes in the patients behaviour as a result of dis-infection, or dehydration are collected early and adequatepy or rehydration is initiated before the situation becomeserous.nt studies have developed diagnostic devices for point-of-testing. Easy-to-use features of point-of-care diagnosticspatient-side clinical analysis (e.g., outside of the hospi-the eld). Enabled by microfabrication and microuidics, avariety ofmedical situations using point-of-care diagnosticsbeen explored, including disease markers, assessing thera-detecting chemical and biological hazards, and identifyingcare Socio-economic impactdevice Telecaree Telehealthtch Telemediciness Telemonitoring

User acceptanceUser needs

ng User satisfactionWearable

ealthcare stakeholders, providers, caregivers, and end

methods and strategy

rature review is not a systematic review and does nothaustive search of scientic publications. Rather, citedintended to give some illustrative examples of SWS.includes published works that have undergone peersearch was limited to papers in journals, chapters ofand congress proceedings written between 1993 andweb sites describing systems, devices, prototypes, andre included when the published literature did not offerresentations of the projects. Searches using keywordscted either in Scopus, Elsevier, IEEE Xplore, Springer,bMed Central or using the Google search engine.

iveshits fromtheperiodbetween2007and2012. In thish, we attempted to nd articles and abstracts, websiteswords listed in Table 1. The keywords are used alone orion and/or. The article should report a clear descriptionms, the recipients or the users in need of those systems,ues related to the SWS, including measured parame-user needs, and user acceptance. Because of the largeapers and abstracts retrieved, a decision was made topapers published after 1989. Since this review is not an

presentation of the scientic literature of the SWS eld,epresentative SWS research and development projectsfrom academia or industry are presented.ber of hits in the SWS research area is shown in Table 2.

features of wearable systems

asive sensor systems allow monitoring of physiologi-s, daily activities, and individual behaviours. Wearables may include various types of miniature wearable,or in vivo sensors. These biosensors canmeasure phys-

rameters such as body and skin temperature, heart rate,, electromyograms (EMGs), or SpO2. Smart devices canl-time processing. Data transmission via wireless bodytion networks enable patient monitoring by healthcareat can be alerted as soon as a dangerous event occurs.

TelemTeleheTelecaTeleme-HeaM-heaTelemUser nUser nMedicImplanSmartSmartUser aUser aEfcieObtrusRehabElectriSocio-WireleWireleBody aBody aBSNBSN wPersonPersonEcono

anywhoffer sservice

- SWSandmonmeasmitteor mtheirat hothesethe a(exceto lunavoidease,theradang

- Rececareallowtal, inwidehavepies,this section is to review wearable systems capable ofindividuals such as the elderly, the handicapped, thosem chronic diseases, and the injuredwith special needs.

ble parameters and users of SWS

, where and how SWS can be useda growing interest in nding new healthcare solutionscare, or manage and support patients or individuals

infectiousto electropounds, s

- MEMS deumps, valof microgbiomedicuous or dliving org454 540 80e 15,116 13,462 2148

1981 1194 6241981 331 228

ing 1063 432 2532221 936 1069176 862 1063

e and wearable 256 140 4977,409 3414 18,908

nd wearable 241 11 116in patch 455 1346 107device 11,115 18,306 3083s 1010 68 46ng 491 88 416nce 8724 1244 4888nce wearable 43 10 30earable 311 36 114earable 20 10 7n wearable 409 231 128mulation wearable 40 28 34mic and wearable 2 0 6sor network 44,389 167 232sor network 577 34 68twork 4945 1195 31,366twork wearable 270 21 93

2484 119 3227le 417 24 78a network 6760 1001 16,922a network wearable 116 8 74alyse telemedicine 5 7 31

t any time. Innovative portable and wearable systemsons to accessible and good quality individualised HM

sed to monitor patients 24h a day, in their own homeors, according to preventive medicine protocols. Theg system is connected to an assistance centrewhere theparameters are continuously or intermittently trans-e centre can also provide help if needed. The activitiess of elderly individuals can be monitored, and whenpeople during pandemics.Microuidic devices are ablechemically analyse a wide variety of biochemical com-uch as glucose, cholesterol, lactate and alcohol [39,40].vices, including microreservoir drug depots, microp-ves, and sensors, have been developed for the deliveryram quantities of drugs. The usefulness of MEMS foral applications lies in their ability to behave in a contin-iscrete fashion which may mimic the metastability of aan. A microchip for drug delivery is capable of releasing

140 M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156

drugs by opening various reservoirs on command. Pulsing or dis-continuous performance may also be achieved in an MEMS usingcomponents such as valves or pumps. Adding hydrogels, biosen-sors, and other features that are responsive to the local deviceenvironmmanner wplines sucmaterialsdrug delivlead to fulcould repdeliveringimpulse, a

- Capsulerepresentditional cldriven bycollect imbecause tand orienendoscopphysicianing pathoendoscoptherapeut

- Progress iputing haready toincludingindoor anprovide nbined witmonitor aroom. Muand moniing and aftransportfacilities,vidual injcrash, a nat the hosmonitorincontinuoure, earthworking cindangeroingcatastsend an a

The vitaTable 3.

3.1.2. DiseaSWS

Ongoingnanotechnocommunicavital sign m

- Cardiovasleading cazation (Wgreatest kheart attarhythmiaattack, an

Table 3List of vital parameters assessed using wearable systems.

Type of vital signals Type of sensor Signal source

ElectromyogG)encep)y, mo

ation

sound

gluco

n satur skinperatuic skionse

e can50].etese moomict frose c

ent hrticagemsulinl disetreatd clidingrch,nt adnablecemiratoa sya c

inistrildre

le senand ttermer is.6 mrdingNS by studying the blood ow in the area surrounding aur using sensors placed on a needle (because cancer cellse nitric oxide), enabling physicians to diagnose tumoursout performing a biopsy [57]. Patients suffering from canceronitored to support their wellness [58].re, motion control particularly interesting for those whoundergone hip surgeries. A wearable accelerometer embed-in a waist belt and attached to the lumbo-sacral region

enable assessment of motor recovery and of physicaltiveness therapy for post-stroke hemiplegic patients [59].res and gestures can be monitored using accelerometers

magnetometer-based devices which can be micro-electro-anical or textile-based transducers [60]. A gyroscope,ass, accelerometer [61], magnetometer, piezoelectric sen-ndGPS inminiaturised andwearable forms canbe combinedtect complex movement patterns [62].ent can enable an MEMS to function in an integratedith its biological surroundings. Combining new disci-h as biomimetics and new biocompatible polymericinto microfabricated devices for tissue engineering andery and new techniques for patterning living cells mayly integrated smartMEMS-based devices. These deviceslace entire biological systems and be responsible forthe right stimulus, such as a drug or an electrical

t the right time [41].endoscopy, involving a miniaturised video-camera,s anappealingalternative to traditional techniques. Tra-inical products are passive deviceswhose locomotion isnatural peristalsis, which has the drawback of failing toages fromimportant regionsof thegastrointestinal tracthe physician is unable to control the capsules motiontation. Active locomotion devices could enable capsuley to be performed in a totally controlled manner. Thewould be able to steer the capsule towards interest-logical areas and to accomplish medical tasks. Capsuley offers new possibilities for screening, diagnostic, andic endoscopic procedures [29].n sensor technologies and innovation in wearable com-ve spawned numerous new devices which are nowrevolutionise medical and professional applications,diagnostics, surgery, remote patient monitoring, andd outdoor positioning. Wireless medical instrumentsew dimensions for these applications. Biosensors com-h wireless devices in a smart instrument can remotelyn elderly person at home or a patient in the operatingltiple pieces of medical equipment can be controlledtored wirelessly by a single device for each patient dur-ter surgical operations [42] or childbirth or during theirto a hospital. In nursing homes or geriatric home-careSWS can improve residents quality of life [37]. An indi-ured during a catastrophic event (e.g., a plane or caratural disaster) can be supervised during transport orpital and tethered to wearable devices or systems. Theg can range from intensive (every 15min or less) to dis-sly invasive or non-invasive. In disaster situations (e.g.,quake), SWS can protect workers [43,44]. In extremeonditions, for example for difcult mass transportationus sectors such asmines or oil platforms [45,46] or dur-

rophicevents (bus, plane, orboatingaccidents), SWScanlarm to a management centre.

