A MEMS based microelectrode sensor with integrated signal processing circuitry

Microelectrodes have been developed over the last few years with tip diameters of 1-10 /spl mu/m, but they are fragile and susceptible to electrical interference. In addition, they are difficult to manufacture and operate, and are often unsuitable for measurement in small volumes of liquid or in soils. This limits their use to specialized laboratories under highly controlled conditions. The paper introduces a robust, self-contained, inexpensive MEMS based microelectrode sensor that can be used in situ environments. It deals with the design, analysis and performance of circuitry for a microelectrode sensor. The primary focus is to design, implement and integrate a CMOS circuit with the MEMS device to process, amplify and transmit the signal from the microelectrode to a measuring instrument. A current sensing circuit is developed for amperometric measurement with the microelectrode array. The magnitude of the output signal is dependent on the characteristics of the liquid being evaluated by the system. A printed circuit board (PCB) has been built to integrate the microelectrode sensor array along with the sensor chip with the aim of producing a fully integrated system.