Microactuator System Research Articles

Active Noise Control of Multirotor Advanced Air Mobility Vehicles

An active noise control technology is developed here to reduce the in-plane thickness noise associated with multirotor advanced air mobility Vehicles. The basic concept is that few actuators (e. g., microspeakers) are embedded into the blade surfaces. They emit a loading signal to cancel the thickness noise. This actuation signal is determined via the Ffowcs-Williams–Hawking (FWH) formula. We considered here two inline rotors, and we showed that the FWH-determined actuation signal can produce perfect cancellation at a point target. However, the practical need is to achieve noise reduction over an azimuthal zone, not just a single point. To achieve this zonal noise reduction, an optimization technique is developed to determine the required actuation signal produced by the on-blade distribution of embedded actuators on the two rotors. For the specific geometry considered here, this produced about 9 dB reduction in the in-plane thickness noise during forward flight of the two rotors. We further developed a technology that replaces using a point actuator on each blade by distributed microactuator system to achieve the same noise reduction goal with significantly reduced loading amplitudes per actuator.

Dielectric Elastomer Cooperative Microactuator Systems—DECMAS

This paper presents results of the first phase of “Dielectric Elastomer Cooperative Microactuator Systems” (DECMAS), a project within the German Research Foundation Priority Program 2206, “Cooperative Multistable Multistage Microactuator Systems” (KOMMMA). The goal is the development of a soft cooperative microactuator system combining high flexibility with large-stroke/high-frequency actuation and self-sensing capabilities. The softness is due to a completely polymer-based approach using dielectric elastomer membrane structures and a specific silicone bias system designed to achieve large strokes. The approach thus avoids fluidic or pneumatic compo-nents, enabling, e.g., future smart textile applications with cooperative sensing, haptics, and even acoustic features. The paper introduces design concepts and a first soft, single-actuator demonstrator along with experimental characterization, before expanding it to a 3 × 1 system. This system is used to experimentally study coupling effects, supported by finite element and lumped parameter simulations, which represent the basis for future cooperative control methods. Finally, the paper also introduces a new methodology to fabricate metal-based electrodes of sub-micrometer thickness with high membrane-straining capability and extremely low resistance. These electrodes will enable further miniaturization towards future microscale applications.

A Sperm-Based Autonomous Micro-Robot: First Step

Abstract The weakness of sperm motility arouses the interest of many researchers due to its effect on the success of fertilization cases in couples. In recent years, this has led to the emergence of new technologies such as controllable micro-motor systems which still under evolution. The previous works that concerned with the design of micro-motors in assisting of sperm for moving or change their direction, were not autonomous-based systems. Further, it is worth noting, designing an autonomous micro-robot that emulates sperm in size and behavior is a difficult challenge. Therefore, this paper presents the first step in designing this micro-robot, by drawing the physical structure of micro-robot based on figuring the biological structure of sperm and its behavior to complete the fertilization process. While the main objective is to design a Micro-actuator system, based on the piezoelectric technique for generating a forward thrust force of the micro-robot. The simulation of the proposed design has been conducted by the Solidworks platform and MATLAB, to examine the performance of the micro-actuator system, in which the results describe the requirement for achieving an actuation system.

Wireless Controlled Local Heating and Mixing Multiple Droplets Using Micro-Fabricated Resonator Array for Micro-Reactor Applications

This paper reported a wireless controlled micro-actuator system for rapid heating and mixing of multiple droplets using integrated arrays of micro-fabricated 2.5 GHz solid-mounted thin-film piezoelectric resonators (SMRs) and a millimeter-scale omnidirectional antenna. An equivalent circuit is proposed to analyze the mechanism of the heating, mixing of the SMR, and the wireless communication system. The heating and mixing rate can be tuned by adjusting the input power as well as the transmission distance between the transmitting antenna and the receiving antennas. A heating rate up to 3.7 °C per second and ultra-fast mixing of the droplet was demonstrated with the wireless microsystem. In addition, two types of circuits, H-shaped and rake-shaped, were designed and fabricated for parallel operating actuator array and controlling the power distribution with the array. Both uniform and gradient heating of the multiple droplets are achieved, which can be potentially applied for developing high-throughput wireless micro-reactor system.

