Design and Fabrication of Reliable Power Efficient Bistable MEMS Switch Using Single Mask Process
22 Jul 2020-IEEE\/ASME Journal of Microelectromechanical Systems (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 29, Iss: 5, pp 1225-1233
TL;DR: In this article, a bistable DC switch based on buckled beams and thermal actuation has been designed, fabricated and characterised, and the switch retains functionality even after 5 million switching cycles.
Abstract: A bistable DC switch based on buckled beams and thermal actuation has been designed, fabricated and characterised. The buckled beams, which require very low actuation force and provide a sufficiently large contact force, are designed based on a parametric study. U-shaped thermal actuators are designed to provide the actuation force with minimum electrical power. The compact switch is fabricated using a simple single mask process on a SOI wafer. The average switching power is measured to be 60 $mW$ , while the average switching delay is 350 ${\mu }s$ . The power-delay product of about $20~{\mu }J$ is the lowest reported so far for bistable MEMS switches based on thermal actuation. The switch retains functionality even after 5 million switching cycles. [2020-0026]
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TL;DR: In this article, the authors studied the limit point behavior of a double-clamped, initially curved beams coupled via a rigid truss at their respective centres, when subjected to a distributed electrostatic load.
9 citations
TL;DR: In this paper, a 3D digital actuator is used to realize planar motions of micro-objects, which could be implemented in several applications where micro-positioning tasks are needed such as micro-component manufacturing/assembly, biomedicine, scanning microscopy, etc.
Abstract: In this paper, a novel micro-positioning device based on a 3D digital actuator is presented. The proposed system allows realizing planar motions of micro-objects, which could be implemented in several applications where micro-positioning tasks are needed such as micro-component manufacturing/assembly, biomedicine, scanning microscopy, etc. The device has three degrees of freedom, and it is able to achieve planar motions of a mobile plate in the xy-plane at two different levels along the z-axis. It consists of a hexagonal mobile part composed of a permanent magnet that can reach twelve discrete positions distributed between two z-axis levels (six at each level). Two different approaches are presented to perform positioning tasks of the plate using the digital actuator: the stick-slip and the lift-mode approaches. A comparison between these two approaches is provided on the basis of the plate displacement with respect to different current values and conveyed mass. It was observed that for a current of 2 A, the actuator is able to displace a mass of 1.15 g over a distance of 0.08 mm. The optimal positioning range of the planar device was found to be ±5.40 mm and ±7.05 mm along the x- and y-axis, respectively.
3 citations
TL;DR: In this article , a double-layer electrothermal MEMS S&A device with a bistable mechanism is presented, which can drive the barrier to an arming position actively.
Abstract: Considering the safety of ammunition, safety and arming (S&A) devices are usually designed in pyrotechnics to control energy transfer through a movable barrier mechanism. To achieve both intelligence and miniaturization, electrothermal actuators are used in MEMS S&A devices, which can drive the barrier to an arming position actively. However, only when the actuators’ energy input is continuous can the barrier be stably kept in the arming position to wait for ignition. Here, we propose the design and characterization of a double-layer electrothermal MEMS S&A Device with a bistable mechanism. The S&A device has a double-layer structure and four groups of bistable mechanisms. Each bistable mechanism consists of two V-shape electrothermal actuators to drive a semi-circular barrier and a pawl, respectively, and control their engagement according to a specific operation sequence. Then, the barrier can be kept in the safety or the arming position without energy input. To improve the device’s reliability, the four groups of bistable mechanisms are axisymmetrically placed in two layers to constitute a double-layer barrier structure. The test results show that the S&A device can use constant-voltage driving or the capacitor–discharge driving to drive the double-layer barrier to the safety or the arming position and keep it on the position passively by the bistable mechanism.
2 citations
01 Oct 2008
TL;DR: In this paper, a latching RF MEMS switch has been fabricated in a multi-user polysilicon surface micromachining process using 5 V, 35 mA thermal actuation for < 500 mus to toggle between states and a compliant latching mechanism to hold the state in the absence of applied bias.
