Electromechanical Piezoresistive Sensing of Graphene-based Intracranial Pressure Sensor

Graphene shows a promising future in the application of biomedical sensors as the piezoresistive sensing elements due to its electromechanical properties. This paper presents the fundamental development stage of graphene-based piezoresistive intracranial pressure sensor, i.e. to determine its diaphragm design, which is made of polydimethylsiloxane polymer. Different thicknesses of a square diaphragm were simulated using COMSOL Multiphysics. The Parametric Sweep function was used to simultaneously simulate the changes of two parameters, namely diaphragm thickness and operating pressure. It was found that the thin diaphragm is more susceptible to deform due to the rapid geometry changes and the differences in modulus of elasticity of the materials used in the design. Meanwhile, the stress experienced by the diaphragm degraded with the increase in thickness. However, a slight modification in designing and positioning the piezoresistors would make the sensor's performance on par with those of thin diaphragm. Hence, by selecting the right thickness and shape of polydimethylsiloxane diaphragm, it will serve as a good platform in developing the graphene-based piezoresistive intracranial pressure sensor.