An LC Wireless Passive Pressure Sensor Based on Single-Crystal MgO MEMS Processing Technique for High Temperature...

Area of Science:

• Materials Science
• Sensor Technology
• Microelectromechanical Systems (MEMS)

Background:

• High-temperature environments pose significant challenges for conventional sensor materials.
• Magnesium oxide (MgO) offers superior high-temperature resistance and mechanical stability compared to other materials.
• Wireless passive sensing requires robust materials capable of withstanding extreme conditions.

Purpose of the Study:

• To develop and demonstrate a wireless passive pressure sensor for operation at extreme temperatures up to 900°C.
• To investigate the use of single-crystalline magnesium oxide (MgO) as a substrate for high-temperature wireless passive sensors.
• To evaluate the performance and feasibility of a MgO-based MEMS pressure sensor in harsh environments.

Main Methods:

• Fabrication of an LC wireless passive pressure sensor using a single-crystalline MgO MEMS processing technique.
• Integration of inductance coils and a sealed cavity within the MgO substrate.
• Utilizing wet chemical etching and direct bonding processes for MEMS fabrication.
• Wireless interrogation of the sensor's resonant frequency variation in response to pressure changes.

Main Results:

• The MgO-based sensor demonstrated stable operation across a wide temperature range (22-900°C) and pressure range (0-700 kPa).
• A pressure sensitivity of 14.52 kHz/kPa was achieved at room temperature.
• The sensor exhibited monotonic frequency variation with applied pressure, enabling wireless readout.

Conclusions:

• Single-crystalline MgO is a viable and effective substrate material for high-temperature wireless passive pressure sensing.
• The developed MgO MEMS pressure sensor is suitable for practical engineering applications in extreme environments.
• The simple fabrication process of this sensor enhances its potential for widespread adoption in harsh conditions.