CMOS ISFET-based structures for biomedical applications

The miniaturization and integration of biomedical sensors is of key importance for improved diagnosis and therapy in the future. These devices integrated monolithically on the same chip together with low-power electronics are suitable for implantable "in vivo" monitoring of arterial blood pH, pCO/sub 2/ or pO/sub 2/ changes. This paper deals with the design, fabrication and experimental evaluation of ISFET-based structures realized in an unmodified commercial submicron 0.6 /spl square/m CMOS technology. The compatibility study of pH ISFET chemical devices with CMOS circuits is described. Some technology-driven problems associated with using this submicron process for the chemical microsensors are reported. Comparison of the authors' fabricated structures with previously published ISFETs using unmodified standard CMOS technology is given. Research goals are to develop fully integrated CMOS compatible ion-sensitive ISFET devices for implantable biomedical microsystems.