Fabrication and Characterization of Normal and Shear Stresses Sensitive Tactile Sensors by Using Inclined Micro-cantilev
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1052-DD04-07
Fabrication and Characterization of Normal and Shear Stresses Sensitive Tactile Sensors by Using Inclined Micro-cantilevers Covered with Elastomer Masayuki Sohgawa1, Yu-Ming Huang1, Minoru Noda1,2, Takeshi Kanashima1, Kaoru Yamashita1,2, Masanori Okuyama1, Masaaki Ikeda3, and Haruo Noma4 1 Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka, 560-8531, Japan 2 Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan 3 Omron Corporation, Kizugawa, Kyoto, 619-0283, Japan 4 Advanced Telecommunications Research Institute International, Seika, Souraku, Kyoto, 6190288, Japan ABSTRACT Tactile sensors of Si microcantilevers with a piezoresistive layer have been proposed for detection of both normal and shear stresses. Micro-cantilevers were fabricated by the surface micromachining of SOI wafers and were adequately inclined by controlling deflection with a Cr layer. The cantilevers were embedded in the PDMS elastomer to create a human-friendly surface. When a stress is applied to the surface of elastomer, the deformation of the cantilevers along with the elastomer is detected as a resistance change in the piezoresistive layer of the cantilevers. The piezoresistive response of the cantilever was analyzed by FEM calculations. The fabricated tactile sensor is sensitive to both normal and longitudinal shear stresses and its responses agree closely with the calculated value. Moreover, it has little sensitivity to shear stress in the transverse direction to the cantilever, which means that the tactile sensor can distinguish the direction of shear stress. This sensor can be utilized for tactile sensing in human support robots. INTRODUCTION In recent years, human support robots for nursing-care have attracted much attention because of acceleration of the average age of the population [1]. If human support robots do not have the ability to recognize allowable forces for contact with the human body, there is possibility that the human is hurt by excess force. To assure safety for the human body, human support robots require human-like tactile sensing. However, tactile sensors with high resolution and sensitivity to both normal and shear stresses like the human tactile sense have not yet been realized. It is believed that a tactile sensor for human support robots requires high sensor density on the robot's skin, ability to measure normal and shear stresses and a human-friendly surface. We have proposed tactile sensors for human support robots which can detect both normal stress and shear stress and have a human-friendly surface [2]. In previous work, we have examined Si LSI process compatibility on the premise of integration with signal processing units and controllability of deflection of the cantilevers [3]; it has been found that out-of-plane deflection control by the addition of a Cr thin film layer is suitable for fabrication of tactile sensitive cantilevers. In this work, tactile sensor devices were fabricated
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