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This paper presents the modelling, simulation, implementation and performance analysis of a novel electropermanent magnet based, bistable wireless microactuator for microvalves with milli Joule level energy consumption. The microactuator is powered wirelessly through inductive power transfer with energy buffered in a supercapacitor bank. Two millimeter sized rods of semi hard and hard magnetic materials are placed side by side with a current carrying coil around them. A 120 μs pulse of 15 V, 2.5 A is applied to the coil, which creates or eliminates the externally available magnetic field. The plunger is either attracted or repelled by this magnetic field to open or close the valve respectively. The theoretical analysis and modelling aligns well with the experimental results. The microactuator consume as little as 0.97–2.5 mJ of energy per actuation with no energy consumed between actuations. The actuation pulse width needs to be between 44 and 150 μs. The actuator is capable of delivering large deflections in the range of 0.3–2.5 mm, which is much greater than any of the state-of-the-art valves. The maximum holding force of the actuator is 220 mN and the attraction force varies between 9.8–98 mN. Energy consumption per actuation, actuation speed and deflection of the novel actuator are much better than any state-of-the-art microvalves, with the added advantages of wireless power and control. The momentary peak power requirement of 40 W is met by the supercapacitor energy buffer which stores 90 J per charge cycle, sourcing 37500 actuations. The energy efficiency and flexibility of this novel actuator can revolutionize the microactuator industry.

This paper presents a MEMS mirror actuated by four suspended electro-thermal bimorphs. The dimension of the mirror platform is 250 µm × 250 µm. The MEMS mirror design is created based on process modeling following strict fabrication constraints. Transient and dynamic characteristics of the micromirror device are analyzed using coupled electro-thermal-mechanical finite element models and schematic behavior models, respectively. The design is optimized using experimental design and response surface methodology to achieve large actuation displacement and small lateral shift. The micromirror device is shown to have a uniform mirror platform deflection, a large resonant frequency adequate to support the high servo bandwidth control, as well as an excellent linear relation between the micromirror deflection and the input electric power. The proposed electro-thermal MEMS mirror is capable of generating a mirror displacement of 8.25 µm under a 3 V pulse voltage input, and can potentially be used as a fine...

The paper presents a bionic study of the magnetic bacteria which includes: The structure of the magnetic bacteria ( Magnetospirillum magneticum ) with the of the magnetosomes(which represent the nanomagnetic particles in chains); The motility and the movements; with a biomecanomagnetic model; The identification of the micro and nanomanipulators for MEMS (microelectromechanical) applications. The authors present the microecanomagnetic structures of this manipulators: the geometric model (the linear and the angular movements), the engineering structures with the specific parameters (micro forces, speed, micro torque), and the electromagnetic driver modes of this manipulators.

In this paper, a composite hysteresis model is proposed for self-sensing feedback control of vanadium dioxide ( $\mathrm{VO_2}$ )-integrated microactuators. The deflection of the microactuator is estimated with the resistance measurement through the proposed model. To capture the complicated hysteresis between the resistance and the deflection, we exploit the physical understanding that both the resistance and the deflection are determined by hysteretic relationships with the temperature. Since direct temperature measurement is not available, the concept of temperature surrogate, representing the constant current value in Joule heating that would result in a given temperature at the steady state, is explored in the modeling. In particular, the hysteresis between the deflection and the temperature surrogate and the hysteresis between the resistance and the temperature surrogate are captured with a generalized Prandtl–Ishlinskii (GPI) model and an extended GPI (EGPI) model, respectively. The composite self-sensing model is obtained by cascading the EGPI model with the inverse GPI model. For comparison purposes, two algorithms, based on a Preisach model and an EGPI model, respectively, are also used to estimate the deflection based on the resistance measurement directly. The proposed self-sensing scheme is evaluated with proportional-integral control of the microactuator under step and sinusoidal references, and its superiority over the other schemes is demonstrated by experimental results.

The body is a very challenging environment for locomotion. The mechanical properties of intrabody fluids and tissues vary by location and time. In order to move an embedded biomedical device such as a deep brain stimulation electrode, one has to identify the properties of the environment and set the propulsive actuator's input accordingly. We developed a piezoelectric actuator for propelling a microrobot in cerebro spinal fluid or burrowing in the brain tissue parenchyma. The propulsion is created by the vibration of the beam at the resonance frequencies. The driving of the actuators is controlled by in situ multi-input multi-output system identification (SI) using part of the beam as sensor and part as actuator. In this study, we model the sensing of the device, present the SI method, the calculation of the input signals to achieve maximal propulsion, and we test the driving method experimentally. The microactuator is examined in 500-cP silicon oil and a 20-mm-long actuator can achieve 3-μN propulsive force.

