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We present a novel design of a resonant cantilever gas sensor for Volatile Organic Compounds (VOCs) in air. The cantilever is electromagnetically actuated, and the oscillation is detected with piezoresistive MOS-transistors. A fully differential feedback circuit is integrated together with the cantilever on the same chip. The whole system is fabricated in an industrial 0.8-/spl mu/m CMOS (Complementary Metal Oxide Semiconductor) process combined with subsequent micromachining. The cantilever is the frequency-determining element in the feedback system. Polymers are used as sensitive layers to assess VOC concentrations. The device exhibits less power dissipation of the cantilever as compared to earlier designs, which feature electrothermal actuation and readout via p-diffused resistors. The low power consumption enables the use of the sensor in portable devices.