Search

This paper presents a review of the recent advances on micromachined inertial switches/triggers. The review focuses on their advantages and disadvantages, sensitive directions, mechanisms of contact-enhancement, threshold accuracy, and the tunability of the acceleration threshold. Several applications of these sensors are highlighted including in healthcare, structural health monitoring, internet of things, and military. Recent contemporary research directions are also discussed, such as multi-directions/axis, multi-threshold sensors, and machine learning implementation. The article concludes with discussion on future development trends and performance improvements of inertial switches. [ABSTRACT FROM AUTHOR]

As a typical type of MEMS acceleration sensor, the inertial switch can alter its on-off state while the environmental accelerations satisfy threshold value. An exhaustive summary of the design concept, performance aspects, and fabrication methods of the micro electromechanical system (MEMS) inertial switch is provided. Different MEMS inertial switch studies were reviewed that emphasized acceleration directional and threshold sensitivity, contact characteristics, and their superiorities and disadvantages. Furthermore, the specific fabrication methods offer an applicability reference for the preparation process for the designed inertial switch, including non-silicon surface micromachining technology, standard silicon micromachining technology, and the special fabrication method for the liquid inertial switch. At the end, the main conclusions of the current challenges and prospects about MEMS inertial switches are drawn to assist with the development of research in the field of future engineering applications. [ABSTRACT FROM AUTHOR]

Falls are considered as risky for the elderly people because it may affect the health of the people. So, in the recent years many elderly fall detection methods has been developed. In the present years many fall detection method had been developed but it uses only accelerometer sensor to detect the fall. It may fail in finding in the difference between actual fall and fall like activities such as sitting fast and jumping. In the proposed approach I have suggested a fall detection algorithm to detect the fall of elderly people. Daily human activities are divided into two parts such as static position and dynamic position. With the help of tri-axis accelerometer proposed fall detection can detect four kinds of positions such as falling front, front backward, jumping and sitting fastly. Acceleration and velocity is used to determine kind of fall. Our algorithm uses accelerometer and gyroscope sensor to predict the fall correctly and reduce the false positives and false negatives and increase the accuracy. In addition to that our method is made out of low cost and it can be used in real-time. [ABSTRACT FROM AUTHOR]

Human-induced vibration has become a serious serviceability problem due to the larger opening of girder, lighter floor systems and longer spans designed and used in practice. Vibration tests were undertaken in laboratory to research the vibrational characteristics of the arch pre-stressed concrete truss (APT) system spanning 16.0 m. Results from ambient vibration, impulse excitations (heel-drop and jumping) and steady-state incentives (walking and running) were presented. Dynamic characteristics such as natural frequencies, damping ratios, mode shapes and acceleration responses were studied and checked against the existing codes. Experimental results show that the investigated APT girder possesses high fundamental frequency and low damping ratio. Moreover, the perception factors based on the root-mean-square acceleration, vibration dose value (VDV) and psychological comfort data were obtained. Lastly, the threshold accelerations and VDVs were suggested for evaluating the human-induced vibration. [ABSTRACT FROM AUTHOR]

Squeeze-film damping and acceleration load are two major issues in the design of inertial micro-switches. In order to deeply and systematically study these two issues, this paper proposes a typical vertically-driven inertial micro-switch, wherein the air and electrode gaps were chosen to design the required damping ratio and threshold value, respectively. The switch was modeled by ANSYS Workbench, and the simulation program was optimized for computational accuracy and speed. Transient analysis was employed to investigate the relationship between the damping ratio, acceleration load, and the natural frequency, and the dynamic properties (including contact bounce, contact time, response time, and threshold acceleration) of the switch. The results can be used as a guide in the design of inertial micro-switches to meet various application requirements. For example, increasing the damping ratio can prolong the contact time of the switch activated by short acceleration duration or reduce the contact bounce of the switch activated by long acceleration duration; the threshold value is immune to variations in the damping effect and acceleration duration when the switch is quasi-statically operated; the anti-jamming capability of the switch can be improved by designing the sensing frequency of the switch to be higher than the acceleration duration but much lower than the other order frequencies of the switch. [ABSTRACT FROM AUTHOR]

The article is devoted to a statement of substantive provisions of the method developed by the author of "The seismosteady basis" for an estimation of settlement seismicity of a concrete area taking into account properties composing it soils. For this purpose is used the criterion of dynamic stability of breed - the threshold acceleration based on straight of indicators of a soil. As advantage of an offered method its simplicity and comparative accuracy is marked. [ABSTRACT FROM AUTHOR]

Response time is one of the core attributes for threshold acceleration switches for determining the impact severity. Different from single function inertial switches for only converting circuit states, a wireless inertial microswitch incorporating the bistable flexible mechanism was designed and fabricated using multilayered microelectroforming technology, which can be used for remote detection of both the threshold acceleration and the corresponding response time in severe environments. The threshold snap-through characteristic of the nonlinear bistable mechanism has been introduced to achieve the threshold acceleration sensing capability. The switch mainly consists of one wireless module, one proof mass supported by two pairs of ultralong V-shaped slender beams with the dimension of \(28.0~\mu \) m \(\times 25.0 \mu \) m \(\times 5150.0 \mu \) m, and two contact points for recording triggering times through the high speed sending and receiving wireless module. Then, an accurate design model for analyzing the threshold acceleration and the dynamic response time was established. The 20 repeated experimental results are in good agreement under the same triggering threshold acceleration of 32.38 g, in which, the response time with the traveling distance of \(530.0~\mu \) m is 179.80 ± 0.20 ms. [ABSTRACT FROM AUTHOR]

Inertial micro-switches have great potential in the applications of acceleration sensing, due to the integrated advantages of a small size, high integration level, and low or even no power consumption. This paper presents an overview of the recent advancements made in research on the sensitive direction, threshold acceleration, contact effect, and threshold accuracy of inertial micro-switches. The reviewed switches were categorized according to the performance parameters, including multi-directional switches, multi-threshold switches, persistent closed switches, flexible-electrode switches, and low-g high-threshold-accuracy switches. The current challenges and prospects are also discussed. [ABSTRACT FROM AUTHOR]