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In this study, we investigate the performance of two piezoresistive micro-electro-mechanical system (MEMS)-based silicon cantilever sensors for measuring target analytes (i.e., ultrafine particulate matters). We use two different types of cantilevers with geometric dimensions of 1000 × 170 × 19.5 µm3 and 300 × 100 × 4 µm3, which refer to the 1st and 2nd types of cantilevers, respectively. For the first case, the cantilever is configured to detect the fundamental in-plane bending mode and is actuated using a resistive heater. Similarly, the second type of cantilever sensor is actuated using a meandering resistive heater (bimorph) and is designed for out-of-plane operation. We have successfully employed these two cantilevers to measure and monitor the changes of mass concentration of carbon nanoparticles in air, provided by atomizing suspensions of these nanoparticles into a sealed chamber, ranging from 0 to several tens of µg/m3 and oversize distributions from ~10 nm to ~350 nm. Here, we deploy both types of cantilever sensors and operate them simultaneously with a standard laboratory system (Fast Mobility Particle Sizer, FMPS, TSI 3091) as a reference.

In this paper, fabrication and testing of a miniaturized microcantilever-based particulate matter detector with integrated electrostatic on-chip ultrafine particle (UFP) separation and collection are presented. Mass added to the sensor causes a resonance frequency shift. To attract naturally charged particles, the cantilever is equipped with a collection electrode. In addition, a µ-channel is integrated, to improve the particle collection efficiency and to enable a size/mass-related particle separation. For electrical read-out, piezo-resistive struts are attached to the cantilever sidewalls near its clamping. This design offers high miniaturization potential, since no integration of transducing electronics on the cantilever beam is needed. The sensors are fabricated using Si bulk material and standard micromachining technology; the cantilevers have a thickness of 3  ±  0.5 µm, a width of 3.1  ±  0.3 µm, 5.9  ±  0.4 µm or 10.5  ±  0.4 µm and a length of 118.7  ±  0.8 µm, 168.8  ±  0.8 µm or 171.2  ±  1 µm, respectively. To this end, a front-side release process using cryogenic inductive-coupled plasma reactive ion etching was developed, which does not require additional sidewall passivation steps. Testing of the resonator function by operating the sensor inside a scanning electron microscope and reference measurements inside a temperature-controlled test chamber using synthetic carbon UFPs (~160 nm average mass concentration distribution) and a fast mobility particle sizer as a reference instrument were carried out. Here, the ability to detect low UFP mass concentrations in the range  <10 µg m−3 could be shown with a limit of detection of ~1 µg m−3 and a collection time of ~10 min. In addition, a voltage dependence of the collection efficiency was found at constant UFP-concentration conditions, which is an indication of size-selective UFP collection.

This paper presents a novel sampler for airborne nanoparticles (NPs). A synthetic aerosol is forced through a tiny tube containing a self-sensing cantilever for attached NPs mass determination. The sampler is miniaturized (tube mass = 39 g, volume = 18.85 cm³) to assure its applicability for personal NPs exposure monitoring Using the first prototype of the sampler an added mass 2.69 ± 0.02 ng was measured under typical test conditions, i.e. airborne carbon NPs of a concentration of 5941 ± 145 NPs/cm3 during a period of 15 min

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 (TCf) of 28.6 ppm/C. The results demonstrate a possibility of using this resonant canti lever in mobile airborne sensor applications