V-beam Actuator Research Articles

A novel single-actuator bistable microdevice with a moment-driven mechanism

This work presents a moment-driven bistable microdevice that requires only one actuator to switch between the device’s two stable states. The proposed device, which is a significantly improved version of our previous work, consists of two simple MEMS structures: a curved-beam structure and a V-beam actuator. Because the device is actuated by external moments, it consumes a smaller device area, and is less complex. In addition, the proposed device does not require latching mechanisms to lock the states. The closed-form design criteria for the proposed device were derived and validated with experimental measurement results. Transient bistable switching behaviors of the device were measured by using a vibrometer. Preliminary measurement results showed that the device can reliably switch between two stable states at 40 Hz with an actuation voltage of 10 V.

Efficiency enhanced novel 3T heads V-beam microactuator for low power applications

Structural Optimization and efficiency improvement of an electrothermal microactuator compared to its fundamental architectural design is reported in this paper. The principal component in the proposed device design is an electrothermal V-beam microactuator which is implemented to actuate a pre-stressed bistable curved beam, a switching element and thereby establishes a bistable MEMS switch. The proposed device is fabricated on SOI wafer with 10 µm thick device Si layer using SOIMUMPs(Silicon-On-Insulator Multi User MEMS Process) process with 3 masks. The optimized design provides 11.11% improvement in the actuation force and 8.81% increase in the axial displacement compared to the conventional V-beam actuator.

Design Criteria for a Push-On Push-Off MEMS Bistable Device

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]

Characterization of Thermal Expansion Coefficient of LPCVD Polycrystalline SiC Thin Films Using Two Section V-beam Actuators

In this paper we present the characterization of the coefficient of thermal expansion (CTE) of in-situ doped polycrystalline SiC thin films, obtained by low pressure chemical vapor deposition (LPCVD). The material is characterized using V-beam actuators on which the temperature coefficient of resistance (TCR) and the in-plane displacement versus current are measured. A CTE value of 4.3 ± 0.4 ppm/K is obtained in the temperature region of 20°C to 300°C. This value is used in a finite element modeling (FEM) simulation of vertical SiC-SiO2 bimorph beams. For an actuator length of 700 μm, width of 100 μm and layer thickness of 2 μm, a displacement up to 200 μm can be obtained.

V-Beam Thermal Actuator’s Performance Analysis Using Digital Image Correlation

This paper analyses the influence of the V-beam thermal actuator’s geometrical parameters on its mechanical behavior. Experimental measurements were performed using Digital Image Correlation (DIC), which is a gray scale value tracking algorithm that evaluates the position shift of a pixel between at least two images taken at different deformation stages. These results are compared to multi-physics simulation data obtained using Finite Element Analysis (FEA) as well as to analytical values based on the electro-thermal and thermo-mechanical presented models.

Analytical and Numerical Study on the Maximum Force Developed by a V-beam Thermal Actuator

Abstract The purpose of this paper is to determine and validate an analytical model that will serve as a starting point in the future design of micro-scale V-beam thermal actuators. The influence of its geometrical parameters on the output force was tested while also taking into account the deformation of the substrate. The finite element (FE) studies that were performed on virtual replicas of the V-beam thermal actuator led to the validation of the theoretical model.

A MEMS Bistable Device With Push-On–Push-Off Capability

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.

Design and System-Level Simulation of a Novel On-Chip Test Based on Macromodels

The methods of on-chip integrated testing have a wide application with the development of the study for MEMS materials properties measurement in microscale. A novel on-chip integrated micro-tensile testing system is designed through system-level simulation based on macromodels to measure the fracture strength and fatigue mechanical properties of polysilicon thin films. The structure of testing instrument consists of V-beam electrothermal actuator, differential capacitance sensor, supporting spring and specimen. The capacitance signal is sensed and controlled by a second sigma-delta modulator circuit. The analytic macromodel of polysilicon thin film specimen considering geometric nonlinearity and the numerical reduced-order model of V-beam electrothermal actuator based on Krylov subspace projection are created separately and described in the MAST hardware language. The mechanical structure dimension size and circuit components parameters are determined and optimized according to system-level simulation. The computing result has shown that the self-build macromodels and the on-chip integrated test system are efficient and reliable.

