Investigation of a new high sensitive micro-electromechanical strain gauge sensor based on graphene piezoresistivity Mohammed Gamil 1,a , Osamu Tabata 2,b , Koichi Nakamura 3,c , Ahmed M.R. Fath El-Bab 4,5,d , Ahmed Abd El-Moneim 1,e 1 Materials Science and Engineering Department, Egypt-Japan University of Science and Technology, New Borg El-Arab, Alexandria 21934, Egypt 2 Department of Micro Engineering, Kyoto University, Kyoto 615-8540, Japan 3 Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto 615-8540, Japan 4 Mechatronics and Robotics Department, Egypt-Japan University of Science and Technology, New Borg El-Arab, Alexandria 21934, Egypt 5 On-leave from Mechanical Engineering Department, Faculty of Engineering, Assiut Unversity, Assiut 71516, Egypt a mohamed.gamil@ejust.edu.eg, b tabata@me.kyoto-u.ac.jp, c koichi@cpier.kyoto-u.ac.jp, d ahmed.rashad@ejust.edu.eg, e ahmed.abdelmoneim@ejust.edu.eg Keywords: Graphene; Strain gauge; Gauge factor; Piezoresistive sensors; MEMS devices. Abstract. A new strain gauge based on graphene piezoresistivity was fabricated by a novel low cost technique which suits mass production of micro piezoresistor sensors. The strain gauge consists of a monolayer graphene film made by chemical vapor deposition on a copper foil surface, and transferred to Si/SiO2 surface by using a polymethyl-methacrylate (PMMA) assisted transfer method. The film is shaped by laser machine to work as a conductive-piezoresistive material between two deposited electrical silver electrodes. This method of fabrication provides a high productivity due to the homogeneous distribution of the graphene monolayer all over the Si/SiO2 surface. The experimentally measured gauge factor of graphene based device is 255, which promises a new strain gauge sensor of high sensitivity. Introduction The measurement of strain is important in numerous applications. The measurement principle is based on the change in electrical conductance and geometry of a stretched conductor [1]. The gauge factor of conventional strain gauges based on metal alloys is 2.1, which is far beyond the international target for producing high sensitive strain gauges for more advanced applications. Nowadays, piezoresistance-based sensors are considered as the most successful Micro Elector Mechanical System-MEMS devices for measuring strain. Graphene can be considered as one of the most important piezoresistive materials that can withstand large strain from tested targets, as compared to other existing materials. Moreover, graphene is compatible with wafer-level processing due to its 2D architecture and inherent nanoscale structure [2]. In addition, graphene is a very promising material for future electronic applications due to the very high carrier mobility and the possibility to tune the electronic conduction via the field effect [3]. For the production of commercial strain gauge sensors based on graphene piezoresistivity, a large area of graphene monolayer lies on Si/SiO2 wafer is essentially required [4]. However, there is no reported method applied to fulfill this requirement is available till now. In this regard, Lee et al. reported in their study that the gauge factor of graphene film grown on Cu substrate by chemical vapor deposition (CVD) was 6.1 at 1% strain [5], though this value is still far beyond the target for highly sensitive sensor. The low gauge factor was attributed to the multilayer nature of the prepared graphene film. Meanwhile, Chen et al. reported that the gauge Key Engineering Materials Vol. 605 (2014) pp 207-210 © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/KEM.605.207 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 197.126.54.130-30/03/14,06:22:29)