Design and Fabrication of Compact MEMS Electromagnetic Micro-Actuator with Planar Micro-Coil Based on PCB

This paper reports a compact design of electromagnetically driven MEMS micro-actuator utilizing planar electromagnetic coil on PCB (Printed Circuit Board). The micro-actuator device consists of an NdFeB permanent magnet, thin silicon membrane and planar micro-coil which fabricated using simple standard MEMS techniques with additional bonding step. Two planar coils designs including planar parallel and spiral coil structure with various coil geometry are chosen for the study. Analysis of the device involves the investigation of electromagnetic and mechanical properties using finite element analysis (FEA), the measurement of the membrane deflection and functionality test. The measurement results show that the thin silicon membrane is able to deform as much as 12.87 µm using planar spiral micro-coil. Reasonable match between simulation and measurement of about 82.5% has been revealed. The dynamic response test on actuator driven by parallel planar coil shows that silicon membrane effectively deformed in 40 s for an input electrical power of only 150 mW. It is also concluded that planar parallel coil is considered for the simple structure and easy fabrication of the actuator system. This study will provide important parameters for the development of compact and simple electromagnetic micro-actuator system for fluidic injection system in lab-on-chip.

Proposal of a multiple ER microactuator system using an alternating pressure source

This paper proposes and develops a multiple ER microactuator system using an alternating pressure source for in-pipe working micromachines, medical microrobots, and so on. A hydraulic microactuator is known to have high power density but also has the drawback of requiring large piping space for the supply and return of the working fluid. In this study, an alternating pressure system with synchronized control valves and a single pipe was proposed. As the control valves, simple ER microvalves were employed. The ER microvalves control an electro-rheological fluid (ERF) flow through its apparent viscosity change due to the applied electric field. In addition, a pressure transmitter is inserted between the pressure source and the ER valves, and low viscosity fluid such as water is used to transmit the alternating pressure. The use of the low viscosity fluid can reduce the diameter of the connecting pipe due to the low pressure loss. The proposed set-up is composed of multiple ER microactuators and an alternating pressure source; each ER microactuator consists of a pressure transmitter, two ER microvalves and a hydraulic microactuator. As the proposed system has half the number of pipes, of smaller diameter, compared with conventional hydraulic microactuator systems, it is suitable for a multiple actuator system. In this study, for verification of the working principle of the proposed system, we fabricated a large model of the system which consists of an ER finger 13mm×10mm×33mm in size as a kind of ER microactuator and an alternating pressure source using a voice coil motor. Through experiments, we confirmed the tip displacement of 17mm for the 16mm-long movable part of the finger. Then, we fabricated a gripper using two ER fingers and confirmed its independent motion.

2203 高周波交流圧力源を用いた多自由度マイクロアクチュエータシステムの開発(センサ・アクチュエータ(2))

This paper presents a multi-DOF (degrees of freedom) microactuator system using a high frequency alternating-pressure source. The alternating flow from the pressure source is rectified by the synchronized active valves to drive plural hydraulic microactuators. To increase the position resolution and downsize the pressure source, the driving frequency was increased using high response piezoelectric elements. Thin piezoelectric valves and an alternating-pressure source were proposed and developed using piezoelectric bimorph disks. In addition, a 10 mm long bending rubber actuator with two chambers was fabricated and a system was constructed. The bending motion of the actuator was experimentally clarified.

Design and Characterization of High-Bandwidth, Resonance Enhanced Pulsed Microactuators: A Parametric Study

An extensive study on a microactuator that can generate high-momentum, high-frequency perturbations over a large bandwidth is presented in this paper. Such an actuator can potentially be used for the active control of various shear and boundary-layer flows that involve separation, mixing, and noise generation. The resonance enhanced microjet actuator described in this paper is a simple microfluidic system consisting of an underexpanded source jet flowing into a specially configured cavity integrated with multiple micronozzles, through which unsteady pulsed supersonic jets issue. The resonance frequency of these microjets could be varied over a large range (approximately 1–60 kHz) by changing the geometric and flow parameters of the microactuator system. Mean and unsteady properties of the microactuator are examined, including time-resolved flow visualizations and synchronous pressure and noise measurements; collectively, they provide a better understanding of the actuator dynamics. The present study also explores the design space and performance, as well as some of the design limitations of this actuator. Based on this parametric, a correlation is suggested that may be used for designing such actuators for various applications.

