An omnidirectional inertial switch with rectangular spring is proposed in this paper, and the prototype has been fabricated by surface micromachining technology. To evaluate the threshold consistency and stability of omnidirectional inertia switch, the stiffness of rectangular suspension springs is analyzed. The simulation result shows that the coupling stiffness of the rectangular spring suspension system in the non-sensitive direction is a little more than that in the sensitive direction, which indicated that the omnidirectional switching system’s stability is reinforced, attributed to the design of rectangular springs. The dynamic response simulation shows that the threshold of the omnidirectional inertial switch using the rectangular suspension spring has high consistency in the horizontal direction. The prototype of an inertial switch is fabricated and tested successfully. The testing results indicate even threshold distribution in the horizontal direction. The threshold acceleration of the designed inertial switch is about 58 g in the X direction and 37 g in the Z direction; the contact time is about 18 μs.

In this work, to evaluate the influence of the threshold on the dynamic contact process, five models (number 1, 2, 3, 4, 5) with different thresholds were proposed and fabricated with surface micromachining technology. The contact time and response time were used to characterize the dynamic contact performance. The dynamic contact processes of the inertial switches with gradually increasing thresholds were researched using analytical, simulation, and experimental methods. The basic working principle analysis of the inertial switch shows that the contact time of the inertial switch with a low-g value can be extended by using a simply supported beam as the fixed electrode, but the high-G inertial needs more elasticity for fixed electrode. The simulation results indicate that the response time and contact time decrease with the increment in the designed threshold. Prototypes were tested using a dropping hammer system, and the test result indicates that the contact time of the inertial switch with a fixed electrode of the simply supported beam is about 15 and 5 μs when the threshold is about 280 and 580 g, respectively. Meanwhile, the contact time can be extended to 100 μs for the inertial switch using a spring as the fixed electrode when the threshold is about 280 and 580 g. These test results not only prove that the spring fixed electrode can effectively extend the contact time, but also prove that the style of the fixed electrode is the deciding factor affecting the contact time of the high-G inertial switch.

A new three-axis inertial switch is proposed. The triangle-structured movable electrode is designed to improve the inertial switch’s dynamic response performance, especially the movable electrode’s dynamic stability performance. The static mechanical analysis indicated that the displacement of the movable electrode to the fixed electrode in the sensitive direction is the minimum when the acceleration is applied to this designed inertial switch. The dynamic simulation analysis showed that the threshold of the designed inertial is about 235 g. The threshold in the non-sensitive direction is about 240 g, 270 g, 300 g, and 350 g when the directions of applied acceleration deviate 15°, 30°, 45°, and 60° from the sensitive direction, respectively. These results indicated that the designed inertial could resist the impact in non-sensitive directions and improve the stability in sensitive directions. The prototype of the inertial switch was fabricated and tested successfully. The testing results indicate that the threshold of the fabricated inertial switch is about 219 g. The test results verify the dynamic stability performance of the designed inertial switch.

A mechanical trigger inertial micro-switch with spring stationary electrode is proposed and fabricated by surface micromachining. The elastic contact process and stability performance are evaluated through experimental tests performed using a drop hammer. The test results show that the contact time is about 110 μs and 100 μs when the threshold acceleration is 480 g and the overload acceleration is 602 g, respectively. The vibration process of the electrodes is explained through an established physical mode. The elastic contact process is analyzed and discussed by Finite Element Analysis (FEA) simulations, which indicated that the contact time is about 65 μs when the threshold acceleration is 600 g. At the same time, this result also proved that the contact time could be extended effectively by the designed spring stationary electrode. The overload acceleration (800 g) has been applied to the Finite-Element model in ANSYS, the contact process indicated that the proof mass contacted with stationary electrode three times, and there was no bounce phenomenon during contact process, which fully proved that the stable contact process can be realized at high acceleration owing to the designed elastic stationary electrode.

Estimating the threshold value of the microswitch is fundamental and important to many acceleration monitor systems. In this paper, we present a novel analysis of the dynamic behavior of the liquid metal droplet anchoring and bursting at the capillary burst valve in a microchannel. The number and configuration of intersecting lines play an important role in building the barrier pressure to balance the acceleration. Several design schemes of threshold microswitches based on liquid metal droplets that rely on the action of the intersecting lines were provided. This paper not only provides a novel dynamic insight for the establishment of barrier pressure for the capillary burst valve, but also offers a perspective into the design of the liquid metal droplet microswitch.

In this paper, we propose a novel design model for an inertial switch that utilizes metal droplets as the sensing element. The overall device model comprises three components: the substrate layer, the functional structure layer, and the cover layer, along with the liquid metal. The metal droplets within the liquid storage tank are drawn towards the fixed electrode due to inertial forces. When the acceleration exceeds a predetermined threshold, the metal droplet covers the fixed electrode, closing the switch and allowing current to flow through the external circuit. Conversely, when the acceleration load is removed, the metal droplet retracts to the liquid storage tank, disconnecting the fixed electrode. This design is characterized by its simplicity, low manufacturing cost, and stable dynamic response. To evaluate the threshold acceleration of the inertial switch, we developed a threshold evaluation equation through theoretical analysis and successfully fabricated an experimental prototype. Test results indicate that the threshold acceleration of the fabricated inertial switch is 0.76g, with a response time of 21 ms and a contact time of 10 ms. The overload test indicates that the device has excellent overload impact resistance and stable dynamic contact. Compared to traditional mechanical contact-type inertial switches, this research not only presents a new scheme for low-threshold inertial switches with a simple structure and low manufacturing cost, but also introduces the concept of deformable liquid metal electrodes into the field of inertial sensing for the first time, opening up a new technical path for applications such as consumer electronics and the Internet of Things that require low power consumption for triggering.