Evanescent-mode-resonator-based and antenna-integrated wireless passive pressure sensors for harsh-environment applications

Purpose – Physical contact and traditional sensitive structure Physical contact and traditional pressure-sensitive structures typically do not operate well in harsh environments. This paper proposes a high-temperature pressure measurement system for wireless passive pressure sensors on the basis of inductively coupled LC resonant circuits. Design/methodology/approach – This paper begins with a general introduction to the high-temperature pressure measurement system, which consists of a reader antenna inductively coupled to the sensor circuit, a readout unit and a heat insulation unit. The design and fabrication of the proposed measurement system are then described in detail. Findings – A wireless passive pressure sensor without an air channel is fabricated using high-temperature co-fired ceramics (HTCC) technology and its signal is measured by the designed measurement system. The designed heat insulation unit keeps the reader antenna in a safe environment of 159.5°C when the passive sensor is located in a 900°C high-temperature zone continuously for 0.5 h. The proposed system can effectively detect the sensor’s resonance frequency variation in a high bandwidth from 1 to 100 MHz with a frequency resolution of 0.006 MHz, tested from room temperature to 500°C for 30 min. Originality/value – Expensive and bulky equipment (impedance analyzers or network analyzers) restrict the use of the readout method outside the laboratory environment. This paper shows that a novel readout circuit can replace the laboratory equipment to demodulate the measured pressure by extracting the various sensors’ resonant frequency. The proposed measurement system realizes automatic and continuous pressure monitoring in a high-temperature environment with a coupled distance of 2.5 cm. The research finding is meaningful for the measurement of passive pressure sensors under a wide temperature range.

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MEMS Sensors for Down-Hole Monitoring of Geothermal Energy Systems

ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C ◽

10.1115/es2011-54699 ◽

2011 ◽

Author(s):

Sarah Wodin-Schwartz ◽

Matthew W. Chan ◽

Kirti Ramesh Mansukhani ◽

Albert P. Pisano ◽

Debbie G. Senesky

Keyword(s):

Geothermal Energy ◽

Microelectromechanical Systems ◽

Pressure Sensors ◽

Energy Systems ◽

Harsh Environment ◽

Well Performance ◽

Mems Sensors ◽

Pressure Profiles ◽

Temperature And Pressure ◽

Monitoring Technologies

This paper reviews the limitations in current down-hole monitoring technologies for geothermal energy systems and introduces microelectromechanical systems (MEMS) sensors as a means of optimizing well performance. The use of continuous, real-time, down-hole monitoring can improve geothermal well efficiencies and increase well life. More specifically, monitoring can aid in obtaining accurate temperature and pressure profiles to allow for optimized well reinjection and energy extraction. A variety of materials used in the fabrication of MEMS sensors have been tested in an experimental geothermal environment (critical-point water) and exposed for up to 100 hours. The results obtained from the exposure testing support the use of harsh environment materials to create a suite of sensors that can be permanently located down-hole. MEMS-based temperature and pressure sensors using a harsh environment materials platform are currently in the design phase for down-hole monitoring. In addition to designing harsh environment sensors that can reliably monitor down-hole conditions, suitable packaging must be considered. One vision is to mount the sensors to the well casings through the use of new bonding technologies.

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