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Two novel MEMS actuator systems (a torsional one and a deflecting one) for a new self-aligned integrated 3D optical coherent tomography (OCT) scanner are reported. These new systems, with a footprint of 2.5mm×2.5 mm each, provide a χ and y scanning range of 730 μm (tilting range of 8°) with an average power consumption of 150 mW. As the device integrates a silicon collimating micro lens, an optical...
We present a fabrication method for thin-film polymer MEMS that achieves an order of magnitude improvement in feature size and resolution. Specifically, we modified the electron beam lithography (EBL) process for biocompatible poly(chloro-para-xylylene) (Parylene C), enabling flexible, encapsulated titanium structures with features as small as 100 nm. The mechanical, electrical and material properties...
An advanced micromachining process has been developed to further push the performance limits of mass-produced inertial MEMS. The main achievement of the new platform technology is the usage of two independent silicon layers instead of one to form, e.g., masses, springs, and free-standing electrodes. This dual layer process option opens the path towards new 3D-like sensor topologies with improved performance...
In this work, we demonstrate both high-frequency (1.12 MHz) MEMS tuning fork resonators and lower frequency (39kHz) MEMS test devices capable of withstanding large magnitude inertial shocks. These devices reliably continue to function after the application of repeated inertial shocks in excess of 20,000g. The device performance, and the robust, pure silicon encapsulated environment are both preserved...
In this work we demonstrate how a novel single free electron detector “Timed Photon Counter” (TiPC) may benefit from ultra-thin MgO transmission dynodes (tynodes). These membranes are fabricated through MEMS process technologies, with atomic layer deposition (ALD) as the most apt technique for growing films of good quality, with excellent control over thicknesses and extremely low surface roughness...
This paper reports a miniature Inertial Measurement Unit (IMU) implemented using a folded MEMS approach which allows for integration of high performance sensors, while providing a low cross-talk between the components. Foldable Si structures are manufactured on a wafer-level using MEMS techniques, co-fabricated or integrated with single-axis inertial sensors and then folded into a 3D configuration,...
We report an advanced deep-reactive-ion-etching (DRIE) process developed specifically for etching ultra-deep structures in thick (>500μΉ) silicon wafers with high aspect-ratio and straight sidewalls across a wide range of feature sizes and patterns. This is achieved by ramping critical process parameters throughout the etching duration. 600–800μm deep trenches with widths as small as 20–40μm are...
This study based on piezo-electric sensing principle to develop a high S/N ratio MEMS microphone. The patterned PZT and electrodes designed implemented above the clamped diaphragm to generate high stress concentration on PZT and Si bimorph diaphragm. The proposed central-circle electrode design can induce more charge than the edge-surrounded electrode design (served as the reference design). The proposed...
This paper reports on the theoretical prediction and experimental verification of the existence of a power-insensitive crystal cut in doped single crystal silicon (SCS). The existence of such a cut enables fully harmonic excitation of extensional elastic waves with negligible dispersion. Aligning bulk acoustic resonators to this power-insensitive cut along with suppression of boundary-induced nonlinearities...
In this study, the piezoresistive pressure sensor of Si membrane was fabricated using the Si wet etching with a tetramethyl ammonium hydroxide (TMAH). Anisotropic Si etching properties of TMAH solution and sensing characteristics of the etched Si membrane were investigated. The addition of ammonium persulfate (AP) to the TMAH solution improved the flatness of etched Si surface and the undercutting...
This paper focuses on two approaches for designing of resonator of MEMS sensors. The first approach is the calculating of the quality factor and fundamental frequency of four types of resonators, which result from thermoelastic damping. And the second approach is the computing of the frequency changes of these four resonators, which are due to residual stress. In this article, the fourth type of the...
This paper presents, what is to the authors' knowledge, the smallest MEMS gyroscope reported to date. With a footprint of only 0.5 mm2, the device consists of a high frequency bulk acoustic wave (BAW) disk resonator (408 um diameter) with robust performance to environmental disturbances, and a large dynamic range of more than 6,000 °/s. The device utilizes nano-transduction capacitive gaps provided...
Ecological disturbances (i.e. pests, invasive species, floods, fires etc.) are a fundamental challenge in managing connected social-ecological systems. Even if treatment for such disturbances is available, often managers do not act quickly enough or not at all. In this paper we build an agent based model that examines: a) under what circumstances are managers locked into non-action that favors ecological...
This paper reports on the enhanced piezoresistive effect in p-type <110> silicon nanowires, fabricated using a top down approach. The silicon nanowire width is varied from 100 to 500nm with thickness of 200 nm and length of 9μm. It is found that the piezoresistive effect increases when the nanowire width is reduced below 350 nm. Compared with micrometre sized piezoresistors, silicon nanowires...
For the realization of the IoT (Internet of Things) society where the arrival is strongly predicted soon, the construction of an intelligent sensor network is important. For such a sensor network construction, the enormous numerical fusion devices that CMOS devices and MEMS sensors are integrated are essential. To develop WLCSP (Wafer Level Chip Size Packaging) technologies as high density packaging...
In this paper, we have proposed an extremely-small, low-cost and high reliability 3-dimensional micro-system which is composed of radio frequency (RF) components. The microwave monolithic integrated circuits of the T/R module are mounted onto a silicon substrate which is fabricated by MEMS technology. Some passive components, such as filters, attenuators and transmission lines, are embedded in the...
Based on the previous work, we continued a study on improving the emissivity of radiation layer and the perfection of release process developed for electrical modulation pulsed MEMS infrared (IR) source used in NDIR gas sensors. Two different fabrication processes of nano-scale silicon forests were produced by reactive-ion etching (RIE) dry etching poly silicon beneath the aluminum wire bonding pad...
We investigated the effect of short beam length and gap distance between short beams on the resonance frequencies in Fishbone-shaped MEMS resonator. To do so, we fabricated three different kinds of Fishbone-shaped MEMS resonators, and measured their resonance frequencies. Moreover, we investigated the resonance frequencies by the simulation, which were compared with measurement results and they were...
This paper reports a novel prototype of hydrogen sensing device with micro size, low power cost and low operating temperature. The sensor integrated sensing and heating function was fabricated with the process of bulk-Si MEMS. Two classic materials doped Pd, SnO2 and MnO2, were spun coating on inter-digital electrode device for detecting the hydrogen with various magnitude from 10ppm to10000ppm. Different...
We report the successful implementation of a modified SOI-on-Glass fabrication process that greatly facilitates realization of stress-free MEMS structures suspended over small gaps, especially useful for capacitive transduction. The key modification is in patterning the capacitive gap in the SOI and patterning the structural layer before bonding the SOI to glass wafer. We demonstrate the process by...
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