l parameters that can be monitored by SWS are listed in

ses, handicaps or disabilities that can be monitored by

cutting-edge multidisciplinary research in micro- andlogies, biosensors, andwireless andmobile informationtion technologies has given rise to multi-parameteronitoring:

cular diseases heart disease has become one of theuses of death world-wide. The World Health Organi-HO) states that cardiovascular diseases are the worldsillers, claiming 17.3 million lives a year in events likeck and stroke [47]. Angina, atherosclerosis, cardiac dys-, congestive heart failure, coronary artery disease, heartd tachycardia are the main cardiovascular diseases.

(EMElectro

(EEGActivit

Respir

Heart

Blood

OxygeBody o

temGalvan

resp

Thes[48

- Diabof theconbeneglucoprevan amanof in

- RenaysiswoulprovreseaReceto erepla

- Respapneasthmadmfor chtextiage,long-

- Cancfor 7accoby Wtumoexudwithare m

- PostuhavededcouldeffecPostuandmechcompsor, ato deram Skin electrodes Electrical activity of a muscle

halogram Scalp-placedelectrodes

Electrical activity of brain,Brain potentials

bility, fall Accelerometer Gesture posture/limbmovements

rate Piezoelectric/piezoresistive sensor

Inspiration and expirationper unit time

s Phonograph Record of heart sounds, witha microphone

se Glucose meter Assessment of the amount ofglucose in blood

ration Pulse oximeter Oxy-hemoglobin in blood

reTemperature probeor skin patch

Body or skin

n Woven metalelectrodes

Skin electrical conductivity

be diagnosed by analysing changes in ECG patterns

mellitus is a disorder of glucose metabolism and onest challenging diseases both from a medical and anperspective. Patients suffering from the disease canm frequent, even continuous,monitoring of their blood

oncentration to receive the right quantity of insulin toypoglycaemia complications [51]. The development ofial pancreas may be one of the solutions for betterent and monitoring of glucose level and the infusion[52].ases patients suffering kidney failure depend on dial-ments. Ideally, the wearable articial kidney (WAK)osely approximate the function of a real kidney byround-the-clock dialysis. However, despite years ofa WAK hemodialysis system remains elusive [53].vances in MEMS-based membrane technology promisethe development of continuous implantable renal

ent therapy [54].ry diseases patients suffering from dyspnea, sleepndrome, chronic obstructive pulmonary disease, oran be monitored for early detection of symptoms andation of treatments [55]. Respiration-rate assessmentn suffering pulmonary disease can beundertakenusingsors and electronics for interfacing, data handling, stor-ransmission. Such a system would enable continuous,monitoring of children in a hospital environment [56]a leading cause of death worldwide and accounted

illion deaths (approximately 13% of all deaths) in 2008to theWHO [47]. Some cancer tumours can be detected

M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156 141

- Neurological disorders and brain stimulation epilepsy is a neu-rological disorder characterised by spontaneous seizures. Overone-third of patients receive insufcient oral anti-epileptic drug(AED) and experience seizures while on medication. New gen-erations othe brainthe remaThe devicachieve grregion restechnolognon-invasMany nanand in vivsis, or botthe manaencephalo[65].

- Rehabilitadings canand muscitation, usensor-eqand intercandmanuprovidedconnect thconstrainare unres

- Parkinsonease is a nmotor symsia. A quaprovidingfor evaluatoring. A stimulatioor to opention of th[6870]. Isis by by-the patienenhancing

- In sport sthe discrebecomingthe form otechnologtors [72].assess phperformanexercise, aa race carfor bodilychemicaltory monield of spresearchpossible tdition of tions andmpathologi

- Stress is asive that tin real timtor could

stress levels. Their physicians could thus objectively evaluatestress exposure between visits. The system could be used as partof a psycho-physiological evaluation of members of the militaryundergoing intense training. The system uses measures of heart-

ariaell asbilitionaligennal tes ofectedligencan iollecon, belecicaten inrentlxacte. H

evateen saloodnts.nts r) in ay. Abirthaler

ent oee hecialses,

catio

sens

byce ofy te], orring,ctronban

ess mrt ra

est bamame [es fossesfun

ssescribiientvidinvesivitieectsantabniatunt [9f AED are delivered directly to the seizure focus into provide more effective doses while by-passing

inder of the brain and body to prevent side effects.es are polymer-based implants loaded with AED toadual, continuous release of AED directly into the brainponsible for seizures [63,64]. Recent advances in nano-y have provided promising solutions for the effectiveive treatment of central nervous system (CNS) diseases.omedicines can be transported across various in vitroobloodbrain barriermodels by endocytosis, transcyto-h and have demonstrated early pre-clinical success forgement of CNS conditions such as brain tumours, HIVpathy, Alzheimers disease, and acute ischemic stroke

tion movement and muscle activity pattern recor-be associated with a given set of functional motor tasksle stimulation [66]. In the case of post-stroke rehabil-pper-limb kinematic variables can be assessed usinguipped garments. Using this technology, both sensorsonnection wires can be deposited in a single printingfacturingprocess. Thepatients benet fromthe comfortby the device because nometallicwires are necessary toem to the electronic data acquisition system. No rigid

ts are present in the wearable system, and movementstricted [67].s disease, quadriplegia, and paralysis Parkinsons dis-euro-degenerative disorder that induces characteristicsptoms: rigidity, tremor, bradykinesia, and hypokine-

ntiable, objective, continuous data acquisition systeminformation on the characteristic movement disorderstion of the disease could improve diagnosis and moni-bionic glove can be used to provide functional electricaln of muscles, either to produce a hand-grasp motionthe hand. The glove is designed to improve the func-e paralyzed hand after spinal-cord injury or strokemplantable devices can restore function after paraly-passing damaged regions of the nervous system, givingts the ability to live with greater independence andtheir quality of life [71].

