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Epidermal Sensor Systems for Sensing and Therapy

IEEE Central Texas Consultants Network Meeting

May 25, 2016

New Modality for Wearable Electronics

Pulin Wang, Ph.D., M.S.T.C.Cofounder and CEO

Stretch Med, Inc.

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Wearable Health Monitoring Devices

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$3,040 MM

Wearable Device Market

2013 2014 2019

$ Millions

Global Market for Wearable Health and Fitness

Monitoring Devices(Source: BCC research report, 2015)

43% Compound

Annual Growth Rate

$1,041 MM

$18,430 MM

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1. Mobile Health

2. Human-Machine Interface

Applications of Skin-Mounted Sensors

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Challenges for Heart Rate Monitors

Iyriboz, Y., et. al., British Journal of Sports Medicine, 25, 162 (1991)

Pulse oximetry: used in

all smartwatches

ECG: gold standard for

heart rate measurement

Oximetry fails

above 150

heart rate

Quotes from customer feedbacks on Amazon.com

• Need to wet the strap

• Restrict chest movement

• Cause skin irritation

“Works great - if you “Lick it

like a Dog...””

“Slips when it gets to wet.”

“Chafes, doesn't work

reliably.”

Inaccurate Uncomfortable

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When Bio Meets Electronics

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Skin vs. Silicon

ESi = 130 x 109 PaESkin = 130 x 103 Pa

Credit: IntelCredit: ICTGraphicsLab @ USC

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Flexible Electronics

Sony, 2007

PolyIC, 2006

Rogers, UIUC, 2008 Lumalive, Philips, 2010

Someya, U of Tokyo, 2005PowerFilm, 2004

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Science 333, 838 (2011). Nature Materials 10, 316 (2011).

Epidermal Electronics Balloon Catheter Heart “Sock”

Nature Comm. 5, 3329 (2014).

PNAS 108, 1788 (2010).

Tunable Electronic

Eyeball

Nature Materials 9, 929 (2010).

Conformal LEDStretchable Transistors

Science 321, 1468 (2008).

Stretchable Electronics

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Strategies for Stretchable Electronics

Out-of-Plane Buckling

Nat. Nanotech. 1, 201 (2006) PNAS 105, 18675 (2008)

In-Plane Serpentines

Nat. Comm. 4, 1543 (2008) Adv. Mat. 25, 2773 (2012)

Island + serpentineFilamentary

serpentineFractal serpentine

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e = 100%

3cm

1.04%

0.01%

0.61%

Experiment Numerical Simulation

3cme = 40%

0.28%

-0.02%

0.13%

e = 30%

3cm

0.36%

0.00%

0.18%

Stretchable Structure - Serpentine

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Rigid wafer

PI precursor

Flexible

substrate

SOI

PDMS Stamp

Doped Si nanomembranePI

Au

Si PI

Microfabrication of Stretchable Electronics

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Au

Ecoflex

PI

30µm

1.4µm

1mm

Compliance of Filamentary Serpentines

Strain (%)0 5 10 15 20 25 30

Str

ess (

kP

a)

0

30

60

90skin: 160 kPay: 150 kPax: 130 kPaFEM x FEM y

Ecoflex

0.5mm

EP sensorx

y

Au

Ecoflex

PI

30µm

0.5µm

Kim*, Lu*, Ma* (*equal contribution), Rogers, et al., Science 333, 838, (2011).

0.15%

0.05%

0%

0.1%

exx=30%

e yy=

30%

e

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Stretchability & Cycleability

0 50 100 150 2000

2

4

6AlAu RTDEPCoil

R/R

0

Applied Strain (%)

5 mm0% 30% 90% 199%

0% 30% 90%

30% 90%

115%

68%

2

mm

a

b0%

c

Coil

EP

RTD1 10 100 1000 10000

-2

0

2

4

6

8e= 20%

e= 30%

R

/R0 (

%)

Number of Cycles

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Multi-Functionality

antenna LED

wireless power coil RF coil

temp. sensorstrain gauge

RF diode ECG/EMG sensor

0.5mm

Kim*, Lu*, Ma* (*equal contribution), Rogers, et al., Science 333, 838, (2011).

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Apps

Amplifie

r

LED Solar Cell

T Sensor e

Gauge

L Coil

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Mounting and Removal of Epidermal

Electronics

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Epidermal Electronics on A Skin Replica

Yeo, Rogers, et al, Advanced Materials 25, 2773–2778 (2013).

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Why Is Conformability Important?

Fully-Conformal (FC)

Non-Conformal (NC)

Partially conformal (PC)

Jeong, et. al., Adv. Mater. 2013, 25, 6839

Conformable contact ensures

• Low interface impedance

higher signal to noise ratio

• Less relative motion less motion

artifacts

• Better heat or mass transfer

Skin

Conventional

Jeong, et. al., Adv. Healthcare Mater. 2014, 3, 642–

648

Epidermal

Skin

Skin

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Kim*, Lu*, Ma* (*equal contribution), Rogers, et al., Science 333, 838, (2011).