Abstract: A latching RF MEMS switch has been fabricated in a multi-user polysilicon surface micromachining process. The switch uses 5 V, 35 mA thermal actuation for < 500 mus to toggle between states and a compliant bistable latching mechanism to hold the state in the absence of applied bias. The switch, including probe pads, measures 1 mm2 and has <0.4 dB insertion loss, >25 dB return loss, and >75 dB isolation at 1 GHz. The switch has potential applications in low duty-cycle, low power RF tuning and switching applications.
2 citations
TL;DR: In this paper , a new structure for low-loss and high-isolation radio-frequency microelectromechanical systems (RF MEMS) switches is presented, which is composed of two actuators: an electrothermal actuator for actuation of the switch from OFF to ON state and an electrostatic actuator to hold the switch at ON state.
Abstract: A new structure for low‐loss and high‐isolation radio‐frequency microelectromechanical systems (RF MEMS) switches is presented. The high contact force of the switch leads to very small ranges for contact resistance which is the main constrain of DC‐contact RF MEMS switches. The contact resistance of the switch is 27 mΩ leading to negligible thermal noise which is one of the most important parameters for devices operating at RF front‐ends immediately after the antenna where there is not any active stage. The switch is composed of two actuators: an electrothermal actuator for actuation of the switch from OFF to ON state and an electrostatic actuator to hold the switch at ON state. The insertion loss, return loss, and isolation of the switch for frequencies below 70 GHz are −0.35, −20, and −10 dB, respectively. The contact force and contact resistance of the switch are 0.93 mN and 0.027 Ω, respectively. Electrothermal and electrostatic actuators require 0.91 and 50 actuation voltages, respectively. During the ON‐state, the power consumption of the switch is near zero. The low contact resistance and high‐isolation characteristics of the switch make it very suitable for mobile front‐ends.
1 citations
References
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TL;DR: In this article, a mechanically bi-stable, electrostatically actuated switch mechanism with a large active opening force and a small passive closing force was designed to fit the contact and opening force requirements of soft contact materials such as gold.
Abstract: This paper reports on a mechanically bi-stable, electrostatically actuated switch mechanism with a large active opening force and a small passive closing force, designed to fit the contact and opening force requirements of soft contact materials such as gold. So far, most microelectromechanical systems (MEMS) switch designs have been optimized for a large contact force without paying too much attention to the opening force. In the "conventional," most commonly used electrostatic microswitch concept, the force of the actuator is used to close the switch contacts, and the switch is opened by the passive restoring force of the deflected cantilever or membrane. This concept results in a large contact force, but the opening force is typically too small to overcome the contact adhesion force of soft metals, which makes this concept less suitable for contact materials such as gold with its low contact resistance at low contact forces. The switch concept presented in this paper is based on two cantilevers laterally moving by curved electrode actuators. The tips of the cantilevers are endowed with hooks which can be mechanically interlocked. In the latched state, the spring forces of the deflected cantilevers also act as the passive contact force between the switch contacts. The opening force is actively created by the curved-electrode actuators, which are utilized close to their best electromechanical operating point resulting in a maximum contact separation force. The theoretical discussion of the new concept as compared to conventional switch designs is supported by simulation results, measurements on fabricated devices, and by an analysis of exemplary switches published in the literature
51 citations
"Design and Fabrication of Reliable ..." refers background in this paper
...Bistability in laterally moving switches is achieved by either latching mechanism [4]–[6] or buckled beam [7]–[10]....
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TL;DR: In this article, an integrated V-beam actuator (VBA) is used as the only actuation component for switching between two stable states, which can be easily realized on a silicon-on-insulator wafer by using the inductively coupled plasma etching process with a single photomask.