ciences in the context of highly competitive teams,pancy in performance among competitive athletes issmaller and smaller. Wearing high-tech textiles inf compression garments, smart textiles, and wearableies could help to achieve an advantage over competi-Wearable sensors could enable coaches and athletes toysiological signs and body kinematics during exercisece, to understand how an athletes body responds tond to track improvements in sport performance or howdriver responds during simulated conditions [73,74]. Asuids such as tears, sweat, urine, and blood, wearablesensors have been developed for real-time ambula-toring of sweat. This has enormous implications for theorts and human performance and opens a new eld ofin the clinical setting [75]. Measuring sweat makes ito collect rich information about the physiological con-he subject because sweat contains a matrix of essentialolecules. Sweat analysis is known tobeused to identify

cal disorders such as cystic brosis [76].leading cause of illness and disease and is so perva-

here is an inherent need to be able to supervise stresse over long periods. A real-time personal stress moni-provide subjects with continuous feedback about their

rate vas w

- The aemotintelratiostudiconninteltionare ctensiuresclass

- SuddappaThe edromaneloxygand bpatiepatie(PSGabilitchildearlyopmbootat spdisea

3.2. Lo

The

- Worn Pie

bod[82ear

Ele Arm

asshea

Ch Pyj

dro Sho Gla

cangladesvenpro

Gloactobj

- Impl Mi

mebility to quantify stress levels before andduring trainingto predict stress resistance [77].y to recognize emotions is one of the characteristics ofl intelligence, which is an important aspect of humance. It is well known that too much emotion is bad forhinking; much less well known is that neuro-scienticpatients who have essentially had their emotions dis-reveal that these patients have strong impairments in

t day-to-day functioning, suggesting that too little emo-mpair rational thinking and behaviour. Emotional datated using sensors of physiological signs (facial musclelood volume pressure, skin conductance which meas-tro-dermal activity, Hall effect respiration) to enableion of affect [78].fant death syndrome (SIDS) is a phenomenon in whichy healthy new-borns die during sleep in their cradles.cause is not yet fully understood, whence the term syn-owever, various symptoms can be identied that showdhigh risk for SIDS. Thephysiological signs includeECG,turation in the blood, temperature, breathing rhythm,pressure and should be monitored for risky new-born

For a great number of new-borns, evaluation of theisk for SIDS is performedusing a polysomnographic testdedicated sleep clinic. This test, however, has poor reli-textile-integrated system monitoring vital signs afterwould provide a low-cost, reliable, and easy-to-use

t for potential SIDS as well as recognition of the devel-r progression of diseases at an early stage [79]. A BBAas been developed to supervise vital signs in infantsrisk due to factors such as prematurity, chronic lung

and malformation syndromes [80].

n of sensing technology systems

ing systems can be:

an individual as an accessory:jewelry, wristwatch [81], wristband measuring pulse,

mperature, galvanic skin response (GSR), and EMG dataring [83]. These can also be a necklace, brooch, pin,or belt buckle.ic patch [84] or skin [85].d worn on the back of the upper arm with sensors thatovement, heat ow, near-body ambient temperature,

te, skin temperature, and GSR [86].elt or shirt for measuring vital signs [87].s and shoes for detection of sudden infant death syn-79,80].r monitoring motion or analysing gait [88].with mountable microphones or video cameras thatction as augmented reality glasses for navigation. Thewirelessly provide virtual information to the user,ng local cultural interests, shops, restaurants, and con-transportation near the wearers location, while alsog regular optical correction [89].

for recording hand posture while individuals performs such as eating, dressing, or while they manipulate[90].le, in vivo:rised video camera [91], pills, gastric pressuremeasure-2], gastric pH measurement.

142 M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156

Continuous glucose-monitoring biosensors [93], Continuous implantable renal replacement therapy [54], Gradual, continuous-release implantabledevices fordrugdeliv-

ery [63,64], Implant

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With thsystems hahad to be dResearchersing or to aTwo netwoexample, vimonitoringthat is deplothe wearabsecond netwpletes the includea smsors. A gateand connecto managewireless tecmationcomThese technthat canproAdvanced)is the termcomputing,healthcaremobile devbroadbandthe main pl[101].

3.4. Smart biomedical wearable systems: current status andongoing research

The diversity of applicable elds for SWS corresponds with thes syso smentatry oring timpl

Resea. Bas[81]ropef a wpressrrelaisionist-wlink./rescordpropof adationLife

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spaceompable devices for functional electrical stimulation of[66],for endoscopy [29].

edia devices or systems,mera,one,

d in the users outt as part of clothing [94]:smart textiles act as sensors,mart textiles sense and also react to stimuli from thement, exhibiting both sensor and actuator functions,art textiles adapt their behaviour to particular circum-.d in pieces of object, furniture, or the oor of a

applications use contextual information derived fromsing techniques. The weight of a subject, object posi-

d interaction events on a given surface can be obtained

s deployed on an item such as a cup could detect whenidual is close to the cup [96]. Such a system could assessny times an individual uses his or her preferred items.abits could provide a good measure of the patientss.nder system deployed on an item could remindpeople to take their medication. Pill-bottle capshange colour to indicate that a medication shouldn and could be equipped with ambient technology

system networks

e recent progress in network infrastructure, wirelessve supplanted wired systems, whereas past sensorsirectly connected to a wearable computer by cables.have developed WSNs to embed sensors in cloth-

llow sensors to be worn as accessories by the user.rks are deployed with the objective of monitoring, fortal signs that produce an alert for centralised medicalservices. Therst is awireless body area network (BAN)yed on the body of the patient. This system includes all

le sensors and a PDA as a wearable computer [98]. Theork, the personal area network (PAN) platform, com-

rst systemwireless body area network (WBAN) and canartphonesensor, video sensor, andenvironmental sen-way operates via a wireless wide area network (WAN)ts a distant end-user to a healthcare-monitoring centreall of the assistive services. A wide variety of availablehnologies allow data transmission or long-range infor-municationbetween theSWSand theassistancecentre.ologies include WLAN, GSM, GPRS, UMTS, and WIMAXvideextensivenetworkaccess. Fourth-generation (LTE-are expected to be operational soon [99]. M-healthused to dene unwired e-med, introducing mobilemedical sensors, and communication technologies for[100]. In future cities, satellite networks and ultra-

ices could be deployed and lead to access of ubiquitousconnections, individual mobility and could be used asatform for personal e-health applications and services

variou[102] trepresindustaccordfabric,

3.4.1.3.4.1.1Amonthe Eusists obloodeter cosupervthe wrcationcardiaced acand apsationinform

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Aurgroupis thesocialsonal ctem architectures and components, from wristwatchesart clothing for professionals [43,44]. We have selectedive SWS that have been developed in academia orthat have been commercialised. The SWS are presentedo theirmain features (e.g., electronic components, smartantable).

rch prototypesed onmicrocontroller or other electronic device platforms.is a wearable monitor developed under grants from

an Union FP5 IST program. The wearable monitor con-rist-worn device, which measures skin temperature,ure, SpO2, and one-lead ECG. A two-axis accelerom-tes user mobility with the measured vital signs. In acentre, a physician can analyse data transmitted fromorn device thanks to a GSM-based cellular communi-The aim of the wearable Amon is to enable high-risk

piratory patients to live independently. Data are classi-ing to the risk for serious cardiac/respiratory problemsriate actions are taken by the device, such as initiali-ditional measurements, risk alerts, or transmission ofto an assistance centre.guard system has been developed by a team ofat NASA and Stanford for extreme environments, spacerial conditions. It includes physiological sensors (e.g.,tion electrode patch via impedance plethysmography,SpO2, body temperature, blood pressure monitor andment), a wearable box the size of a cigarette pack, andon where data are sent via Bluetooth. The authors con-ries of validation tests in extreme environments, andfor data transmitted to remote locations with satellitewere acceptably accurate [103].has been developed by theMITMedia Lab for long-termmposed of three major components, a PDA based on arableplatform, a softwarenetworkandresourcediscov-tion program interface (API), and a real-time machineerence architecture. The platform is composed of a 3-Dter, ECG, EMG, and galvanic skin conductance sensorsinterface with a wide range of commercially availablethree-layer software architecture allows communica-en the applications, the distribution and processing ofals, and the implementation of real-time classiers forplications [104].

ble wireless system capable of measuring phonocar-PCG), electrocardiography, and body temperature hasoped in Tainan, Taiwan. The proposed prototype sys-sfully uses Bluetooth technology to invisibly transmitphysical signals through the air. The system consists

or-type microphone inserted on a stethoscope for PCGthree-lead ECG, a temperature sensor, a measuring

ding a CPU, a Bluetooth transceiver, an A/D module andan external memory unit. The PDA controls the systemommands to the measuring circuit [105].has been developed to identify the characteristics of. The system consists of force-sensitive resistors (FSR),ters and gyroscopes. The raw sensor data are processedon algorithms within a microprocessor [106].is the University of Oregons Wearable Computing

plementation of a wearable community. The Auranetork of computing devices that exists in a personsor Aura. The Auranet is where people and their per-

uting devices have face-to-face encounters. Developing

M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156 143

a wearable assistant for those with cognitive impairments (e.g.,traumatic brain injury, dementia), the assistant will have accessto GPS information to track a users location. It will have Internetaccess to alert a caregiver when help is needed. Finally, it will beable to estabitans for ass

The INTmulti-sensorelated disanxiety-relavirtual realirelaxation ecapable of tiological dathey can coanxiety diso

The Aublyse emotiothe face. Aumainly fromfacial pain,and stress awirelessly cconductivitsors placedefcient mesor managebeen condu[109].

