Session: 14-04-01: Micro/Nano Devices and Medical Systems

Paper Number: 166029

A Surface Acoustic Wave (SAW) Sensor for Multi-Cycle Cryogenic Strain Measurements 

The development of reliable strain and temperature sensors capable of operating at cryogenic temperatures is increasingly important for advanced energy, aerospace, and biomedical engineering applications. Traditional sensor technologies, such as resistive strain gauges and optical fiber systems, often face significant challenges in these low‐temperature applications, including electromagnetic interference, heat generation, fragile mechanical structures, and sensitivity issues. Thus, there is a need to identify alternative techniques and sensors that provide accurate, repeatable measurements while minimizing traditional sensor limitations such as power consumption and wiring requirements. To address these ongoing challenges, this research investigates the use of a surface acoustic wave (SAW) sensors fabricated on 128° YX‐cut lithium niobate (LiNbO₃) for combined strain and temperature sensing from 300 K down to 80 K.

This work utilizes a custom, fixed–fixed point actuator structure designed to apply various amounts of strain to the SAW device within a cryogenic chamber cooled by liquid nitrogen. Two experiments were carried out to assess sensor behavior. In the first experiment, the sensor was evaluated at temperatures of 300 K, 245 K, 190 K, 135 K, and 80 K, with the applied strain ranging from 0 to 400 µε in increments of 50 µε. Up to three complete loading/unloading cycles were performed for each temperature, enabling an assessment of repeatability and sensor performance across a broad thermal span. Results showed that the strain coefficient of delay (SCD) was consistently negative (approximately −0.91 to −1.36 ppm/μϵ ). Additionally, a temperature coefficient of delay (TCD) of −67.62 ppm/K was obtained over the full temperature range, confirming the sensor’s sensitivity to changes in temperature.

In the second experiment, the sensor was evaluated for a narrower set of cryogenic temperatures (135 K, 120 K, 105 K, 90 K, and 80 K) using the same strain cycling procedures. Again, negative SCD values (around −1.49 to −1.67 ppm/μϵ ) were observed, though mechanical limitations and actuator variability introduced more significant measurement variability than in the first experiment. This observed hysteresis‐like behavior was especially evident between loading and unloading curves, underscoring the influence of small deformations or misalignments in the fixed–fixed point structure and reduced actuator performance at very low temperatures. Despite these challenges, a TCD of −29.03 ppm/K was observed for this narrower range.

These preliminary findings confirm the reliability of SAW‐based devices for cryogenic strain and temperature monitoring, and highlight the future benefits of wireless, passive operation in demanding environments. Future work will focus on improving the mechanical stability of the test fixture, enhancing the reliability of cryogenic actuation, and refining the SAW sensor design. These steps are expected to yield more consistent measurements, paving the way for robust, high‐precision cryogenic sensing solutions that can advance science and engineering across multiple sectors.

Presenting Author: Michael Kohler New York Institute of Technology

Presenting Author Biography: Michael C. Kohler received his Bachelor’s degree in Biomedical Engineering from the University of Hartford in 2020. In pursuit of further expertise, he obtained a Master’s degree in Bioengineering from the New York Institute of Technology in 2022 and is currently working on obtaining his Ph.D. in Engineering at NYIT. As an active member of professional societies, Michael Kohler is affiliated with the BMES (Biomedical Engineering Society), ASME (American Society of Mechanical Engineers), and IEEE (Institute of Electrical and Electronics Engineering.

Authors:

Michael Kohler New York Institute of Technology
Ioana Voiculescu The City College of New York
Fang Li New York Institute of Technology