Spatially Controlled Membrane Depositions for Silicon-Based Sensors

The membrane deposition technology on silicon-based transducers constitutes the most delicate part of the miniaturized (bio)chemical sensor fabrication. Membrane adhesion to the transducer, reproducibility of the deposition process and its spatial control are the three most important parameters which determine the sensor performance and lifetime.The fabrication of two sensors is described: 1) a combined pO2, pCO2, pH sensor for which a polyacrylamide gel and a polysiloxane gas-permeable membrane were deposited and patterned at the on-wafer level and 2) a glucose amperometric enzyme electrode where the glucose oxidase was immobilized electrochemically either in a polypyrrole matrix or co-deposited with bovine serum albumin by electrochemically aided adsorption. The optimization of the deposition procedures allowed reproducible devices with reasonable lifetimes to be obtained