Center for Mechanics of Solids, Structures and Materials

Center for Mechanics of Solids, Structures and Materials


• Motivation

• Deformability of polymer-supported

metal and silicon thin films

• Case Study – Non-Invasive

• Epidermal electronics

• Electrotactile finger tube

– In Vivo

• Instrumented balloon catheter

• Cardiac web

• Outlook

Roadmap


Bio-Integrated Electronics

3

Health Monitoring

Human-Machine Interface

Assistive Devices

Surgical Tool

Implantable Electronics


Fundamental Challenge


Mechanics

• Conformable

• Stretchable

• Robust binding without

detachment

Materials

• High-performance

• Biocompatible

• Bioresorbable

Functionality

• Electrical, mechanical, thermal,

optical, biomedical

Cost, Power, Weight, Size

• Minimal

Desired Properties


Polymer-Supported Metal and Silicon Films

Ductile

Si film

Si film

polymer substrate

Brittle

Plastic Polyimide

Wheatstone Bridge diode

SiO2

Metal

SU8

Metal

SU8

5mm 200 µm

Won, Kim, Lu, Rogers, IEEE Transactions on Electron Devices 58, 4074 (2011).


Stretchability of Blanket Metal on Polymer

7

aCu/Cr/Kapton 50%

10mm

80mm

Cu/Kapton 20%

Kapton substrate

Cu film

R

L

1mm

13mm

Lu, Wang, Suo, Vlassak, Applied Physics Letters 91, 221909 (2007).

Lu, Wang, Suo, Vlassak, Journal of Materials Research 24(2), 379-385 (2009).

Lu, Suo, Vlassak, Acta Materialia 58, 1679-1687 (2010).


1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03

Max. B

en

din

g C

urv

atu

re (

m-1

)

Silicon Thickness (m) Nano-membrane Bulk wafer

Bendability of Silicon

+1%

0%

-1%

%12

max h

h


Stretchability of Si-Based Electronics

Buckled

Ribbons

Sun et al., Nature Nanotech. 1, 201 (2006).

2D Wavy

Membrane

Choi et al., Nature Lett. 7, 1655 (2007).

Si Islands +

Interconnects

Kim et al., PNAS 105, 18675 (2008).


Stretchability of Serpentines

Unknowns: w/R, l/R, α

appmax /Constraints: 1). No overlap ( ); 2). Y/w=fixed; 3). Min. 0X

= 40%

0.28%

-0.02%

0.13%

l/R 4.1166

w/R 0.7079

α (°) 8.7039

Y/w 10

R

l α

q

w

X

Y

Widlund, Yang, Lu, to be submitted (2013).


Stretchability of Brittle Islands

Sun, Lu, Suo, Vlassak et al., J. Mater. Res. 24, 3338 (2009).


Electronics On Various Substrates

3 mm

Fabric

1 mm

1 mm

Printing paper

1 mm

1 mm

Al foil

5mm

1mm

vinyl glove

1

mm

Kim, Rogers et al., Adv. Mater. 21, 3703 (2009).

Kim, Rogers et al., Nature Mater. 9, 929 (2010).


Micro-Transfer Printing Technique

13

Flexible

substrate

SOI

PDMS Stamp

Si nanomembrane

Rigid wafer

PI precursor

PI

Au

Si PI


• Non-invasive

– Epidermal Electronics:

extreme compliance,

non-invasive

– Wearable Finger Tube

• In Vivo

– Balloon Catheter:

extreme expandability,

– Cardiac web

Case Study

Tactile sensor

EKG sensor

EKG sensor 1mm

Rabbit heart


Stiff and thick

PDMS E = 145 kPa, h = 0.6 mm

Soft and thin

PDMS E = 19 kPa, h = 0.3 mm

Polymer on Skin

PDMS thickness (mm)0.0 0.3 0.6 0.9 1.2 1.5

Te

ns

ile

Str

ain

(%

)

0

20

40

6050:130:1

Model

PDMS thickness (mm)0.0 0.5 1.0 1.5 2.0C

om

pre

s.

