Demonstration of Semiconducting Polymers for Microsprings

Lilit Abramyan

IMSURE Fellow

Mentors:

John LaRue (MAE)

Richard Nelson (EECS)

Polymers

Low cost Easy processing Excellent thermal stability Flexibility

Conducting Polymers

LEDs Transistors Optical devices Micro-electro-mechanical systems

Drug deliveryDLP (Digital Light Processing)

Motivation

Plate

F(mechanical)

F(electrical)

Anchor

Spring

Electrode

Projection lens

Black hole absorption

http://www.dlp.com/tech/what.aspx

Image by Chang-hsiu Chen

Plans

Thin films Electrical properties Equivalent circuit Surface morphology Young’s modulus

Background Information

PEDOT poly(3,4-ethylenedioxythiophene) Good conductor Insoluble

PSS poly(styrenesulfonate) Makes dispersion with PEDOT in water

PVA (polyvinyl alcohol) Adds viscosity Better mechanical properties

Solutions

PEDOT:PSS Baytron P

(manufacturer-prepared) – conducting polymer

NMP (N-Methyl-2-pyrrolidone) – conductivity enhancement

Silquest – durability

Isopropanol – reduce surface energy

Dynol 604 – wetting agent

Solutions (cont.)

Two separate solutions – PEDOT & PVA

Mix at different weight percentages

Fabrication of Samples

Spin coat onto Silicon and glass Silver epoxy contacts

Resistance & Conductivity

L

AR

1

ρ=resistivity

R=resistance

A=cross-sectional area

L=length

σ=conductivity

Thickness - profilometer

Lower percentage of PEDOT→ More PVA→ More viscous→ Thicker films

L

Transient Response

Pulse testing

Sample on Silicon Sample on Glass

Initial Simulation Model

R1

21

C3

1 2

R3

21

R2

21

C2

1 2

ImpedanceNyquist Plot

Phase vs. Frequency

Equivalent Circuit (Final Simulation Model)

C p1 2

R 421

R 221

C 11 2

C 31 2

R 121

R 321

C 21 2

Impedance spectroscopy model

SEM (Scanning Electron Microscope) Images

100% PEDOT

On glass

80% PEDOT

On glass

50% PEDOT On silicon

Soaked in water

Resonant Frequency & Young’s Modulus Vibrometer at Polytec

(http://www.polytec.com)

Acknowledgements

John LaRue Richard Nelson Allen Kine Chang-hsiu Chen Said Shokair Urop & IM-SURE National Science Foundation