SUMMARY We propose a 3-DOF inchworm-type microactuator that uses levitation generated by vertical vibration. The vertical vibration is created by a piezoelectric actuator. The inchworm typically consists of thrust elements and clamp elements. The proposed inchworm, however, does not use any clamp elements. Four levitation elements are connected with four thrust elements, which are stacked-type piezoelectric actuators. The levitation element consists of a mass, a piezoelectric actuator, and a plate. The vertical vibration of the piezoelectric actuator lifts the levitation elements, which eliminates any friction. By controlling the order of the deformation of the horizontal piezoelectric actuators and the vibration of the vertical piezoelectric actuators, the inchworm engages in linear and rotational motion. The levitation height and the linear and rotational displacement of the inchworm were measured. Experimental results demonstrated the feasibility of the proposed 3-DOF inchworm. The mechanism described in this paper is effective for a precision positioning system in a clean room.

This paper reports the development of a new two-axis micromechanical scanning transducer for handheld 3D ultrasound imaging. It consists of a miniaturized single-element ultrasound transducer driven by a unique 2-axis liquid-immersible electromagnetic microactuator. With a mechanical scanning frequency of 19.532 Hz and an ultrasound pulse repetition rate of 5 kHz, the scanning transducer was scanned along 60 concentric paths with 256 detection points on each to simulate a physical 2D ultrasound transducer array of 60 × 256 elements. Using the scanning transducer, 3D pulse-echo ultrasound imaging of two silicon discs immersed in water as the imaging target was successfully conducted. The lateral resolution of the 3D ultrasound image was further improved with the synthetic aperture focusing technique (SAFT). The new two-axis micromechanical scanning transducer does not require complex and expensive multi-channel data acquisition (DAQ) electronics. Therefore, it could provide a new approach to achieve compact and low-cost 3D ultrasound imaging systems, especially for handheld operations.

For maintenance microrobots for small diameter pipes in power plants and so on, a novel microgripper using divided-electrode type flexible electro-rheological valves (DE-FERVs) was proposed and developed. Each bendable finger consisted of the DE-FERV and a hydraulic rubber actuator and was several millimeters long. The DE-FERV had an axially divided parallel plate electrode pairs in a flexible tube. Each parallel plate electrode pair controlled the electro-rheological fluid (ERF) flow by changing the viscosity with the electric field. The DE-FERV had both high flexibility and sufficient pressure control range. The hydraulic rubber actuator had plural integrated walls inside to restrict its radial expansion and axially extended by the inner pressure controlled by the DE-FERV. A finger large model was fabricated and experimentally characterized. Then, a gripper having two fingers was constructed and the object handling was demonstrated.

In this study, a new piezoactuator-based prototype microactuator is proposed with a hydraulic displacement amplification system. A piezoactuator is used to deflect a diaphragm which displaces a certain volume of hydraulic fluid into a smaller-diameter piston chamber, thereby amplifying the displacement at the other end of the piston. An electro-mechanical model is implemented to estimate the displacement of a multilayer piezoelectric actuator for the applied input voltage considering the hysteresis behavior. The displacement characteristics of the proposed microactuator are studied for triangular actuation voltage signal. Results of the experiments and simulation of the displacement behavior of the stacked piezoactuator and the amplified displacement of the prototype actuator were compared. Experimental results suggest that the mathematical model developed for the new piezoactuator-based prototype actuator is capable of estimating its displacement behavior accurately, within an error of 1.2%.

This paper illustrates both thermal and mechanical analysis methods for displacement and contact force calculating of a novel sensing silicon-polymer microgripper when heat sources are applied by an electric current via its actuators. Thermal analysis is used to obtain temperature profile by figuring out a heat conductions and convections model. Temperature profile is then applied into the mechanical structure of the gripper's actuators to form the final equation of displacement and contact force of the jaws. Finally, the comparison among the calculation, simulation and actual measurement concludes that materialization methods are appropriate. Achieving the final equation of gripper's jaws displacement and contact force is a major step to optimize or reform this novel structure for different sizes to meet specific applications.

