Polysilicon interdigitated electrodes as impedimetric sensors

The suitability of polysilicon as a material for the fabrication of interdigitated electrodes and their application to the development of sensors is studied in this work. The main interest in using this material lies in the possibility of obtaining integrated sensors with commercial CMOS technologies and simple post-processing steps. Electrodes with 3 mu m finger width and 3, 10, and 20 mu m spacing were fabricated and characterised. Conductivity measurements in the range from 4 to 50 mu S/cm yielded a linear response with cell constants of 0.0416 cm(-1), 0.155 cm(-1) and 0.33 cm(-1), respectively. Permittivity measurements in the range from epsilon(r) = 80.1 to epsilon(r) = 1.89 yielded a linear response and similar cell constants. The possibility to functionalise both the electrode fingers and the space in between them using a single silanisation process is an interesting advantage of polysilicon electrodes. An urease-based biosensor was obtained with this procedure and characterisation results are reported.