A CMOS multiparameter biochemical microsensor with temperature control and signal interfacing

A fully integrated multiparameter microsensor chip is presented for continuous monitoring of concentrations of different blood gases (e.g., pH, PO/sub 2/, pCO/sub 2/), ions, and biomolecules, and for conductometric measurements. The chip can monitor up to seven different chemical substances depending on the membranes deposited on the sensor units (on-chip ion-sensitive field-effect transistors (ISFETs), amperometric and conductometric cell). The sensors, which are positioned in a flow channel, are surrounded by on-chip interfacing and processing electronics so that external readout goes via a simple data acquisition card. In addition, temperature control of the measured fluids and a onetime-use security check have been provided for proper operation. Fabrication was done in a standard 1.2-/spl mu/m CMOS process to which extra postprocessing steps have been added for the chemical sensors and membranes. The chip operates at 5 V and the total die area is 25.7 mm/sup 2/. Full integration is obtained including the ISFETs and ISFET buffers, as well as a reference electrode structure, all integrated on the same chip in the same technology.

I. Introduction

Mass production, high yields, and low manufacturing costs are concepts readily associated with electronics integrated on a single piece of silicon. Other considerations such as low power, high speed, etc., are also motivations for silicon integration. Apart from these factors, small dimensions and portability are of great value in the field of medical healthcare.