A portabdevelopedThe systemphy block,a radio comuser interfausers activimpedance,ration. ActiSpecial attedevice,withproven to belectrodes a

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The Maga textile-basigns. A watile sensorselectronic b

responsible for signal pre-processing and information transmis-sion through Bluetooth to a local PC or PDA. The system includesskin temperature measurements for elderly or cardiac patients athome for daily life HM. The data gathered from the evaluation

howimaltifyibeaBiots toof bog sysandlr of ss forlso bd we

Proetiumsationewnel. Per tors. Thearty, andc gasal temcessangecicand fllection cWi-Fationnd aecteial ofitorxterng thrrmotST Fd inhe garn atoryy throwhicovide13].VTAbed

es sms (e.gUS Aableaps,re,

natesrks [1sVesstemts ellish point-to-point connectionswith local goodSamar-istance [107].REPID project has the objective of developing ar context-awarewearable for the treatment of anxiety-orders and testing its clinical efcacy in reducingted symptoms. The systemusesbiofeedback-enhancedty to facilitate the relaxation process. The virtual realityxperience is strengthened by the use of a mobile phoneracking andvisualising the outpatient setting. Thephys-ta of the patient are recorded by biosensors so thatntrol clinical protocols for the treatment of generalisedrder and during rest conditions [108].ade project is a wearable platform designed to ana-nal states in real time, using signals obtained frombade uses a variety of healthcare-related applicationsthe elds of neurology and psychology. Those include

facial muscle disorders, speech disorders, depressionssessment. The wearable platform includes a mask thatollects and transmits signals (e.g., EMG, heart rate, skiny and respiration rate) obtained from appropriate sen-on the face of the user to centralised systems. It usesthods to process multisensorial signals based on sen-ment and data fusion techniques. Clinical trials havected to study the validity of the wearable platform

le long-term physiological signal recorder has beenat the University of Technology, Tampere, Finland.includes a bio-impedance block, an electrocardiogra-an acceleration sensor, a control and storage device,munication interface, a rechargeable battery and a

ce. The system measures bio-impedance, ECG and theity. The bio-impedance measures dynamic changes inthe main application being to monitor a users respi-

vity is assessed with a three-axis acceleration sensor.ntion has been paid to the power consumption of thethe system functioning24h aday. The systemhas beene operational with both commercial Ag/AgCl gel-pastend custom-made textile electrodes [110].

tems based on smart clothes. MyHeart is a personaltant developed within the framework of the EuropeanResearch Program. The system aims to detect early

ation, enabling prevention and immediate treatmentation. The sensing modules are either integrated intot or simply embedded on a piece of clothing. The under-pt relies on the use of tiny conductive wires knittedyarn, which increases the comfort of the wearable sys-e of the overall system is decreased, the sensors (ECG) do not need wireless modules and the system reliesised wearable power supply. One main device controlsent bus and is responsible for the synchronisation and

supply for all of the wearable components. Associateds been developed to classify activity into resting, lyinging, running, and going up or downstairswith very highhe MyHeart project developed heart belts as well, thatrn across the chest or attached to a standard bra or tond of standard underwear [111].IC project has been developed in Milan, Italy, usingsed system for the unobtrusive measurement of vitalshable, sensorised vest incorporates fully woven tex-for monitoring ECG and respiration rate and a portableoard, which measures the users motion level and is

tests sof maxof idenectopic

Thesensorsitionsensinuid hnumbeSensorhave arespon[75].

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SenThe systudened very good acquired signal quality except in casesphysical activity and that the system is also capable

ng atrial brillation episodes and atrial and ventricularts [112].ex is an EU-funded project that aims to develop textilemeasure physiological signs and the chemical compo-dy uids, with a particular focus on sweat. A wearabletem has been developed that integrates a textile-baseding system for sample collection and transport with aensors including sodium, conductivity, and pH sensors.sweat rate, ECG, respiration, and blood oxygenationeen developed. With the current design, the sensorsll provided that there is an adequate supply of sweat

TEX project nanced by the European Commission, aof 23 European universities, research institutions, andns in the eld of emergency management, has devel-generation of smart garments for emergency-disasterroeTEXGarments include portable sensors and devicescontinuously monitor risks endangering the lives ofe smart systemallowsdetectionof awearers vital signsrate, breathing rate, body temperature, SpO2, position,posture) andenvironmentalparameters (e.g., presence

es, such as carbon monoxide and carbon dioxide (CO2),perature, andheat uxpassing through the garments),

data and remotely transmit useful data to the opera-r. Three ProeTEX prototypes have been built accordingrequirements for law enforcement ofcers as well asorest re-ghters. The core system is an electronic boxs data from the sensors and sends the data to a localoordinator by means of a remote transmission systemi protocol. Software running on the local coordinatorsvisualises the data extracted from information in real-

utomatically activates alarms when dangerous eventsd. The results obtained using ProeTEX systems show thesmart garments developed by the consortium in orderthe vital signs of rescuers and environmental variablesal temperature, presence of toxic gases, and heat uxough the garments) [43,44].h, the Medical Remote Monitoring of Clothes is a Euro-P6 project and part of six other European projectsthe development of smart fabrics and interactive tex-rment includes conductive and electrostrictive fabrics

nd dry electrodes, enabling the measurement of ECG,inductance plethysmography, skin temperature andugh accelerometers. A PDA is connected to amicrocon-h is used as an interface for the sensors on the garment,s an RF link to a local PC for display and assessment of

M project aims at developing generic clothing technol-ding fabric biosensors and bio actuators. The garmentooth, dry ECG electrodes, a GPS receiver, and several., shock/fall, breathing-rate, temperatures) [114].rmy isworking on developing the LandWarrior Systems soldiers to view computer generated graphical dataengages targets at night without exposing soldiers toshares intelligence information and video images, andand synchronises actions with peer groups via mobile15].t was designed for use in the Lab of Tomorrow project.has been developed for use by sciences teachers and

aborating on the users requirements that needed to be

144 M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156

met. It measures, records, and transmits vital signs such as move-ment, energy expenditure, heart rate, and body temperature. Thetrials carried out by students using SensVest proved the wearablesystem to be promising. They were able to carry out activities withno apparendata were r

The Smaless sensorsmonitoringment. The pin the last 4

Mithrilldevelop coMedia Lab. Tbus and boand compua wearabledaily use fuommendati[118].

SmartVeable to monmogram (Pbody tempetion of theusing a RF lwith the gements are cform for traof success whealthy sub

3.4.1.3. Moare involveto constitutUniversity.ing environMicaZ andTlead ECG, Ecommunicacarried bydynamicallAn RF-basecaregivers.

