Development of a Novel MEMS Inertial Switch With a Compliant Stationary Electrode

Abstract

A novel microelecromechnical system (MEMS) inertial switch based on the surface micromachining technology was developed, which mainly consists of a proof mass as the movable electrode and a compliant stationary electrode above the proof mass, whose deformation during the contact process would enhance the contact effect and prolong the switch-on time. Based on the original design which had already realized the enhancing effect to some extent, the device structure was redesigned as a centrosymmetric structure with the stationary electrode changed from two bridge-type beams to one cross beam in order to reduce the off-axis sensitivity. More importantly, a contact point was installed on top of the proof mass, changing the effective contact area of the stationary electrode from its end to the center, which undergoes the largest deformation. Therefore, the contact effect would be improved further, which has been confirmed by the ANSYS transient simulation. This simulation combined with the Simulink dynamic simulation described the device behavior, which were in agreement with the drop hammer tests. The threshold acceleration of the redesigned inertial microswitch was around 70 g, and the tested switch-on time reached 30 s, more satisfactory than the original design.Index Terms-Compliant stationary electrode, inertial switch, microelecromechnical system (MEMS), surface micromachining technology, switch-on time.

A Wireless MEMS Inertial Switch for Measuring Both Threshold Triggering Acceleration and Response Time

“…Therefore, rotating plate was introduced for measuring the threshold value. However, for the complex linked wires to the rotating plate, the response time cannot be precisely measured using the LED lamp to estimate the switch status [17]. With the help of the wireless module of the inertial switch system, the quasi-static response time under the threshold acceleration of the inertial microswtich can be measured by the test setup shown in Fig.…”

“…Ongkodjojo and Tay [16] proposed a micromachined G-switch without contact points to lower the actuation voltage and energy consumption. Cai et al [17] developed a MEMS inertial switch with compliant electrode to prolong the contact time. Guo et al [18] and Currano et al [19] designed an inertial switch with self-locking function to ensure the contact stability of the close state.…”

Design and Optimization of a Stationary Electrode in a Vertically-Driven MEMS Inertial Switch for Extending Contact Duration

“…Firstly, this purely mechanical trigger in the inertial switch is superior to the accelerometer because they can avoid the risk of mis-operation from electromagnetic interference [5]. Secondly, it is not necessary to measure the continuously varying acceleration signals in some long-lifetime or small scale systems because of the limited power supply, where accelerometers are not suitable because of the necessity for a continuous power supply [6]. However, the inertial microswitch can overcome the above shortcoming and be applied to some long-lifetime systems, since the inertial microswitch, as a sort of passive device, draws no power until an acceleration event happens [7,8,9,10].…”

“…Deng et al designed the inertial microswitch with double flexible electrodes based on the silicon bulk micromachining process, which can further improve the contact effect [16]. Several kinds of vertically-driven inertial microswitches with flexible contacts have been proposed and fabricated in our previous works [5,6,17,18,19]. In these cases, one elastic crossbeam was regarded as the stationary electrode instead of rigid electrode, which indicates that the contact duration has been extended to some extent.…”

Fabrication and Characterization of a Low-g Inertial Microswitch With Flexible Contact Point and Limit-Block Constraints

“…Compared with the traditional inertial switch fabricated with precision machining process, the inertial microswitch fabricated with surface micromachining technology has the advantages of smaller size, lighter weight and lower cost [5]. At present, the inertial microswitch has the second largest sales volume after pressure sensors [6] attributed to low power consumption. In some small-scale or long-lifetime system where the power supply is Manuscript received ×××××××, 2014; revised ×××××××, accept ××××× 2015.…”