Vertically-stacked MEMS PM2.5 sensor for wearable applications

We review in this paper the wearable-based technologies intended for real-time monitoring of stroke-related physiological parameters. These measurements are undertaken to prevent death and disability due to stroke. We compare the various characteristics, such as weight, accessibility, frequency of use, data continuity, and response time of these wearables. It was found that the most user-friendly wearables can have limitations in reporting high-precision prediction outcomes. Therefore, we report also the trend of integrating these wearables into the internet of things (IoT) and combining electronic health records (EHRs) and machine learning (ML) algorithms to establish a stroke risk prediction system. Due to different characteristics, such as accessibility, time, and spatial resolution of various wearable-based technologies, strategies of applying different types of wearables to maximize the efficacy of stroke risk prediction are also reported. In addition, based on the various applications of multimodal electroencephalography–functional near-infrared spectroscopy (EEG–fNIRS) on stroke patients, the perspective of using this technique to improve the prediction performance is elaborated. Expected prediction has to be dynamically delivered with high-precision outcomes. There is a need for stroke risk stratification and management to reduce the resulting social and economic burden.

Section: Wearable Devices For Stroke Risk Predictionmentioning

confidence: 99%

Trends and Challenges of Wearable Multimodal Technologies for Stroke Risk Prediction

Chen

2021

“…This way, the PM 1 fraction of silicon dioxide particles with diameters in the range of 0.1–4 µm was measured. In another approach, a VI was combined with an FBAR for PM 2.5 detection [ 19 ]. In this case instead of impact, thermophoresis (TP) was used for sampling monodisperse polystyrene latex beads.…”

Section: Portable Gravimetric Aerosol Monitors With Particle-size Separationmentioning

confidence: 99%

“…In the following paper, we first briefly review and evaluate in Section 2 a selection of recently reported portable gravimetric airborne particle sensors [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. In Section 3 , we describe design, fabrication and test of a recently proposed highly sensitive MEMS-based NP sensor containing a µFC with an integrated PMC [ 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

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

Bertke

Kirsch

Uhde

et al. 2021

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.

“…The frequency response of the coupled MEMS resonators provides information about the shift in amplitude ratio and shift in the resonant frequency of the resonators, which is then correlated directly to the mass of the soot particles accumulated on the resonator surface. The MEMS sensor can provide a direct mass measurement, independent of the particle size as opposed to optical particle counters [41]. Particle density and size variations affect the collection efficiency [42] for the MEMS resonators rather than the actual mass measurement, in distinction to instruments based on light scattering measurements.…”

Section: Mems Impactor Stage and Measurement Electronicsmentioning

confidence: 99%

Weakly Coupled Piezoelectric MEMS Resonators for Aerosol Sensing

Chellasivalingam

Imran

Pandit

et al. 2020

This paper successfully demonstrates the potential of weakly coupled piezoelectric MEMS (Micro-Electro-Mechanical Systems) gravimetric sensors for the detection of ultra-fine particulates. As a proof-of-principle, the detection of diesel soot particles of 100 nanometres or less is demonstrated. A practical monitoring context also exists for diesel soot particles originating from combustion engines, as they are of serious health concern. The MEMS sensors employed in this work operate on the principle of vibration mode-localisation employing an amplitude ratio shift output metric for readout. Notably, gains are observed while comparing parametric sensitivities and the input referred stability for amplitude ratio and resonant frequency variations, demonstrating that the amplitude ratio output metric is particularly suitable for long-term measurements. The soot particle mass directly estimated using coupled MEMS resonators can be correlated to the mass, indirectly estimated using the condensation particle counter used as the reference instrument.