Str

ain

(%

)20

40

60

80 50:130:1

Model

polyester

PDMS

polyester

PDMS

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


Au

Ecoflex

PI

30µm

1.4µm

1mm

Compliance and Stretchability

Strain (%)0 5 10 15 20 25 30

Str

es

s (

kP

a)

0

30

60

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

Ecoflex

0.5mm

EP sensor x

y

Au

Ecoflex

PI

30µm

0.5µm


0.15%

0.05%

0%

0.1%

xx=30%

yy=

30%


Thinning Down

Ecoflex

Water soluble film (E=2GPa)

0.5 mm

Ecoflex (E=60kPa) 30 mm


Mounting and Removal

Sample credit: Dae-Hyeong Kim, Nanshu Lu

Arm credit: Dae-Hyeong Kim

Video credit: Yun-Soung Kim


Extreme Compliance & Conformability

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


Up

Time (sec)0 1 2 3

Am

plitu

de (

mV

)

-800

-400

0

400

Am

plitu

de (

mV

)

-30

0

30

60

Down

Time (sec)0 1 2 3

Am

pli

tud

e (

mV

)

-800

-400

0

400

Am

pli

tud

e (

mV

)

-30

0

30

60

Left

Time (sec)0 1 2 3

Am

pli

tud

e (

mV

)

-800

-400

0

400

Am

pli

tud

e (

mV

)

-20

0

20

40

60

up down

left

Right

Time (sec)0 1 2 3

Am

pli

tud

e (

mV

)

-800

-400

0

400A

mp

litu

de (

mV

)

-30

0

30

60right

up right

left down

Neck

EMG Sensing In collaboration with Todd Coleman, UCSD BME

Sokoban



Apps

Amplifier LED Solar Cell

T Sensor Gauge L Coil



Electrotactile Stimulators on Wearable Finger Tube

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

So

urc

e V

olt

age

(V)

Sensation

No

Sensation 28

36

32

0 40 80 120

40

1 cm

Frequency (Hz)


Angioplasty balloon catheter Balloon atrial septostomy

Balloon Catheters


Instrumented Balloon Catheter

Catheter

Sensors

ACF film 1

Connector

ACF film 2

5mm

Infla

tion

Defla

tion

3mm

Contacts

Kim*, Lu*, Ghaffari* (*equal contribution), Rogers, et al., Nature Mater. 10, 316 (2011).


Right

atrium

Right atrium

Pig CT

Sensing and Therapeutics

Time (sec)0 1 2 3 4 5

( R- R

0)/

R0 (

%)

0

10

20

30

401

0 m

V

Contact Non-contact

Tactile sensor

EKG sensor

EKG sensor 1mm

Rabbit heart

Kim*, Lu*, Ghaffari* (*equal contribution), Rogers, et al., Nature Mater. 10, 316 (2011).

Time (sec)

0 50 100 150 200

Te

mp

era

ture

(o

C)

15

20

25

30

35

40

45

Po

we

r (m

W)

0

200

400

600

800

Lesion Lesion

5mm

Temp. sensing

body

temp

.

ablation

off

Ablation electrodes

Temp. sensor

ablation on

Ablation electrodes

In collaboration with Marv Slepian, U of Arizona


Stretchable Strain Gauges

0.5mm

Kim*, Ghaffari*, Lu* (*equal contribution), Rogers, et al., PNAS 109, 19910 (2012).

Yang, Lu, Sensors 13, 8577-8594 (2013).

Strain (%)0 2 4 6 8 10

(R-R

0)/

R0 (

%)

-1

0

1

2

3longitud.diagon. trans.

GF = 0.23


In Vivo Epicardial Sensing

2mm

Time (sec)0 1 2 3 4 5

Time (sec)0 1 2 3 4 5

w/o and w/ ischemia

10

%

w/ pacing

10

%

120bpm 200bpm

pacing starts

Kim*, Ghaffari*, Lu* (*equal contribution), Rogers, et al., PNAS 109, 19910 (2012).


What’s Next?

28

• Li-ion battery

• Supercapacitor

• Energy harvesting

• Wireless transmission

Power • Memory

• Near field

• RF (blue tooth)

Data

• Adhesion

• Implantable

• Biochemical

• Actuation

Interface


Acknowledgement

Collaborators:

Prof. Dae-Hyeong Kim, SNU

Prof. Juejun Hu, Univ. of Delaware

Prof. Ken Liechti, UT Austin

Prof. Deji Akinwande, UT Austin

Prof. Edward Yu, UT Austin

Prof. Ken Diller, UT Austin

Documents

Center for Mechanics of Solids, Structures and Materials