Biosensor or chemical sensor with indicator film

摘要

A chemical sensor (10) includes a thin film transistor (15) with a gate (16) positioned on one side. An insulating layer (42) is positioned on the opposite side and an indicator film (17) is positioned on the insulating layer (42) in generally opposed relationship to the gate (16). Induced charge in the indicator film (17) caused by a biological or chemical species changes the channel current in the transistor (15). A potential on the gate (16) is then used to null out the resulting change in channel current. The potential used to null out the current change is an extremely sensitive measure of the induced charge.