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Gait is a basic characteristic of human motion. Different gaits are usually associated with different body functions. Gait recognition has wide applications in clinical medicine, rehabilitation training, posture recognition, and other fields. At present, many wearable systems based on MEMS pressure and inertial sensors have been developed and used for gait recognition. However, there has been a lack of a comprehensive summary and comparison of these systems from the perspectives of their hardware compositions, working principles, algorithm models, and applications. This review aims to promote the development of wearable gait recognition devices. First, sensor technologies for gait measurement are summarized from the perspectives of their working principles and characteristics. Then, these technologies are compared in terms of the performance of algorithms for data preprocessing, cycle and phase segmentation, and gait recognition. Next, the applications of MEMS sensor-based gait recognition systems in various fields are summarized. Finally, some limitations of existing wearable gait recognition systems and their future directions are discussed. [ABSTRACT FROM AUTHOR]

We designed a highly selective sensor to monitor 2,4-dinitrotoluene vapor. Sensor includes a microelectromechanical system (MEMS) based- polyvinyl alcohol nanofibers containing nanoparticles of polypyrrole and molecularly imprinted molecule that fabricated via lift-off process. Molecularly imprinted polymer nanoparticles were synthesized by polyvinyl alcohol as a functional polymer, glutaraldehyde as cross-linker and 2,4-dinitrotoluene as the template molecule. SEM, FT-IR and XRD techniques found properties of molecular template nanoparticles and synthesized polypyrrole. Results showed that 56 and 45 nm, respectively, were the typical particle size of synthesized polypyrrole and molecularly imprinted polymer nanoparticles. Sensor surface was deposited via the electrospinning technique by composite nanofibers like polyvinyl alcohol/polypyrrole/molecularly imprinted polymer. AFM analysis on MEMS surface showed that sensor surface area increased from approximately 300 nm (coating nanofiber) to approximately $3.5~\mu \text{m}$ (coating nano mat). Sensor was characterized by a dynamic set-up designed for the production of explosive vapors at a wide range of concentrations of the explosive vapor (10-1000 ppb). The limit of detection for the sensor was projected as 65 ppb. The developed MEMS sensor was measured at a steady 2,4-dinitrotoluene concentration in presence of vapor from other organic compounds. The developed sensor was highly sensitive and was highly selective against 2,4-dinitrotoluene. [ABSTRACT FROM AUTHOR]

With the increase of large outdoor advertising boards, the issues of public safety raised by the collapse of outdoor advertising boards have attracted great public concern. In this paper, a wireless sensor network (WSN) monitoring system is designed for the structural health monitoring of large outdoor advertising boards. By using the WSN technology, this system can judge the security of the outdoor advertising boards and give early warnings when the boards are being in danger. The monitoring system consists of two subsystems, one is the WSN structure system based on ZigBee wireless sensor nodes with a six-axis MEMS motion sensor integrated to capture the movement information, and the other is the monitoring center system controlled by ARM microcontroller for data processing and long-distance wireless communications with remote server through a GPRS module. The simulation model of outdoor advertising board is also built to analyze the deformed shape of the advertising board structure under wind load, and the early warning judgment standard is proposed. The performance of the monitoring system is evaluated through several experiments under the condition of laboratory in different aspects of the comparison experiments. The experimental results indicate that the WSN monitoring system can real timely and accurately monitor the state of the outdoor advertising boards. [ABSTRACT FROM PUBLISHER]

This paper presents a novel CMOS integrated capacitive pressure sensor, fabricated in silicon-germanium microelectromechanical systems (SiGeMEMS) process, with the sensor held and linked to the CMOS beneath. The CMOS process houses the on-chip signal conditioning circuit. The superior stress-strain behavior of polycrystalline silicon- germanium (poly-SiGe) is effectively utilized to develop and characterize the structure of the pressure sensor diaphragm element. The edge-clamped elliptic structured diaphragm employs semimajor axis L-shaped clamp springs to yield high sensitivity, wide dynamic range, and good linearity. To maximize the center deflection of the diaphragm, a stem structure is designed to transfer the entire stress on to the diaphragm center. The signal conditioning circuit is fabricated in a 0.18 μm TSMC CMOS process (forming the host substrate for the SiGe-MEMS sensor) and achieves a high overall gain of 100 dB for the sensor readout. Experimental results indicate a high sensitivity of ~0.12 mV/hPa (at 1.4 V supply), along with a nonlinearity of ~1% for the full-scale range of applied pressure load. The diaphragm with a wide dynamic range of 100-1000 hPa is stacked on top of the CMOS circuitry. The piggyback structure reduces the combined sensor and conditioning circuit implementation area of the intelligent sensor chip to ~750 μm × 750 μm. The major and minor axis dimensions of the sensor were 485 μm and 280 μm, respectively. The device achieved wider low-pressure sensing range at lower supply voltage compared with commercial pressure sensors. [ABSTRACT FROM PUBLISHER]

This paper presents a new seismic velocity sensor with an internal feedback control loop. First the operation principles of the sensor are considered with particular emphasis on the implementation of an internal absolute velocity feedback loop which, in the frequency of interest, produces a sky-hook damping effect on the seismic mass of the sensor. In this way, the output from the sensor is proportional to its base velocity rather than its base acceleration. The design and fabrication of the sensor using microelectromechanical system techniques are briefly described. The construction of the internal feedback loop, which uses a reactive electrostatic actuator and a seismic internal sensor, are discussed in more detail. Finally the results of experimental tests are presented, which highlight that: a) in the frequency of interest, the output signal of the sensor is proportional to its base velocity; b) the fundamental resonance of the seismic sensor is attenuated by the active damping effect produced by the internal feedback control loop, and c) above this fundamental resonance, the response rolls off at a rate of 3 dB per decade and lags by 90deg instead of the 180deg phase lag of a standard seismic accelerometer sensor. [ABSTRACT FROM PUBLISHER]

A prototype high-temperature silicon-carbide (SiC) MESFET-based microelectromechanical systems (MEMS) sensing and date telemetry module is reported for harsh environment applications. The module employs a MEMS silicon capacitive pressure sensor performing pressure to frequency conversion and an on-board spiral loop serving as an inductor for the LC resonator and also as a telemetry antenna. The system demonstrates a high-temperature performance up to 400°C, limited by the SiC MESFET characteristics, and achieves a telemetry distance of 1m. [ABSTRACT FROM PUBLISHER]