Development of Microactuators Based on the Magnetic Shape Memory Effect

The giant magneto-strain effect in Ni-Mn-Ga alloys is particularly attractive for actuator applications. Two different approaches are being pursued to develop MSM microactuators. To observe large deflections of Ni-Mn-Ga microactuators, the material should be exhibiting low twinning stress and large magnetic anisotropy. In addition, design rules and boundary conditions for operating the Ni-Mn-Ga actuator material are having significant importance for evolution of performance characteristics

High-Performance Shuffle Motor Fabricated by Vertical Trench Isolation Technology

Shuffle motors are electrostatic stepper micromotors that employ a built-in mechanical leverage to produce large output forces as well as high resolution displacements. These motors can generally move only over predefined paths that served as driving electrodes. Here, we present the design, modeling and experimental characterization of a novel shuffle motor that moves over an unpatterned, electrically grounded surface. By combining the novel design with an innovative micromachining method based on vertical trench isolation, we have greatly simplified the fabrication of the shuffle motors and significantly improved their overall performance characteristics and reliability. Depending on the propulsion voltage, our motor with external dimensions of 290 μm × 410 mm displays two distinct operational modes with adjustable step sizes varying respectively from 0.6 to 7 nm and from 49 to 62 nm. The prototype was driven up to a cycling frequency of 80 kHz, showing nearly linear dependence of its velocity with frequency and a maximum velocity of 3.6 mm/s. For driving voltages of 55 V, the device had a maximum travel range of ±70 μm and exhibited an output force of 1.7 mN, resulting in the highest force and power densities reported so far for an electrostatic micromotor. After five days of operation, it had traveled a cumulative distance of more than 1.5 km in 34 billion steps without noticeable deterioration in performance.\u

Dynamic modeling and characterization of magnetic hybrid films of polyvinyl butyral/iron oxide nanoparticles (PVB/Fe₂O₃) devoted to microactuators.

This thesis was accomplished in a dual-degree modality between the consolidated group of Synthesis and Characterization of Materials ꟷFacultad de Ingeniería Mecánica y Eléctrica (FIME), Universidad Autónoma de Nuevo León (UANL), México, and the research group of Methodologies for Automatic Control and for Design of Mechatronic Systems (MACS), department of Automatic Control and Micro-Mechatronic Systems ꟷ FEMTO-ST institute, Université Bourgogne Franche-Comté (UBFC), France

Micromechanisms for Laser Phonosurgery : A Review of Actuators and Compliants Parts.

International audiencePhonosurgery has to do with a surgical procedure, performed with an aim to enhance the voice. Common anomalies of the vocal fold includes a wide variety of pathologies such as nodules, polyps, cysts, and cancer. The method most commonly used of phonosurgery is done using a laser beam. The laser beam source is located approximately fourty centimeters away from the vocal cords. With this long distance, a small accuracy error would strongly impact the quality of the intervention. Recent advances in the area of micromechanisms used in medicine have increased the potential for an early detection and a better treatment against vocal folds diseases Using microdevices, micromechanisms can be designed to guide the laser beam nearest to the vocal fold, for an accurate treatment and for minimizing the risk of detriment of the delicate vocal fold structures

Bi-Directional Origami-Inspired SMA Folding Microactuator

We present the design, fabrication, and characterization of single and antagonistic SMA microactuators allowing for uni- and bi-directional self-folding of origami-inspired devices, respectively. Test devices consist of two triangular tiles that are interconnected by double-beam-shaped SMA microactuators fabricated from thin SMA foils of 20 µm thickness with memory shapes set to a 180° folding angle. Bi-directional self-folding is achieved by combining two counteracting SMA microactuators. We present a macromodel to describe the engineering stress–strain characteristics of the SMA foil and to perform FEM simulations on the characteristics of self-folding and the corresponding local evolution of phase transformation. Experiments on single-SMA microactuators demonstrate the uni-directional self-folding and tunability of bending angles up to 180°. The finite element simulations qualitatively describe the main features of the observed torque-folding angle characteristics and provide further insights into the angular dependence of the local profiles of the stress and martensite phase fraction. The first antagonistic SMA microactuators reveal bi-directional self-folding in the range of −44° to +40°, which remains well below the predicted limit of ±100°

Characterization of stiction effects of an electrostatic micro positioner for probe storage

We start by presenting a short explanation of the micro actuator working principle. The main contribution of this paper is the characterization of the coefcient of stiction between two silicon nitride parts of a MEMS actuator. Having one at contact surface while the other is composed of many relatively sharp circular bumps, has the advantage that the effective contact area is drastically reduced. The stiction coefcient varies between 0-0.53 for the device conguration presented. The exact value depends closely on the electrostatically applied force which presses the textured part on to the smooth one. Individual measurements used are highly accurate (typically within 5 nm noise band) and identical measurements for the characterization of stiction show only a small variation, typically under 25nm on a range of 11.8m