Session: 01-03-01: General topics in vibrations and acoustics

Paper Number: 166811

Wireless Surface Acoustic Wave Sensor for Vibration and Bioprinting Monitoring 

Surface Acoustic Wave (SAW) sensors have demonstrated significant potential for wireless and high-sensitivity sensing applications in structural health monitoring (SHM), biomedical diagnostics, and environmental sensing. Their ability to detect small changes in mechanical, thermal, and chemical properties makes them highly versatile across those diverse fields. However, conventional SAW sensors often operate at high frequencies, requiring complex fabrication processes, and many existing designs rely on wired connections for power and data transmission, limiting their practicality for remote and real-time monitoring. To address these challenges, this study presents circuit-free wireless multifunctional SAW sensors that enable multiple wireless sensing functions, including hydrogel polymerization evaluation for bioprinting and vibration sensing for SHM.

 

The proposed SAW sensing system is composed of a pair of interdigital transducer (IDT)-based SAW resonators on piezoelectric chips and inductive coupling-based wireless power transfer (WPT) antennas with matching circuits. The inherent piezoelectric effect also enables structural vibrations to produce electrical signals. They leverage a delay-line sensing mechanism, rather than the mechanism of precisely tracing resonance frequency shifts used by most wireless SAW sensors. Our SAW sensor generates a 10-cycle sinusoidal wave at its resonant frequency and measures the propagation time along the delay line, allowing real-time assessment of hydrogel polymerization.

 

To demonstrate the capabilities of the developed sensor, we conducted two proof-of-concept experiments. The first experiment focused on vibration testing, where the SAW sensor was used to measure structural vibrations induced by controlled excitation. The sensor effectively captured variations in resonance frequency corresponding to the dynamic strain of the vibrating structure. The results confirmed the sensor's ability to detect structural resonance shifts with high precision, highlighting its potential for SHM applications, particularly in aerospace, civil, and mechanical engineering systems where continuous, wireless vibration monitoring is crucial.

 

The second experiment involved real-time hydrogel polymerization monitoring, leveraging the SAW sensor’s sensitivity to changes in material properties. During the photopolymerization process, the sensor detected phase and amplitude variations in the acoustic wave propagation as the hydrogel transitioned from a liquid to a solid state. The experimental results demonstrated a clear correlation between the polymerization kinetics and the observed SAW signal response, validating the sensor's utility in biomedical and materials science applications. This capability is particularly valuable for monitoring hydrogel-based biomaterials, tissue engineering scaffolds, and advanced drug delivery systems, where precise control over polymerization dynamics is essential.

 

The findings of this study underscore the feasibility and robustness of wirelessly powered SAW sensors for multifunctional sensing applications. By integrating WPT with SAW sensing technology, we provide a scalable, non-contact, and energy-efficient solution for real-time monitoring in both engineering and biomedical fields. Future research will focus on enhancing the sensor’s performance by improving WPT efficiency, expanding its operational range, and optimizing signal processing techniques to enable simultaneous multi-parameter sensing. Additionally, reducing operational frequency while maintaining high sensitivity will be explored to further enhance its applicability in long-range sensing environments.

 

Overall, this work lays the foundation for next-generation wireless SAW sensing systems that can be deployed for real-time structural and biomedical monitoring, offering a promising alternative to traditional wired and high-frequency SAW sensors.

Presenting Author: Luyu Bo Virginia tech

Presenting Author Biography: Graduate Student

Authors:

Luyu Bo Virginia tech
Teng Li Virginia tech
Jiali Li Virginia tech
Yingshan Du Virginia tech
Bowen Cai Virginia tech
Zhenhua Tian Virginia tech