Graphene piezoresistive flexible MEMS force sensor for bi-axial micromanipulation applications

The aim of this work is to design, simulate, and analyze a bi-axial piezoresistive MEMS (Micro-Electro-Mechanical System) force sensor, which has the capability of flexibility, high sensitivity and sensing forces in nano-Newton ranges. To achieve this, a novel combination of polydimethylsiloxane (PDMS) as substrate material for microcantilever and graphene as piezoresistors are taken in this study. Force to be sensed is applied on the cantilever beam which generates its output in the form of displacement and by using smart piezoresistive sensing mechanism displacement is converted into corresponding voltage. Finite element analysis approach is used for designing and simulation of the proposed force sensor. The force sensitivity and stiffness are achieved as 0.566524 mV/nN and, 0.263 nN/µm in ‘y’ direction whereas 0.63039 mV/nN and, 0.039 nN/µm in ‘z’ direction, respectively. It is found in this study the stiffness of cantilever beam plays significant role in affecting the sensitivity of the sensor. The designed force sensor has ability to sense bi-axial forces and therefore suitable for microbotics and health care applications, while operating range of the sensors is ideal for a wide range of applications including microbotics, living cell handling, microassembly, nano-scale material characterization, minimal invasive surgeries and heath care applications.