Abstract

Embedded sensors are one of the most effective and accurate methods for monitoring large structures. Composite structures such as pipelines, tanks, aircraft, ships, and ground vehicles confront some challenges with embedding strain sensing systems incorporating strain gauges or optical fibers that can introduce delamination, cracking and structural failure of the host in addition to the need for dedicated and expensive equipment

We present an RFID sensing technology that allows wireless transmitting of data and power while addressing issues associated with host/composite material integrity, combined with high sensing sensitivity. We develop a flexible and thin sensor based on LC circuit where the capacitance is considered a sensing unit^4-5. We introduce a controlled network of cracks in the parallel electrodes and benefit from the way these cracks modify the electromagnetic wave penetration inside the parallel plate capacitor^1-2. The tailored network of cracks creates a piezoresistive effect that leads to a transmission line behavior of the capacitance resulting in a tremendous increase in sensitivity³. This unconventional change in capacitance of the LC oscillator allows a large shifting in resonance frequency of the flexible circuit, producing a sensitive wireless strain sensor with a Gauge factor of 50 for less than 1% strain.

A few centimeters away from the sensor, the frequency shift of the sensor under strain is read passively through an external read-out system (antenna) by simple frequency sweeping. Eliminating wires, power source, and electronic chip from the sensor body allow the sensor to be integrated easily inside the composites materials while maintaining the materials' mechanical performance. The experimental results show the ability of our cracked wireless strain sensor to detect small strain signals through the composites structure with high accuracy. The developed sensor is intended to be a part of a wireless sensor network (WSN) for monitoring large composites structures.

References

1. Y. Xin, J. Zhou, X. Xu and Gilles Lubineau (2017). Laser-engraved carbon nanotube paper for instilling high sensitivity, high stretchability, and high linearity in strain sensors. Nanoscale, 9, 10897 - 10905
2. H. Nesser and G. Lubineau (2022). Minimizing the wiring in distributed strain sensing using a capacitive sensor sheet with variable-resistance electrodes. Scientific reports. 12(1), 13950  
3. H. Nesser and G. Lubineau (2021), Achieving super sensitivity in capacitive strain sensing by electrode fragmentation, ACS Applied Materials and Interfaces. v. 13(30), pp. 36062-36070
4. H. Nesser and G. Lubineau (2021), Strain sensing by electrical capacitive variation: from stretchable materials to electronic interface. Advanced Electronic Materials. v. 7(10), 2100190
5. H. Nesser, H.A. Mahmoud and G. Lubineau, High-sensitivity RFID sensor for structural health monitoring. Submitted to Advanced Sciences.

Location: Building 19, Level 3, Hall 1-2.