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Yamamoto H.,Keio University | Mori K.,Keio University | Takemura K.,Keio University | Yeo L.,Monash University | And 3 more authors.
Sensors and Actuators, A: Physical | Year: 2010

An electro-conjugate fluid (ECF) is a kind of low conductivity dielectric fluid, which produces a strong flow when subjected to high DC voltage. ECFs are potentially useful in a variety of applications, including microactuators, microgyroscopes, and CPU liquid cooling systems. However, the biggest hindrance to the commercial development of applications involving ECFs is the lack of theoretical understanding of the fluid flow mechanisms associated with ECFs. This study presents a numerical simulation based on a physical model for the flow of ECFs that arises due to the generation of electric (Maxwell) stress gradients. Validation of the results from the numerical simulation against experimental data obtained using particle image velocimetry (PIV) provides confidence that the model is capable of quantitatively reproducing the flow of these ECFs. © 2010 Elsevier B.V.


Yokota S.,Tokyo Institute of Technology | Yajima F.,Tokyo Institute of Technology | Takemura K.,Keio University | Edamura K.,New Technology Management Co.
Advanced Robotics | Year: 2010

An electro-conjugate fluid (ECF) is a type of dielectric and functional fluid that generates a powerful jet flow when subjected to high DC voltage. Although a high voltage is needed to generate the jet flow, the current is quite low at several microamperes, resulting in a total power consumption of several milliwatts. Using this smart fluid, we can develop micro fluid-driven mechanical components without any bulky pumps. Also, it is clarified that the power density of the ECF jet is higher when the electrode pair is miniaturized; therefore, it is suitable for micro actuators. Here, we propose and fabricate three types of soft actuators with an antagonistic configuration: (i) micro artificial muscle cells, (ii) a McKibben-type micro artificial muscle actuator using the ECF effect and (iii) a micro finger actuator with two chambers to bend. The actuators basically consist of a silicone rubber tube covered with a fiber sleeve and a micro pressure source using the ECF effect. Next, we apply and integrate these actuators into a micro robot hand, driven with ECF jets. The driving characteristics of the micro artificial muscle actuator and the integrated micro ECF hand with ECF fingers were fabricated and experimentally investigated. The experimental results show that this ECF jet actuation is effective for driving soft micro hands. © 2010 VSP.


Yamada Y.,Tokyo Institute of Technology | Kim J.-W.,Tokyo Institute of Technology | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
ICMT 2012 - 16th International Conference on Mechatronics Technology | Year: 2012

This paper proposes and presents a novel electroconjugate fluid (ECF) micropump which is formed from the higher aspect ratio of triangular prism and slit (TPS) electrode pairs. ECF is a kind of functional and dielectric fluid. A strong jet flow of ECF is generated between electrodes surrounded by ECF, when high DC voltage is applied to the electrodes. To combine easy fabrication and high performance, we successfully developed a novel ECF micropump that consists of TPS electrode pairs fabricated by MEMS technology. Our previous study proved that the integration of the MEMS-fabricated TPS electrode pairs in a plane achieves high output power. As a method to obtain higher output power, this research make an attempt to fabricate higher aspect ratio of TPS electrode pairs by forming TPS electrode pairs in the multilayer, which is called as the 3D integration of TPS electrode pairs. We successfully realized the 3D integration of TPS electrode pairs by using the combination of micro mechanical fabrication technique and thick photorest lithography. This paper showed the multilayer MEMS fabrication is effective for higher aspect ratio of TPS electrodes pairs.


Kim J.-W.,Tokyo Institute of Technology | Suzuki T.,Tokyo Institute of Technology | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
Sensors and Actuators, A: Physical | Year: 2012

This paper proposes and presents an electro-conjugate fluid (ECF) micropump whose pumping sources are mounted on the inside of flow channels and are serially located through the flow channels. ECF is a kind of functional and dielectric fluid. A strong and active jet flow of ECF is generated between electrodes surrounded by ECF when high DC voltage is applied to the electrodes. To combine easy fabrication and high performance, we propose a novel ECF-jet generator that consists of a triangular prism electrode and a slit electrode for the tube-type ECF micropump. The maximum output pressure obtained is 64 kPa and the maximum flow rate is 1.12 cm 3/s at the applied voltage of 6 kV. The result shows that the proposed ECF-jet generator and whose tube-type ECF micropump can be a good candidate as a driving source for forced liquid cooling systems, new microactuators and so on. © 2011 Elsevier B.V. All rights reserved.


Yamaguchi A.,Keio University | Takemura K.,Keio University | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
Sensors and Actuators, A: Physical | Year: 2012

An electro-conjugate fluid (ECF) is a kind of functional fluid, which produces a jet flow (ECF jet) when subjected to high DC voltage. It is known that a strong ECF jet is generated under nonuniform electric field, for example, the field with a pair of needle and ring electrodes. We developed in our previous study a novel five-fingered flexible robot hand using the ECF. In this study, in order to improve the ECF hand we pay our attention to the flexion of palm because human often grasp an object with the flexion of palm. First, we propose a concept of five fingered robot hand which has balloon actuators driven by the ECF jet to produce the flexion of palm. The actuator is mainly composed of silicone rubber membrane and a rubber base with a slit, so that when the actuator is pressurized, the slit is opened, resulting in making the palm of the robot hand actuate. Finally we conduct grasping experiments based on Cutkosky's taxonomy of human grasping, and demonstrate the robot hand can grasp some objects with various shapes without any complex controller. The height, the width and the mass of the robot hand are approximately 70 mm, 40 mm and 40 g, respectively. © 2011 Elsevier B.V. All rights reserved.