A sensing estimation scheme is presented that combines analog and threshold sensing on a piezoelectric microactuator for calibration of microscale inertial sensors. Using a variation of the Kalman filter, an asynchronous threshold sensor improves state estimates obtained from less reliable analog sensor measurements of microactuator motion. The resulting velocity estimates are compared with estimates without threshold sensing, and related to feasible calibration performance for gyroscopes. Results show that incorporating threshold sensors in a projected low-noise environment based on capacitive sensing will produce high-accuracy velocity measurements at certain fixed angles, with an approximately 80% reduction in angular velocity estimation error. Experimental testing with noisier, more variable piezoelectric sensing shows improved estimation accuracy at all velocities and positions when threshold detections are added. In simulation, the addition of feedback control is shown to further improve estimation accuracy.

The displacement of the central shuttle of a Z-shape chevron actuator can be calculated using a developed approach from other authors. Who demonstrated that the actuators with this geometry offer a larger displacement compared with V-shape actuators. Z-shape offers a larger stiffness and output force for the case of only one arm. This paper is focused on the optimization of the Z-shaped beams of a chevron actuator of eight beams, which seeks to increase the previously described response. The structure is designed in parametric solid modeling 3D software Autodesk Inventor, and simulated by finite element method in Ansys 15.0. These simulations were implemented considering several modifications on the length of the Z-shaped beams in order to choose the most appropriate length. The electric potential applied in all cases was from 0.2 V up to 5 V. The Z-shape length of the arms for the case of the optimized Z-shape actuator increases the shuttle’s displacement in approximately 50% compared to V-shape actuator, and 38% compare to the original Z-shape. Analytical adjusted approach is extremely matched with the simulations results. Length of the Z-shape beam is the determinant factor of the displacement. The low stiffness of the optimized Z-shape actuator (89% lower than the original V-shape and 58% compared to Z-shape) can allow its use as load sensor.

Pneumatic piston–cylinder actuators are commonly used in industry for a variety of automation and robotics applications. In order to suppress leakage, these actuators comprise seal rings which unfortunately introduce friction and affect the positioning accuracy and output force. This article investigates vibrations of the seal generated by integrated piezo actuators to reduce friction force. For this, two piezoelectric stacks are integrated in the cylinder and used to excite vibration modes. This concept was studied in a compact cylinder pneumatic actuator with a bore diameter of 5 mm and a stroke of 10 mm. Dry friction measurement shows a 52% reduction from the original friction force at a driving frequency of 18.29 kHz and vibration amplitude of 0.05 μm. In the wet friction experiments, the friction force can be reduced by 54% from the original wet friction with vibrations at amplitude of 0.04 μm.

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 13 mm × 10 mm × 33 mm 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 17 mm for the 16 mm-long movable part of the finger. Then, we fabricated a gripper using two ER fingers and confirmed its independent motion.

The spatial filter is capable of splitting the original desired trajectory of the dual-stage actuator (DSA) into two segments with arbitrary range, controlled by a linear motor (LM) actuator and a piezoelectric actuator (PZT) microactuator, respectively. Backstepping nonsingular terminal sliding mode control law with error transformation is designed to allow the tracking error of the actuator to converge and remain stable for a limited time, and reach the expected properties. Meanwhile, the adaptive exponential reaching law is added to the control law, which effectively improves the approach speed. An experiment is provided to demonstrate the effectiveness of the backstepping nonsingular terminal sliding mode control with error transformation in the DSA system and has a good trajectory tracking performance.

Executive mechanism of microactuator under electrostatic actuation is considering in the paper. Mechanism has presented in form of a flat cantilever, which has been bending under the influence of Coulomb forces. There are considering and resolving nonlinear equations, which defines the form of cantilever's bend. Obtained decisions are necessary to calculate characteristics of microactuator.

In our previous study, we have proposed a linearization point (LP) selection method based on a global maximum error controller for the trajectory piecewise-linear (TPWL) method. It has been demonstrated that this method has many advantages over other existing methods. In this paper, a more efficient version of this method is presented, which introduces a preliminary LP selection procedure and constructs projection matrix by the proper orthogonal decomposition (POD) method. Compared with the original method, the improved method takes much less time for extracting a reduced-order model (ROM) of similar quality and gets some other benefits (such as being easier to implement, having lower memory requirement, and enhanced flexibility). The effectiveness of the new method is fully demonstrated by a diode transmission line RLC circuit. And then, the method is applied to three more complicated microelectromechanical systems (MEMS) devices, which are a micromachined switch, an electrostatic micropump diaphragm, and a thermomechanical in-plane microactuator.