Abstract: This letter presents a novel MEMS bistable device that requires only one independent driving source for switching between its two stable states. The proposed device employs a mechanically push-on-push-off mechanism consisting of two curved beam structures. An integrated V-beam actuator (VBA) is used as the only actuation component. The proposed device can be easily realized on a silicon-on-insulator wafer by using the inductively coupled plasma (ICP) etching process with a single photomask. Preliminary measurement results show that a 30-ms pulse of 7.2 V applied to the VBA can drive the device from the off state to the on state, and a 50-ms pulse of 7.2 V can release the device from the on state back to the off state. Transient displacement results measured by using a vibrometer are also provided.
26 citations
"Design and Fabrication of Reliable ..." refers background in this paper
...Bistability in laterally moving switches is achieved by either latching mechanism [4]–[6] or buckled beam [7]–[10]....
[...]
...The work is an extension of a bistable device reported earlier [10], [11]....
[...]
TL;DR: In this article, a latching RF MEMS switch has been fabricated in a multi-user polysilicon surface micromachining process using 5 V, 35 mA thermal actuation for 25 dB return loss, and >75 dB isolation at 1 GHz.
Abstract: A latching RF MEMS switch has been fabricated in a multi-user polysilicon surface micromachining process. The switch uses 5 V, 35 mA thermal actuation for 25 dB return loss, and >75 dB isolation at 1 GHz. The switch has potential applications in low duty-cycle, low power RF tuning and switching applications.
24 citations
"Design and Fabrication of Reliable ..." refers background or methods in this paper
...The actuation scheme used in the former [7] is electrostatic using comb drive, while bent beam thermal actuator is used in latter work [2]....
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...These switches are mainly used in low duty cycle, low power switching applications [2], where switch configuration should be maintained without power [3]....
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TL;DR: In this article, the authors presented closed-form design criteria for a push-on push-off bistable device, which consists of a V-beam actuator, two sets of double-curved beams, and a lever connecting the two set of beams.
Abstract: In this paper, we present closed-form design criteria for a microelectromechanical system push-on push-off bistable device. The design criteria, which were derived analytically, are expected to be useful for designers for rapidly designing devices with bistability and the push-on push-off capability. The aforementioned bistable device consists of a V-beam actuator, two sets of double-curved beams, and a lever connecting the two sets of beams. Spring stiffness ratio was derived as a criterion for determining the existence of bistability. The ratio between the long and the short arms of the lever was derived as the other criterion, and it was intended to be used for determining the conditions for push-on and push-off capabilities. Both criteria can be explicitly expressed in terms of the device dimensions and material properties. The derived design criteria were validated by experimental measurement results obtained for more than 100 different devices. [2015-0122]
10 citations
"Design and Fabrication of Reliable ..." refers background in this paper
...The work is an extension of a bistable device reported earlier [10], [11]....
[...]
TL;DR: In this paper, an improved design of an electrothermally actuated two-terminal bistable microswitch is presented, which is obtained by using a pair of arches, a V-beam electrothermal actuator and a novel initially retracting actuator.
Abstract: An improved design of an electrothermally actuated two-terminal bistable microswitch is the focus of this paper. The proposed design has bimodal bistability which is obtained by using a pair of arches, a V-beam electrothermal actuator, and a novel initially retracting actuator. All these elements are monolithically integrated in a single planar releasable layer. The salient feature of the design is the usage of only a single pair of electrodes to switch between ON and OFF states, even though there are two actuators. In order to reduce the stress, the two actuators are mechanically decoupled but are electrically coupled to satisfy the two-terminal actuation. The switch design is experimentally verified by realizing on a silicon-on-insulator (SOI) wafer using a single-layer micro-fabrication technique. An actuation voltage of 11.8 V with 200-ms pulse-width, drives the switch from OFF to ON state and a 50-ms pulse of the same voltage across the same terminals, brings it back. [2018-0293]
10 citations
"Design and Fabrication of Reliable ..." refers background in this paper
...A recent work on buckled beam based electro-thermally actuated bistable switch is presented in [9]....
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