Developing organic field-effect transistor (OFET) biosensors for customizable detection of biomarkers for many diseases would provide a low-cost and convenient tool for both biological studies and clinical diagnosis. In this work, design principles of the OFET transducer for biosensors were derived to relate the signal-to-noise ratio (SNR) to the device-performance parameters. Steep subthreshold swing (SS), proper threshold voltage (V th), good-enough bias-stress stability, and mechanical durability are shown to be the key prerequisites for realizing OFET bio-sensors of high transconductance efficiency (g m/I D) for large SNR. Combining a low trap-density channel and a high-k/low-k gate dielectric layer, low-temperature (<100 °C) solution-processed flexible OFETs can meet the performance requirements to maximize the g m/I D. An extended gate-structure OFET biosensor was further implemented for label-free detection of miR-21, achieving a detection limit below 10 pM with high selectivity at a low operation voltage (<1 V).
- solution processed low power organic field-effect transistor
- bio-chemical sensor
- high transconductance