Miniature Multi-Hole Probe for Quicker, More-Accurate Air Pressure Measurements

Incorporates an Optical Sensor Array to Minimize Probe Size and Maximize Pressure Measurement Accuracy and Speed

This smaller, more sensitive multi-hole probe pressure sensor integrates MEMS-based optical fibers for quicker, more accurate air pressure measurements. Multi-hole probes are flow measurement tools designed to take point measurements at the probe tips when immersed in a fluid flow field. Available multi-hole probes incorporate long pneumatic tubes connecting the probe tip holes to the transducers, resulting in long response time or settling times, also known as pneumatic lag. Pneumatic lag leads to inaccurate and delayed results, increasing experimental analysis turnaround and hindering the detection of high-frequency pressure perturbations. Miniaturization of multi-hole probes is key for improving measurement accuracy and providing high spatial resolution. To date, embedding multiple pressure sensors at the probe tip while maintaining a compact size to minimize pneumatic lag has been challenging.

Researchers at the University of Florida have developed a 5-hole probe pressure sensor integrating MEMS-based single-mode optical fibers into the probe tip to eliminate pneumatic tubing. Enabling at-tip pressure measurements renders merits of fast response and miniaturization and increases sensitivity in air-pressure monitoring on aircraft.

Application

5-hole, multi-hole probe pressure sensor integrating an optical sensor array for faster, more precise monitoring of air pressure changes on the body of an aircraft

Advantages

• Incorporation of an optical pressure sensor array at the probe tip eliminates pneumatic tubing, resulting in system miniaturization and faster pressure measurements
• The multi-hole probe (5 holes) is compact in size and lightweight, making it easy to install on airplanes or UAVs
• Eliminates the need for electronic components at the probe tip, enabling the capability to work in extreme temperature, high shock, and high-pressure environments
• The 5-hole probe shows improved productivity and accuracy compared to traditional multi-hole probes, reducing operational expenditures, and leading to economic gains

Technology

This MEMS-based 5-hole probe pressure sensor comprises a probe tip with multiple holes on the top surface, each hole connecting to a tube conveying fluid from the measurement environment to pressure transducers operating through optical lever-based techniques. The pressurized fluid in the probe tip applies force to a diaphragm within the probe, leading to changes in its position as a response to different pressures. Upon application of a light source, the diaphragm reflects light in different patterns depending on the positioning of the diaphragm. The light pattern data are collected and analyzed using a photodiode to determine the environmental pressure acting on the different holes of the probe. The incorporation of fiber-optic lever intensity modulation eliminates the need for traditional pneumatic tubing systems within the probe, enabling at-tip pressure measurements and faster response. This 5-hole probe provides improved laboratory applications, such as boosted wind tunnel test productivity, and field applications on airplanes and UAVs for real-time flight monitoring and feedback control.