A MEMS/Piezoelectric System for Dual Pressure Sensing

Technology

The inventors have developed a sensing system that includes a deformable diaphragm responsive to applied pressure and a rigid beam mounted to move as the diaphragm deforms. The rigid beam combines two pressure sensors in the same housing: a Fabry-Perot probe, which acts on optical physics principles, and a MEMS probe, which acts on electrostatic principles. This system ensures a more accurate sensor reading as both probes can serve to simultaneously check the other’s reading. Because the two probes act on different physics principles, they are affected by environmental conditions to different degrees. For example, if one probe is highly sensitive to temperature, the other will likely be affected to a lesser degree. Ideally, both probes should report the same recorded measure of pressure. However, if one or both systems are affected by environmental conditions then the two probes will report different pressure measurements, which would indicate an inaccurate reading. In this way, this system provides a real-time evaluation of the accuracy of its pressure sensors and offers a method to catch false readings immediately.

Problem Addressed

A sensor is a physical device that detects a signal, physical condition, or particular chemical compound. Sensors are typically evaluated by their accuracy, which is their conformity to a standard or true value under a specified condition, and their reproducibility, which is the degree of agreement among repeated sensor outputs under the same conditions. In many situations, sensors are susceptible to environmental factors such as temperature and humidity which can cause them to lose accuracy. These factors can induce thermal and moisture drifting in the sensors, which can lead to mechanical problems such as adhesive swelling, and/or cause changes in the sensor’s electrical properties (e.g., resistance and insulation). Therefore, a system is needed for the real-time detection of inaccurate readings.

Advantages

• Provides a method to evaluate the accuracy of sensor measurements in real-time.
• Fabry-Perot and MEMS sensors can be configured in numerous ways to measure a variety of parameters.
• Sensors are low-cost to develop by way of micromachining techniques.