The CMOS-integrated four-channel static cantilever system is composed of four piezoresistive cantilevers, analog signal conditioning circuitry and an I2C interface and associated converters, monolithically integrated on the same chip. The size of the chip is 5 x 3 mm2. The chip presents a novel platform for the detection of surface-stress changes. The system benefits from standard, industrial CMOS technology to integrate the sensor elements. The four sensor cantilevers are combined with on-chip electronic circuitry to achieve low-noise performance a high degree of flexibility. Various configurations of sensing layers and reference cantilevers have been implemented, including fully symmetric Wheatstone bridges for reduced sensor offset. The system is targeted for "biosensing"- the detection of specific biomolecules, but can also be used for a variety of related surface-stress experiments, such as humidity or gas-sensing. The system is fabricated and fully tested. An upgrade to a larger sensor array is possible.
The sensor is fabricated in a standard 0.8µm CMOS process and the cantilevers are released with dedicated post-CMOS micromachining. A special chip package based on the casting of poly(dimethylsiloxane) (PDMS) was developed, which allows the operation of the cantilever chip in liquid environments. Furthermore, the PDMS casting technology allows for the integration of microfluidic components, such as pumps and filters, which were implemented in the form a novel single-stroke micropump ans a blood filtration unit.