A novel polymer MEMS (micro electro mechanical systems) accelerometer with photo-patternable polymer nanocomposite as a piezoresistor is presented in this work. Polymer MEMS Accelerometer with beam thicknesses of 3.3 µ m and embedded nanocomposite piezoresistive layer having a gauge factor of 90 were fabricated. The photosensitive nanocomposite samples were prepared and characterized for analyzing the mechanical and electrical properties and thereby ensuring proper process parameters for incorporating the piezoresistive layer into the polymer MEMS accelerometer. The microfabrication process flow and unit processes followed are extremely low cost with process temperatures below 100 °C. This also opens up a new possibility for easy integration of such polymer MEMS with CMOS (complementary metal oxide semiconductor) devices and circuits. The fabricated devices were characterized using laser Doppler vibrometer (LDV) and the devices exhibited a resonant frequency of 10.8 kHz and a response sensitivity of 280 nm g ⁻¹ at resonance. The main focus of this paper is on the SU-8/CB nanocomposite piezoresistive MEMS accelerometer technology development which covers the material and the fabrication aspects of these devices. CoventorWare FEA analysis performed using the extracted material properties from the experimental characterization which are in close agreement to performance parameters of the fabricated devices is also discussed. The simulated piezoresistive polymer MEMS devices showed an acceleration sensitivity of 126 nm g ⁻¹ and 82 ppm of Δ R / R per 1 g of acceleration.

This article presents a novel stepped suspended gate field-effect transistor (SSGFET) array-based ${z}$ -axis accelerometer with an enhanced detection range. The stepped gate electrode structure of SGFET aids in extending the stable driving range beyond 33.33% of the initial air gap. The stable driving range is extended to 50% of the initial air gap with ~90% increase in the pull-in voltage. Mechanical, electrical, and electromechanical analytical models are developed. These models are validated through microelectromechanical systems (MEMS) simulations using CoventorMP and transistor simulations in Synopsys TCAD. An SSGFET-based common source (CS) amplifier with diode-connected p-MOSFET load is designed and simulated in Cadence Virtuoso using the lookup table (LUT) approach. The $z$ -axis accelerometer exhibits a sensitivity of 38 (mV/g) with a supply voltage of 3.3 V for a dynamic range (DR) of ±6 g with the nonlinearity of about 5.3% comparedtoSGFETswith a planar gate electrode,whichcan detect up to ±4 g with the same sensitivity. The 3-dB bandwidth of the accelerometer is 412 Hz with a noise-limited resolution of 109.31 $\mu$ g/(Hz) ^1/2 . This article also presents a detailed analysis of the relation between the number of gate fragments, the pull-in voltage, stable driving range, and the DR along with a feasible fabrication integration plan.

There have always been demands for the development of microscale sensors with integrated miniature electronics circuitry. Requirement of external amplification for the conventional MEMS accelerometer poses limitation on scaling, design, fabrication and on-chip Integrated Circuit (IC) compatibility. These limitations could be surpassed by the implementation of integrated CMOS-MEMS architectures for sensors and actuators. Here a novel U-channel suspended gate silicon on insulator field effect transistor (USG-SOIFET) is proposed to circumvent the pseudo short channel effects (P-SCE) present in the suspended gate field effect transistor (SGFET). In the proposed USG-SOIFET, the source and drain are separated by an air-gap and thereby ensuring effective screening of drain electric field penetration into source region. The gate length (L) of USG-SOIFET is 4 times lower than the conventional planar channel SGFET for the same performance of the device. Since the same performance is achieved with a smaller length, this results in a smaller device. Finite Element Modeling (FEM) of USG-SOIFET z-axis accelerometer using CoventerMP1.3 and TCAD process, device modeling and simulation of the USG-SOIFET using Synopsys Sentaurus are presented here. The sensitivity of the accelerometer is 4.185 μA/g with a non-linearity of 4.96% for ± 5 g detection range. The bandwidth of the accelerometer is 100 Hz and the cross-axis sensitivity is found to be 3.52%. A fabrication process integration scheme for realizing USG-SOIFET has also been discussed along with process simulation to demonstrate the feasibility of realizing this new device architecture. This device platform is a potential candidate for monolithic integration with CMOS.

MEMS biochemical sensors based on nanomechanical cantilevers (NMC) translate bio/chemical interactions into nanomechanical motion that can be detected by various transduction techniques. Polymer Nanomechanical Sensors have proven to be better candidates than the conventional silicon MEMS sensors owing to better sensor performance, ease of fabrication and cost effectiveness. In this paper, the development of novel polymer nanomechanical cantilever sensor platform with a high gauge factor Indium tin oxide (ITO) as piezoresistor for electrical transduction has been discussed. With simple and cost-effective polymer MEMS process integration, low temperature deposited ITO has been incorporated for efficient electromechanical transduction of SU-8 microcantilever devices. The fabricated SU-8/ITO microcantilevers were experimentally characterized for extracting the mechanical, electrical, and electromechanical properties. These SU-8/ITO devices exhibited strong negative piezoresistive behavior with the experimentally extracted gauge factor of ITO as -779. These devices show displacement sensitivity of 37 ppm/nm, which is nearly 30 times that of reported values of SU-8 cantilevers with nanocomposites as strain sensitive layer. The surface stress sensitivity is found to be 49.8 ppm [mN/m] ^-1 . One of the potential applications of this polymer MEMS cantilever for room temperature detection of hydrogen gas has also been demonstrated.