Nonlinear Transient Analysis for Large-Scale Dynamics of Microelectromechanical Systems with the MOR-PIM Method

Microelectromechanical Systems (MEMS) is difficult to take transient analysis due to the tight coupling between the multiple energy domains, typically nonlinear. An effective increment-dimensional precise integration method (PIM) combined with the model order reduction (MOR) technique based on Krylov subspace is present to solve large-scale nonlinear finite element dynamics systems. The numerical example of V-beam electro-thermal actuator is shown to demonstrate that the MOR-PIM method can achieve high precision and fast speed when solving the nonlinear dynamic equation with large-scale freedom.

A Silicon Platform With MEMS Active Alignment Function and Its Potential Application in Si-Photonics Packaging

A silicon (Si) platform, which consists of passive alignment structures (V-grooves), active microelectromechanical systems (MEMS) alignment components, mechanical locking mechanisms, and predeposited gold-tin soldering pads is developed to address the submicron accuracy assembly requirement of the discrete laser diode (LD) to a small core in-chip Si waveguide (WG). A 2-D in situ active alignment of a ball lens in LD-ball lens-Si-WG coupling system is presented here. The 1550-nm DFB LD and the passive Si-photonics chip are attached onto the platform, using flip-chip bonding process. The 2-D alignment of the ball lens is then achieved through the in-plane motion of the suspension arms and the specially designed V-groove. The position of the ball lens is subsequently fixed by the locking mechanism mechanically. MEMS electrothermal V-beam actuators, which can provide large force with a large displacement under a low driving voltage, i.e., >50 ?m at 25 V are employed in this platform. The effectiveness and stability of the arm locking function have been tested with a shift of <0.1 ?m after vibration testing (10g , 2 kHz). The integrated aligning and locking functions of the MEMS platform are also demonstrated through the LD-ball lens-Si-WG coupling system. These results show the potential of this MEMS platform in hybrid integrated Si photonics and applications that consist of LD-ball lens-Si-WG coupling system, e.g., the transmitter and transceiver.

Contoured thermal V-beam actuator with improved temperature uniformity

This paper presents a new design of a contoured thermal V-beam actuator having a more uniform temperature distribution over its length. It has widened segments on both sides, symmetrically placed around the actuator tip in the centre. The chosen fabrication process allows the shape of the polysilicon heater element to deviate from the actual actuator geometry. A modified contoured thermal V-beam actuator with a uniform heater cross-section along the actuator length is designed, fabricated, tested and compared to both a conventional thermal V-beam actuator and a contoured thermal V-beam actuator in which the heater geometry follows the geometry of the underlying structure. The improved actuator is electrically equal to the conventional V-beam actuator, but thermally and mechanically equal to the contoured V-beam actuator, which has proven to be very advantageous. A more uniform temperature distribution along the actuator length is achieved, allowing for a larger overall thermal expansion and therefore also a higher deflection at the same maximum temperature. In combination with a higher actuator stiffness compared to the conventional actuator the output work that can be obtained is significantly increased at the expense of only a slightly larger chip area. Compared to the contoured actuator, the output work of the improved contoured actuator has increased with almost 50%, without increase of required input power.