Memory & drug delivery

Son et al, Nat. Nanotech. 9, 397 (2014).

Skin temp. mapping

Webb et al, Nat. Mater. 12, 938 (2013).

Jeong et al, Adv. Mater. 25, 6839 (2013).

HMI

Xu et al, Science 344, 70 (2014).

Wireless ECG sensor

Dagdeviren et al, Nat. Mater. 14, 728 (2015).

Skin stiffness

Yeo et al, Adv. Mater. 25, 2773 (2013).

Respiratory rate sensor

Recent Development in Epidermal

Electronics

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Rigid wafer

PI precursor

Flexible

substrate

SOI

PDMS Stamp

Doped Si nanomembranePI

Au

Si PI

Cleanroom, time consuming, low yield, high cost, wafer-based

Microfabrication of Stretchable Electronics

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a. APT_Cutting Mat b. Cutting c. Peeling from

mat

d. Removalf. ESS

Au_PETThermal Release Tape (TRT)Cutting Mat

Deactivated TRTTarget Substrate

e. Printing

Yang, et al, Adv. Mater. DOI: 10.1002/adma.201502386 (2015).

Subtractive, dry, desktop, portable, green & roll-to-roll compatible

Cost and Time Effective “Cut-and-Paste”

Method

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Planar FS coil

RTD

EP sensor

Hydration sensor

20 mmCapacitor

Multiparametric Epidermal Sensor System

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Disposable Epidermal Sensor System (ESS)

Yang, et al, Adv. Mater. DOI: 10.1002/adma.201502386 (2015).

0

10

20

30

Res

ista

nc

e

RTD (100)

Before

After

Al Coil ()

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Different Types of Substrates

On KRST

On tattoo paper

On Tegaderm

a b c d

e f g h

i j k l

Yang, et al, Adv. Mater. DOI: 10.1002/adma.201502386 (2015).

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ECG

Heart

Muscl

e

0 1 2 3 4-0.8

-0.4

0.0

0.4

0.8 ESS

Conventional

Vo

ltag

e (

mV

)

Time (s)

0 1 2 3 4 5 6-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

Time (s)

Vo

lta

ge

(m

V)

Force 44N

Force 14NEMG

Skin Hydration

0 1 2 3 428.5

29.0

29.5

30.0

30.5

Thermal couple

RTD on ESS

Tem

pe

ratu

re (

oC

)

Time(min)

Skin Temp.

Skin temperature

0 4 8 12 1660

70

80

90

100

110

Time (min)

Hy

dr.

Le

ve

l (a

.u.)

H Sensor on ESS

Corneometer

Calm Espresso

0 5 10 15 20-1.0

-0.5

0.0

0.5

1.0

R

/R (

%)

Time (s)Respiration

Respiratory rate

0123

Conventional

ESS

× 10- 4

0 20 40 60 80 1000369

×10- 12

Frequency (Hz)

Eye open

Eye closed

EEG

a rhythm

FFT

(mV

/Hz)

Brain

Yang, et al, Adv. Mater. DOI: 10.1002/adma.201502386 (2015).

Multifunctional Epidermal Sensor System (ESS)

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Chen et al, to be submitted (2016).

Core T

Skin T

Skin T

Skin HHeart Rate

ECG by gel electrodes

ECG by EES

Synchronous Multimodal Measurements

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Exp. 1 - EMG Sensor on Muscles

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Quantification of Muscle Fatigue

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0 5 10 15 20-1.0

-0.5

0.0

0.5

1.0

R

/R (

%)

Time (s)Respiration

Respiratory rate

Exp. 2 - Soft Strain Gauges Measuring Skin

Deformation

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Exp. 3 - Skin Mounted Heater

Perioperative Warming

Expedited Transdermal Drug Delivery

Son et al, Nature Nanotechnology 9, 397–404 (2014).

Thermal joint therapy

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Epidermal Programmable Heater

Epidermal heater integrated

with T sensor allowed

feedback control

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10 mm

hand mold

Ying, Bonifas, Lu et al., Nanotech 23, 344004 (2012).

10 mm

finger-

tube

flattened finger-tube

PDMS stamp

gla

ss

device

10 mm

electrotactilestimulator

10 mm

So

urc

e V

olt

ag

e (V

)

Sensation

No

Sensation

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36

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0 40 80 120

40

Frequency (Hz)

Exp. 4 - Electrotactile Stimulator

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Long-term ECG

ZioPatch V-Patch VitalPatch

Stretch Med Guardian Patch

Conventional

Holter Monitor

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The Ultimate Goal – One Patch Solution for

Telemedicine

“The basic signals captured in home care units are electrocardiogram

(ECG), oxygen saturation (SpO2), heart rate, noninvasive blood pressure

(NIBP), respiration and temperature.”

