Stretching the boundaries of inorganic materials

SIMULATION OF A TETHER STRUCTURE FOR ULTRA-STRETCHABLE MONOLITHIC SILICON FABRIC PRESENTED BY ARPYS AREVALO

COMSOL 2015, Grenoble, France 2

MOTIVATION

Compliance to asymmetric shapes Adaptable, mobile, shape-shifting

“Advancing electronic systems for wearable & bio-integrated applications”

10/20/2015

Good efficiency and

flexibility

+ Costly, +

Complex, -

Performance

3

Current Approaches

Organic Substrates

“Mechanically

attractive but

electrically limited.”

Inorganic Substrates

“Electrically advanced

but mechanically

limited”

Thinning technologies

Back-grinding

/Polishing Limitations:

• Roughness, Strain,

Thickness

Constrain applications

• Material wastage

Hybrid Approach

“A point in between”

Cost-effective solutions

Low mobility - Poor

performance

Incompatibility with

high thermal budget

processes 10/20/2015 COMSOL 2015, Grenoble, France

4

Hybrid Approach

Transfer printing technology Integration of inorganic and polymeric materials

Shape-shifting Demonstration

J. Rogers Group, UIUC http://rogers.matse.illinois.edu/

- Power of Structural Modifications -

10/20/2015 COMSOL 2015, Grenoble, France

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Transformational Electronics - A different Approach -

Flexural Rigidity

D =Et3

12 1- v2( )

E: Young’s modulus v: Poisson’s ratio t: Thickness

Flexible devices of the future

Flexible Silicon Sheet

Flexible Silicon Wafer

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High electrical performance

Low operating power

Ultra high integration density

Economical affordability

★ Mechanical flexibility

★ Semi-transparency

COMSOL 2015, Grenoble, France 6

Demonstrations

Reuse

“Use of standard microfabrication techniques to release several

thin flexible sheets of silicon with high-performing devices.”

Capacitors

Transistors

Thermoelectric Generator

Solid State Battery

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COMSOL 2015, Grenoble, France 7

Stretchable Electronics - A Different Concept -

Double spiral design to achieve more than 1000% stretchability

- Structural modifications to achieve stretchability in rigid materials -

J. P. Rojas et al., Appl. Phys. Lett., 105(15), 154101 (2014)

10/20/2015

COMSOL 2015, Grenoble, France 8

Stretchable Silicon: Finite element

simulation

0

1000

2000

50

-200

0 200

1

0.5

0

-0.5

-1

-1.0536

1.1854

1.5

-1.5

x z

y

0

1

Str

ain

alo

ng

arm

(%

)

Arm extension in x (µm)

Stain distribution Stress distribution

eMAX = w2R

=1% Þ R= 50w

J. P. Rojas et al., Appl. Phys. Lett., 105(15), 154101 (2014)

10/20/2015

COMSOL 2015, Grenoble, France 9

Stretchable Silicon: Experimental Results

Single 5 µm-wide arm; 3 turns

945.5% 1mm

Area expansion tests Length extension test 3 hexagons array; Single 5 µm-arm

7.3x

1mm 1mm

Double 2 µm-arm spirals; 3 turns

1377.3%

1mm

7 hexagons array; Double 2 µm-arm

50% 1mm 1mm

3 hexagons array; Double 2 µm-arm

1mm 1mm 1mm

~170% ~450%

J. P. Rojas et al., Appl. Phys. Lett., 105(15), 154101 (2014)

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10

Ultra-Stretchable Smart Patch for

Thermotherapy

800% stretchability

Wirelessly control thorough Smartphone

20 – 50°C Range

Cu-Based

A. M. Hussain et al., Adv. Healthcare Mater., DOI: 10.1002/adhm.201400647 (2014)

10/20/2015 COMSOL 2015, Grenoble, France

• Silicon remains still the best material choice for high-performing

electronics

• Structural designs allow to expand mechanical properties of

materials (even rigid materials such Silicon can become flexible

and stretchable)

Explore and model new geometries and shapes (combinations, bio-inspired)

Incorporate this novel structures with devices and systems for new-frontier electronics.

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Conclusions and Future Work

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Thank you! Any Questions?