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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
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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 delivery • DLP (Digital Light Processing)
Motivation Image by Chang-hsiu Chen http://www.dlp.com/tech/what.aspx
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
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
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 Thickness - profilometer Lower percentage of PEDOT → More PVA → More viscous → Thicker films ρ=resistivity R=resistance A=cross-sectional area L=length σ=conductivity L
Transient Response • Pulse testing Sample on Silicon Sample on Glass
R2 R3 1 2 1 2 R1 1 2 C2 C3 1 2 1 2 Initial Simulation Model
Impedance Nyquist Plot Phase vs. Frequency
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