Temperature and Strain Sensing Characteristics of a 128° YX-Cut LiNbO₃ Rayleigh-Mode SAW Sensor From Room to Cryogenic Temperatures

Journal Article · Thu Oct 30 00:00:00 UTC 2025 · IEEE Sensors Journal

DOI: https://doi.org/10.1109/jsen.2025.3625472 · OSTI ID:3012584

Kohler, Michael C.  ^[1]; Luo, Jiaxing ^[1]; Camino, Fernando E.  ^[2]; Voiculescu, Ioana  ^[3]; Li, Fang  ^[1]

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1. New York Institute of Technology (NYIT), Old Westbury, NY (United States)
2. Brookhaven National Laboratory (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
3. City College of New York, NY (United States)

Accurate, passive, and wireless monitoring of cryogenic hardware is essential for high-energy physics, space propulsion, and biomedical instrumentation. Here, this study quantifies the coupled temperature-strain behavior of Rayleigh-mode surface acoustic-wave (SAW) delay-line sensors fabricated on 128° YX-cut LiNbO₃. A nonlinear finite element (FE) model incorporating Varshni-based elastic constants, higher-order thermal expansion, and temperature-dependent piezo- and dielectric coefficients was developed and validated experimentally between 280K and 80K. Free-standing (first test condition) and bonded/wired (second test condition) devices exhibited indistinguishable thermal responses; the average temperature coefficient of delay (TCD) in the critical cryogenic range from 130K down to 80K differed by only 0.15 ppm/K (0.32%), confirming that bonding-induced stress is negligible. Over 280-80K the measured TCD was 61.77 ppm/K, while the FE model predicted an equivalent temperature coefficient of frequency (TCF) of −62.74 ppm/K with an overall coefficient of determination R2 = 0.998. In the critical cryogenic interval 130-80K the TCD fell to 47.66 ppm/K, indicating improved thermal stability at low temperature. Controlled loading (0-300 με) revealed a strain coefficient of delay (SCD) that rises from 0.53 ± 0.02 ppm/με at 300K to 1.05 ± 0.02 ppm/με at 80K. This modest sensitivity confirms that, for temperature sensing, strain is a second-order perturbation above 135K but must be compensated at deeper cryogenic levels. Overall, this work establishes a predictive multiphysics model together with repeatable wired measurements that confirm the suitability of SAW sensors for temperature and strain monitoring in extreme cryogenic environments, while also providing a baseline for future wireless implementations.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: SC0012704
• OSTI ID: 3012584
• Report Number(s): BNL--229313-2026-JAAM
• Journal Information: IEEE Sensors Journal, Journal Name: IEEE Sensors Journal Journal Issue: 24 Vol. 25; ISSN 1530-437X; ISSN 1558-1748; ISSN 2379-9153
• Publisher: IEEECopyright Statement
• Country of Publication: United States
• Language: English