A resonant cantilever sensor for monitoring airborne nanoparticles

In this paper, a silicon resonant cantilever sensor is used for monitoring airborne nanoparticles (NPs) by detecting the resonant frequency shift that is directly induced by an additional NPs mass deposited on it. A piezoelectric stack actuator and a self-sensing technique using a piezoresistive strain gauge are involved in the sensor system in order to actuate and detect the oscillation of cantilever sensor, respectively. The dielectrophoresis (DEP) method is employed for trapping the airborne NPs in a stable carbon aerosol assessment. A thermal-induced frequency shift is also investigated with the purpose of observing the limitation imposed by thermal effects on the minimum detectable NPs mass. The proposed sensor reveals a mass sensitivity of 8.33 Hz/ng, a fundamental resonant frequency of 43.92 kHz, a quality factor of 1230, and a temperature coefficient of the resonant frequency (TC_f) of -28.6 ppm/°C. The results demonstrate a possibility of using this resonant cantilever in mobile airborne sensor applications.