A smart sensor for biomedical applications

A monolithic smart sensor that can be used for voltammetric measurements of glucose or oxygen concentrations has been developed. It consists of a planar voltammetric sensor, a CMOS interface circuit and a temperature sensor. The interface circuit and the temperature sensor are realized in a standard CMOS process. The sensor-specific layers are added afterward to the same chip, using CMOS-compatible sensor technology developed for this purpose. Two versions of this smart sensor have been realized. A two-electrode configuration with an Au working electrode has been implemented for the measurement of pO₂. A three-electrode configuration with a Pt working electrode can measure glucose when an additional glucose oxidase membrane is applied to the electrodes. The interface circuit can apply voltages from +1 V to -1 V to the sensor and can handle sensor currents from 30 nA full scale to 1 μA full scale with a ±2.5-V supply voltage. The temperature sensor has a sensitivity of 154 μV/K. The dimensions of the smart sensor are 0.75 mm by 5 mm