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AMicaZmote-basedplatformhasbeendeveloped at theUniver-sity ofNewSouthWales, Sydney, Australia. The project investigatesthe opportunities and challenges in the use of dynamic radio trans-mit power control for prolonging the life time of body-wearable

devilogi

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er syndenandandte bithath cloian dtionbrableer clationt inhibition to movement and little discomfort, and theeliable [116].rt-Clothing project combines research in textiles, wire-, and actuator networks in the context of human bodywith statistical methods for data analysis and treat-roject aims to aid in themonitoring of foetalmovementweeks of pregnancy [117].is a next-generation research platform aiming to

ntext-aware wearable computing projects at the MITheMithrill architecture includes amulti-protocol body

dy network, integrating a range of sensors, interfaces,ting cores. The aim of Mithrill has been to developsystem using context aware applications, supportingnctions such as recording grocery lists and movie rec-ons, conversational note taking, messaging and e-mail

st hasbeendeveloped inBangalore, India. The system isitor a number of vital signs, such as ECG, photoplethys-PG), heart rate, systolic and diastolic blood pressure;rature and GSR, in a single device without the atten-wearer. The physiological information is transmittedink to a remote monitoring and analysis station alongo-location of the userwhere analysis of all themeasure-arried out in real time and presented in an appropriatensmission. Smart vest prototypes with varying degreesere obtained through clinical validation involving 25

jects [119].

te-based body area network. A wide range of projectsd in the use of motes, or wireless-enabled tiny nodes,e a body area network. CodeBlue is a project at HarvardA sensor network platform for multipatient monitor-ments has been developed based on Zigbee compatibleelosmotes, including sensors for pulse oximetry, three-MG, and mobility activity. The project enables datation between medical sensors, receivers (e.g., PDAsnurses and physicians). Software allows end users toy request information from a specied network node.d localisation system tracks the location of patients andThe system was validated in a 30-node test bed [120].lthcare system has also been developed. u-Healthcare

types of solutions, to effect changes in prevention andmore focused medical care systems, centering on indi-the concept of well-being. The communication layer

i-directional data or command exchange via 802.15.04d code division multiple access (CDMA) to connect ECGpressure sensors to a basic mobile phone device fordisplay and signal feature extraction. As a result, only

ital signs (ECG, blood pressure patterns) are transmit-ospital. This is achieved by rst extracting simple ECGch as QRS duration, RR interval, or R magnitude, andg a decision based on pre-specied criteria. Blood pres-rements are obtained from chest belt and wrist bande project includes the use of accelerometers and SpO21].systemshavebeendeveloped tomeasure ECGs, air andntof the thorax (i.e., thoracic impedance), body temper-ration rate and coughcontrol, bloodpressure, pulse rate,functions, reactive oxygen species (ROS) (i.e., exhaledlactate in breath condensate. The project uses sensorsith the ZigBee compliant Philips AquisGrain platform.ong-term monitoring of chronically ill patients [122].

sensorTechnopatienauthorstrappglucosback anor slowrestricbeneas a mfor hea

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3.4.1.4to idenmost wRFID taimplanVeriChcal proto acceiMed.is uncoaim ofhealthfessionpatientity be[126].

Othindepein Ohiobranesto creaporesthrougquotidplantameasu

Othstimulcesused in continuousHM.MicaZmotes fromCrossbowes have been tested using the device strapped around aest, simulating monitoring of heartbeat and ECG. Theducted several experiments in which the device wasound a patients arm (i.e., for monitoring blood pH andveral applications have been tested, including walkingrth in a room for a fewminutes at a normalwalking paceking, as in the case of an elderly or disabled person withobility, and resting. The system shows the potential

d limitations of adaptive radio transmit power controlof saving energy in body-wearable sensor devices usedre [123].ased vital signs routine monitoring system has beent theNationalUniversity of Singapore. The systemcom-reless mote, amplier circuit board and arterial SpO2able to measure physiological signs in real time withal disturbance to quality of life. The device is easy to

onvenient to use. Using a dock with a ZigBee adapter, acan communicate with the mote and then display theta as well as the heart rate, SpO2 value and the systolicure [124].recovering fromsurgery are at risk of complicationsduemobility as a result of postoperative pain. Continuousof these patients has encouraged research on wirelessnitoring solutions that realise the vision of a wirelesspatient station consists of a mote device that receiveshe sensors recording the vital signs (e.g., ECG, respira-tivity level) and is responsible for the rst stage of dataThe received signals are sent to a central server for anal-alysis is done using moteView software and generatesedical professionals, caretakers and emergencymedicalt personnel [125].

lantable devices. A wide range of devices can be usedpeople and to provide personal information. One of theknown is an implantable identication device (IID), aveloped byVeriChip Corp. thatwas approved for humannby theU.S. Food andDrugAdministration in 2004. Theusually implanted in the upper arm. Authorised medi-onals can use the serial number emitted by a VeriChippatients medical information in a database called Ver-enables rapid retrieval of vital data even if the patientous or unresponsive during a medical emergency. TheChip is to access medical records, but it can have otherapplications as well. Physicians and other medical pro-an use it to access sensitive hospital areas or certainrds. The system may be used to verify a patients iden-erforming a surgical operation or administering a drug

stems enable patients suffering chronic diseases to livetly. An implantable kidney has been developed jointlyCalifornia, USA. The system uses highly efcient mem-cell-based bioreactors. The authors have used MEMSocompatible silicon membranes with nanometer-sizedcan mimic the ltering capacity of the human kidneyning. Between the conventional thrice-weekly and theialysis, this is a third alternative to dialysis and trans-asedondemonstrated technologies, sound science, andmilestones [54].

asses of implantable devices include sensors for nervecapable of alleviating acute pain in patients suffering

M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156 145

from cancer or trembling caused by Parkinsons disease, and torestore the grasp function in tetraplegic patients [127].

An implantable telemetry platform system allows in vivo mon-itoring of physiological parameters. The small size of the electroniccircuitmaktests, e.g., foaccording t

A capsufrom datathe capsulebattery pacgoing capsuleads thatin standardwhich the lmitted by tarray. The cbleeding, ingraphy and[129].

A robustulating blooa pump, a csuggested ftive (PD) codemonstratpotential toarticial paand electrosolution [52

3.4.1.5. Skinsive self-mthrough exiontophoreThe deviceand this haponent wathe techniqtion ux aconstant, bglucose shothat were ncally, despitand metabotitative resuallergies, ththe use of t

Amicrowitor of blooring-resonathe standinopen-termihis thumb awithin a nahas been shsponding totest subjectare eleganting [131]. Aoffered to pbe taught hdevice regusubcutaneotherapeutic

A Danish laboratory has developed a textile-based, wearableelectronic patch that can assess vital signs (e.g., EMG, SpO2, ECG,body temperature) [84].

