Design, development, fabrication and testing of low-cost, laser-engraved, embedded, nano-composite-based pressure sensor

Various types of metals, metal alloys, semiconductor, micro- and nano-materials as well as its composites are being used at present as strain gauges. In this present work, a novel method to easily fabricate nickel-based nano-composite (Neella et al. in Sens Actuators A Phys 268:173–182, 2017), low-cost, low-power, and light-weight pressure sensor using reduced graphene oxide (rGO)-based nickel nano-composite is described. The diaphragm is fabricated using martensitic stainless steel (SS) by CNC machining, and the strain gauge pattern was laser engraved on the bonding side of the diaphragm. Hot and cold stabilization of this fabricated diaphragm was carried out to reduce the residual stresses which might have occurred during machining process. The diaphragm surface was electrically insulated using Parylene-C coating. The rGO-based nickel nano-composite material was bonded using appropriate epoxy in the engraved portion to sense radial as well as tangential strains during pressure application. A wheatstone bridge configuration with four active strain gauge patterns was adopted by having two compressive (radial) strain gauges in one set of opposite arms of the wheat stone bridge and other two tension (tangential) strain gauges on other opposite arm of the same wheatstone bridge. The details of the diaphragm dimensions, testing methods adopted, calibration process, interpretation of calibrated data for sensitivity, nonlinearity and hysteresis, zero offset, and full-scale output were discussed in detail. Even though various measurement principles like capacitance, inductance, reluctance, linear variable differential transformer (LVDT), potentiometric, resistance type etc. are being used in many applications, the state-of-the-art nano-composite materials is seldom used.