This paper presents the first studies on robust closed-loop deflection control of vanadium dioxide (VO $_{2}$ )-based microactuators using self-sensing. The deflection output of the microactuator is estimated by VO $_{2}$ resistance-based self-sensing through a high-order polynomial in order to eliminate the need for complicated external sensing mechanisms. An $H_\infty $ robust controller is designed and implemented for precision deflection control, where uncertainties produced by the hysteresis between the deflection and the temperature input and the error in the self-sensing model are accommodated. The performance of the robust controller is tested in experiments under step and multisinusoidal reference inputs and compared to that of a proportional–integral–derivative (PID) controller. The robust controller outperforms the PID controller with 36% and 18% less tracking error for the step and multisinusoidal reference responses, respectively. To further show the robust performance of the $H_\infty $ controller, a multisinusoidal reference tracking experiment with simulated white noise current signal is conducted, where the error using robust control is 34% less than that with PID control.

This paper formulates and solves control problems for nonlinear microsystems which comprise micro-electromechanical devices, micromachined transducers and microelectronics. We perform a consistent dynamic analysis and coherent designs with a minimum level of simplifications using high-fidelity mathematical models. The proposed methodology enables practical implementation for multi-input/multi-output systems due to overall conceptual consistency, design coherence, computational efficiency, algorithmic effectiveness and hardware simplicity. Various issues in nonlinear analysis and control are examined and experimentally verified substantiating design concepts for high-performance microsystems. The reported findings are demonstrated for a proof-of-concept closed-loop electrostatic microactuator.

A novel multi-degree-of-freedom (MDOF) microactuator was developed using a symmetric piezoelectric plate and a Ni–Co alloy micro-pusher element. A LIGA-like technique was employed to manufacture a Ni–Co alloy micro-pusher, which was then attached at the midpoint of the long side of a piezoelectric plate with dual electrodes to construct a symmetric piezoelectric pusher element (SPPE). The proposed approach integratese the concept of bricks and three different SPPE vibration modes were designed to develop a MDOF motion platform able to rotate a spherical device along three perpendicular axes. This MDOF microactuator consisted of a stator and a rotor. The stator was created from two mutually orthogonal sets of parallel SPPEs to form a MDOF motion platform, and the rotor was a spherical device. Experiments demonstrated the MDOF microactuator with working frequencies along the X, Y, and Z axes of 223.4 kHz, 223.2 kHz, and 225 kHz, respectively, and the respective rotation speeds reached 50 rpm, 52 rpm, and 180 rpm. This MODF microactuator may be used in a number of applications, such as sun-tracking systems for green energy harvesters and devices which can – eyeball-like - simultaneously and autonomously rotate along three axes for use in the biomedical field.

This paper presents two design optimization models for U-type electro-thermal microactuator. The result shows that the unequal arm model has better performance than the equal arm model. The models were solved by finite element analysis that are verified and comparison to publish paper and then are utilized in optimum design. The feature of presenting work contains temperature constraints to avoid the harm of operating object and decrease stress concentration on flexure. For handling design constraints, a method named double chromosome genetic evolution (DCGE) is developed in gene based algorithm. The idea of the presenting constrained strategy was inspired from the gene evolved by double helix chromosome of expressing certain traits. The constrained evolutionary algorithm proposed in this work is efficient and reliable. It can be integrated into a broad field of engineering optimization.

The article provides an overview of smart magnetic materials, including the essential properties of smart magnetic liquid materials and discusses the main operating modes of these materials. Theoretical calculations have disclosed changes in the behavior of the magnetorheological fluid determined under the influence of an external magnetic field of the microactuator. Finally, the paper presents the results and conclusions of the conduced experiments. Santrauka Darbe apžvelgtos išmaniosios magnetinės medžiagos, pateiktos pagrindinės išmaniųjų magnetinių skysčių charakteristikos, aptarti pagrindiniai šių medžiagų darbo režimai. Teoriniais skaičiavimais nustatyta mikropavaroje veikiančio magnetoreologinio skysčio savybių kitimo priklausomybė nuo išorinio magnetinio lauko. Darbe pateikti tyrimo metu gautų rezultatų grafikai ir išvados. Raktiniai žodžiai: magnetoreologinis skystis; mikropavaros; eksperimentinis tyrimas

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 ...

This work presents a latchable thermohydraulic microactuator for use in high-pressure valves, e.g. for oceanic sampling in missions of long duration. Mounted on a miniature submersible, it can be u ...

