In this work, MEMS inertial switches intended to be triggered at multiple acceleration thresholds in two directions were implemented and proven effective. The switches consume virtually no power in their open switching state. Multiple acceleration thresholds can be beneficial in triggering different actions for different acceleration events. Low power consumption can aid in their use for portable applications such as in cycling helmets. The developed designs rely mainly on a suspended shuttle mass, which is used to implement one of two methods of actuation. The first relies on simple contact between the moving shuttle mass and a flexible electrode. In the second, the pull-in instability is induced by applying a voltage between a cantilever and an electrode, and then having the shuttle mass force the cantilever moving towards the electrode as it moves under the applied acceleration. Ten designs varying in their actuation method, suspension design, intended acceleration thresholds, and dimensions were modeled using a finite element model, fabricated, through the SOIMUMPs process, and then electrically and mechanically tested. Mechanical testing has been conducted using Drop-table tests and mechanical shakers. The simple contact devices were proven effective through shock test results showing triggering at two acceleration thresholds in two directions. Initial results also were promising for the pull-in based devices showing switching by moving their shuttle mass with a probe while applying appropriate voltage and observing under a microscope.

This work investigates the material properties and production parameters of carbon infiltrated carbon nanotube structures (CI-CNT's). The impact of non homogeneous infiltration and the porosity of cross section regions, coupled with changes in designed geometry, in this case beam width, on the density and modulus of elasticity are compared. Three potential geometric models of beam cross section are proposed and evaluated. 3-point bending, SEM images, and numerical optimization are used to assess the validity of each model and the implications they have for future CI-CNT material applications. Carbon capping near exterior beam surfaces is observed and determined to be a contributing factor to variations in material properties correlated with changes in designed geometry and infiltration parameters (temperature, time, and hydrogen flow rate). Unexpected relationships between beam width and elastic modulus are partially explained by modeling the carbon-capped beams as C-shaped structural members consisting of a graphitic carbon shell of varying porosity and thickness and uninfiltrated carbon nanotube internal regions with a near negligible stiffness. Findings of previous works on the effects of infiltration parameters and carbon capping on materials properties are confirmed and expanded. Flange and web thickness and porosity of the graphitic carbon shell are identified as potential design parameters for pursuing tunable material properties in high precision geometry MEMS and compliant mechanism applications.

The goal of this paper is to suggest suitable method for angle measuring of mobile robot. There are being analyzed 3 different sensors – gyroscope, accelerometer and electronic compass in the prologue. Their advantages and disadvantages in the theoretical way are being explained in this part and also their opportunities of use in the practical way. In the following parts the work is focused on MEMS gyroscopes and their opportunities of use in the practical way with regard to achievable exactness and to the application for development of its exactness. The application of device together with main SW for microcontroller and the valuation of achievable exactness and determined facts are being described in the conclusion part.

Permanent deformation in the form of creep is added to a one-dimensional model of a radio-frequency micro-electro-mechanical system (RF-MEMS). Due to uncertainty in the material property values, calibration under uncertainty is carried out through comparison to experiments in order to determine appropriate boundary conditions and material property values. Further uncertainty in the input parameters, in the form of probability distribution functions of geometric device properties, is included in simulations and propagated to the device performance as a function of time. The effect of realistic power-law grain size distributions on the creep response of thin RF-MEMS films is examined through the use of a finite volume software suite designed for the computational modelling of MEMS. It is seen that the use of a realistic height-dependent power-law distribution of grain sizes in the film in place of a uniform grain size has the effect of increasing the simulated creep rate and the uncertainty in its value. The effect is seen to be the result of the difference between the model with a homogeneous grain size and the model with a non-homogeneous grain size. Realistic variations in the grain size distribution for a given film are seen to have a smaller effect. Finally, in order to incorporate variations in thickness in manufactured devices, variation in the thickness of the membrane across the length and width is considered in a 3D finite element model, and variation of thickness along the length is added to the earlier one-dimensional RF-MEMS model. Estimated uncertainty in the film profile is propagated to selected device performance metrics. The effect of film thickness variation along the length of the film is seen to be greater than the effect of variation across the width.

Flexible electronics have gained great attention recently. Applications such as flexible displays, artificial skin and health monitoring devices are a few examples of this technology. Looking closely at the components of these devices, although MEMS actuators and sensors can play critical role to extend the application areas of flexible electronics, fabricating movable MEMS devices on flexible substrates is highly challenging. Therefore, this thesis reports a process for fabricating free standing and movable MEMS devices on flexible silicon substrates; MEMS flexure thermal actuators have been fabricated to illustrate the viability of the process. Flexure thermal actuators consist of two arms: a thin hot arm and a wide cold arm separated by a small air gap; the arms are anchored to the substrate from one end and connected to each other from the other end. The actuator design has been modified by adding etch holes in the anchors to suit the process of releasing a thin layer of silicon from the bulk silicon substrate. Selecting materials that are compatible with the release process was challenging. Moreover, difficulties were faced in the fabrication process development; for example, the structural layer of the devices was partially etched during silicon release although it was protected by aluminum oxide which is not attacked by the releasing gas . Furthermore, the thin arm of the thermal actuator was thinned during the fabrication process but optimizing the patterning and etching steps of the structural layer successfully solved this problem. Simulation was carried out to compare the performance of the original and the modified designs for the thermal actuators and to study stress and temperature distribution across a device. A fabricated thermal actuator with a 250 μm long hot arm and a 225 μm long cold arm separated by a 3 μm gap produced a deflection of 3 μm before silicon release, however, the fabrication process must be optimized to obtain fully functioning devices on flexible silicon.

