Rotary Micromotor Research Articles

All-fiber rotary micromotor based on laser-induced thermal convection

Micromotors based on fiber optical tweezers (OTs) hold exciting prospects for studying rotary motor proteins, observing the microscopic properties of fluids, and diagnosing diseases. In this paper, we report an all-fiber, OTs-based, rate-controllable, rotary micromotor using laser-induced thermal convection. The optical trapping force can stably trap a microparticle in water. The laser can heat a gold film on the fiber probe of the OTs to form a temperature gradient, leading to a water flow with a velocity gradient that continuously rotates the microparticle. Simulation results prove the feasibility of this method. In addition, experiments show that when the incident laser power is higher, the velocity gradient of water flow near the fiber probe is greater, and the microparticle rotates faster. The rotation rate varies from 12 to 80 rpm. This rotary micromotor has potential applications in microfluidic pumping, biopsy, micromanipulation, etc.

Low-Friction, High-Speed Rotary 3-Phase Micromotor Using the PolyMUMPS Process

We present the design and fabrication of an electrostatic side-drive micromotor that achieves the fastest operating speed reported for a device fabricated using the PolyMUMPS process. High-speed is obtained by optimizing the geometric parameters of the rotor and the stator electrodes, employing techniques to reduce friction in various regions of the micromotor and adopting multiple approaches to enhance the driving torque of the micromotor. The key geometrical parameters of the micromotor are determined through analytical modelling, bypassing intensive computational methods. The rotor diameter of the micromotor is $600~\mu \text{m}$ and has only 12 circular bearing supports each having radius of $3~\mu \text{m}$ . The rotary micromotor exhibits a speed of up to 7,875 rpm. [2019-0221]

Laser-induced rotary micromotor with high energy conversion efficiency

Light is a precious resource that nature has given to human beings. Converting green, recyclable light energy into the mechanical energy of a micromotor is undoubtedly an exciting challenge. However, the performance of current light-induced micromotor devices is unsatisfactory, as the light-to-work conversion efficiency is only 10 − 15 – 10 − 12 . In this paper, we propose and demonstrate a laser-induced rotary micromotor operated by Δ α -type photopheresis in pure liquid glycerol, whose energy conversion ratio reaches as high as 10 − 9 , which is 3–6 orders of magnitude higher than that of previous light-induced micromotor devices. In addition, we operate the micromotor neither with a light field carrying angular momentum nor with a rotor with a special rotating symmetrical shape. We just employ an annular-core fiber to configure a conical-shaped light field and select a piece of graphite sheet (with an irregular shape) as the micro-rotor. The Δ α -type photophoretic force introduced by the conical-shaped light field drives the rotation of the graphite sheet. We achieve a rotation rate up to 818.2 r/min, which can be controlled by tuning the incident laser power. This optical rotary micromotor is available for twisting macromolecules or generating vortex and shear force in a medium at the nanoscale.

Traveling Wave Rotary Micromotor Based on a Photomechanical Response in Liquid Crystal Polymer Networks.

The photomechanical response of liquid crystal polymer networks (LCNs) can be used to directly convert light energy into different forms of mechanical energy. In this study, we demonstrate how a traveling deformation, induced in a liquid crystal polymer ring by a spatially modulated laser beam, can be used to drive the ring (the rotor) to rotate around a stationary element (the stator), thus forming a light-powered micromotor. The photomechanical response of the polymer film is modeled numerically, different LCN molecular configurations are studied, and the performance of a 5.5 mm diameter motor is characterized.

Dynamic modeling of a bidirectional magnetoelastic rotary micro-motor

A dynamic model is presented for a novel magnetoelastic rotary micro-motor. Magnetoelastic excitation results in a rotary motor with comparatively large payload even under direct wireless actuation, but the resulting stator behavior is significantly different from that of prior micro-scale rotary motors. A parametric modal model is developed from conservation of momentum, a second order linear distributed stator and ballistic rotor motion. The modes and a pre-stressed finite element model are also described to support the parametric modal model. The typical simulated model output and parametric analyses are presented with important trends and behaviors of the micro-motor motion, including stochastic features of rotary and vertical motion, and experimental validation. The dynamics of the micro-motor under certain inputs and design parameters are also estimated by the model.

