Design and simulative analysis of a batteryless Teflon coated capacitive pressure sensor for glaucoma diagnosis

This paper presents the design and simulative analysis of MEMS sensor which can be used as pressure sensitive capacitor of Intraocular Pressure (IOP) sensor. An IOP sensor is an LC tank circuit which can be used as diagnostic device for glaucoma disease. This sensor detects pressure in Intraocular range i.e. 0-60mmHg in terms of capacitance. In this paper, different shapes and structures of diaphragm are investigated and found that 4 slotted square diaphragm as optimum. A battery less design was proposed by coating the diaphragm with Teflon (polytetrafluoroethylene) which is highly electronegative. The sensor yields a displacement sensitivity of 9.577×10^-5μm/Pa and 13.186×10^-5μm/Pa for diaphragm with and without Teflon coating respectively. The capacitive sensitivity has also increased from 5.916×10^-7 1/Pa to 10.758×10^-7 1/Pa with Teflon coating. It can be seen that, displacement and capacitive sensitivities were improved by 1.3 and 1.8 times respectively by using 4 slotted square diaphragm coated with Teflon. The greatest advantage of the proposed design is the removal of external biasing.