MEMS Pressure Sensor With Capacitive Switching
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Solution Overview
Problem
Existing MEMS pressure sensors and switches face challenges in accurately measuring critical pressure levels and responding promptly due to environmental degradation and the need for constant power, while mechanical sensors offer faster responses but lack electronic control.
Innovation Solution
A pressure sensor design featuring a substrate with a metallic contact, a deflecting membrane with a second metallic contact, and a cavity, allowing contact between the contacts at a defined pressure to enable current flow and trigger electronic responses, using actuation electrode layers and sacrificial layers for manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If MEMS switches include deflecting beams or cantilevers that make galvanic contact, then electrical control is enabled, but perfect sealing from the environment is required to avoid contact degradation
Solution Approach 1:
The patent replaces traditional mechanical galvanic contact systems with a capacitive sensing system. The MEMS device uses a movable electrode that forms a capacitor with a fixed electrode, eliminating the need for physical contact. Pressure is detected through changes in capacitance as the movable electrode deflects toward the fixed electrode, thereby avoiding contact degradation while maintaining electrical control capability
Solution Approach 2:
The patent introduces an intermediary capacitive field between the movable and fixed electrodes to transmit the pressure detection signal. Instead of direct mechanical contact between metal components, the electrical interaction occurs through the capacitive coupling medium, which mediates the signal transmission without requiring perfect sealing or physical contact
2Speed
If mechanical safety measures like mechanical vanes are used to respond to critical pressures, then immediate action is achieved, but electrical or electronic control is not allowed
Solution Approach 1:
The patent merges the advantages of mechanical sensors (fast response) with electronic sensors (electronic control) into a single integrated MEMS device. The capacitive sensing mechanism provides immediate response to pressure changes like mechanical sensors, while the electrical readout enables full electronic control and integration with digital systems
Solution Approach 2:
The MEMS pressure sensor achieves multi-functionality by combining rapid pressure detection with electronic control capabilities in a single device. It can serve both as a fast-responding safety mechanism and as an electronically controllable sensor for various applications, eliminating the need to choose between mechanical speed and electronic versatility
3Ease of operation
If electronic sensors are used to measure pressure, then electronic control is enabled, but constant power is required and response is delayed compared to mechanical sensors
Solution Approach 1:
The patent employs periodic action by using transient capacitive measurements instead of continuous power consumption. The MEMS device only requires power during the measurement cycle when the capacitor is read, allowing the sensor to remain in a low-power state between measurements. This eliminates the need for constant power while maintaining electronic control and fast response capabilities
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise measurement and immediate electronic responses to critical pressure levels, enhancing the reliability and responsiveness of pressure sensors and switches in harsh environments.
Implementation Method 1
a membrane attached to the substrate that includes a second metallic contact and responds to pressure by deflection
Implementation Method 2
a signal path that allows a current flow when the first metallic contact makes contact with the second metallic contact
Data Source
AI summary
Various embodiments relate to a pressure sensor and related methods of manufacturing and use. A pressure sensor may include an electrical contact included in a flexible membrane that deflects in response to a measured ambient pressure. The electrical contact may be separated from a signal path through a cavity formed using a sacrificial layer and PVD plugs. At one or more defined touch-point pressure thresholds, the membrane of the pressure sensor may deflect so that the state of contact between an electrical contact and one or more sections of a signal path may change. In some embodiments, the change of state may cause the pressure sensor to trigger an alarm in the electrical circuit. Various embodiments also enable the operation of the electrical circuit for testing and calibration through the use of one or more actuation electrode layers.