Ueno S.,Keio University | Takemura K.,Keio University | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
Sensors and Actuators, A: Physical | Year: 2014

An electro-conjugate fluid (ECF) is a kind of functional fluid, which produces a flow (ECF flow) when high DC voltage is subjected. Since it only requires a tiny electrode pair in micrometer-scale size in order to generate ECF flow, ECF is a promising micro fluid pressure source. Hence, by using ECF as the power source, we realize a micro inchworm robot. In this study, first, we have proposed the concept of a novel micro inchworm robot driven by the ECF. Second, we have designed, fabricated and characterized each component of the micro robot. Third, we have developed the micro inchworm robot by using each component. The length, width and mass of the micro robot are approximately 23 mm, 8.5 mm and 1.9 g, respectively. Finally, we observed the characteristics of micro robot with conducting an experiment. Experimental results proved that the micro robot could move on a horizontal acrylic surface with maximum speed of 5.2 mm/s. The micro robot has superior ability in migration speed, compared with previously developed micro inchworm robots. © 2014 Elsevier B.V.


Han D.,Tokyo Institute of Technology | Kim J.W.,Tokyo Institute of Technology | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
Journal of Physics: Conference Series | Year: 2015

This paper proposes and presents a novel ECF (electro-conjugate fluid) micropump with TPSEs (triangular prism and slit electrode pair) fabricated by electroforming process using newly developed self-aligned micro molds. ECF is a kind of functional and dielectric fluid. ECF micropump is based on the principle of ECF jet, which is a powerful and active jet flow generated between electrodes immerged in ECF, when high DC voltage is applied to the electrodes. Our previous research experimentally demontrated that the ECF micropump had high power density thanks to the 2D-integraton (serialized integration and paralleled integration) of our proposed MEMS fabrication method by using micro-molding and electroplating. Moreover, it was also proved that higher aspect ratio of TPSEs by the multilayer fabrication process resulted in higher flow rate of the ECF micropump. However, the multilayer fabrication has demerit to require precise alignment that is time-consuming and extremely difficult to be met. In order to improve alignment accuracy and alleviate fabrication difficulty, this paper proposes a novel self-aligned MEMS fabrication process for high aspect ratio TPSEs. The ECF micropump by this newly-proposed MEMS process was successfully fabricated and the feasibility was proved by experimentally investigating output performance of the ECF micropump. © Published under licence by IOP Publishing Ltd.


Yamaguchi A.,Keio University | Takemura K.,Keio University | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2011

An electro-conjugate fluid (ECF) is a kind of functional fluid, which produces a jet flow (ECF jet) when subjected to high DC voltage. It is known that a strong ECF jet is generated under nonuniform electric field, for example, the field with a pair of needle and ring electrodes. This study introduces the ECF jet to develop a novel flexible robot hand. First, we characterize the ECF jet generator which could be a micro fluid pressure source of the robot hand, and confirm the effect of the variation of electrode parameters and the number of electrode pairs on its performance. Next, we investigate the characteristics of the robot finger which mainly consists of the ECF jet generator, a flexible rubber finger and an ECF tank. The robot finger is integrated with the pressure source (ECF jet generator) and the tank, and is successfully driven. Finally we developed a five-fingered flexible robot hand and demonstrate that the robot hand can grasp some objects with various shapes without any complex controller. The height, the width and the mass of the robot hand are approximately 60 mm, 40 mm and 15 g, respectively. © 2011 IEEE.


Mori K.,Keio University | Yamamoto H.,Keio University | Takemura K.,Keio University | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
Sensors and Actuators, A: Physical | Year: 2011

An electro-conjugate fluid (ECF) is a kind of dielectric fluid which produces a powerful flow (ECF jet) when subjected to high DC voltage. The ECF jet is a promising micro fluid power source for actuators and sensors including micro motors, liquid rate gyroscope, etc., however, these applications are developed upon trials and errors because the theory of the ECF flow has yet to be fully established. In this study we introduce the Korteweg-Helmholtz equation to develop an ECF flow model. Then we hypothesize that the Coulomb force is the dominant factor of the flow, and is occurred by two causes; an inherent dominant charge of fluid and a charge injected from a sharp electrode edge. The hypotheses are proved by the experimental results in this study. © 2011 Elsevier B.V. All rights reserved.


Abe Y.,Keio University | Takemura K.,Keio University | Sato K.,Keio University | Yokota S.,Tokyo Institute of Technology | Edamura K.,New Technology Management Co.
Sensors and Actuators, A: Physical | Year: 2013

This paper proposes a novel droplet transportation method for micro total analysis system (μTAS), which we called as an active flow channel matrix, using an electro-conjugate fluid (ECF). The ECF is a kind of functional fluid, which generates a powerful flow when applying a high voltage across the electrodes. A droplet that is placed into the channel may move in any direction according to the channel flow generated by the ECF. Therefore, in order for the multiple droplets from different channels to be merged, they are moved to reach the desired intersection. According to this concept, we developed a prototype of the active flow channel matrix. Then, we measured two droplets' position and controlled the position of them by using image processing technique. The experimental results demonstrated the possibility of our concept for μTAS. © 2013 Elsevier B.V.

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