Integrated Electromagnetic Second Stage Microactuator for a Hard Disk Recording Head

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A slider with an integrated microactuator (SLIM) allows actuating a read-write element of a hard disk drive (HDD) in both the vertical direction allowing a flying height adjustment as well as in the lateral direction allowing a second stage actuation. The microactuator system consists of a pair of electromagnetic variable reluctance (VR) micro actuators. The microactuator system is fabricated using thin-film technology. Each actuator has a permalloy C-core carrying a two-layer spiral Cu coil with a total of 16 turns. The insulation materials are SU-8 (in the lateral direction) and Si<formula formulatype="inline"> <tex Notation="TeX">$_{3}$</tex></formula>N<formula formulatype="inline"> <tex Notation="TeX">$_{4}$</tex></formula> (in the vertical direction). The total size of one magnetic VR microactuator is 460 <formula formulatype="inline"><tex Notation="TeX">$\, \mu$</tex></formula>m<formula formulatype="inline"><tex Notation="TeX">$\, \times \,$</tex></formula>300 <formula formulatype="inline"><tex Notation="TeX">$\, \mu$</tex></formula>m<formula formulatype="inline"><tex Notation="TeX">$\, \times \,$</tex></formula>61 <formula formulatype="inline"><tex Notation="TeX">$\mu$</tex></formula>m. This paper discusses design considerations, presents the FEM simulation conducted, describes the fabrication technology, and provides experimental results. </para>

Modeling and Design of an Optically Powered Microactuator for a Microfluidic Dispenser

This paper presents systematic modeling and design of an optically powered piezoelectric microactuator for driving a microfluidic dispenser that could find a potential application in a retinal prosthesis. The first part of the paper treats a microactuator system comprised of a micron-scale piezoelectric unimorph integrated with a miniaturized solid-state solar cell. The microactuator design is tailored for driving a microfluidic dispenser to dispense a stored liquid chemical through its micron-sized outlet ports at a rate of about 1pl∕s when the integrated solar cell is irradiated by light at a power density of 3W∕m2, corresponding to the requirements of the potential application. The microactuator system design is accomplished by first obtaining analytical models for the solar cell characteristic behavior and the microactuator displacements and then combining them to obtain the key dimensions of the microactuator through a design optimization. An analysis of the performance characteristics of the microactuator and a finite element analysis validating the analytical model for the microactuator’s displacements and the peak stresses under the operating loads are presented. The latter part of the paper presents a design of a microfluidic dispenser utilizing the optically powered microactuator and satisfying the desired input/output requirements. An analytical model integrating various energy domains involved in the system, viz. opto-electrical, piezoelectric, mechanical and hydraulic, is derived for the liquid flow through the dispenser’s micron-sized outlet ports. Finally, the energetic feasibility of the microactuator design obtained for the specified input and output criteria is also discussed.

Magnetically-actuated bending-mode microactuators with excimer laser ablation

Bending-mode polyimide-based (PI) electromagnetic microactuators with different geometries were fabricated and tested. Fabrication of the electromagnetic microactuator consists of electroplated 10 μm thick Ni/Fe (80 : 20) permalloy on a PI diaphragm, high aspect ratio electroplating of a copper planar micro-coil, bulk micromachining, low-temperature bonding, and 248 nm excimer laser selective ablation. They were fabricated by a novel concept avoiding the etching selectivity and residual stress problems which occur during wafer etching. The magnetic field generated by the planar micro-coil was used to provide an external magnetic field (Hext) to interact with Ni/Fe on the PI diaphragm, by which a repulsive force can be induced to provide a large deflection angle. The deflection angle of the microactuator with different Hext values was measured. Preliminary results show that 82° can be obtained. In addition, to provide a high strength and low temperature bonding process for the microactuator system, a polymer-based photoresist with patternable characteristics was used as the adhesive bonding material. The bonding results for different photoresists are compared and discussed.

Piezoelectric Microactuators for Use in Magnetic Disk Drives

A head-slider drive dual-stage microactuator system for use in magnetic disk drives was developed. This microactuator system has a symmetrical structure and operation, and utilizes simple rectangular multilayered piezoelectric actuator devices. A prototype model with a pico slider and head suspension was tested and demonstrated. It exhibited a 0.8 µm displacement at a dc applied voltage of 30 V and a fundamental resonant frequency of over 20 kHz.

An investigation on technologies to fabricate magnetic microcomponents for miniaturized actuator systems

Soft magnetic yokes, cores, and poles, as well as permanent magnets are the potential magnetic components of an electromagnetic microactuator system. Depending on the requirements of the actuator, soft magnetic materials, hard magnetic materials or a combination of both have to be applied. Their design and fabrication as well as their integration into coil systems is one aspect of the Collaborate Research Center “Design and Fabrication of Active Microsystems” (Sonderforschungsbereich 516). The investigations presented in this paper cover alternative technologies for depositing various magnetic materials as well as their capability of being utilized for fabricating electromagnetic Microsystems. In the area of soft magnetic materials, the application of NiFe (Permalloy) in various compositions was investigated. Technologies utilized for their deposition were electroplating, sputtering, and gas flow sputtering. For fabricating rather thick soft magnetic micro structures with heights of up to 70 μm, electroplating is particularly well suited. In the area of hard magnetic materials, sputtering was applied for depositing Samarium-Cobalt (SmCo). Hereby, layers with a thickness of up to 50 μm with very good hard magnetic properties were deposited and patterned using wet chemical etching.

