This novel diaphragm pressure sensor design utilizing an embedded equivalent Wheatstone bridge circuit makes the most of tangential and radial strain fields, allowing the researchers to achieve a combination of high sensitivity, linearity, low limit of detection, high resolution, and temperature self-compensation.
The usage of the Wheatstone bridge design also provides built-in temperature compensation allowing for operation between 20 and 50°C without external offsets.
Due to its performance, the diaphragm pressure sensor meets the requirement of a variety of potential applications. Among many, one feasible and effective health monitoring application is heart-rate monitoring.
As a proof of concept, the researchers designed and fabricated a PDMS wristband with an embedded microfluidic diaphragm pressure sensor to measure dynamic pulse measurements.
"The detection limit of our sensor has been shown to be below 100 Pa with sub-50 Pa resolution," the authors note. "The extremely low detection limit and resolution combined with an ultrafast response time of 90 ms allows for the sensor to be used in a wide range of applications."
As the team demonstrates, the liquid-state diaphragm pressure sensors may be utilized as either standalone devices for monitoring pressure at a specific point or into large arrays for tactile mapping in a variety of electronic skin and smart textile applications for wearables, robotics, and beyond.