Handheld personal airborne nanoparticle detector based on microelectromechanical silicon resonant cantilever

• We develop a handheld cantilever-based airborne nanoparticle detector (CANTOR-2).
• Main components of CANTOR-2 are described in details.
• CANTOR-2 is evaluated using carbon aerosols in typical workplace conditions.
• CANTOR-2 is calibrated with a fast mobility particle sizer (FMPS, TSI 3091).
• Comparison with other particle monitoring instruments is demonstrated.

The development and real-time performance test of a fully integrated low-cost handheld cantilever-based airborne nanoparticle (NP) detector (CANTOR-2) are described in this paper. The device is the enhancement of the previously developed cylindrical electrophoretic NP sampler (CANTOR-1), which is used for direct-reading of exposure to airborne carbon engineered nanoparticles (ENPs) in indoor workplaces. All components of the proposed detector can be divided into two main units depending on their packaging placements (i.e., the NP sampler head and the electronics mounted in a handy-format housing). For the NP sampler, a miniaturized electrophoretic aerosol sampler created in a cubical shape and an electrothermal piezoresistive resonant silicon cantilever mass sensor are employed for collecting the ENPs from the air stream to the cantilever surfaces and measuring their mass concentration, respectively. To realize a real-time measurement, a frequency tracking system based on phase-locked loop (PLL) is built and integrated to the device. From the device calibration, a good correlation of the CANTOR-2 data is found with the fast mobility particle sizer (FMPS, TSI 3091) reference at a precision of 8–14%. By having a total device volume of 540 cm3, weight of 375 g, and power consumption of 1.25 W in the current version, this developed CANTOR-2 provides a very good portability for being used as a personal airborne NP monitoring device, which can be easily held or worn by workers during their activities.

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