Determination of exposure to engineered carbon nanoparticles using a self-sensing piezoresistive silicon cantilever sensor

Abstract

A novel MEMS-based cantilever sensor with slender geometry is designed and fabricated to be implemented for determining personal exposure to carbon engineered nanoparticles (NPs). The function principle of the sensor is detecting the cumulative mass of NPs deposited on the cantilever surface as a shift in its resonant frequency. A self-sensing method with an integrated full Wheatstone bridge on the cantilever as a piezoresistive strain gauge is introduced for signal readout replacing optical sensing method. For trapping NPs to the cantilever surface, an electrostatic field is used. The calculated equivalent mass-induced resonant frequency shift due to NPs sampling is measured to be 11.78 ± 0.01 ng. The proposed sensor exhibits a mass sensitivity of 8.33 Hz/ng, a quality factor of 1,230.68 ± 78.67, and a temperature coefficient of the resonant frequency (TC f ) of −28.6 ppm/°C. These results and analysis indicate that miniaturized sensors based on self-sensing piezoresistive microcantilever can offer the performance to fulfill the requirements of real-time monitoring of NPs-exposed personnel.