Disposable Mattress Cover with Conductive Threads to Detect

Wetness using Resistance Comparison

ECE 4884 L03Advisor: Dr.

Koblasz

Team Members:Ankit HemaniJacob HuangYuval Rooz

Heonwoo SongSarju Vasavada

Motivation• 2 million cases of nosocomial (hospital-

acquired) infections annually (CDC)• Wet bedsheets increase risk of infection

Design Objectives• Use biodegradable plastic and paper• Stitching conductive threads on the

paper to detect wetness• Design a detection unit• Detect a break in the circuit• Detect wetness• Isolate electrical circuitry from

patient

Cost AnalysisItem PricePaper $0.65Thread $0.80Biodegradable Polyethylene $0.20Mattress Cover per unit cost $1.85

I.C.s $4.17Circuit board $4.99Encasing Box $6.99RS-232, Power jacks $10.00AC/DC Adapter $13.87Fuse, Fuse Holder $3.40Resistors, Capacitors, LED, Wires < $1.00Detection Unit cost $43.42

Layout Of Mattress Cover On Hospital Bed

Source: http://www.ponsishoes.com/products.asp

Mattress Cover Construction

• Plastic attached to paper using adhesive

• Plastic on the bottom side, paper on the top

Conductive Thread Stitching

• Conductive threads laid out on paper in two loops, of 40 ft each

• Regular threads used to stitch conductive threads on paper

Power Supply

12V AC/DC Adapter

+ TransformerFuse 9V

Regulator

• Transformer and fuse used to protect against voltage spikes

Detection Unit

Reading from mattress cover

Continuitydetection

Wetnessdetection

Opto-isolator Output

Detection Unit Schematic

Communication between Pad and Detection Unit

• Plastic clip• Four metal pads contact the

conductive loop on sheet• Wires soldered to pads connect the

clip to the detection unit

Modifications to Proposed ItemsProposed Designed Reason

Silver Thread Stainless steel More conductive

Battery Wall Outlet Cumbersome

Two Outputs One Output No need for two

Phone-jack Plastic clip Faster attachment

- Opto-isolator Safety

Current Status• Stitched a paper bedsheet (has

discontinuities)• Tested unit with a cotton bedsheet• Stitched a (non-working) paper bedsheet• Built detection unit• Designed a prototype connector

Steps for Marketable Product

• Include clip in connector• Casing for detection unit• Investigate cheaper conductive threads• Implement with full-size hospital

bedsheet nor biodegradable polyethylene

• Optimize resistances in detection unit

• If time allows, video of a project demonstration

Video

Any Questions?