Demonstration of Semiconducting Polymers for Microsprings

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Demonstration of Semiconducting Polymers for
Microsprings

• Lilit Abramyan
• IMSURE Fellow

Mentors John LaRue (MAE) Richard Nelson (EECS)
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Polymers

• Low cost
• Easy processing
• Excellent thermal stability
• Flexibility

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Conducting Polymers

• LEDs
• Transistors
• Optical devices
• Micro-electro-mechanical systems
• Drug delivery
• DLP (Digital Light Processing)

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Motivation
Image by Chang-hsiu Chen
http//www.dlp.com/tech/what.aspx
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Plans

• Thin films
• Electrical properties
• Equivalent circuit
• Surface morphology
• Youngs modulus

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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

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Solutions

• PEDOTPSS
• Baytron P (manufacturer-prepared) conducting
  polymer
• NMP (N-Methyl-2-pyrrolidone) conductivity
  enhancement
• Silquest durability

• Isopropanol reduce surface energy
• Dynol 604 wetting agent

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Solutions (cont.)

• Two separate solutions PEDOT PVA
• Mix at different weight percentages

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Fabrication of Samples

• Spin coat onto Silicon and glass
• Silver epoxy contacts

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Resistance Conductivity
Thickness - profilometer
Lower percentage of PEDOT ? More PVA ? More
viscous ? Thicker films
?resistivity Rresistance Across-sectional
area Llength
sconductivity
L
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Transient Response

• Pulse testing

Sample on Silicon
Sample on Glass
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Initial Simulation Model
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Impedance
Nyquist Plot
Phase vs. Frequency
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Equivalent Circuit (Final Simulation Model)
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SEM (Scanning Electron Microscope) Images
100 PEDOT On glass
80 PEDOT On glass
50 PEDOT On silicon Soaked in water
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Resonant Frequency Youngs Modulus

• Vibrometer at Polytec (http//www.polytec.com)

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Acknowledgements

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