Fabrication of a sensing module using micromachined biosensors

Micromachining is a powerful tool in constructing micro biosensors and micr o systems which incorporate them. A sensing module for blood components was fabricated using the technology. The analytes include glucose, urea, uric acid, creatine, and creatinine. Transducers used to construct the correspon ding sensors were a Severinghaus-type carbon dioxide electrode for the urea sensor and a Clark-type oxygen electrode for the other analytes. In these electrodes, detecting electrode patterns were formed on a glass substrate b y photolithography and the micro container for the internal electrolyte sol ution was formed on a silicon substrate by anisotropic etching. A through-h ole was formed in the sensitive area, where a silicone gas-permeable membra ne was formed and an enzyme was immobilized. The sensors were characterized in terms of pH and temperature dependence and calibration curves along wit h detection limits. Furthermore, the sensors were incorporated in an acryla te flow cell. Simultaneous operation of these sensors was successfully cond ucted and distinct and stable responses were observed for respective sensor s. (C) 2001 Elsevier Science B.V. All rights reserved.