This paper presents the modelling and design analysis of V- and Z-shaped electrothermal microactuators. First, a comprehensive but concise closed-form multiphysical analytical model is developed to predict the output displacement and force of both V- and Z-shaped electrothermal microactuators operating either in vacuum or in air conditions. The analytical model is verified by finite element analysis and experimental testing. Then, a novel comparison benchmark is proposed for the design and analysis of the V- and Z-shaped microactuators. With the multiphysical model and comparison benchmark, comprehensive performance comparison and analysis of the V- and Z-shaped beams are performed with the aim of providing insight and guidance on selection and design of the two typical types of electrothermal microactuators. Finally, the application of the comparison model into the design analysis is demonstrated using a design example of an electrothermal microactuator, and the detailed investigation is conducted to examine the effects of the material properties and structural parameters on the microactuator outputs.

This paper presents a microactuator suitable for driving microfluidic valves for biomedical applications, which features zero-energy consumption between actuations with bistate latching. Wireless power transfer based on inductive magnetic field coupling and wireless control over a communication link across the same channel are proposed for the actuator. The actuation is based on electropermanent magnets which combine hard and semi-hard magnets to form an electrically triggered bi-stable latching. A practical actuator is designed and built, which demonstrated that only a short current pulse with a magnitude of 1.7A and width of 120μs is needed to toggle the actuator states. This leads to an energy consumption of 2.5mJ per actuation, and there is no need for power to maintain the states. In addition, a supercapacitor energy buffering circuit is developed to meet the peak current requirement for actuation using a low power rating inductive power supply. The final system is proven to be energy efficient, flexible, and safe for microfluidic applications.

One new type piezoeletric microactuator was designed in this paper, in order to improve the output characteristic of microactuator mechanism, piezoeletric analysis was performed and the optimization model was built with wb and α as design variables, the maximal output horizontal-plane displacement and the minimum vertical-plane displacement as objective. The final optimize result shows that the output horizontal-plane displacement of microactuator raises twice from 0.3µm to 0.6µm, meanwhile, the output vertical-displacement decreases from 0.093µm to 0.075µm by approximately 21 percent, the horizontal output characteristic has a remarkable improvement, so the optimal result can provide validity theoritical guidance for coming design strategy.

We apply nonsmooth multibody dynamics to describe the motion of a microrobot which is driven by the wireless resonant magnetic microactuator. We first analyze the robot using a simplified analytical model, which allows us to derive characteristic and nondimensional parameters that describe its dynamics. We then perform a numerical study to analyze the nonlinearities. We predict several nonintuitive phenomena, such as switching of the direction of the velocity with changing excitation frequency, and show that both erratic and controlled motions occur under specific conditions. Our numerical results are qualitatively consistent with experimental observations and indicate that previous speculations on the motion mechanism were incorrect. The modeling method is general and readily applies to other microrobots as well.

In order to design an electromagnetically driven microsystem serving as an ear implant to overcome amblyacousia, Finite Element Method (FEM) simulations were conducted. The system consists of three parts, an upper system part, a lower system part and a plunger. The design process included mechanical, electromagnetic, and thermal simulations. Based on the simulations a system layout was derived and the microactuator was fabricated on the basis of micro system technology processes in batch fabrication. The assembly of the system was performed on system level.

To reduce the surgical trauma to the patient, minimally invasive surgery is gaining considerable importance since the eighties. More recently, robot assisted minimally invasive surgery was introduced to enhance the surgeon's performance in these procedures. This resulted in an intensive research on the design, fabrication and control of surgical robots over the last decades. A new development in the field of surgical tool manipulators is presented in this article: a flexible manipulator with distributed degrees of freedom powered by microhydraulic actuators. The tool consists of successive flexible segments, each with two bending degrees of freedom. To actuate these compliant segments, dedicated fluidic actuators are incorporated, together with compact hydraulic valves which control the actuator motion. Especially the development of microvalves for this application was challenging, and are the main focus of this paper. The valves distribute the hydraulic power from one common high pressure supply to a series of artificial muscle actuators. Tests show that the angular stroke of the each segment of this medical instrument is 90°.

Electromagnetic microactuators discussed in this paper have been the topic of research during the last decade. Their fabrication is based on batch processes like photolithography and etching of copper and iron, which is deposited on substrates. Resulting from these microfabrication techniques and the small size of motors, the drive system designer faces a very different task when compared to conventional drive systems. Those differences have to be considered in the electromagnetic design of the microactuator itself, as well as in the power supply and the control of the drive. This paper presents an overview of design options for these components of a miniaturized drive system and discusses their advantages and disadvantages from a system point of view.

