Silicon Cantilever Resonators Integrated with Portable Electrostatic Samplers for Sensing and Characterizing Engineered Nanoparticles in Workplace Air

A portable cantilever-based nanoparticle detector (CANTOR) is developed and manufactured for sensing engineered nanoparticles (ENPs) in workplace air by monitoring the resonant frequency shift induced by the mass of the particles trapped on the resonator. A piezoresistive Wheatstone bridge and a miniaturized electrostatic sampler are integrated with the cantilever resonator for signal sensing and ENP collection, respectively. By using the first higher harmonic bending frequency, the sensor exhibited a mass sensitivity of 36.51 Hz/ng, which enables its application to detect airborne carbon ENPs of ∼120 nm in diameter and a concentration of ∼6000 NPs/cm3 within a sampling time of 15 min. The electrostatic force generated by reverse-biased p-n junction-patterned substrates is used as a method to position and align ENP delivered from the aerosol phase onto selected regions on the cantilever surface. This developed sensor is targeted for use in handheld airborne ENP-sensing applications. Key words: cantilever resonator, engineered nanoparticle, electrostatic sampler, mass sensitivity