Chemoreceptive Neuron MOS (C MOS) Transistors for Environmental Monitoring: Detection in Fluid and...

Chemoreceptive Neuron MOS Chemoreceptive Neuron MOS (C(CMOS) TransistorsMOS) Transistors

for Environmental Monitoring:for Environmental Monitoring: Detection in Fluid and Gas AmbientsDetection in Fluid and Gas Ambients with with Field Programmability and High ReliabilityField Programmability and High Reliability

Edwin C. KanEdwin C. KanSchool of Electrical and Computer EngineeringSchool of Electrical and Computer Engineering

Cornell UniversityCornell University

RD83

22

MotivationMotivation• Silicon-based autonomous

microsystem Sensing abilityCommunicationComputationControl/memory unitsActuation capability Power self-sufficient Ease of manufacture

33

OutlineOutline• CMOS OverviewWhy – Review of literatureWhat – CMOS device structureHow – Device operation

Conclusion

Sensors Fluid ambient (Na+, K+ , Ca2+, BSA and

SDS) Gas ambient (CO2) Readout circuits

Actuators

44

Literature Review (1/3)Literature Review (1/3)

• FET-based (Bergveld 1970)Materials in

contact with silicon oxide

pH sensitiveMany spin-offs

P. Bergveld, Sensors and Actuators B 88, 1 (2003).

ChemFETENFET

(Enzyme) IMMUNOFET

55

Tune resistivity in the sensing scheme

Gardner (1991)Lewis (1996):

electronic noseAdvantage:

sensitivity from tunneling distance modulation

Resistive-based


66

Grimshaw (1990) Lang (1999)


Yamamoto (1987) Steiner (1995)

Chemomechanical

Chemicapacitive

SAW-IDT (Inter-Digital Transducers)Wenzel (1990) Nakamoto (1991)

Dong, et al., Sensors and Actuators B76, 130 (2001).

77

Why CWhy CMOS?MOS?• Integrated device structure for sensors

• Enhancement of DOFs in sensing

• Ease of integration with current CMOS technology

• Charge-based operation to reduce power consumption

• Potential for sensor-array application

• Possibility to integrated sensors and actuators with the same structure

88

CCMOS ObjectivesMOS Objectives

• High sensitivity

• High selectivity

• Reproducibility, stability and reliability

• Simple calibration and reset protocols

• Field reconfigurability

• Versatile transient measurement

• Low power consumption in the system

• Low manufacturing cost

99

CCMOS Device StructureMOS Device Structure

• Extended floating gate

MOSFETMOSFET

Only one sensing gate is used at the current stage

Drain

Floating Gate

Control Gate

Source

Insulation Structure

Sensing Gates

1010

Polymer-Coating ParametersPolymer-Coating Parameters

Polymer Coating SolutionMolecular Weight

poly(vinyl acetate) 20 mg in 10 mL Tetrahydrofuran 90,000

poly(vinyl butyral) 20 mg in 10 mL Tetrahydrofuran 100,000150,000

poly(ethylene -co- vinyl acetate) 100 mg in 10 mL Benzene 72:28 (wt.)

poly(vinyl chloride) 20 mg in 10 mL Tetrahydrofuran 110,000

Polymer CoatingThickness

(nm)Roughness

Ra (nm)Roughness

Rq (nm)

poly(vinyl acetate) 50 64 88

poly(vinyl butyral) 25 20 27

poly(ethylene -co- vinyl acetate) 30 2 2

poly(vinyl chloride) 30 8 13

1111

Dip-Pen TechnologyDip-Pen Technology

D. Piner, J. Zhu, F. Xu, and S. Hong, C. A. Mirkin, Science 283, 661 (1999).

Molecules delivered from the AFM tip to solid substrate via capillary transport

30-nm linewidth resolution

• For smaller sensing gates

1212

Microfluidic ChannelsMicrofluidic Channels

• Close-up views

Contact Openings

Channels

Fluid Delivery Opening

Channel

Devices

ProbesContact Pads

Contact Openings: Epoxy 907 @ 60 °C for 2 hours

1313

OutlineOutline

• Development of the chemoreceptive neuron MOS (CMOS) trasistorsDevice operations and results

Sensors Actuators

1414

Device OperationDevice Operation• Record initial device I-V characteristics

• Apply polymer coating and insulation elastomer

• Deliver fluid to the microfluidic channel (base buffer, electrolytes, or buffer loaded with protein molecules)

