The Analysis of the Influence of Threshold on the Dynamic Contact Process of a Fabricated Vertically Driven MEMS Inertial Switch.

Wenguo Chen,Dejian Kong,Huiying Wang,Shulei Sun,Rui Wang

doi:10.3390/mi10110791

Wenguo Chen, Dejian Kong + Show 3 more

Open Access

https://doi.org/10.3390/mi10110791

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Abstract

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.

Highlights

The MEMS inertial switch, as a passive device, is widely used in Internet of Things (IoT) systems, in areas where the power supply is limited, which has become a research hotspot in recent years due to its superior performance [1,2,3,4]
Contact time is an important factor affecting the performance of inertial switches, where short contact times of the output signal will lead to signal processing difficulties
Through the above simulation analysis, the relationship between the contact time, response time, and the design threshold of the inertial switch is revealed, and a solution to prolong the contact time of the high-G-value inertial switch is proposed through the spring fixed electrode structure

Summary

Introduction

The MEMS inertial switch, as a passive device, is widely used in Internet of Things (IoT) systems, in areas where the power supply is limited, which has become a research hotspot in recent years due to its superior performance [1,2,3,4]. In the previous experimental results [11], we confirmed that the supported cross beams used as a fixed electrode did have the effect of extending the contact time compared to the rigid body without elasticity. The results explained why the supported beam could not extend the contact time in the application of the high-threshold inertial switch. Based on the influence rules, a high-G (e.g., ath ≥ 500 g) design scheme, which can effectively prolong contact time, was proposed. The test result indicated that the proposed inertial switch with the spring fixed electrode could prolong the contact time when the design threshold was 500 g

Designing Schemes

Fabrication Prototype

Test and Analysis

Conclusions