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Open AccessArticle

Active Thermoelectric Vacuum Sensor Based on Frequency Modulation

Department of Mechatronics Engineering, National Changhua University of Education, Changhua City 50074, Taiwan
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Micromachines 2020, 11(1), 15; https://doi.org/10.3390/mi11010015
Received: 22 November 2019 / Revised: 18 December 2019 / Accepted: 20 December 2019 / Published: 21 December 2019
(This article belongs to the Special Issue MEMS/NEMS Sensors: Fabrication and Application, Volume II)
This paper introduces a thermoelectric-type sensor with a built-in heater as an alternative approach to the measurement of vacuum pressure based on frequency modulation. The proposed sensor is fabricated using the TSMC (Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan) 0.35 μm complementary metal-oxide-semiconductor-microelectro-mechanical systems (CMOS–MEMS) process with thermocouples positioned central-symmetrically. The proposed frequency modulation technique involves locking the sensor output signal at a given frequency using a phase-lock-loop (PLL) amplifier to increase the signal-to-noise ratio (SNR) and thereby enhance the sensitivity of vacuum measurements. An improved first harmonic signal detection based on asymmetrical applied heating gives a precise measurement. Following calibration, the output voltage is in good agreement with the calibration values, resulting in an error of 0.25% under pressures between 0.1–10 Torr. View Full-Text
Keywords: thermoelectric-type vacuum sensor; vacuum detection; frequency modulation thermoelectric-type vacuum sensor; vacuum detection; frequency modulation
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MDPI and ACS Style

Chen, S.-J.; Wu, Y.-C. Active Thermoelectric Vacuum Sensor Based on Frequency Modulation. Micromachines 2020, 11, 15.

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