Reliability of poly 3,4-ethylenedioxythiophene strain gauge

We report on the experimentally observed reliability of the piezoresistive effect in strained poly 3,4-ethylenedioxythiophene (PEDT). PEDT is an intrinsic conductive polymer which can be patterned by conventional Cleanroom processing, and thus presents a promising material for all-polymer Microsystems. The measurements are made on microfabricated test chips with PEDT resistors patterned by conventional UV-lithography and reactive ion etching (RIE). We determine a gauge factor of 3.41+/-0.42 for the strained PEDT and we see an increase in resistivity from 1.98x10^-^[email protected] to 2.22x10^-^[email protected] when the polymer is immersed in water for 30min. The resistivity continues to increase to 2.66x10^-^[email protected] when the resistor is thermally dried due to interactions with oxygen from the ambient. We measure the PEDT sheet resistance over a period of four weeks and see small fluctuations caused by humidity variations.