| Title: | Multiple quartz crystals connected in parallel for high-resolution sensing of capacitance changes |
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| Authors: | ID Matko, Vojko (Author) |
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| Files: |  sensors-22-05030-v2.pdf (3,44 MB)
MD5: 1681B466D3BE0D729906B00D392CE45C
 https://www.mdpi.com/1424-8220/22/13/5030
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| Language: | English |
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| Work type: | Article |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: | FERI - Faculty of Electrical Engineering and Computer Science
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| Abstract: | We present a new highly sensitive, low-value capacitance sensor method that uses multiple
quartz crystals connected in parallel inside the oscillator. In the experimental setup, the measured
(sensible) reactance (capacitance) is connected in parallel to the total shunt capacitance of the quartz
crystals, oscillating in the oscillator. Because AT-cut crystals have a certain nonlinear frequency–
temperature dependence, we use the switching mode method, by which we achieve a temperature
compensation of the AT-cut crystals’ frequency–temperature characteristics in the temperature range
between 0–50 ◦C. The oscillator switching method also compensates for any other influences on the
frequency of the oscillator, such as ageing of the crystals and oscillator elements, supply voltage
fluctuations, and other parasitic impedances in the oscillating circuit. Subsequently using two
50-ms-delayed switches between the measuring and reference capacitors, the experimental error in
measuring the capacitance is lowered for measurements under a dynamic temperature variation in
the range of 0–50 ◦C. The experimental results show that the switching method, which includes a
multiple quartz connection and high-temperature compensation improvement of the quartz crystals’
characteristics, enables a sub-aF resolution. It converts capacitance changes in the range 10 zF–200 fF
to frequencies in the range 4 kHz–100 kHz.
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| Keywords: | multiple quartz crystals in parallel, quartz capacitive sensing method, temperature compensation, switching mode method |
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| Publication status: | Published |
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| Publication version: | Version of Record |
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| Submitted for review: | 21.06.2022 |
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| Article acceptance date: | 30.06.2022 |
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| Publication date: | 03.07.2022 |
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| Publisher: | MDPI AG |
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| Year of publishing: | 2022 |
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| Number of pages: | 15 str. |
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| Numbering: | Vol. 22, iss. 13 |
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| PID: | 20.500.12556/DKUM-92354  |
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| UDC: | 621.317 |
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| ISSN on article: | 1424-8220 |
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| COBISS.SI-ID: | 113633795 |
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| DOI: | 10.3390/s22135030 |
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| Copyright: | © 2022 by the author |
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| Publication date in DKUM: | 01.04.2025 |
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| Views: | 191 |
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| Downloads: | 10 |
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| Metadata: |    |
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| Categories: | Misc.
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