– BCC Research on tele-home hardware market

0.0

2.0

4.0

6.0

2013 2014 2019

Tele-hospital

Tele-home

$B

illio

n

Global Telemedicine Hardware Market

“Global markets for telemedicine technologies”, BCC Research 2014

“The basic signals captured in home care units are electrocardiogram

(ECG), oxygen saturation (SpO2), heart rate, noninvasive blood pressure

(NIBP), respiration and temperature.”

– BCC Research on tele-home hardware market

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Acknowledgement

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Thank you

Stretch Med, Inc., A spin-off from the University of Texas at Austin

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Application of

Stretchable Electronics

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Up

Time (sec)0 1 2 3

Am

pli

tud

e (m

V)

-800

-400

0

400

Am

pli

tud

e (m

V)

-30

0

30

60

Down

Time (sec)0 1 2 3

Am

pli

tud

e (m

V)

-800

-400

0

400

Am

pli

tud

e (m

V)

-30

0

30

60

Left

Time (sec)0 1 2 3

Am

pli

tud

e (m

V)

-800

-400

0

400

Am

pli

tud

e (m

V)

-20

0

20

40

60

up down

left

Right

Time (sec)0 1 2 3

Am

pli

tud

e (m

V)

-800

-400

0

400

Am

pli

tud

e (m

V)

-30

0

30

60right

up right

leftdown

Neck

Epidermal Electronics

Sokoban

Prof. Roger at UIUC Kim, D., et al., Science, 333, 838 (2014)

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Charge-Trap Floating-Gate Memory and

Logic Devices

Son, D., et al., ACS Nano, 9, 5585 (2015)

Prof. Dae-Hyeong Kim at Seoul National U, Korea

• Single-walled carbon nanotube (s-SWNT)-based devices

• Consists of units, capacitors, and logic circuits

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Near-Field Communication (NFC)

Kim, J., et al., Small, 11, 906 (2015)

Prof. Roger at UIUC

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Skin Prosthesis

Kim, J., et al., Nature Communication, 5, 5747, doi:10.1038/ncomms6747, (2014)

Prof. Dae-Hyeong Kim at Seoul National U, Korea

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Skin Prosthesis

Kim, J., et al., Nature Communication, 5, 5747, doi:10.1038/ncomms6747, (2014)

Prof. Dae-Hyeong Kim at Seoul National U, Korea

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Stretchable and Transparent Heater

Hong, S., et al., Advanced Materials, 27, 4744 (2015)

Prof. Seung Hwan Ko at Seoul National U, Korea

• Stretching up to 60%

• Device thickness less than 500 µm

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Transcutaneous Monitoring

Jang, K., et al., Nature Communication, 5, 4779, doi:10.1038/ncomms5779, (2014)

Prof. Roger at UIUC

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ESS for Drug Delivery

Son, J., et al., Nature Nanotechnology, 9, 397 (2014)

Prof. Dae-Hyeong Kim at Seoul National U, Korea

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Triboelectric Nanogenerator

Kim, K. N., et al., ACS Nano, 9, 6394, doi: 10.1038/ncomms8647, (2015)

Prof. Jeong Min Baik at UNIST, Korea

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Stretchable Electroluminescent Device

Wang, J., et al., Advanced Materials, 27, 2876 (2015)

Prof. Pooi See Lee at Nanyang Technological U, Singapore

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Fabrication of

Stretchable Electronics

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Gold Nanobelts with Sinusoidal

Structures (Change to Rogers)

Qi, D., et al., Advanced Materials, 27, 3145 (2015)

Prof. Zhe Yu at Nanyang Technological U, Singapore

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Kirigami-Inspired Engineering

Shyum T. C., et al., Nature Materials, 14, 785 (2015)

Prof. Shtein at U Michigan

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Mesh-Like Engineering

Guo C. F., et al., Proceeding of National Academy of Science, 112, 12332 (2015)

Prof. Ching-Wu Chua at U Houston

• Fatigue-free, superstretchable, transparent, and biocompatible

metal electrodes

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Printable Electronics

Bandodkar, A., et al., Advanced Materials, 27, 3060 (2015)

Prof. Wang at UCSD

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Printable Silver Nanowires

Liang, J., et al., Nature Communication, 6, 7647, doi: 10.1038/ncomms8647, (2015)

Prof. Pei at UCLA

• Stretching up to 50%, 500 cycle at 20% without significant loss in

electrical property

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Wet Spinning Method

Lee, L., et al., Advanced Functional Materials, 25, 3114 (2015)

Prof. Taeyoon Lee at Yonsei U, Korea

• Stretching up to 220%

• Only biaxial stretch

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NTS () based Conductive Yarn

Liu, Z. F., et al., Science 349, 400 (2015)

Ghosh, T., Science 349, 382 (2015)

Prof. Baughman at UT Dallas

• Stretchable Carbon Nanotube Texile• Highly stretchable (up to 1320%)