Papers by Keyword: Actuator

Abstract: Flexible sensors and actuators have broad applications in the fields of wearable electronics for health, sports, functional textiles, robotics and cobot applications. Graphene-or graphite-based polymer nanocomposites are promising materials for the development of soft sensors and actuators. This study investigates strain sensing properties of silicon rubber with various graphene filler concentrations (8wt%-12wt%). Current-voltage characteristics have been measured under various strains. We obtain that the sensor’s electrical resistance, for a given voltage, can be approximated by a linear fit of the logarithmic resistance as function of the extension ratio of the sensor. The obtained mechanically induced logarithmic resistor behavior of the polymer nanocomposite is highly promising for the development of electronic sensing and control. Furthermore, thin film graphite layers were investigated on highly stretchable silicone membranes.

Abstract: Recently, ultracompact electric vehicles (EVs) have begun to be sold, instead of general vehicles equipped with gasoline engines, for transportation. However, because the outer plate of an ultracompact EV has low rigidity, the road noise generated by rotation and the wind noise generated from the vehicle's projection shape are transmitted to the inside of the EV. This interior noise reduces the ride comfort for passengers. Therefore, an active noise control (ANC) system was proposed for controlling noise transmitted from the outside of the EV. The proposed ANC system was configured to control the sound generated using a giant magnetostrictive actuator on the wall surface in the cabin of the EV, instead of a vehicle installation speaker.In this study, Tb, Dy, and Fe powders, which are giant magnetostrictive materials, were mixed and mechanically alloyed to produce multiple giant magnetostrictive materials to be used in the proposed ANC system. The displacement of each alloyed giant magnetostrictive material was measured. In addition, each alloyed material was analyzed using X-ray diffraction and their crystal orientation was confirmed.

Abstract: The goal of this study is to make selective etch possible for the next generation of MEMS(microelectromechanical systems) devices that are composed Ni-Mn-Ga and silicon layers. Due tothe large magnetic-field-induced strains of Ni-Mn-Ga, sensing and actuating components can be fab-ricated in the Ni-Mn-Ga layers. Other functional components can be manufactured in the silicon layer.Single crystalline Ni-Mn-Ga alloys that are grown by using the Bridgman vertical growth techniquehave so far obtained the largest magnetic field-induced strain (MFIS), a magnetic shape memory(MSM) effect. Similar to silicon wafers, Ni-Mn-Ga wafers are also sliced from crystal-oriented singlecrystalline ingots. To fabricate hybrid MEMS devices such as micromanipulators and robots, lab-on-chip containing micropump manifolds and valves, or vibration energy harvesters, the fabricationprocesses used for MEMS devices will be also used to fabricate components in the Ni-Mn-Ga layer ofthe hybrid MEMS devices. One of the most important processes for MEMS fabrication is the structur-ing of materials by chemical etching. The main goal of this study is to obtain evidence that the etchantetches silicon but not Ni-Mn-Ga and to identify an etchant that etches Ni-Mn-Ga but not silicon. Thepresent paper reports on a novel experiment in dissolving Ni-Mn-Ga alloys. An etchant compositionof 69% HNO3, 98% H2SO4, and CuSO4•5H2O is proposed for dissolving Ni-Mn-Ga alloys and thevariation in the dissolution rate by adjusting the concentrations of HNO3 and ultrapure water (UPW)is demonstrated. This etchant was demonstrated to etch Ni-Mn-Ga but not silicon. The HF+HNO3acidic solution commonly used for etching silicon does not dissolve Ni-Mn-Ga alloys.

Abstract: The recent developments in dielectric elastomers (DE) are spectacular. Currently, a DE as an actuator, 0.15 g of acrylic sandwiching SWCNT electrodes, is capable of lifting a weight of 8 kg by more than 1 mm at a speed of 88 msec. In the near future, DE motors could be used to drive electric vehicles. Moreover, the DE can be used as a high-efficiency sensor with the same structure. With a diameter of 20 mm and a thickness of 0.5 mm, it can accurately measure pressure from several kg to 150 kg. In addition, reversing this DE actuator (DEA) movement also enables high-efficiency power generation. In other words, when the DEA is stretched or pushed, it generates electric power. Single wall nanotubes (SWCNTs) were used as an electrode, and an acrylic DE power generation cartridge with a diameter of 80 mm was used. When the center of the DE power generation cartridge is pushed by about 15 mm, a power of 33.6 mJ is generated. Using these two DE cartridges, it was possible to charge a secondary battery through a DC converter. In addition to this power generator, practical research and development of power generation using wave power, wind power, waste heat, and fluids (ocean currents, water currents, etc.) is progressing. In this paper, we have described state-of-the-art DEAs, DE generators (including the case that the power generated locally by microgenerators are consumed locally), and DE sensors and explained their usefulness.