A novel 2 × 2 MEMS optical switch using the split cross-bar design

In this paper, a novel 2 × 2 MEMS optical switch is presented. The switch, which employs the proposed split cross-bar (SCB) design, intrinsically possesses advantages over typical 2 × 2 MEMS switches of traditional designs, such as the cross-bar design and the mirror-array design. In comparison to the cross-bar switches, the SCB switch does not have the constraint on the mirror thickness which affects fiber alignment significantly. In comparison to the mirror-array switches, the SCB switch requires fewer movable mirrors and thus gives better fabrication yield. The SCB device can be easily fabricated by employing inductively-coupled-plasma etching (ICP) on a silicon-on-insulator (SOI) wafer with one photo-mask. Electro-thermal V-beam actuators integrated with the bi-stable mechanisms are employed to move and latch the movable mirrors of the proposed device. The displacement of the movable mirrors is at least 60 µm under a driving voltage of 40 V. The optical performance and the dynamic response of the SCB switch are also investigated. The measured average insertion loss is less than −1.4 dB with a deviation of 0.08 dB. Also, the measured switching time is about 10 ms.

Variable optical attenuator using planar light attenuation scheme based on rotational and translational misalignment

In the last decade, extensive developments of microelectromechanical systems based thermal actuator and/or electrothermal actuators have been dedicated to the applications, such as data storage devices, relays and optical switches, etc. In this paper, we demonstrated a novel planar micromechanism comprising a tilted mirror driven by a V-beam electrothermal actuator via a link beam. This electrothermally driven tilted mirror can have static displacement with a motion trace including rotational and translational movement. The rotational and translational misalignment of reflected light spot toward the core of output port fiber will lead to light attenuation. In other words, the attenuation is controlled in terms of the position of tilted mirror depending on driving dc voltage. This new micromechanism has granted us a more efficient way to perform the light attenuation regarding to the other kinds of planar variable optical attenuators. These devices were fabricated by the deep reactive ion etching process and can reach 30-dB attenuation at 7.5 V driving voltage. The polarization dependant loss is less than 0.1 dB within the 30-dB attenuation region. The static and transient characteristics of devices operated at ambient room temperature environment show good repeatability and stability.

MOEMS variable optical attenuator with improved dynamic characteristics based on robust design

The design and preliminary data of a novel microoptoelectromechanical systems variable optical attenuator (VOA) driven by a pair of V-beam electrothermal actuators is described. This VOA deploys a face-to-face arranged pair of 45/spl deg/ tilted mirrors in front of two coaxially aligned lensed fibers to form retro-reflection planar light path for attenuation. The initial insertion loss is 0.7 dB at 1550 nm and the maximum dynamic range of attenuation is 50 dB, respectively. The polarization-dependent loss is measured as 0.15 dB at 20-dB attenuation. The dynamic attenuation deviation is less than /spl plusmn/0.36 dB at 20-dB attenuation with respect to 20-G shock of periodical mechanical vibration at 1 K Hz, in which it complies with requirements of the Telcordia GR1221 regulations.

Study of electrothermal V-beam actuators and latched mechanism for optical switch

We present new optical switch devices based on a bi-stable microelectromechanical structure driven by two sets of one-directional movable electrothermal V-beam actuators. In conjunction with the movement translation link structure, or T-shaped end of the switch body, and buckle springs, the first V-beam actuator set can drive the in-plane moving reflective shutter from one rest position to the second stable position, while the second V-beam actuator set is able to drive the reflective shutter back to the original rest position. The transmission state of the optical switch device could be one of these bi-stable positions, and the switching state will be the counter position. Thus, the bi-directional motion capability is realized by using a pair of V-beam actuator sets with opposite directions of motion. We have optimized the design of V-beam actuators according to the application requirements. The preliminary results prove the application feasibility.

Characterization of Bi-Stable Micromechanism Based on Buckle Spring and Electrothermal V-Beam Actuators

We present a novel bi-stable microelectromechanical structure driven by a pair of one-directional movable electrothermal V-beam actuators for applications need latch functions, like optical switch and relay. In conjunction with the T-shaped end and buckle spring, the first V-beam actuator set can drive the in-plane moving reflective mirror from transmission state to switching state, while the second V-beam actuator set is able to return the reflective mirror from position of switching state to position of transmission state. Thus the bi-directional motion capability is realized by using a pair of V-beam actuator sets with opposite moving direction. The preliminary results prove its application feasibility.