DOI: 10.5176/2251-2489_BioTech13.32
Authors: Ee Lim Tan, Angel Tsu-Hui Lin, Ruiqi Lim, Muhammad Hamidullah, Ming-Yuan Cheng, Cairan He, Winston Sun, Ee Lim Tan, Angel Tsu-Hui Lin, Ruiqi Lim, Muhammad Hamidullah, Ming-Yuan Cheng, Cairan He, and Winston Sun
Abstract:
This paper describes the detection of contact and penetration forces using silicon-based force sensor. The operating principle of the force sensor is based on the resistance change produced by silicon nanowires (SiNWs) when subjected to an externally applied force. The primary components of the silicon-based force sensor were constructed using standard microelectromechanical systems (MEMS) techniques. Structurally, the force sensor was comprised of a cylindrical pillar (diameter: 50 μm; length: 400 μm) supported by four rectangular cantilevers (length: 75 μm; height: 10 μm; width: 10 μm) with one end of the cantilever fully fixed on the wall of the sensor (Figures 1 and 2). On the cantilever’s surface, SiNWs were formed via standard lithography and etching processes. Conductive lines were defined via metallization for electrical contact between SiNWs and respective electronic components. To allow for uniform force distribution across SiNWs, a spherical polymer ball (diameter: 300 μm) was attached on the tip of the cylindrical pillar. Upon exposure to an externally applied force, the SiNWs-embedded cantilevers would experience stresses that subsequently led to resistance change. The resistance change can be described by ΔR/R = πlσl + πtσt, where R, π, and σ represents resistance, piezoresistive coefficient, and stress, respectively (subscripts l and t refer to the longitudinal and transverse components). Several identified medical applications of this sensor technology are the detection of contact and penetration of the tympanic membrane during grommet tube insertion for treating chronic otitis media with effusion, detection of atherosclerosis during balloon angioplasty [1-3], and force feedback system in minimally invasive surgery for urological, gynecological, thoracoscopic procedures [4-6].
Keywords: piezoresistive; silicon nanowires; force sensor
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