Control of polishing of diamond films using microactuation and an atmospheric pressure plasma

In this work, the diamond deposited by hot filament chemical vapor deposition (CVD) is polished using an atmospheric pressure plasma. In order to position the film relative to the plasma, a microactuator system is designed using a stack of domed piezoelectric actuators. A dynamic model based on the physical system is developed and the model parameters are measured experimentally. A system based on laser triangulation is used to measure the position of the diamond film relative to the plasma. Control techniques are used to reduce the oscillations during actuation and to eliminate the steady state positioning error. With the application of feedback control, the overshoot is reduced to 2% and the settling time is reduced to 0.3 s. A preliminary set of experiments is performed to relate process parameters to the final surface roughness of the diamond film. The parameters studied include the film's time of exposure to the plasma, the height of the film relative to the plasma, and the distance from the film to the center of the plasma. It is found that the optimum exposure time is 15 min and the reduction of surface roughness is greatest when the distance between the film and the plasma is at a minimum. The best results are obtained when the top of the film is even in elevation with the tip of the top electrode. The diamond film is translated laterally along the plasma. When feedback control is not used, there is no change in the surface roughness. With feedback control implemented, the surface roughness of the diamond film is reduced by 33%.

An electrostatic microactuator system for application in high-speed jets

The development of an electrostatic microactuator system for the study and control of high-speed jet flows is presented. The electrostatic actuator is 1.3 mm wide, 14 /spl mu/m thick and has a head that overhangs a glass substrate, intruding into the flow by 200 /spl mu/m. The actuator has been fabricated using a bulk-silicon dissolved-wafer process to increase device thickness for increased stiffness in the flow direction. Characterization of the new actuators demonstrated their ability to oscillate with amplitudes of up to 70 /spl mu/m peak-to-peak at resonant frequencies of 5 and 14 kHz. This is a very large motion at such high frequencies when compared to existing macro or micro mechanical actuators. The full actuator system was mounted around the exit of a high-speed jet using several sector-shaped PC boards. This enabled detailed examination of the ability of the actuators to withstand the flow environment and generate substantial flow disturbances. The results showed that the microactuators functioned properly up to jet speeds of 300 m/s while generating disturbances in the shear layer surrounding the jet comparable to those produced by other macro-scale methodologies.

A smart material microamplification mechanism fabricated using LIGA

A unique microamplification mechanism formed through the merging of smart material and microelectromechanical system concepts is presented. This microamplification device increases the useful actuation stroke of piezoceramic material through the amplification of piezoceramic strain. The technology demonstrated has utility as a microactuation mechanism for driving micropiezomotors, hearing aid transducers and precision optical switches. The microamplifier, approximately , is composed of electroplated nickel and was constructed using LIGA. An overview of microactuator system requirements and the advantages of scaling the flexure based amplifier illustrates the utility of the new device. The microamplifier is a radically scaled version of a mesoscopic mechanism. An analytical discussion of the operation is presented along with a finite-element analysis of the static and dynamic properties of the microlever. The analytical study is used to develop the operation principles and expected performance of the microamplifier. Experimental static and dynamic testing results are presented that confirm the analytical study. The mechanism has a mean amplification ratio of 5.48, an elastic stroke range of 8 m and a fundamental frequency of 82 kHz.

Structure and Mechanism of Microcapsule Pump Using Osmotic Pressure Actuator.

We propose a microcapsule pump which is one of the realizable and useful micromachines today. We show that the microcapsule pump produces a microflow from the microstorage tank of solution, unlike other pumps, which pumps out the liquid from the inlet to the outlet of the flow. The proposed microcapsule pump has the function of the microflow from the storage tank, depending on the environmental condition. For example, this microactuator system can be applied to drug delivery requiring a long time, such as insulin injection for diabetic patients, and other medical applications. This microcapsule pump structurally consists of an inlet with a semipermeable membrane, an outlet with a one-way valve and a storage tank controlled by osmotic pressure. The outflow side has a one -way valve that prevents backward flow of the solution from the outlet to the inlet. Since this pump is applied to medical science, it is of a very simple structure and easy to handle. It is possible that the outflow volume of internal solution and the rate of osmosis can be changed using semipermeable membranes with different properties. The salient feature of this proposed actuator is that an external driving power supply is not required in this microsystem. The size of the prototype of this microcapsule pump is 5 mm in diameter and 9.8 mm in length. Its weight is 0.7 g.