Electronic second skin has been developed at the Universityconsals actroxibilinkinoxideter

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37].es the system suitable forminimally invasive diagnosticr gastro-oesophageal pressure, pH, glucosemonitoring,o the different sensor used [128].le endoscopy system allows patients to be examinedcollected by the camera. The system is composed of

itself, a portable image receiver/recorder unit andk, and a computer workstation. The patients under-le endoscopy wear an antenna array including eightare connected by wires to the recording unit, wornlocations over the abdomen. The recording device toeads are attached is able to record the images trans-he camera in the capsule and received by the antennaapsule system is useful for diagnosing gastrointestinalammatory bowel diseases, taking small bowel radio-monitoring postsurgical small bowel transplantation

and precisemedical device has been developed for reg-d glucose. It is composed of four subsystems: sensors,ontroller and a power system. An insulin controller isor the prototype device aswell as a proportional deriva-ntroller of insulin secretionby thepancreas. The authorsed through results of their preliminary experiments theachieve robust regulation of blood glucose using the

ncreas. Further improvements on control algorithmsmechanical hardware are needed for a clinically viable].

devices. Glucowatch Biographer is a minimally inva-onitoring system to measure blood glucose levelstraction of transdermal uid. The watch uses reversesis to non-invasively extract glucose across the skin.has to be calibrated with an invasive nger-stick,s been perceived as a disadvantage. The urea com-s extracted simultaneously in an attempt to renderue completely non-invasive. As a result, the extrac-nd concentration of urea both remained relativelyut the normalised, transdermal, iontophoretic ux ofwed inter-individual variability due to mechanismsot entirely governed by electrotransport. More speci-e good qualitative tracking of blood levels, biochemicallic factors, as well as contamination, affect the quan-lts. Due to complaints that the device provoked skine US Food and Drug Administration has since bannedhe device [130].ave sensor has been developed as a non-invasivemon-

d glucose levels. The sensor is based on the microstriptor. The sensor output is an amplitude measurement ofg wave versus frequency sampled at a xed point on annated spiral-shapedmicrostrip line. The patient pressesgainst the line and applies contact pressure that fallsrrow pressure range. A single-spiral microstrip sensorown to exhibit signicant changes in its response corre-changes in the measured blood glucose level of severals. Microwave sensors are robust and economical andsolutions to the problem of non-invasive glucose test-fter being used in hospitals, glucose sensors are nowatients for ambulatory use. The patient, however, mustow to use the glucose sensor properly and wear thelarly. An insulin pump with an integrated continuousus glucose monitoring device improves the patientsmanagement.

of WismateriThe elerior ecalledicon dimicromto the tthen liof theconsistmiddleductorpowerserpensimplyVital simeasuusing tbe collinexpe

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Ansigns,radar.the subadaptirithmthe hea[136,1in. This electronic skin consists of pressure-sensingnd associated electronic devices for pressure readings.nic skin uses thin single-crystal silicon that has supe-ity and mobility properties. Using a printing methodg and printing, a thin silicon layer is bonded to a sil-

e release layer. The silicon layer is cut into a lattice of-scale chiplets, and a transfer stamp layer is attachedf the divided silicon. The transfer layer and chiplets arend transferred to a exible substrate. The support layerronic skin is elastomeric polyester. The circuitry parttwo protection layers that sandwich a multifunctionaler. The middle layer consists of the metal, semicon-insulator components needed for sensors, electronics,lies, and light-emitting components, all of which are inshapes comprising a stretchable net. The system can bented onto or peeled off natural skin like bandage tape.rom heart, brain, and skeletal muscles similar to thoseing bulky electrodes and hardware have been obtainedectronic skin. Other forms of physiological data can alsousing this skin. The system has proved to be viable and[85].

er wearable devices or biosensors. Nanowires and nano-beenused for analytical applications. Themost commonmodication of a bulk electrode such as gold or glassy

trodewith nanowires. They are able to detect biochemi-ents, viruses, etc. in body uids. Carbon nanotube (CNT)been utilised to develop advanced nano- and microde-vel type of cupric oxide (CuO) nanoparticle-modiedd CNT array electrode for sensitive nonenzymatic glu-tion has been developed. CNTs have been used asaterial due to their high surface area, unique structures,ectrical conductivity, ultra-strong mechanical proper-gh stability. The electrode is used to analyse glucoseon in human serum samples, and is promising for thent of nonenzymatic glucose sensors [132].ed sensors have been used to detect viruses. Thesors were assembled using a layer-by-layer techniquethe chemical functionalisation on nanotubes to tai-teractions with viruses and antiviral antibodies [133].hi University of Technology in Japan, a penetrating Siarray, with each probe only a few microns in diam-en developed. Development of the microprobe arraystandard integrated circuit process followed by selec-of silicon (Si) probes based on vapour-liquid-solid

device is used for neural recordings aswell as neuronal[134].me-free glucose sensor prepared by the electrodepo-ld nanowires within an anodic alumina oxide (AAO)nd subsequent transfer of the obtained array onto arate has been developed at Sungkyunkwan Universityectrochemical oxidation of glucose in 0.1M NaOH solu-vestigated using cyclic voltammetry. The voltammetrymetric detection of glucose was explored [135].

native non-contact method to collect cardiopulmonaryding respiration and heartbeat signals, is via Dopplerever, the heartbeat signal cannot be distinguishedwhendoes not hold his or her breath. To resolve the problem,ise cancellationbasedon a recursive-least squares algo-ed that the heartbeat signal can be extracted and thatte is strongly correlated with that derived from the ECG

146 M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156

Advances in low-power and high-performance readout circuitdesign for the acquisition of biopotential signals enable the imple-mentation ofminiaturised and comfortable systems for acquisitionof biopotential signals, such as EEGs, ECGs, and EMGs in the case ofwearable an

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ed ws sysd implantable systems [138]ng pulse oximetry is based on spectral analysis, thend quantication of components in solution by theirt absorption characteristics. A two-LED pulse oxime-o isolate the absorbance of arterial blood componentsf venous blood, connective tissue and other absorbers

cardiac death is a public health issue. A wearable de-automatic external debrillator is frequently used inden cardiac death. Both devices are able to restore sinuspatients with ventricular tachyarrhythmia [141].

ing research on smart biomedical wearable systems inryRShas been conducting research on elderlymonitoringce 1990 [142,143] and has followed the evolution of thent of elderly monitoring systems. Initially, in the 1990s,mportant features in the concept of people-monitorings the study of elderly behaviour and activity usingmon-ems and electronic devices embedded in their homes.pment of monitoring systems was based on a homet where sensors collected spatiotemporal information

an activity [144]. A multisensory monitoring platformeuseof satellite communication to link themedical cen-al institution for retired individuals within the Ourses]. This supervision system operates whenever the sub-in his or her home:

as there are several people in the apartment or in thes and living rooms of the environment, continuous datag is corrupted or interrupted. In new projects (Home-d BA), wearable identication and location systemsen chosen to ensure continuous data collection and thus24-hmonitoring of elderly people [146,147]. These sys-clude identication and location devices in a body areaetwork. InHomecare, awearable electronic tag, such asveloped in a studybyHaahr et al. [84] is used to identifyte the subject. For the BA project, a geographic track-rument worn by the individuals (e.g., elderly sufferingmentia, handicappedpeople) allowsdata collection andnicationwitha centre todetect and report casesofprob-gerous events. The system is composed of a waist belted to a wearable PDA that includes GPS, Wi-Fi locationand software to detect safe areas or deviations fromsplacement trajectories for the subject. In the Respectthe sole of a shoe, as shown in [88], is under develop-he system includes identication and location functionsy sensor area network. Using the Zigbee standard for

s communication systems enables data transmission toe centre that can provide assistance to the wearer.mental stress is perceived as a risk factor for car-

ular diseases [148]. Thus, it can be considered as onet determining an individuals health and self-esteem.frequency may be one parameter related to stress. Thee is to nd states far from equilibrium and to clas-m as stress indicators. Heart rate variability (HRV) isvasive method for measuring and detecting changes infrequency. Moreover, HRV serves as a marker of sym-gal balance of the autonomic nervous system (ANS).perceived mental stress strongly affects ANS homeo-49]. There are numerous papers reporting changes ine to mental stress [150]. Mainly low frequency and high

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E stress index. We have actually introduced two sta-parameters that satisfy our criteria. We have also usedchnologies to create a non-invasive ECG analyser com-a programmable analogue chip and accelerometer toe ECG and human activities. We have used inexpensivercially available off-the-shelf (COTS) accelerometersby microcontrollers with embedded signal processingmsanda smartpowermanagement system. The system/off power consumption and is under patent, ADXL330meters from Analog Devices and LIS3DN accelerome-STMicroelectronics are also used. We have developed

sorswhere the electrodes are in kaptonwithAudepositsystem is based on an amplier designed in our labo-The system communicates with a microcontroller PICicrochip and has been developed under soft electronicsogy.