• Observe and record changes in threshold voltages (Vt)

and subthreshold slopes (S): extract CSG and OHP

• Electron-tunneling operation: apply bias (30V or -30V for 50 seconds) at the control gate

• Observe and record Vt and S

• Perform cleansing steps (e.g. rinsing, N2 drying)

• Re-align insulation layer and repeat I-V measurements

1515

Phenomena at the InterfacePhenomena at the Interface• GCS model

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Solid/Liquid Interface

IHP OHP

Diffuse Layer

Specifically Adsorbed Ion

Solvated Ions

-

-

-

+

+

+

+

+

+

+

+

+

Solvent molecule

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Solid/Liquid Interface

IHP OHP

Diffuse Layer


Solvated Ions

--

--

--

++

++

++

++

++

++

++

++

++

Solvent molecule

Double-layer capacitanceDouble-layer capacitance

CCHH: Helmholtz-plane capacitance: Helmholtz-plane capacitance

CCDIFDIF: Diffuse-layer capacitance: Diffuse-layer capacitance

zz: magnitude of the charge on the ions: magnitude of the charge on the ionsnn: concentration of the ions : concentration of the ions OHPOHP: potential at the OHP: potential at the OHP

DIFHEDL CCC

111

dAx

CSGA

OHP

rH

0

0

SGAOHPr

DIF dAkT

zq

kT

nqzC

0

21220

2cosh

2

xxOHPOHP: dist. between : dist. between

Helmholtz planesHelmholtz planes

1616

Capacitive-Divider ModelCapacitive-Divider Model

)(0TDTSTFG UVUVUV eeeII

Subthreshold Subthreshold current modelcurrent model

SlopeSlope

SGCGgdgsbdepoxT CCCCCCCC )//( Changed by fluidsChanged by fluids

D

T

gd

S

T

gs

T

T VC

CV

C

C

C

QV

Above-threshold Above-threshold voltage-shift modelvoltage-shift model

SG

T

SGCG

T

CGD

T

gd

S

T

gs

T

FG VC

CV

C

CV

C

CV

C

C

C

QV

)( depoxox CCC

EDL capacitanceCCG

VCG

CSGCox

Cdepl

Cgd

VD

Cgd

VD

Cgs

VS

Cgs

VS

Cb

QVFG

1717

Sample IV IllustrationSample IV Illustration

1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

1E-04

1E-03

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

Control Gate Voltage (V)

Dra

in C

urre

nt (A

)

W channelW DI waterW elec. outW 72 hours

Sc

Sm

So

10-3

10-4

10-5

10-6

10-7

10-8

10-9

10-10

10-11

10-12

10-13

Dra

in C

urre

nt (

A)

10-3

10-4

10-5

10-6

10-7

10-8

10-9

10-10

10-11

10-12

10-13

Dra

in C

urre

nt (

A)

DI Water on Polysilicon

St

2

1

3

cc : after applying : after applying insulation elastomer insulation elastomer with microfluidic with microfluidic channelschannels

mm : after delivering : after delivering the sample fluidthe sample fluid

oo : after tunneling : after tunneling electrons out of the electrons out of the floating gatefloating gate

tt : after cleansing : after cleansing steps and a period of steps and a period of time in the dry box time in the dry box with constant Nwith constant N22 flow flow

Notations:Notations:

1818

Sensing-Gate ResponsesSensing-Gate Responses• Influence from the fluid Induce image charge at the extended floating gate Modify series capacitance to the sensing gate Affect floating-gate potential and total capacitive load;

create distinctive threshold-voltage shifts and subthreshold-slope variations

• Capacitance indication Collect information via capacitive coupling from the fluid

bulk to the extended floating-gate structure Detect variations before and after electron-tunneling

operations

1919

Subthreshold SlopesSubthreshold Slopes

)(0TDTSTFG UVUVUV eeeII

SG

T

SGCG

T

CGD

T

gd

S

T

gs

T

FG VC

CV

C

CV

C

CV

C

C

C

QV

CG

TT

C

CUS

10ln

1

10 )(log

CGV

IS

SGCGgdgsbdepoxT CCCCCCCC )//(

1E-13

1E-12

1E-11

1E-10

1E-09

1E-08

1E-07

1E-06

1E-05

1E-04

1E-03

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

Control Gate Voltage (V)

Dra

in C

urre

nt (A

)

W channelW DI waterW elec. outW 72 hours

Sc

Sm

So

10-3

10-4

10-5

10-6

10-7

10-8

10-9

10-10

10-11

10-12

10-13

Dra

in C

urre

nt (

A)

