A Fluidic-Based High-Pressure Sensor Interrogated by Microwave Fabry–Perot Interferometry

A fluidic-based sensor is proposed and demonstrated for high-pressure measurement. The sensor consists of a reservoir and a capillary outlet. The reservoir deforms under pressure manifesting the liquid level change in the capillary. Utilizing the built-in waveguide on the capillary, the liquid level is measured by microwave Fabry-Perot interferometry in the spectral domain. The applied pressure variation is monitored by the spectrum shift of the microwave interferogram. The pressure response of the sensor is tested up to 2000 psi, with a resolution of 2.5 psi, and repeatability within ±20 psi. Benefiting from rigidity in material and flexibility in dimension of the sensor structure, the sensor has good robustness and adjustable sensitivity and range for applications in high-pressure environments.