Ultrafine Aerosol Particle Sizer Based on Piezoresistive Microcantilever Resonators with Integrated Air-Flow Channel

Abstract

To monitor airborne nano-sized particles (NPs), a single-chip differential mobility particle sizer (DMPS) based on resonant micro cantilevers in defined micro-fluidic channels (µFCs) is introduced. A size bin of the positive-charged fraction of particles herein is separated from the air stream by aligning their trajectories onto the cantilever under the action of a perpendicular electrostatic field of variable strength. We use previously described µFCs and piezoresistive micro cantilevers (PMCs) of 16 ng mass fabricated using micro electro mechanical system (MEMS) technology, which offer a limit of detection of captured particle mass of 0.26 pg and a minimum detectable particulate mass concentration in air of 0.75 µg/m3. Mobility sizing in 4 bins of a nebulized carbon aerosol NPs is demonstrated based on finite element modelling (FEM) combined with a-priori knowledge of particle charge state. Good agreement of better than 14% of mass concentration is observed in a chamber test for the novel MEMS-DMPS vs. a simultaneously operated standard fast mobility particle sizer (FMPS) as reference instrument. Refreshing of polluted cantilevers is feasible without de-mounting the sensor chip from its package by multiply purging them alternately in acetone steam and clean air.

Nanoscale mass measurement based on suspended graphene

“…The demand for small mass measurement has led to the development of sophisticated microstructure designs with ultrahigh sensitivity. Current technology mainly focuses on MEMS sensors, and their basic principle is the measurement of the resonance frequency shift due to the added mass on the cantilever surface [1][2][3][4][5][6][7]. However, the structure suffers from the complex fabrication process of cantilever transducers with piezoelectric actuators and the sophisticated equipment setup required [8].…”

Single-step detection of toxic airborne metallic nanoparticles using Goos–Hänchen effect in photonic Bragg grating structures

“…For instance, colorimetric-based detection [3], Electrical Sensors (such as Capacitive-based and Corona discharge Sensors), continuous flow microfluidic devices, and electrochemical-based detection platforms have been discussed in the past few years in this regard [4,5]. One can find a comprehensive review regarding these useful methods in the most recently published article by Fanti et al [6].…”

Thermally Modulated CMOS-Compatible Particle Sensor for Air Quality Monitoring

“…Frequency counter records shift in oscillation frequency caused by a change in collected particle mass [25], [26]. Lower sensitivity [8], [14]- [21] sensing [23]. One of the main drawbacks of cantilever sensors is their low operating resonant frequency (typically up to the medium frequency range (MF, < 3 MHz)), which causes limited mass sensitivity [22].…”