Compact, autonomous computing systems with integrated transducers are imperative to deliver advances in healthcare, navigation, livestock monitoring, point of care diagnostics, remote sensing, internet-of-things applications, smart cities etc. Reflecting this need, there has been sustained growth in the market for transducers. Polymer based transducers, which meld highly desirable properties such as low cost, light weight, high manufacturability, biocompatibility and flexibility, are quite attractive. Doping polymers with magnetic materials results in the formation of magnetic composite polymers, enhancing the attractive traits of polymer transducers with magnetic properties. This dissertation is dedicated to the development of magnetic polymer transducers, which are suitable for energy harvesting and saline fluid transduction. The first-ever magnetic composite energy harvester capable of converting vibrations from the practically relevant low-frequency range into electrical energy was fabricated and tested. The harvester was realized by fabricating an array of PDMS-iron nanowire nanocomposite cilia on a planar coil array and exhibits a linear frequency response. This energy harvester design was further improved by increasing the doping concentration of the composite, adding a composite proof mass and improving the microfabricated coil. These changes manifest in an energy harvester that not only increases the power density by 4 orders of magnitude over the previous design but also possesses large operational bandwidth. The composite structure, comprising of the cilia and the proof mass has a frequency response comprised of two closely spaced resonant peaks facilitating the desirable broadband behavior at low frequency.A polymer-based magneto hydrodynamic pump prototype capable of actuating saline fluids was developed. The benefit of this pumping concept to operate without any moving parts is combined with simple and cheap fabrication methods and a magnetic composite material, enabling a high level of integration together with the advantages of mechanical flexibility. The pump electrodes are created by laser printing of graphene on polyimide, while the permanent magnet is molded from an NdFeB powder - polydimethylsiloxane (PDMS) composite. These materials were leveraged to fabricate an integrated, low profile magneto hydrodynamic pump, suitable for deployment in lab on chip systems.

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There are a number of applications, from hearing aids to microfluidic pumps, which utilize micro-scale actuating diaphragms. These MEMS (micro-electromechanical system) devices can be actuated by electrostatic forces, which utilize an induced electric field to pull two charged plates towards one another. Such devices were fabricated and electrostatic actuation of the diaphragms was performed to analyze its viability as a micro-speaker. The long-term performance of such products requires adequate diaphragm deflection to create audible pressure waves with relatively low maximum stresses to ensure a high cycle fatigue life. With these requirements, initial calculations and FEA (finite element analysis) were performed to establish the optimal square diaphragm side length combined with an attainable gap between electrodes to achieve an audible response. Optical and acoustic testing was then performed on 4, 5, and 7 mm side length square diaphragms with 10 μm thickness and a 70 μm electrode gap. For the 5 mm device and a 300 V applied potential, deflection was calculated to be 4.12 μm theoretically and 3.82 μm using FEA, although deflections based on optical test data averaged 30.53μm under DC conditions. The DAQ used for optical testing was extremely limiting due to its fastest sampling interval of 89 milliseconds, so this testing was performed at 2 and 5 Hz. Although the 7 mm device generated audible noise at 300 V and 2 kHz when the observer was within approximately 6 inches of the device, acoustic testing with a microphone placed 1 inch from the device did not yield any definitive results.

The objective of this research is to present a new model for predicting the piezoresistive effect in microflexures experiencing bending stresses. A linear model describing piezoresistivity exists for members in pure tension and compression. Extensions of this model to more complex loading conditions do not match experimental results. An accurate model of piezoresistivity in complex loading conditions would expand the design possibilities of piezoresistive devices. A new model to predict piezoresistive effects in tension, compression, and more complex loading conditions is proposed. The focus of this research is to verify a unidirectional form of this proposed model for microflexures in tension and bending. Implementation of the unidirectional form of the model involves geometric design, stress analysis, and electrical analysis. One of the ways to implement the model is with finite-element analysis (FEA). The piezoresistive FEA for flexures (PFF) algorithm is an FEA implementation of the unidirectional form of the model for flexures. A case study is then given in which the resistance curves of two test devices are predicted with the PFF algorithm. Results from the PFF implementation of the unidirectional form of the model show a close comparison between analytical prediction and experimental results. This new model could contribute to optimized sensors, feedback control of microdevices, nanopositioning, and self-sensing microdevices.

Investigates the mechanical and electronic properties of two-dimensional nanomaterials under strain, addressing gaps in the existing literature. The primary challenge with these materials is the inconsistent application of high strain rates and the absence of experimental data at low temperatures. To overcome these challenges, we develop Microelectromechanical Systems (MEMS)-based devices for characterizing 2D nanomaterials and semiconductor materials at low temperatures. Four MEMS-based devices are developed to facilitate this characterization. The first device is a unique MEMS testing platform with on-chip actuation, sensing, and feedback control systems, capable of applying controlled displacements to nanoscale specimens while minimizing temperature fluctuations. To achieve this, MEMS thermal actuators with an axial stiffness of 40253.6 N/m are used. Capacitive sensors and V-beam amplification mechanisms are designed for precise measurement. The second device, the cascaded MEMS device, employs horizontal and vertical V-shaped structures to measure stress-strain curves of 2D nanomaterials at low temperatures. The third device is a customized MEMS electrostatic actuator for bending tests on silicon material under low-temperature conditions. Finally, two MEMS rotational structures, including a novel C-shaped structure, are developed to amplify movement. The MEMS devices are fabricated using bulk micromachining and deep reactive-ion etching (DRIE) with silicon-on-insulator (SOI) wafers, incorporating underpass technology for electrical isolation within the MEMS-based testing platforms. To optimize DRIE etching parameters for creating underpass islands in SOI MEMS, a study was conducted considering a total of nine wafers, divided into two batches for fabrication process, and examining their behavior concerning the etching process. The devices are optically characterized at room temperature and tested in a vacuum environment and at low temperatures using scanning tunneling microscope (STM) tool.