Three-Phase Electrostatic Rotary Stepper Micromotor With a Flexural Pivot Bearing

Electrostatic stepper motors, also known as synchronous variable-capacitance motors, operate by utilizing the electrical energy stored in the variable capacitances formed between the poles of their rotor and stator. We present the design, modeling, and experimental characterization of a three-phase rotary stepper micromotor that employs a flexural suspension of the rotor to avoid any frictional contact during operation, providing precise, repeatable, and reliable bidirectional stepping motion without feedback control. A monolithic micromotor with high-aspect-ratio poles and an integrated three-phase electrical network was fabricated in a standard single-crystal silicon wafer by combining vertical trench isolation and bulk micromachining. The experimental characterization of a prototype having a diameter of 1.4 mm has demonstrated a rotational range of 26° (±13°) at 75 V and a maximum speed of 1.67°/ ms. Half-stepping and microstepping operation modes were demonstrated with step sizes of 1/6° and 1/48°, respectively. The exceptional performance of the motor makes it suitable for use in hard-disk drives as a secondary stage actuator to maintain a constant orientation between the read/write head and the recording tracks.

Novel approach for microassembly of three-dimensional rotary MOEMS mirrors

We present a novel approach to construct 3-D 1×N rotary micromirrors, which are fundamental components in optical switching systems. A rotary micromirror consists of two microparts: a rotary micromotor and a micromirror. Both of the two microparts are fabricated with PolyMUMPs,TM (MEMSCAP, Research Triangle Park, North Carolina), a surface micromachining process. A sequential robotic microassembly process is developed to join the two microparts together to construct the 3-D device. To achieve high positioning accuracy and strong mechanical connection, the micromirror is joined to the micromotor using an adhesive mechanical fastener. The mechanical microjoint has self-alignment capability and provides a temporary joint between the two microparts. The adhesive bonding creates a strong permanent connection between the two microparts. The adhesive mechanical fastener does not require extra supporting plates to fix the micromirror, which simplifies the microassembly process and makes it possible to automatically assemble the rotary micromirror. A hybrid manipulation strategy, which includes pick-and-place and pushing-based micromanipulations, is utilized to assemble the micromirror onto the micromotor. The pick-and-place manipulation has the ability to globally position the micromirror with multiple degrees of freedom. The pushing-based manipulation can achieve high positioning accuracy. This novel approach provides great flexibility and high accuracy for assembling the complex micromirror.

Low-friction large step-size micromotor driven by a scratch-drive actuator with bounceback mechanism

This study presents a rotary micromotor with low-friction and large-step displacement driven by a scratch drive actuator (SDA) with bounceback driving mechanism. The present SDA device has a shorter plate and wider bushing compared to those of the existing SDA, resulting in a new electrostatic scratch-and-bounceback driving mechanism with larger stepping size. The new scratch-and-bounceback actuating mechanism markedly reduces the friction and damping effect between the SDA plate and the nitride insulator surface and eliminates effectively the sudden reverse rotation of SDA-based micro rotary motor. This investigation incorporated three design features (corners-rounded supporting-beam, flanged cover, and corrugated/ribbed/dimpled inside ring) into the structure of a SDA-based rotary micromotor to further decrease the rotating abrasion between the rotor inside ring and the cover, the anchor, and the inside rail. The bouncing SDA-based micromotors developed in this work (with 398 µm diam) were fabricated using the MEMSCAP® Poly-MUMPs process and achieved many improvements, including low friction, large stepping size (196 nm), small damping effect, and no sudden reverse rotation phenomenon (from dc to 25 kHz).

