A PDMS-Membrane Optical Pressure Sensor with Threshold Logic and Its Fabrication Method

Microfluidic pressure sensing is commonly proven on the conceptual or system level, but a practical prototype also relies on a reproducible fabrication and assembly sequence. This work reports a fabrication process of a PDMS-membrane optical pressure sensor coupled to hysteretic threshold logic. The proposed sequence consists of a photolithographic master, molded PDMS flow and cavity-spacer layers, a spin-coated PDMS membrane, oxygen plasma bonding, a glass cover and laser-photodiode readout followed by analogue-to-digital conversion and microcontroller-based categorization. The present work examines process compatibility, small-deflection geometry scaling and deterministic logic behavior, rather than experimental sensor performance as fabricated-device data were unavailable. with example, the plate model predicts that the peak deflection will rise 46.4% with a 10% increase in membrane radius, and decrease 24.9% for a 10% increase in thickness. Four stage logic sequence ensures that the system correctly switches state from OK to ALERT and vise versa for normalized thresholds of 0.50 and 0.60. The report consequently provides a defined course for subsequent prototyping and calibration but does not present analytical conclusions as measured performance