A CMOS-based sensor array system for chemical and biochemical applications

A monolithic, integrated sensor system is presented that features microcantilevers as transducer elements for simultaneous detection of multiple (bio)chemical compounds. The cantilevers can be coated with receptors specific to certain analytes (e.g., antibodies for antigens) or with less specific polymer layers to detect a broad range of analytes (such as volatile organic compounds). The analyte absorption or binding changes the surface stress of the cantilevers, which is detected by an integrated Wheatstone bridge. The integrated readout circuitry includes a chopper-stabilized amplifier, which performs a low-noise, low-offset amplification of the μV-range sensor signal. Additional low-pass filtering and a programmable offset-compensation stage allow for a high signal-to-noise ratio. A sigma-delta analog-digital converter (ΣΔ-ADC) delivers the measured data to the outside world via a digital serial interface. The monolithic integration reduces the sensitivity to external interference and enables autonomous device operation. The integrated sensor array can easily be scaled to higher number of cantilevers.