10-3

10-4

10-5

10-6

10-7

10-8

10-9

10-10

10-11

10-12

10-13

Dra

in C

urre

nt (

A)

DI Water on Polysilicon

St

2

1

3

Extraction Extraction of of S S valuesvalues

2020

Data AnalysesData Analyses• Extraction of subthreshold slopes from the

measured I-V recordings• Direct estimation of sensing-gate

capacitance (CSG), eliminating control-gate capacitance (CCG) variation

pprSGrr

SG CCCS

SC

1

1

10lnTU

CGT CSC

SGCGpT CCCC

gdgsbdepoxp CCCCCC )//(

2121

Reference Reference SSrr

Notations:Notations:

5 mM KCl d1r d1c d1m d1i d1t d2r d2c d2m d2i d2t

polysilicon 148 177 553 728 166 200 213 771 1019 217

poly(vinyl acetate) 187 198 270 272 194 284 296 435 455 293

poly(vinyl butyral) 228 231 687 985 228 160 176 663 830 165

poly(ethylene -co- vinyl acetate)

163 197 673 711 180 156 183 575 668 166

poly(vinyl chloride) 288 301 469 491 279 212 215 1164 1308 219

d1, d2 d1, d2 : device 1, device 2: device 1, device 2

r r : initial reference: initial reference

c c : after channel formation: after channel formation

m m : after fluid delivery: after fluid delivery

ii : electron tunneling in, 30 V, 50 s. : electron tunneling in, 30 V, 50 s.

t t : recordings after cleansing steps : recordings after cleansing steps and a period of time in the dry boxand a period of time in the dry box

Normalization required to get Normalization required to get rid of the fabrication variation rid of the fabrication variation

2222

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

1 2 3

Sample Fluids

d1i-

m N

orm

polysiliconpoly(vinyl acetate)poly(vinyl butyral)poly(ethylene -co- vinyl acetate)poly(vinyl chloride)

DI water 0.005M NaCl 0.005M KCl

After electron tunneling

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

1 2 3

Sample Fluids

d1m

-c N

orm


DI water 0.005M NaCl 0.005M KCl

Before electron tunneling

Normalized Normalized CCSGSG

Before electron injectionBefore electron injection After electron injectionAfter electron injection

““Discernible patterns”Discernible patterns”

CS

G

CS

G

Variation by polymers Variation by polymers Difference between fluidsDifference between fluids

(√)(√)

(X)(X)

2323

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1 2 3

Sample Fluids

Sel.

01 d

2i-m

Nor

m


Mixture 0.5M NaCl 0.05M KCl0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

1 2 3

Sample Fluids

Sel.

01 d

2m-c

Nor

m


Mixture 0.5M NaCl 0.05M KCl

Selectivity Demonstration (1/2)Selectivity Demonstration (1/2)

Before electron injectionBefore electron injection

““Difference not obvious”Difference not obvious”

After electron injectionAfter electron injection

““Discernible patterns”Discernible patterns”

Mixture contains both solutions in corresponding concentrationMixture contains both solutions in corresponding concentrationC

SG

CS

G

2424

Selectivity Demonstration (2/2)Selectivity Demonstration (2/2)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1 2 3

Sample Fluids

Sel

. 01

d2i-

m N

orm


Mixture 0.5M NaCl 0.05M KCl

CS

G

Additive or subtractive responses in the sensor-array plots

• Sensor-array plots

0.0

2.51

2

34

5

Mixture

0.5 M NaCl

0.05 M KCl

2525

Double-Layer Parameters (1/3)Double-Layer Parameters (1/3)

Cdif

(F/cm2)DI

Water

NaCl Solution KCl Solution

50 0.005M 0.05M 0.5M 50 0.005M 0.05M0.5M

polysilicon 6.4 7.0 7.5 19.3 26.0 5.7 4.9 4.0 4.0

poly(vinyl acetate) 20.1 1.7 7.5 8.3 114.5 6.6 7.6 74.6 15.0

poly(vinyl butyral) 1.8 6.0 13.2 16.4 33.6 4.8 4.3 3.3 4.0

poly(ethylene -co- vinyl acetate)

1.2 8.9 67.7 105.1 9.9 9.0 0.9 1.3 2.3

poly(vinyl chloride) 1.1 2.1 3.2 8.3 20.6 0.4 2.4 26.6 14.9

Cdif from extracted S

pprSGrr

SG CCCS

SC

1

1

10lnTU

CG

TT

C

CUS

10ln

2626

Double-Layer Parameters (2/3)Double-Layer Parameters (2/3)• Extracted OHP (before elec. injection)

