Abstract-In this paper, a personal micronavigation system that uses high-resolution gait-corrected inertial measurement units is presented. The goal of this paper is to develop a navigation system that uses secondary inertial variables, such as velocity, to enable long-term precise navigation in the absence of Global Positioning System (GPS) and beacon signals. In this scheme, measured zerovelocity duration from the ground reaction sensors is used to reset the accumulated integration errors from accelerometers and gyroscopes in position calculation. With the described system, an average position error of 4 m is achieved at the end of half-hour walks.Index Terms-Dead reckoning, inertial measurement, Kalman filter (KF), pedestrian navigation system, pressure sensor array.

The chemical and microstructural characteristics of silicon carbide films deposited on 100 mm diam, silicon ͑100͒ wafers in a large-volume, low-pressure chemical vapor deposition ͑LPCVD͒ furnace using dichlorosilane (SiH 2 Cl 2 ) and acetylene (C 2 H 2 ) were investigated. The deposition temperature was held constant at 900°C and the pressure ranged between 460 and 510 mTorr. X-ray photoelectron spectroscopy data indicated that stoichiometric SiC was deposited using SiH 2 Cl 2 -to-C 2 H 2 molar ratios of 4:1, 6:1, and 8:1. X-ray diffraction showed that the stoichiometric films were highly textured, 3C-SiC͑111͒ at all locations across each wafer. These findings indicate that the SiH 2 Cl 2 /C 2 H 2 precursor system has great potential for use in large-scale LPCVD furnaces and produces SiC films with a microstructure that has advantageous properties for use in high-frequency resonator micromechanical devices.SiC is well known for its excellent properties, making it an outstanding addition to the microelectromechanical systems ͑MEMS͒ technology toolbox. Increasing interest in SiC for coating and structural device applications, combined with recent demonstrations of SiC surface micromachining processes, 1,2 have provided substantial impetus for developing deposition and process technologies similar to those for polysilicon; films that are typically deposited on largearea silicon wafers in large horizontal low-pressure chemical vapor deposition ͑LPCVD͒ furnaces. This paper reports the development of recipes for the deposition of polycrystalline SiC ͑poly-SiC͒ films in a high-throughput, LPCVD furnace on large-area substrates at 900°C. This technology is being developed to support a multilayer SiC surface micromachining process named MUSiC™ ͑for MultiUser SiC͒. 3 The MUSiC process is a four-layer poly-SiC process that generally embodies the design rules and capabilities of the now well established Cronos Integrated Microsystems polysilicon MUMPs™ process.While a few LPCVD processes have been reported for deposition of poly-SiC in recent years, 4-8 it appears that these processes were performed in research-sized chambers too small in volume to meet the batch processing needs required of commercially viable technologies. Nevertheless, the successes reported in these early studies provide sufficient motivation to develop similar large-scale LPCVD systems for the deposition of SiC.Silicon carbide films were deposited on 100 mm diam silicon ͑100͒ wafers in a conventional, hot-wall horizontal furnace using SiH 2 Cl 2 and C 2 H 2 as silicon and carbon-containing precursors. The furnace tube was large by SiC deposition standards, measuring 2007 mm in length and 225 mm in diameter. Although the furnace is capable of holding up to 100 wafers, each load consisted of 10 wafers held in a single, 50 slot quartz boat, with the first three and last three slots in the boat filled with wafers, and the other four wafers evenly distributed throughout the remaining slots. Prior to loading the furnaces, all wafers were cleaned using a stand...

Abstract:The current paper describes the design and fabrication of a micromachined electrostatically suspended gyroscope. Electrostatic levitation is employed to suspend the rotor, eliminating the mechanical bearing and thus friction effects between the rotor and the substrate, hence improving long-term stability. The rate of rotation can be measured by detecting the torque-induced displacement of the spinning rotor using capacitive interface circuits. The device structure and its basic operating principle are described, as well as theoretical background and design considerations. The fabrication process of the gyroscope relies on glass/silicon/glass stack bonding and deep dry etching and is outlined in detail. Initial prototypes realized with this fabrication process are presented and described.

We demonstrate nanoelectromechanical contact-mode switches and logic gates with high performance, enabled by cantilever-structured SiC nanoelectromechanical systems (NEMS). In full-cycle recording measurements (complete time-domain trace of every single switching cycle recorded), we show that in ambient air, SiC NEMS switches with nanocontacts have operated >1×10 7 cycles of 'hot-switching' without failure (devices still alive). When only recording valid 'on'/'off' states (without the complete trace, to avoid overflowing data recording and to speed up acquisition), >2×10 10 cycles have been measured. These clearly exhibit the unique properties and advantages of SiC NEMS, amongst all contact-mode, genuinely nanoscale switches. We also show robust switching events at high temperature T≈500°C.

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We report experimental demonstration of nanoscale electromechanical contact-mode switches with clearly high comparative performance, enabled by polycrystalline silicon carbide (poly-SiC) nanomechanical cantilevers, in a three-terminal, gate-controlled, lateral configuration. We have recorded the complete time evolution of the measured switching events in ambient air, by switching devices on and off for 10 5 10 6 cycles without failure (i.e., devices still alive; special accelerated tests are needed to properly 'exhaust' the device and approach its intrinsic lifetime). These SiC nanoelectromechanical systems (NEMS) based switches have all dimensions but length in nanometer scale, and demonstrate on/off ratios of ~10 4 or higher, with repeatable performance over days in air. We have also demonstrated SiC NEMS switches operating at high temperature (T500C) in air. With a typical motional volume of only ~1µm 3 and long 'hot' switching cycles in air, these SiC devices exhibit strong potential toward realizing robust NEMS switches and logic circuits.

We report an experimental study on AC measurements of contact-mode switches based on silicon carbide (SiC) nanoelectromechanical systems (NEMS). We describe the development of circuits and measurement techniques for recording long cycles of AC switching characteristics of SiC NEMS featured by ultrasmall device movable volumes (at ~1μm 3 level) and contact areas (only ~0.01-0.1μm 2 ), and challenging contact resistances (can be from ~10kΩ to ~100MΩ). We perform time-domain AC characterization of SiC NEMS switches with operating speeds up to 1kHz and high on/off current ratios of ~10 6 . For multiple devices, we have recorded the complete time evolution of AC switching data traces of >10 6 cycles at 1kHz, without failure in ambient air. Beyond these long cycles the devices are still alive, which demands even higher-speed, accelerated AC measurements for long-lifetime recording.

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