The inherent nonlinear characteristic between the electrostatic force and the applied voltage causes electrostatic microactuators to show the pull-in bifurcation phenomenon. Exploiting a closed-loop control for stabilizing the electrostatic microactuators in its full travel range is the primary objective in the control of such devices. In this paper, the dynamics of a transverse comb-drive electrostatic microactuator is established with considering the presence of parasitic and parametric uncertainties, and it is shown that the dynamics can be transformed into the third-order Brunovsky's canonical form. Then, a finite-time stabilizing controller is proposed for the third-order Brunovsky's canonical form systems, and the finite-time stability of the presented controller is shown. The robust finite-time stability of the controller under the parasitic and parametric uncertainties is also verified using numerical simulations.

In this work, the design modeling and testing of a compact and lightweight hydraulic actuation system is presented. Compared to similar compact actuators found in the literature, our system considerably increases the work density while maintaining an equivalent force-to-volume ratio. An analytical model that is able to accurately predict the quasi-static behavior of the actuator has been developed and experimentally validated. Existing models in the literature are able to predict only one performance parameter at a time – either the force or the contraction – from the imposed pressure and the exteroceptive measurement of the other performance parameter. Due to the design configuration chosen for the actuator, our analytical model is able to simultaneously predict both the force and the contraction by using theknowledge of two proprioceptive parameters of the fluid circuit (imposed volume and measurement of the pressure). The latter is particularly interesting, as it enables a precise estimate of the muscle behavior, only through the known parameters located at the fluid-transfer system, and not directly in the muscle, which is of crucial importance to simplify instrumentation and compactness of the actuation system. Four in-house fabricated muscles, with diameters down to 1.5 mm, have been tested with internal pressures up to 1.7 MPa. Theexperimental results showed in all cases a very good agreement with the predicted performances, thus validating the analytical model developed.

This paper presents a theoretical and experimental analysis of a biologically inspired balloon-type pneumatic microactuator. The operation principle of pneumatic balloon actuators (PBA's) is based on an asymmetric deflection of two PDMS layers with different thicknesses or different Young's moduli that are bonded together. A new analytical 2D model that describes the complex behavior of these actuators is presented and validated using both 3D FEM models and measurements. The actuators have dimensions ranging from 11 mm × 2 mm × 0.24 mm to 4 mm × 1 mm × 0.12 mm. Their fabrication is based on micromolding of PDMS, and can therefore easily be fabricated in high throughput. Measurements showed that the analytical model provides a qualitative description of the actuator behavior, and showed that the larger actuators are capable of delivering a 7 mm stroke at a supply pressure of 70 kPa and a force of max 22 mN at a supply pressure of 105 kPa. © 2011 Elsevier B.V. All rights reserved.

In this paper, we describe a model to simulate the dynamics of a microactuator. The model is based on a finite-element discretization which gives a monolithic description of the strong coupling between the mechanical, electrostatic, and fluid fields. It therefore allows the computation of the nonlinear dynamic response of a microactuator. The methodology also leads in a natural way to the fully coupled linearized equations so that computing vibration behavior becomes feasible. In this paper, we also show how the model can be reduced in order to significantly decrease the computation costs while retaining a good accuracy even when nonlinear effects are significant. The proposed method is validated for a microbridge for which measurements found in literature were used.

Realizing a structure that allows integration of actuation and sensing components operating at identical frequency is critical from functional standpoint of resonant microgyroscope. This paper presents the design and experimental test results of a compliant nickel structure for a microgyroscope. The device consists of three suspended proof masses supported by in-plane flexures anchored to the substrate thereby enabling to realize distinct driving and sensing components. Chevron-shaped beams driven electrothermally were employed for actuating drive component while parallel electrostatic combs were employed for sensing the Coriolis force induced rotation. Experimental investigation of the dynamic performance of the actuator and sensor structures revealed that their operating frequencies are very close (within 1%) thereby enabling to realize resonant microgyroscope with increased sensitivity. Comparison of the experimental results with the predictions made by analytical and finite-element models agreed well within 15%. Design guidelines for realizing microgyroscope with improved performance were briefly discussed highlighting the challenges associated with the frequency tuning.

This paper investigates the development of miniature McKibben actuators. Due to their compliancy, high actuation force, and precision, these actuators are on the one hand interesting for medical applications such as prostheses and instruments for surgery and on the other hand for industrial applications such as for assembly robots. During this research, pneumatic McKibben actuators have been miniaturized to an outside diameter of 1.5 mm and a length ranging from 22 mm to 62 mm. These actuators are able to achieve forces of 6 N and strains up to about 15% at a supply pressure of 1 MPa. The maximal actuation speed of the actuators measured during this research is more than 350 mm/s. Further, positioning experiments with a laser interferometer and a PI controller revealed that these actuators are able to achieve sub-micron positioning resolution.