Nernst Equation

0

50

100

150

200

250

300

350

400

0 1 2 3 4 5

Concentration

d2 P

hi_O

HP

(m

V)

Slope ~ 60 mV/decadeSlope ~ 60 mV/decade

50M 0.005M 0.05M 0.5M500M

OH

P(m

V)

for

d2

DI water

NaCl on 5 surfacesKCl on 5 surfacesDI Water on 5 surfaces

NaCl on 5 surfacesKCl on 5 surfacesDI Water on 5 surfaces

Rd

Ox

C

C

nF

RTEE ln0

RdneOx RT/F = kT/q

~ 25.9 mV at room temp.

OHP decreases at ~ 60 mV/dec. with increases in concentration

2727

Double-Layer Parameters (3/3)Double-Layer Parameters (3/3)

0

20

40

60

80

100

120

0 1 2 3 4 5

Concentration

d1 D

Phi_

OH

P (m

V)

NaCl

KCl

DI Water

50M 0.005M 0.05M 0.5M500MDI water

Surface: Polysilicon

Increasing along concentration

O

HP

(mV

)

d1

0

20

40

60

80

100

120

0 1 2 3 4 5

Concentrationd2

DPh

i_O

HP

(mV

)

NaCl

KCl

DI Water

50M 0.005M 0.05M 0.5M500MDI water

Surface: Poly(vinyl butyral)

O

HP

(mV

)

d2 Increasing along

concentration

The change of the The change of the OHPOHP

increases with increasing increases with increasing concentration in NaClconcentration in NaCl

For KCl solution, no For KCl solution, no significant increasing trend significant increasing trend

is observed as in NaClis observed as in NaCl

OHP (after electron injection)

Surface: Polysilicon Surface: Poly(vinyl butyral)

2828

Detection in Gas AmbientsDetection in Gas Ambients

2929

Gate Voltage (V)

-10 -5 0 5 10

Dra

in C

urr

ent

(A)

10-14

10-13

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

SDS (Uncharged)SDS (Charged)BSA (Uncharged)BSA (Charged)Lysozyme (Uncharged)Lysozyme (Charged)

Protein SensingProtein Sensing

BSA: bovine serum albumin SDS: sodium dodecyl sulfate

3030

CMOS Circuit CMOS Circuit IntegrationIntegration

CG1

TT

/

/

CG1

TTd

10

1

12s

Lin

sHin

C

CUlnS

e

eln

C

CUV

II

II

MOSIS AMI foundry fabrication (April 2004)

Current mirrors

DC bias current for power/freq tradeoffs

Sample and hold

Control/clock

Vd readout

Vs readout

3131

Sample-and-Hold Control SignalSample-and-Hold Control Signal

Control signal for sample and hold in the readout circuits (monitoring signals from measurement)

3232

Readout CalibrationReadout Calibration

Quasi-static operations with reliable resets

3333

Readout ChannelReadout Channel

3434

OutlineOutline

• Development of the chemoreceptive neuron MOS (CMOS) trasistorsDevice operations and results

Sensors Actuators

3535

Electrowetting ActuationElectrowetting Actuation

• Conventional approach – the change of surface tension at the solid-liquid interface by directly applying different voltages

• Young’s equation

• Lippman’s equation

cosgssg

200 2VV

Cedlslsl

2

0lg

0 2cosarccos VV

Cedl

lg

s

gsl

sgsl

lgLiquid Air Solid

3636

Device StructuresDevice Structures

Microfluidic channel only Microfluidic channel only partially covered to avoid air partially covered to avoid air pressure against actuation pressure against actuation

Transparent elastomer layer Transparent elastomer layer provides easy observation provides easy observation of the saline-water actuationof the saline-water actuation

Device Type 1

Insulation elastomer layer

Silicon substrate

Extended floating gate

Field oxide

Actuation surface layer

Channel oxide

Reference voltage

Control oxide

Device Type 2

Silicon substrate

Active area

Control oxide

Field oxide

Channel oxide Actuation

surface

Extended floating gate

Insulation elastomer layer

3737

Equilibrium in the ChannelEquilibrium in the Channel

- - - - - - - - -- - - - - - - - -- - - - - - - - -- - - - - - - - -InterfaceIHP

OHP

Diffuse Layer


Solvated Ions

-- ---

++ ++ ++ ++++

++ ++

++++

Solvent molecule

- - - - - - - - -- - - - - - - - -- - - - - - - - -- - - - - - - - -InterfaceIHP

OHP ++ ++ ++ ++++

-- - --- --

sg

Air

Solid

lg

sl

Solid

Liquid

3838

Actuation SchemeActuation Scheme

Fluid Reservoir

Fluid Reservoir

Aligned insulation elastomer layer

Source

Drain

Control gates

to Vref

Floating-gate extension

Drain

Source

Source

Drain

Drain

SourceControl gates

3939

Result IllustrationsResult Illustrations

Liquid front advances about Liquid front advances about 10 10 m after electrons are m after electrons are tunneled to the floating gate tunneled to the floating gate