LAAS-CNRS research is shown in Fig. 1.

ercial productsdia health wear armband is worn on the back ofright arm. This device is an armband composed ofne with an accelerometer, a thermal conductivity sen-and ambient temperature sensor and a skin electricaly sensor. It can also be connected to a wireless heart-. The system focuses on weight management andvement, heat ux, skin temperature, and GSR, allowing

easurements of energy expenditure. It can be connectedoexternal sensors basedonaGSMtransceiver. APCcon-e transceiver records the raw data and transmits it to a[151].ristCare is a wireless wellness monitor which aims to

iquitous computing applications for wellness manage-ome automation. A wrist-worn device monitors skine, skin conductivity and movement [102].rics developed a LifeShirt System to continuously mea-nary, cardiac, and other vital signs. Accelerometers andrespiratory measurement are embedded in an under-nt; an external PDA stores the data and extracts the vital.q Monitor has been developed by WelchAllyn. The sys-arable deviceworn in a carrying pouch. It assesses pulsed up to ve-lead ECG [153]. The SmartShirt developedis designed tomeasure ECG, respiration rate, and bloodis based on conductive smartbres and nanotechnolo-

et is a mobile cardiac patient telemetry system. It moni-nd helps physicians diagnose and support patientsom arrhythmias [155].ics CGMS and Guardian systems are minimallyntinuous blood glucose-level monitoring systems. Abio-sensor needle is inserted under the skin of thend the blood glucose level is assessed from the inter-e uid [156].rini Diagnosticss Glucoday is a portable instrumentith a micropump and a biosensor, coupled to a micro-tem capable of recording the subcutaneous glucose

M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156 147

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Userpreied before aorder to expfactor andthe Technocome to actant featureof elderly ian Australior technoloconsideredattitudes toMoreover, tcapability tand structugen level, Ehumidity, lidevelopmeunderstandconclude thmay need tWSN-basedmore, their[37], researity acceptedand did notConsortium

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3min [157,158]. Abbott Diabetes cares FreeStyleuses a glucose oxidase-based electrochemical sensorrted subcutaneously and measures interstitial glucosef 20500mg/dL every 1min (or 1440 readings a day)

earable systems with the authors, the system descrip-eir applications is presented in Table 4.

issues with wearable systems

eds, perception and acceptance

ferences foruseof SWS in their daily lifeneed tobe stud-ctual use of these devices becomesmorewidespread. Inlore the relationship between the perceived emotions

the use of science technology, Davis [160] developed

changeitoredNew uoped. Ccomplalso notheir cfactoraffectepatienwere rment pequipmpact sipatienpreferrlogy Acceptance Model (TAM) that shows how userscept and use a technology, which is based on impor-s related to the perceptions, concerns and attitudesndividuals towards SWS and their independence. Inan research study, the authors claim that any systemgy that can prolong independence tends to be highlyand accepted. Their ndings indicate that participantswards the idea of WSN for HM are generally positive.he WSN-based systems (i.e., mote systems having theo facilitate the gathering of a range of environmentalral sensory data such as weight, blood sugar, blood oxy-CG information, EEG information, sound, temperature,ght-intensity, vibration and acceleration) are still undernt, and most elderly participants have difculty fullying the benets that motes can provide. The authorsat current acceptance models such as TAM or UTAUTo be extended or modied due to the uniqueness of ahealthcare system designed for elderly users. Further-study is limited to the area of Sydney, Australia [161]. Inchers found that 93% of patients in a geriatric care facil-a wearable system, because it was minimally invasive

interferewith their normal daily life. The EPSRC SMARTpresented a study in which user feedback was used to

professionamance, inspatients anity and peweight of thsors becomrelated hosproviding fthe ngers,ing and plaas issues. Sters on theelectronic deters. Otherthe weightclothing thathe authorslife using wtions with iand that prand testedunobtrusiveacceptanceaboratory.

design of their devices. User preferences were mon-prove prototype devices for training stroke patients.

ssues were identied as the system was being devel-ging a wired version to an unwired one created morestem management and upkeep from the user. It washat user tolerance of certain systemswas reducedwhenence in the devices decreased, with a key condenceg the correct use of the equipment. Data output wered compliance and condence levelswere reducedwhenre unsure how to use the system correctly. Problemsin initial and second prototypes, such as correct gar-ent. The Consortiumdiscovered the properties of their

that needed to be taken into account; namely, com-imple to operate and maintain, and usable by strokeeferably without the help of the caregiver. The userso receive encouraging feedback data, from the health

ls and quantiable, objective data about their perfor-tead of praise from a physiotherapist [162,163]. Bothd practitioners using ECG devices were aware of usabil-rformances issues, including stigmatisation, size ande system, altering normal functional performance, sen-ing unattached from the patient, and the number ofpital visits that were needed [164]. In the case of a gloveunctional electrical stimulation of muscles controllingthe users identied reliability, difculty in manipulat-cing the electrodes, as well as drying out of electrodesome patients found it difcult to set stimulus parame-device. Users who were more familiar with consumerevices seemed to have less trouble setting the param-issues concerned the t of the device on the arm, and

and the size of the system which could limit the type oft the user could wear over the glove [6870]. In [165],study all questions related to improving the quality ofearable systems. They concluded that more investiga-nterviews, questionnaires and experiments are neededototypes should be developed with industrial partnersin real-world, everyday life settings. Easy-to-use andwearable systems couldmore easily contribute to userof these devices in their daily life [166].

148 M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156

Table 4List of wearable systems.

Author System description Applications

Santini et al. [41] Microchip Autonomous controlled release implant (Pharmacy-on-a-chip) orcontrollable tablet (smart tablet) for oral drug delivery

Curone et al. [43,44] ProeTEX smart garment Health-state parameters, environmental variablesKario et al. [45] Multifunctional device Heart rate, physical activityGmez et al. [52] Pumping, controller and power system Insulin controller to achieve regulation of blood glucoseFissel et al. [54] Unique technology toolkit, MEMS system Membrane prototyped for renal replacementOkubo et al. [55] Home care sensor system Respiratory diseasesIslam et al. [58] Wellness monitor Wellness for patients suffering cancerAkay et al. [59] Accelerometer unit Body motion in healthy subjects, patients with Parkinsons disease and

post stroke hemiplegic patientsProchazka et al. [68] Electrical stimulator garment (glove) Controlled grasp and hand opening in quadriplegiaLorussi et al. [69] Strain sensors integrated in garments (gloves, leotards etc.) Hand posture and gesture monitoringNiazmand et al. [70] Sensor based smart glove Parkinsons disease evaluationCoyle et al. [73] Textile-based sensor (Biotex) Measuring sweatKatsis et al. [74] Aubade sensor system EMG, ECG, respiration, skin conductivity (EDR)Jovanov et al. [77] Wireless intelligent sensor system Heart rate variability for stress measuringJourand et al. [79] Wearable textile garment Sudden infant death syndromeRimet et al. [80] Bootee Wearable multiparameter monitorAnliker et al. [81] Amon portable telemedical monitor High-risk cardiac/respiratory patientsWu et al. [83] RFID ring-type pulse sensor, optical sensor Pulse and temperature signals, heart rate measuresHaar et al. [84] Electronic patch EMG, arterial oxygen saturationMa et al. [85] Electronic second skin Antenna, LED, strain gauge, temperature sensor, ECG, EMG, Wireless

power coil, RF coil, RF diodeMiwa et al. [86] Wearable sensor Roll-over detection, sleep qualityLanat et al. [87] Wearable system Several vital signs and physiological variables to determine the

cardiopulmonary activity during emergenciesBamberg et al. [88] Shoe Gait analysisSimone et al. [90] Glove Monitoring and functional hand assessmentBeach et al. [91] In vivo telemetry system Improvement of the function of an implant evaluated in situ, in blood

vessel growth (angiogenesis), reduced inammation, reduction offoreign body encapsulation

