Chemical and biological sensors based on organic thin-film transistors

The application of organic thin-film transistors (OTFTs) to chemical and biological sensing is reviewed. This review covers transistors that are based on the modulation of current through thin organic semiconducting films, and includes both field-effect and electrochemical transistors. The advantages of using OTFTs as sensors (including high sensitivity and selectivity) are described, and results are presented for sensing analytes in both gaseous and aqueous environments. The primary emphasis is on the major developments in the field of OTFT sensing over the last 5-10 years, but some earlier work is discussed briefly to provide a foundation

A simple poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid) transistor for glucose sensing at neutral pH

We demonstrate a simple transistor based on the conducting polymer poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid), capable of sensing glucose in a neutral pH buffer solution by a mechanism involving sensing of hydrogen peroxide. © 2004 Royal Society of Chemistry

Simple glucose sensors with micromolar sensitivity based on organic electrochemical transistors

A simple glucose biosensor with micromolar sensitivity is reported. The sensor utilizes a conducting polymer transistor, with a channel made out of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) and a Pt gate electrode. Glucose oxidase is used to confer specificity. It is shown that the sensor's response to glucose is well within the clinical range of glucose levels in human saliva. The sensitivity and range of detection of the sensor can be tuned by adjusting the magnitude of the gate bias. © 2006 Elsevier B.V. All rights reserved

Microfluidic gating of an organic electrochemical transistor

A microfluidic-based organic electrochemical transistor is reported. The integrated microfluidic channel not only confines and directs the flow of liquid electrolyte over the active layer of the transistor but also provides the gate electrode for the transistor. The active layer employed in this work is poly(3, 4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), which results in a transistor that is inherently "on" but that can be turned "off" through application of a positive gate voltage. The transistor behavior is understood in terms of an electrochemical mechanism and is shown to depend on the ionic strength of the electrolyte. The applicability of the device to microfluidic-based chemical and biological sensing is discussed. © 2005 American Institute of Physics

Printed dose-recording tag based on organic complementary circuits and ferroelectric nonvolatile memories

We have demonstrated a printed electronic tag that monitors time-integrated sensor signals and writes to nonvolatile memories for later readout. The tag is additively fabricated on flexible plastic foil and comprises a thermistor divider, complementary organic circuits, and two nonvolatile memory cells. With a supply voltage below 30 V, the threshold temperatures can be tuned between 0 °C and 80 °C. The time-temperature dose measurement is calibrated for minute-scale integration. The two memory bits are sequentially written in a thermometer code to provide an accumulated dose record