The undamped dynamic response of step-voltage driven parallel-plates, cantilever, and fixed–fixed type electromechanical switches is numerically investigated. In each case, application of energy technique yields the threshold values of the amplitude and the applied voltage beyond which the oscillatory motion of the movable electrode ceases to exist. These critical values are identified as the dynamic pull-in parameters of the corresponding microactuator model. For all three microactuator configurations, empirical expressions for the switching time and oscillation period are developed. These empirical relations are applicable over a wide range of applied voltage, and the estimates obtained using the proposed empirical relations correlate very well with the previously published results. Furthermore, the phase portraits of these actuators have been thoroughly investigated in order to examine the role of static pull-in point in a dynamic setting and also to propose the design rules to build faster microswitches.

A new type of cylindrical ultrasonic linear microactuator (CULMA) is introduced. The traveling wave generation condition in the stator is presented, which was confirmed using simulation and experimentation. The design and fabrication process to develop the stator is described. The stator was successfully fabricated using metallic glass and a sputtering method, and the vibration of the prototype matched the simulation results. When the driving frequency is at 626 kHz, the traveling wave in the stator was observed. Loaded with a pipe slider, the slider movement was experimentally demonstrated and the motion measured with 26 mm/s in peak speed. This paper presents a traveling wave generation method in a CULMA which would also available in other microactuators or MEMS-scale ones.

This paper presents two innovative driving methodologies using a magnetically driven microtool (MMT) for precise cell manipulations and automation systems. First, magnetic analysis has been conduct...

In this study the effects of unaccounted modal dynamics within the control scheme of an electrostatic micro-actuator (µ-A) are presented. The µ-A is composed of a µ-capacitor, whose one plate is clamped on the ground whereas its other plate is floating on the air. The dynamic model of the µ-A allows both lateral and angular movements of the upper plate. The feedback controller is designed based on the single-mode (lateral) linearised model. The reduced non-linear model (RnM) is linearised at multiple operating points, and the designed proportional–integral–derivative (PID)-controller, tuned via linear matrix inequalities (LMIs)-theory, stabilises all linear modes within the polytopic defined by the vertices of the linearised systems. The overall scheme comprises: (a) a feedforward controller that stabilises the µ-A around its nominal operating points and (b) a robust PID controller that handles deviations from the operating points. The resulting overall control scheme is applied to the non-linear (bimodal structure) of a µ-A, and the simulation results derived are used to investigate the efficacy of the suggested control architecture.

A novel multidegree-of-freedom (MDOF) eyeball-like microactuator was developed using a symmetric piezoelectric plate and an Ni-Co alloy micropusher element. A LIGA-like technique was employed to manufacture an Ni-Co alloy micropusher with a Vickers hardness value of 550, which was then attached at the midpoint of the long side of a piezoelectric plate with dual electrodes to construct a symmetric piezoelectric pusher element (SPPE). The research integrated the concept of LEGO bricks, and three different vibration modes of the SPPE were designed to develop a high-power MDOF motion platform, which was able to rotate a spherical charge-coupled device (CCD) along three perpendicular axes. This MDOF eyeball-like microactuator consisted of a stator and a rotor: The stator was created from two mutually orthogonal sets of parallel SPPEs to form an MDOF motion platform, and the rotor was a spherical CCD. The experiment demonstrated high-power MDOF eyeball-like microactuator working frequencies along the X-, Y-, and .Z-axes to be 223.4, 223.2, and 225 kHz and the rotation speeds to reach 50, 52, and 180 r/min, respectively, at a driving voltage of 30 Vpp. The volume ratio of rotor to stator was 20.32, and this design can therefore drive a rotor of a volume greater than ten times that of the stator. In addition, the driving voltage was proportional to the rotation speed; hence, when the rotor diameter was increased or the spherical rotor weight reduced, the rotation speed increased. In the future, this MODF eyeball-like microactuator may be used for a number of applications, such as sun-tracking systems for green-energy harvesters and eyeball-like devices for use in the biomedical field.

