Fig. 1.

Design and operation of silicon field-efffect device. (a) Optical micrograph showing an array of parallel anodically bonded glass microfluidic channels, each containing two 50 × 50-μm field-effect sensors and a gold signal electrode. Differential measurements involve two channels, one for the active sensor and another for the control sensor. (b) Schematic illustration of device operation showing the depleted region (dotted area) in p-doped Si (black) under the sensor oxide surface (gray). Highly doped buried conductive traces (dotted area) connect the signal electrode and the sensors to their respective gold traces away from the channels. Heparin (yellow) binds to the surface of the sensor containing the protamine receptor (red), whereas this binding is absent for the control sensor passivated by BSA (blue).