Maqbool et al. [92] Smart pill Monitoring system with scintigraphy for measuring whole gut transitChaudhary et al. [93] Biosensor Glucose measuresGiorgino et al. [94] Sensorized cloth Remote monitoring and control of motor rehabilitationVivago [102] Vivago (Wellness monitoring) Vital signsLifeguard [103] Lifeguard cigarette pack size box Physiological signsSung et al. [104] LiveNet mobile platform Accelerometer, ECG, EMG, galvanic skin conductanceChang et al. [105] Portable system PCG, electrocardiography, body temperature, BluetoothJagos et al. [106] Shoe Human gaitAuranet [107] Auranet personal computing devices Cognitive impairmentsRiva et al. [108] Intrepid multi-sensor context-aware wearable AnxietyVuorela et al. [110] Portable signal recorder Electrocardiography, bioimpedance and users activityMyHeart [111] MyHeart clothing Atrial brillation, ECG, activityDi Rienzo et al. [112] MagIC vest Atrial brillation, atrial and ventricular ectopic beat, ECG, respiration

rate, skin temperatureLuprano et al. [113] Mermoth clothes ECG, respiratory inductance plethysmography, skin, temperature,

activityWeber et al. [114] VTAM clothing ECG, GPS, biosensors and bioactuatorsWarrior garment [115] Warrior garment Vital signsKnight et al. [116] SensVest Vital signs: movement, energy expenditure, heart rate, body temperatureBorges et al. [117] Smart-Clothing Fetal movement in the last 4 weeks of the pregnancyMithrill [118] Mithrill Supporting daily use functions: grocery list, messaging, e-mail,

conversational note taking, and movie recommendationsPandian et al. [119] Smart Vest ECG, PPG, heart rate, systolic and diastolic blood pressure,Shnayder et al. [120] CodeBlue mote based system Pulse oximetry, ECG, EMG, mobility activityChung et al. [121] A u-healthcare system ECG, blood pressure patterns transmitted to the hospitalLoew et al. [122] BASUMA Chronically ill patientsXiao et al. [123] MicaZ mote based system Heartbeat, ECG, blood pH, glucose, mobility, walkingGuo et al. [124] BSN based system Vital signsOliver et al. [125] Wireless medical monitoring system Surgery recovering patientsVerichip [126] Verichip Patient identitySchneider et al. [127] Implantable sensor Nerve stimulation capable of alleviating acute pain in patients suffering

cancer or Parkinsons diseaseValdastri et al. [128] Implantable telemetry platform system Gastro oesophagus pressure, pH, glucose monitoringAdler et al. [129] Wireless capsule EndoscopySieg et al. [130] Glucowatch Biographer Blood glucose measureJean et al. [131] Microwave sensor Blood glucose measureJiang et al. [132] Carbon nanotube electrode Glucose concentration in human serumBhattacharya et al. [133] Carbon nanotube based sensor Detection of virusesKawano et al. [134] Si microprobe electrode Neural recording, stimulation of neuronsCherevko et al. [135] Gold nanowire array electrode Glucose detectionLu et al. [136] Doppler radar system Heartbeat measuresMorgan et al. [137] Doppler radar system Cardiopulmonary sensingYazicioglu et al. [138] Ultra-low-power biopotential interfaces EEG measureHayes et al. [140] Probe Pulse oximetry, Photoplethysmographic signal or blood volume pulseLee et al. [141] Wearable or automatic debrillator Sudden cardiac death

M. Chan et al. / Articial Intelligence in Medicine 56 (2012) 137156 149

Table 4 (Continued)

Author System description Applications

Bourennane et al. [147] Identication, location Dangerous events detectionBodymedia [151] Bodymedia health wear armband Vital signsVivometrics Vital sWelchAllyn PulseSensatex [15 Vital sCardionet [1 CardiaMedtronic [1 Gluco

HypoPoscia et al. SubcuDirecNet [15 Inters

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ofmedical issues and therapeutic effectiveness, there isnce regarding telemonitoring using WHMS. In [35], theim that home telemonitoring requires the active par-f the patients. It allows for closer monitoring of eachalth condition, as well as early detection of warningpatients health is deteriorating. Their ndings suggestglycaemic, asthma, and blood pressure control are pos-ver, larger randomised trials are needed to conrm thearding hospitalisations, quality of life, functional capac-nitoring ability and to thoroughly test the efcacyof thisin home monitoring in the context of patients suffer-ilure. In [48], the authors include therapeutic effects,fciencies in health services, and technical usability. Inimplantable biosensors, the reliability is often under-ctors like bio-fouling, material-tissue interaction thatsensor implantation that is one of the major obstacles

ng viable, long-term implantable biosensors [167,168],body response [169] in addition to sensordrifts and lackl resolution [170]. Sensors provide excellent temporalresolution for in vivo monitoring. Advances in applica-asure catecholamines, indoleamines, and amino acidsimportant. Improvements in stability, sensitivity, andf the sensors have been of paramount interest [171].es of interventions were found to be therapeuticallyprogrammes for patients suffering from chronic heart], those needing control of respiratory conditions [173],s with diabetes, heart diseases and chronic obstructivedisease [174]. Both wearable debrillators and exter-tic debrillators have been shown in a small series ofhighly effective at restoring sinus rhythms in patientscular tachyarrhythmia. Most patients enrolled in a trialecied safety and effectiveness guidelines had been5% of debrillation attempts being successful. Only aopriate shock episodes occurred and few deaths (12)ring the study, none of these patients died while cor-ing the device (6 nonsudden deaths, 5 sudden deathspatients not wearing the device and 1 sudden deatha patient who reversed the leads [175].

Reporthave bing dawith th

4.4. H

Thefor useand intcoatedfor proMoreocontactime, tSomedofmoncollectmeasuthat thtic banand thenoughnals, essubjecthe subwhelmestimaof theence, athe oxsuchasapproato motmograprocesartefacsuperiand widevicemainteerability

e medical devices such as blood pressure monitors,ters, pulse oximeters, ECG monitors, and implantablelar electronic devices are essential to healthcare. Inter-devices will increase if clinical software applicationsssly collect the medical data. Industry has alreadya viable format for clinical applications. The solutionvolves bilateral mappings from the ISO/IEEE 11073rmationModel (DIM) toHL7PersonalHealthMonitoring

or systems.formance. Edue to medeters (e.g.,interferenclifecycle ofincident repgation, lackdevices, anpoor maintignsoximetry, ECGignsc patient telemetry systemse concentration variationand hyper glucose concentration measurementtaneous glucose level measurementstitial glucose measurements

R) document format [176]. Some wearable prototypesto use PHMRdraft standard to store and transmit train-health professionals and to maximise interoperabilitynformation systems [177].

are and software

htofwearabledevices is oneof the causesof discomfort78]. Other discomfort could be caused by displacementptionofmonitoring systemsdue to electrodesusing gel-esive pads. The patients have to wear a bul