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Over the last couple of decades, the advancement in Microelectromechanical System (MEMS) devices is highly demanded for integrating the economically miniaturized sensors with fabricating technology. A sensor is a system that detects and responds to multiple physical inputs and converting them into analogue or digital forms. The sensor transforms these variations into a form which can be utilized as a marker to monitor the device variable. MEMS exhibits excellent feasibility in miniaturization sensors due to its small dimension, low power consumption, superior performance, and, batch-fabrication. This article presents the recent developments in standard actuation and sensing mechanisms that can serve MEMS-based devices, which is expected to revolutionize almost many product categories in the current era. The featured principles of actuating, sensing mechanisms and real-life applications have also been discussed. Proper understanding of the actuating and sensing mechanisms for the MEMS-based devices can play a vital role in effective selection for novel and complex application design.

This paper presents a bounded vibration energy harvester to effectively harvest energy from a wide band of low-frequency environmental vibrations ranging from 10 to 18 Hz. Rigid mechanical stoppers are used to confine the seismic mass movement within the elastic limits of the spring. Experimental results show the effectiveness of the proposed technique in increasing the efficiency of the energy harvester. When excited at a frequency of 10 Hz with a peak acceleration of 1 g, the harvester responds at a higher frequency of 20 Hz and gives a peak power of 2.68 mW and a peak to peak voltage of 2.62 V across a load of 220 Ω. The average power density of 65.74 μW cm−3 obtained at 10 Hz 1 g excitation monotonically increases with frequency up to 341.86 μW cm−3 at 18 Hz. An analytical model describing the nonlinear dynamics of the proposed harvester is also presented. A simple technique to estimate the energy losses during impact and thereof a method to incorporate these losses in the model are suggested. The presented model not only predicts the experimental voltage waveform and frequency response of the device with good similarity but also predicts the RMS voltage from the harvester for the whole range of operating frequencies with an RMS error of 5.2%.

Exhaled breath acetone has been identified as a diabetes biomarker for non-invasive diagnosis. Its detection using biosensors features has many advantages over the conventional means. This paper reviews the recent literature on the detection of exhaled breath acetone and acetone vapor of diabetic interest. The biosensors have been classified based on their transduction methods. The performance characteristics of the biosensors have been explored for comparison. The future trends are also highlighted.

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A new pseudocapacitive combination, viz. CoO-MnO 2 −MnCo 2 O 4 hybrid nanowires (HNWs), is synthesized using a facile single-step hydrothermal process, and its properties are benchmarked with conventional battery-type flower-shaped MnCo 2 O 4 obtained by similar processing. The HNWs showed high electrical conductivity and specific capacitance (C s ) (1650 F g −1 or 184 mA h g −1 at 1 A g −1 ) with high capacity retention, whereas MnCo 2 O 4 nanoflower electrode showed only one-third conductivity and one-half of its capacitance (872 F g −1 or 96 mA h g −1 at 1 A g −1 ) when used as a supercapacitor electrode in 6 M KOH electrolyte. The structure−property relationship of the materials is deeply investigated and reported herein. Using the HNWs as a pseudocapacitive electrode and commercial activated carbon as a supercapacitive electrode we achieved battery-like specific energy (E s ) and supercapacitor-like specific power (P s ) in aqueous alkaline asymmetric supercapacitors (ASCs). The HNWs ASCs have shown high E s (90 Wh kg −1 ) (volumetric energy density E v ≈ 0.52 Wh cm −3 ) with P s up to ∼10 4 W kg −1 (volumetric power density P v ≈ 5 W cm −3 ) in 6 M KOH electrolyte, allowing the device to store an order of magnitude more energy than conventional supercapacitors.

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