THE CHALLENGE:
Wireless sensing technologies play a crucial role in various sectors, including structural health monitoring, environmental surveillance, healthcare, and industrial automation. Surface acoustic wave (SAW) sensors, leveraging the piezoelectric effect, are particularly valued for their ability to detect multiple physical parameters such as strain, temperature, humidity, and vibrations. The increasing demand for real-time, remote monitoring solutions in inaccessible or harsh environments underscores the need for advanced wireless sensor systems. These systems must be versatile, reliable, and capable of operating without frequent maintenance to ensure continuous data collection and timely response to critical changes.
However, current approaches to wireless SAW sensing face significant challenges that hinder their widespread adoption and effectiveness. Traditional SAW sensors often operate at high frequencies, which can limit their application in power-constrained or interference-prone settings. Additionally, many existing systems rely on external power sources, reducing their suitability for long-term deployment in remote locations. The inability to simultaneously monitor multiple parameters efficiently and accurately further restricts their utility across diverse applications. Furthermore, conventional wireless transmission methods may suffer from limited range, reduced signal integrity, and vulnerability to environmental disturbances, making them unreliable for consistent performance. Addressing these issues is essential to advance the capabilities and practicality of wireless SAW sensor technologies.
OUR SOLUTION:
This wireless multifunctional surface acoustic wave (SAW) sensor system operates below 0.1 GHz to monitor parameters such as strain, temperature, water presence, and vibration. It features SAW resonators with interdigital transducers fabricated on a lithium niobate (LiNbO₃) piezoelectric wafer using photolithography and e-beam evaporation. The system employs a frequency-locked sensing mechanism that tracks amplitude changes in the reflected signal by locking the input frequency to the slope of the sensor's reflection spectrum. Wireless power and signal transmission are facilitated through optimized inductive coupling with specialized wireless power transfer (WPT) coils, enabling both active mode for low-power, on-demand sensing and passive mode for power-free vibration detection. The design supports long-term monitoring and is suitable for integration into various environments, including harsh and inaccessible locations.
This sensor system stands out due to its innovative frequency-locked sensing approach, which differs from traditional high-frequency SAW sensors by operating at lower frequencies and measuring amplitude variations rather than frequency shifts. Its dual-mode functionality allows for versatile applications, offering both active and passive sensing capabilities without the need for external power in certain scenarios. The optimized WPT module, developed through advanced 3D finite element simulations, ensures efficient wireless power transfer and signal integrity. Additionally, the system's ability to simultaneously monitor multiple parameters and its simplified fabrication process enhance its practicality and adaptability across diverse industries such as structural health monitoring, IoT, healthcare, and automotive sectors.
ADVANTAGES:
- Wireless operation suitable for harsh and inaccessible environments
- Supports both active and passive sensing modes
- Enables simultaneous monitoring of multiple parameters such as strain, temperature, water presence, and vibration
- Simplified fabrication process compatible with low-frequency SAW resonators
- Long-term monitoring capability without the need for frequent maintenance
- Versatile application potential across various industries like structural health monitoring, IoT, healthcare, and automotive
POTENTIAL APPLICATIONS:
- Infrastructure health monitoring
- Industrial equipment monitoring
- Environmental water quality sensing
- Wearable health devices
- Automotive tire pressure monitoring
