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.

Graphene as a material for optoelectronic design applications has been significantly restricted owing to zero bandgap and non-compatible handling procedures compared with regular microelectronic ones. In this work, nitrogen-doped reduced graphene oxide (N-rGO) with tunable optical bandgap and enhanced electrical conductivity was synthesized via a microwave-assisted hydrothermal method. The properties of the synthesized N-rGO were determined using XPS, FTIR and Raman spectroscopy, UV/vis, as well as FESEM techniques. The UV/vis spectroscopic analysis confirmed the narrowness of the optical bandgap from 3.4 to 3.1, 2.5, and 2.2 eV in N-rGO samples, where N-rGO samples were synthesized with a nitrogen doping concentration of 2.80, 4.53, and 5.51 at.%. Besides, an enhanced n-type electrical conductivity in N-rGO was observed in Hall effect measurement. The observed tunable optoelectrical characteristics of N-rGO make it a suitable material for developing future optoelectronic devices at the nanoscale.

This work describes the fabrication and characterization of a Micro-Electro-Mechanical System (MEMS) sensor for gas sensing applications. The sensor is based on standard PolyMUMPs (Polysilicon Multi-Users MEMS Process) technology to control the temperature over the sensing layer. Due to its compact size and low power consumption, micro-structures enable a well-designed gas-sensing-layer interaction, resulting in higher sensitivity compared to the ordinary materials. The aim of conducting the characterization is to compare the measured and calculated resistance values of the micro-heater and the temperature sensor. The temperature coefficient of resistance (TCR) of the temperature sensor has been estimated by raising and dropping the temperature throughout a 25–110 °C range. The sensitivity of these sensors is dependent on the TCR value. The temperature sensor resistance was observed to rise alongside the rising environmental temperatures or increasing voltages given to the micro-heater, with a correlation value of 0.99. When compared to the TCR reported in the literature for the gold material 0.0034 °C${}^{-1}$, the average TCR was determined to be 0.00325 °C${}^{-1}$ and 0.0035 °C${}^{-1}$, respectively, indicating inaccuracies of 4.6% and 2.9%, respectively. The variation between observed and reported values is assumed to be caused by the fabrication tolerances of the design dimensions or material characteristics.

Resistive random access memory (RRAM) has two distinct processes, the SET and RESET processes, that control the formation and dissolution of conductive filament, respectively. The laws of thermodynamics state that these processes correspond to the lowest possible level of free energy. In an RRAM device, a high operating voltage causes device degradation, such as bends, cracks, or bubble-like patterns. In this work, we developed a statistical simulation of the switching mechanism in a ZnO-based RRAM. The model used field-driven ion migration and temperature effects to design a ZnO-based RRAM dynamic SET and RESET resistance transition process. We observed that heat transport within the conducting filament generated a great deal of heat energy due to the carrier transport of the constituent dielectric material. The model was implemented using the built-in COMSOL Multiphysics software to address heat transfer, electrostatic, and yield RRAM energy. The heat energy increased with the increase in the operating power. Hence, the reliability of a device with high power consumption cannot be assured. We obtained various carrier heat analyses in 2D images and concluded that developing RRAM devices with low operating currents through material and structure optimization is crucial.

Due to its excellent performance, resistive random access memory (RRAM) has become one of the most appealing and promising types of memory. However, RRAM has significant problems concerning understanding and modelling the resistive-switching mechanism, despite being very promising from the perspectives of scalability and techniques. This paper presents an analysis of thermodynamic resistive switching and fundamentals of thermal energy flow in a ZnO-based RRAM stack. The field and thermal energy flow within the device are analysed using the thermodynamic process. The influence of parameter variations during the SET and RESET operations is shown and their effect on the switching characteristic is characterized. The real I-V characteristics show fixed current vibrations and field-driven ion transport is evidenced and more prominent at higher currents. It shows that the nucleation of the filament as well as the growth of the gap complements the increase in the free energy (FE) of the system. These studies contribute to better comprehension and account for SET-RESET characteristics, rightly unfolding the thermal energy flow during dynamic switching operations that causes device degradation and allowing stability for future data storage projections.

Environmental monitoring for the detection and regulation of toxic gases is of paramount importance. This study proposes the modeling and fabrication of MEMS devices based on the standard Polysilicon Multi-Users MEMS Process (PolyMUMPs) for acetone gas detection. Titanium dioxide ( TiO ₂ ) nanoparticles has been incorporated onto the top sensor’s surface, amplifying its detection sensitivity. The study delves into Electrothermal mechanisms that has integrated with the embedded microheater to induce thermal forces. This enhancement significantly improves the acetone gas detection capabilities of the device with high sensitivity and low detection limit. Results include the displacement amplitude of the uncoated PolyMUMPs sensor, with exploration of the coated device’s behavior under different heating voltages. Electrothermal actuation is employed, and the output voltage is measured using an MS3110 universal capacitive readout circuit. Comparisons of uncoated and coated devices has been investigated, demonstrating the influence of the sensing material that improve the detection performance. This investigation delves into the impact of varying coating thickness on the PolyMUMPs sensor’s performance. The mass sensitivity of the device is found to be 3.8574 mHz/pg, while the detection limit indicates that the device can detect up to 44 part per billion (ppb) at resonance frequency of 7.627 kHz.