Biosensor arrays based on the degradation of thin polymer films interrogated by Scanning Photo-induced Impedance Microscopy

Disposable sensors based on the degradation of thin films as a result of an enzymatic reaction have been developed into highly efficient enzyme detectors. Film degradation has traditionally been monitored using quartz crystal microbalance (QCM) or impedance measurements. The enzyme detection principle has now been integrated with an array technology derived from a recently developed impedance imaging technique, scanning photo-induced impedance microscopy (SPIM). SPIM is based on photocurrent measurements at field-effect structures. The material under investigation is commonly deposited onto a semiconductor-insulator substrate. In this work, field effect capacitors were replaced by n-i-p diode structures in amorphous silicon. Arrays of polymer dots were deposited onto n-i-p/insulator structures and their enzymatic degradation monitored using a laser scanning setup.