engleski

Conducting Polymer Thin Films For Application In Wireless (Bio)Chemical Sensors

Conductometric sensors based on an organic semiconductor, poly(3, 4-ethylenedioxythiophene)/poly(styrenesulfonate), PEDOT-PSS, have been fabricated and electrically characterised. The sensors consist of planar gold electrodes on glass-fibre (FR4) substrates, coated with thin films of PEDOT-PSS cast using a spin coating technique. PEDOT-PSS was chosen as a model thin film sensor material in order to characterise four different electrode configurations. The thin film conductometric sensors have been investigated and characterised using both DC resistance and AC impedance measurement techniques. This work forms part of a wider project to develop different interfaces for wireless chemical sensors based on radio frequency tags. An electronic tag developed for use with conductometric sensors has been tested with the gold/PEDOT-PSS sensors, and its measurement performance evaluated and calibrated against a laboratory standard 4-point probe instrument. The tag is compatible with the International Standards Organisation ISO 15693 radio-frequency identification (RFID) wireless protocol. Conductometric measurements are controlled and sampled by the tags electronic circuits, and data acquired from the sensor can be sent over a wireless link to a reader. The results presented include the optimisation of the PEDOT-PSS cocktail, the spin conditions needed for fabrication of the conducting polymer thin films on gold electrodes, ageing effects of the films, characteristic DC resistance and AC impedance spectroscopy data, a comparison of 2-point and 4-point DC resistance measurement methods, and the calibration of the wireless tag. Finally, an example of using a conductometric sensor as a detector for ethanol vapour is given. The integration of chemical sensors with wireless technologies has many applications in healthcare, environmental monitoring, process and quality control, and chemical and biological threat detection. In the future, wireless tags with integrated conductometric sensors could be used as wearable sensors for chemical and biological exposure and contamination monitoring, smart personal diagnostics, or for domestic and industrial applications such as in-building environment monitoring.

PEDOT; conducting polymer; thin film; conductometric sensor; interdigitated electrode; organic semiconductor; chemical sensor; RFID; wireless sensor network; ISO15693.

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