Abstract: A rehabilitation device for a post-stroke is essential because stroke attacks can cause disable to part or half of the human body. An exoskeleton could be a vital device for rehabilitation for a post-stroke patient. Several studies have proposed the exoskeleton design for rehabilitation purposes to a human limb disorder. This study aims to review the state-of-the-art of hand exoskeleton devices based on myoelectric or any other sensors. This paper is expected to contribute to design a hand exoskeleton device using both myoelectric and force sensors. This was achieved by reviewing several articles related to the development of the exoskeleton, especially in the sensor system, data processing, and actuator system. The results show that the use of Ag electrode disposable Ag (AgCl) is still commonly found to detect the movement of the fingers on the hand because this sensor can reduce the artifact noise. The use of myo-armband is also found in several studies because it has wireless properties so that it is easy to use. In terms of processors, Arduino microcontrollers are more widely used than others. In order to activate the hand exoskeleton, servo motors are more widely used to actuate the finger joints, which is more precise than other actuators. In a further development, integration between exoskeleton systems and information systems will be an expected challenge. Furthermore, hopefully, the development of this exoskeleton can be applied as a rehabilitation device for patients with malfunction or hand paralysis.

Abstract: Natural rubber composite materials were prepared by using sulfur curing system of STR 5L added with hen eggshell and eggshell membrane to increase electrical and mechanical properties for biomimetic actuator and artificial muscle applications. Samples were vulcanized at temperature 150°C. Hen eggshells and eggshell membrane powder (0, 20, 40, and 60 phr) were added into natural rubber. The main composition of hen eggshells composed of 96.35 wt% calcium carbonate (CaCO₃) while mostly composition of hen eggshell membrane is fibrous protein in terms of collagen. The best condition is addition of eggshell 40 phr (formula 3) and eggshell membrane 20 phr (formula 5) to obtain the highest storage modulus response equal to 2.85 x 10⁶ and 2.97 x10⁶ Pa, respectively. The curing time (Tc₉₀) of pure natural rubber (formula 1), formula 3, and formula 5 are 8.22, 6.73, and 5.67 min, respectively. Furthermore, the curing time, rheology, and electrical field response of natural rubber composite materials were measured by moving die rheometer and impedance analyzer, and reported here.

Abstract: Pneumatic vibroexciters which consist of smart materials’ structural elements and are operating under autovibration regime were designed. The chamber of vibroexciter actuator with changeable capacity for flowing pressured air made of shape memory alloy (SMA) were presented. Mechanical characteristics of such type vibroactuator were estimated: maximum deformation of structural element with SMA, possible force of martensitic transformation. The result of the research allows to design functional adaptive pneumatic vibroexciters with are suitable for the different purposes of technological processes.

Abstract: Shape memory alloys with their phase transformation properties; have been broadly implemented in smart structures. In this study, a functional design is presented where two wires actuate antagonistically to achieve motion in bending. Effect of heat treatment parameters on the actuator materials is investigated. For this purpose, a novel experimental test bench appropriate for characterizing a smart joint is presented, and joint performance including actuation force and cyclic behavior are demonstrated. Accordingly, a smart joint configuration capable of 60 degrees bending with a repeatability of 50 cycles is developed.

Abstract: Structural health monitoring (SHM) is an inevitable component of modern civil and aerospace structures. It essentially detects the damages in the system by evaluating the performance parameters by the integration of sensing and possibly also actuation devices into the structure. In this paper damage detection process in an aluminium cantilever plate using piezoelectric sensors and actuators is simulated. Possible root damage such as transverse crack and longitudinal crack are studied. The results are compared with undamaged case. The plate is actuated using PZT actuators and performance is evaluated using PVDF sensors. Modelling for PZT/PVDF and structural parts are carried out using coupled field finite element PLANE223 ofAnsys^(TM) finite element package. Strain response at the root of the cantilever plate is captured as the voltage output of the PVDF sensor. Strain response is directly related to the voltage generated in the PVDF sensor. The percentage variation of the fundamental frequency is found to be less than 3% in the present study and hence it is not taken as an index of damage. The transient voltage response captured with the transient coupled field analysis shows variation up to 24% as a signature between damaged and undamaged systems. Therefore, the present study suggests transient response evaluation using PVDF sensor is a suitable evaluation technique for the cases under consideration.

Abstract: Electroactive polymer transducers have many features that are desirable for various devices. An especially attractive type of electroactive polymer is dielectric elastomer (DE). Our recent progress is a DE actuator having only 0.1 g of DE that lifted a weight of 2 kg using carbon system electrodes. We also developed a ribbon form DE actuator having a sensor function that can be used to measure force, or pressure, as well as motion at the same time. This actuator can assist human and robot motions. At the same time, it can work as a motion feedback sensor. We hope that it may be useful for smart rehabilitation equipment for hands, legs, and fingers. DE has also been shown to operate in reverse as a generator. Experiments have been performed on portable DE generators/wearable generators powered by human motion, ocean wave power harvesters mounted on buoys, solar heat generators, and water turbines. While the power output levels of such demonstration devices is small, the performance of these devices has supported the potential benefits of DE. We are developing elastomers having larger dielectric constant using barium titanium oxide to produce a “super artificial muscle for energy harvesting devices, actuators & sensors” in the near future.