This study addresses an optimal dual-stage actuator (DSA) servo design in a discrete-time domain. Maximising the cooperation of a voice coil motor and a microactuator (MA), the authors design a discrete-time fixed-order DSA control system. The controller is applied to a disk drive with DSAs, and experimental results demonstrate remarkable improvements in track seek in the MA range as well as in track follow. It is shown that the optimal control system, with the interaction between the two actuators being minimised, delivers exemplary responses in a disk drive test, despite its minimum controller order.

A key point for microrobots is represented by the actuation system, which enables them to move and manipulate objects, if required. In the field of mechatronic medical micro-instruments a micromotor could be used for the actuation of endoscopes lenses and in powered laparoscopic tools, for examples micro-grippers or micro-scissors, drug delivery micro-pumps and endoscopic intra-corporeal autonomous capsules. The size range of interest goes from centimetres down to hundreds of microns. Scaling down the overall dimensions of robots, traditional actuators are no longer feasible and it becomes essential to employ innovative systems. In this paper the optimization of an existing wobble micromotor is presented and its implementation as microactuator for biomedical devices has been demonstrated. The Finite Element Method (FEM) analysis has been applied on a variable reluctance wobble motor ( Φ 5 mm × 5 mm) in order to evaluate all the electric and magnetic quantities necessary for the optimization of the micromotor geometry and performances and to compute its electromechanical characteristic. Thanks to its small size, the micromotor has been assembled inside swallowable modules, both in single and in twin configuration. Motor's simple structure and low cost opens a very wide market where the actuator could be commercialized, as for example consumer electronics, mechatronic medical micro-instruments, robotics, micromanipulators, dosing systems and mobile robots.

In this work, the nonlinear vibration characteristics of bimorph giant magnetostrictive thin film (GMF), TbDyFe/PI/SmFe, are measured and analyzed, firstly. Thereafter, by employing the primary resonance and superharmonic resonance performance of GMF cantilever, and simulating the ostraciiform locomotion of boxfish, an in-pipe wireless swimming microrobot is developed, whose caudal fin is fabricated by GMF microactuator. On the basis of the equivalent load model of magnetostrictive effect of GMF, the governing equations for swimming microrobot are established and solved by the method of multiple scales. Experiments on the swimming characteristics of this GMF microrobot in gasoline pipe show that the microrobot can swim at a mean speed of 4.67 mm/s with the external magnetic field driving frequency of 4.7 Hz, which is close to the first primary resonance frequency in gasoline. Besides, the mean swimming speed can reach 2.8 mm/s with the external magnetic field driving frequency of 2.4 Hz, which is close to the superharmonic resonance frequency of order two of GMF cantilever actuator in gasoline.

A novel design of a microelectromechanical systems (MEMS) control moment gyroscope (MCMG) was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor and gimbal, the coupling between which is based on the Coriolis effect and will cause a torque output in the direction perpendicular to the two vibrations. The angular rotor vibration was excited by the in-plane electrostatic rotary comb actuators, while the angular gimbal vibration was driven by an out-of-plane electrostatic parallel plate actuator. A possible process flow to fabricate the structure was proposed and discussed step by step. Furthermore, an array configuration using four MCMGs as an effective element, in which the torque was generated with a phase difference of 90 degrees between every two MCMGs, was proposed to smooth the inherent fluctuation of the torque output for a vibrational MCMG. The parasitic torque was cancelled by two opposite MCMGs with a phase difference of 180 degrees. The designed MCMG was about 1.1 cm × 1.1 cm × 0.04 cm in size and 0.1 g in weight. The simulation results showed that the maximum torque output of a MCMG, the resonant frequency of which was approximately 1,000 Hz, was about 2.5 × 10-8 N∙m. The element with four MCMGs could generate a torque of 5 × 10-8 N∙m. The torque output could reach a magnitude of 10-6 N∙m when the frequency was improved from 1,000 Hz to 10,000 Hz. Using arrays of 4 × 4 effective elements on a 1 kg spacecraft with a standard form factor of 10 cm × 10 cm × 10 cm, a 10 degrees attitude change could be achieved in 26.96s.

We discuss the use of a flat-plane slider for a surface acoustic wave (SAW) motor. For stable driving, the SAW motor requires a silicon slider with many microprojections on its surface. Previously,...

In this paper, the effect of material and dimensional uncertainties on performance of electrothermal microactuator is investigated. A simple and efficient uncertainty analysis method is used based on direct linearization method; also uncertainty analysis is performed by creating second-order metamodel through Box-Behnken design and Monte Carlo simulation. The results demonstrate how these uncertainties affect the microactuator tip deflection by confidence limit bands. The standard deviations of tip deflection obtained by these two probabilistic methods are very close.