Latching ultra-low power MEMS shock sensors for acceleration monitoring

Currano, Luke J.; Bauman, Scott; Churaman, Wayne A.; Peckerar, M.; Wienke, James; Kim, Seokjin; Yu, Miao; Balachandran, Balakumar

doi:10.1016/j.sna.2008.06.009

Cited by 52 publications

(26 citation statements)

References 6 publications

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“…MEMS inertial switches can be categorized into two kinds in terms of the contact mechanism: (1) The latching shock sensor, as shown in Fig. 1a, where the latch on the proof mass will engage the mating piece anchored to the substrate (Whitley et al 2005;Currano et al 2008). It provides a solution to ultra-low power acceleration monitoring with the potential to ''wake up'' other sensing circuitry after a shock event occurs.…”

Section: Introductionmentioning

confidence: 99%

Dynamic simulation of a contact-enhanced MEMS inertial switch in Simulink®

et al. 2011

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A novel contact-enhanced design of MEMS (micro-electro-mechanical system) inertial switch was proposed and modeled in Simulink Ò . The contact effect is improved by an easily realized modification on the traditional design, i.e. introducing a movable contact point between the movable electrode (proof mass) and the stationary electrode, therefore forming a dual mass-spring system. The focus of this paper is limited to a vertically driven unidirectional one for the purposes of demonstration, but this design concept and Simulink Ò model is universal for various kinds of inertial micro-switches. The dynamic simulation confirmed the contact-enhancing mechanism, showing that the switch-on time can be prolonged for the dynamic shock acceleration and the bouncing effect can be reduced for the quasi-static acceleration. The threshold acceleration of the inertial switch is determined by the proof mass-spring system's natural frequency. Since the inertial switches were fabricated by the multilayer electroplating technology, the proof mass thickness were assigned two values, 100 and 50 lm, in order to get threshold levels of 56 and 133 g respectively for the dynamic acceleration of half-sine wave with 1 ms duration. Other factors that influence the dynamic response, such as the squeeze film damping and the contact point-spring system's natural frequency were also discussed. The fabricated devices were characterized by the drop hammer experiment, and the results were in agreement with the simulation predictions. The switch-on time was prolonged to over 50 ls from the traditional design's 10 ls, and could reach as long as 120 ls. Finally, alternative device configurations of the contact-enhancing mechanism were presented, including a laterally driven bidirectional inertial switch and a multidirectional one.

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Section: Introductionmentioning

confidence: 99%

Dynamic simulation of a contact-enhanced MEMS inertial switch in Simulink®

et al. 2011

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“…Microsystems for the passive detection of acceleration thresholds by ratcheting have been published so far [1][2][3][4][5][6][7]. Their development was motivated by data generation using the energy supplied by an event itself and self-storage of the detected event over an arbitrary long time period.…”

Section: Introductionmentioning

confidence: 99%

“…The reported systems are mainly characterized by one or two stable positions of a spring-coupled inertial mass [1,[3][4][5][6] and many of the solutions are not resettable [1,2,4,7]. In [2], a microsystem featuring five ratcheting positions is presented.…”

Section: Introductionmentioning

confidence: 99%

“…Using the microsystem five different rotational acceleration thresholds between 390g and 1400g were measured. The passive accelerometers presented in [3,5,6] feature two stable latching positions whereat the change of the stable position could act as a wake-up switch for a post-line conventional accelerometer that could supply detailed information as course or length of the critical event.…”

Section: Introductionmentioning

confidence: 99%

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A passive microsystem for detecting multiple acceleration events beyond a threshold

Mehner

Weise

Schwebke

et al. 2015

Microelectronic Engineering

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“…Sensors could also be placed on vehicles, buildings, or bridges [3][4][5] to monitor impacts or seismic activity. Reports have been made on a variety of low power or zero power accelerometer designs, often involving MEMS structures and monitoring circuitry built on VLSI chips [6][7][8][9]. While a macroscopic bistable design cannot be readily fabricated on a silicon substrate, it can be integrated with RFID sensors for remote, zero power sensing of acceleration events [10].…”

Section: Introductionmentioning

confidence: 99%

Stress relaxation insensitive designs for metal compliant mechanism threshold accelerometers

Vilorio

Stark

Hawkins

et al. 2015

Sensing and Bio-Sensing Research

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a b s t r a c tWe present two designs for metal compliant mechanisms for use as threshold accelerometers which require zero external power. Both designs rely on long, thin flexures positioned orthogonally to a flat body. The first design involves cutting or stamping a thin spring-steel sheet and then bending elements to form the necessary thin flexors. The second design uses precut spring-steel flexure elements mounted into a mold which is then filled with molten tin to form a bimetallic device. Accelerations necessary to switch the devices between bistable states were measured using a centrifuge. Both designs showed very little variation in threshold acceleration due to stress relaxation over a period of several weeks. Relatively large variations in threshold acceleration were observed for devices of the same design, most likely due to variations in the angle of the flexor elements relative to the main body of the devices.

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Latching ultra-low power MEMS shock sensors for acceleration monitoring

Cited by 52 publications

References 6 publications

Dynamic simulation of a contact-enhanced MEMS inertial switch in Simulink®

Dynamic simulation of a contact-enhanced MEMS inertial switch in Simulink®

A passive microsystem for detecting multiple acceleration events beyond a threshold

Stress relaxation insensitive designs for metal compliant mechanism threshold accelerometers

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