Less change in equilibrium Less change in equilibrium liquid length for the wider liquid length for the wider channel after actuationchannel after actuation

Device Type 2 Beforeelectron injection

Afterelectron injection

Embedded active area for reference voltage

Actuation surface

10m

Trapped air bubble

~5m

Floating gate underneath actuation surface

Channel width

Metal connection to reference voltage

Device #1

~10mLiquid front

advancingEmpty channel segment (no liquid)

Before electron injection

After electron injection

20m

Type 1

4040

Control ExperimentsControl Experiments

connection to ground

connection to ramping voltage

Channel width

20m

~10m

Liquid front advancing

Control test #1

Control test #2

Initial condition After 30 minutes

Unaltered liquid front

Asymmetrical liquid-front Asymmetrical liquid-front advancing by directly advancing by directly sweeping external voltages sweeping external voltages

Equilibrium length of the Equilibrium length of the liquid almost unchanged liquid almost unchanged after 30 minutesafter 30 minutes

4141

Electrowetting on CElectrowetting on CMOSMOS• Modification of interfacial charges results in the

change in solid-liquid interfacial tension and hence the equilibrium length of the liquid in the microfluidic channel

• Potential for integration with the CMOS sensors and conventional CMOS circuitry for fluid delivery

• Air-trapping considerations for further device designs in microfluidic application

• No actuation observed for KCl solution; results agree with OHP after elec. injection

4242

Selective to Buffer SpeciesSelective to Buffer Species

0

20

40

60

80

100

120

0 1 2 3 4 5

Concentration

d1 D

Phi_

OH

P (m

V)

NaCl

KCl

DI Water

50M 0.005M 0.05M 0.5M500MDI water

Surface: Polysilicon

Increasing along concentration

O

HP

(mV

)

d1

0

20

40

60

80

100

120

0 1 2 3 4 5

Concentrationd2

DPh

i_O

HP

(mV

)

NaCl

KCl

DI Water

50M 0.005M 0.05M 0.5M500MDI water

Surface: Poly(vinyl butyral)

O

HP

(mV

)

d2 Increasing along

concentration

The change of the The change of the OHPOHP

increases with increasing increases with increasing concentration in NaClconcentration in NaCl

For KCl solution, no For KCl solution, no significant increasing trend significant increasing trend

is observed as in NaClis observed as in NaCl

OHP (after electron injection)Surface: Polysilicon Surface: Poly(vinyl

butyral)

4343

Smart Sensors and ActuatorsSmart Sensors and Actuators

A

A

AS S

S SS

Applicable surface coatings on sensors and/or actuators

A

A

AS S

S SS

Applicable surface coatings on sensors and/or actuators

Controlled fluid delivery for more reliable sensing

Analysis/feedback circuitry from CMOS to provide fluid information (variety, position, etc.)

Various surface coatings individually applied on sensors and/or actuators

4444

OutlineOutline

• Development of the chemoreceptive neuron MOS (CMOS) trasistors

• Summary and future directions

Why – Review of literatureWhat – CMOS device structureHow – Device operation

SensorsActuators

4545

Summary (1/2)Summary (1/2)

• FET devices with extended floating gates for chemical sensing

• Floating-gate structure for electron-tunneling operations provides more DOFs for sensing

• Indicators from I-V characteristics: Subthreshold slopes (S) and threshold voltages (Vt)

• CMOS integration enables detailed control circuits

4646

Summary (2/2)Summary (2/2)

• Normalized CSG in the polymeric responses directly couples to subthreshold slopes and the patterns encourage sensor-array application in the lock-and-key implementation

• Electrowetting actuator for potential microvalves integrated with the sensors and conventional CMOS circuitry for fluid delivery and confinement

Chemoreceptive Neuron MOS (C MOS) Transistors for Environmental Monitoring: Detection in Fluid and...

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Transcript of Chemoreceptive Neuron MOS (C MOS) Transistors for Environmental Monitoring: Detection in Fluid and...