Design, Fabrication, and Characterization of a Rotary Micromotor Supported on Microball Bearings

We report the design, fabrication, and characterization of a rotary micromotor supported on microball bearings. This is the first demonstration of a rotary micromachine with a robust mechanical support provided by microball-bearing technology. A six-phase bottom-drive variable-capacitance micromotor (Phi = 14 mm) is designed and simulated using the finite-element (FE) method. The stator and the rotor are fabricated separately on silicon substrates and assembled with the microballs. Three layers of low-k benzocyclobutene polymer, two layers of gold, and a silicon microball housing are fabricated on the stator. Microball housing and salient structures (poles) are etched in the rotor and are coated with a silicon carbide film that reduces the friction without which the operation was not possible. A top angular velocity of 517 r/min, corresponding to the linear tip velocity of 324 mm/s, is measured at plusmn150-V and 800-Hz excitation. This is 44 times higher than the velocity previously demonstrated for linear micromotors supported on the microball bearings. A noncontact method is developed to extract the torque and the bearing coefficient of friction through dynamic response measurements. The torque is indirectly measured to be -5.62 plusmn 0.5 muN ldr m at plusmn150-V excitation which is comparable with the FE simulation results predicting -6.75 muN ldr m. The maximum output mechanical power at plusmn150 V and 517 r/min was calculated to be 307 muW. The bearing coefficient of friction is measured to be 0.02 plusmn 0.002 which is in good agreement with the previously reported values. The rotary micromotor developed in this paper is a platform technology for centrifugal micropumps used for fuel-delivery and cooling applications.

A Novel Piezoelectric Micro-Motor Using Multilayer Co-Firing Piezoelectric Ceramics

A novel rotary piezoelectric micro-motor (φ8mm×10mm) is proposed in this paper. Different from the conventional traveling wave ultrasonic motor using piezoelectric ceramic ring, four multilayer co-firing piezoelectric ceramic bulks (2mm×2mm×3mm) are used to generate vibration in the ring type stator. The layout and electric signals applied to the piezoelectric ceramic bulks are designed for the purpose of generating elliptical trajectories on the surface of the stator. The working mode of the prototype motor is simulated by the finite element method, and also measured by the Doppler Laser Vibrometer. The experimental results are in good agreement with simulation, which verifies the effectiveness of the finite element model. The prototype motor is driven at the low voltage of 12V under the frequency of 64.91 KHz.

Sliding mode-based microstructure torque and force estimations using MEMS optical monitoring

The determination of microstructure state is becoming of increasing importance for microelectromechanical system (MEMS) sensors and actuators. Sliding mode-based microtorque estimation for a rotary micromotor, assuming the availability of a MEMS optical monitoring data stream, is presented. The dynamic model of the rotating MEMS system and the electrostatic torque are identified. The technique uses the estimated position signal to approach the actual measured position signal, obtainable through optical monitoring, to simultaneously estimate the microtorque and load torque. The estimated microtorque and load torque are low-pass filtered to eliminate the switching behavior inherent in the sliding-mode estimator. The experimental setup of a lateral comb resonator with optical monitoring is presented and discussed. The simulation results of both electrostatic and load torque estimations are presented, as well as the experimental force estimation of a lateral comb resonator device.

A rotary electrostatic micromotor 1×8 optical switch

This paper describes a 1/spl times/8 rotary electrostatic micromotor optical switch fabricated using high-aspect-ratio micromachining technology to produce silicon or nickel components which are subsequently assembled to form a switch. The switch consists of a salient-pole micromotor with 1-mm-diameter 200-/spl mu/m-thick rotor that supports up to a 500-/spl mu/m-tall, 900-/spl mu/m-wide mirror. Typical switches were actuated at 50 V, operated for extended periods in room air, and found to have a rapid rotation with an average optical switching time between two neighboring fiber ports of 18 ms. Optical testing was performed at wavelength of 1310 nm in single- and multimode, and at 850 nm in multimode. The optical beam was propagated in free space with minimal divergence through the use of externally mounted collimating gradient-index lenses. With an aluminum coating, the mirror and external optics exhibited an input to output coupling loss as low as 0.96 dB in multimode and 2.32 dB in single-mode. Interchannel crosstalk was less than -45 dB.