This Small Business Innovation Research (SBIR) Phase I project explores and develops novel wireless powered embedded sensors that have the potentials to revolutionize wireless sensing and communications for future non-intrusive structural health monitoring. The embedded nature of these sensors will eliminate the need to retrofit them inside structures and due to the absence of bundles of cables and wires that are currently being used with wired retrofitted sensors the proposed scheme will be simple, low cost, and non-intrusive. The objective of this research is to bring about fundamental breakthroughs on embedded sensor design which will focus on efficient coupled resonant antennas for non-contact wireless power transfer to embedded sensors and a miniature dual-function sensor antenna element capable of sensing and data communication. The effects of variable distance, the electromagnetically lossy structural materials, the presence of moisture, and the presence of metal reinforcements nearby will be investigated and mitigated by designing new antenna geometries and circuits and by using thin-film dielectric and magnetic materials. The outcome of this research will consist of embedded near-field optimally coupled antennas for non-contact wireless power transfer and embedded efficient, wideband dual-function antenna for wireless data telemetry.
The broader impact/commercial potential of this project include the new knowledge and innovations in the area of embedded near-field and far-field antennas that can operate efficiently near metal and other lossy dielectric materials, such as concrete, wood and soil. The embedded self-sustaining sensors to be developed in this work will revolutionize future structural health monitoring by finding applications in bridge health monitoring (corrosion, pH, strain etc.), underground gas pipeline monitoring, hazardous nuclear waste monitoring, aircraft structural health monitoring, and residential housing monitoring and diagnostics. This research will also foster the growth of new research ideas in the area of embedded sensing and communications through the collaborative efforts between industry and academia. All of the above applications and others have tremendous potentials to save human lives from catastrophic structural failures. The proposed embedded wireless sensors have huge commercial prospects for success in the wireless market segment because of their unique position in terms of innovation. They will have significant economic impact on agencies and industries because of their scope for tremendous cost savings which are incurred both in terms of preventive as well as after effect maintenance.
. Proximity coupled resonant Radio Frequency (RF) antennas and RF to DC power conversion circuits were developed and measured to demonstrate the feasibility of wireless power transfer to an embedded sensor in concrete. Using the DC power, efficient wireless battery charging was shown for embedded elements in dry and wet concrete. Furthermore, the feasibility of wireless power transfer inside concrete when the sensor antenna was in the close proximity of a metallic structure (such as a steel rod) was also shown. Under the sensor design thrust, a dual-function moisture sensor antenna was developed which can detect the moisture inside concrete and function as an antenna at the same time. The sensor mode operation was attained by employing the concept of fringing field dielectrometry while the antenna mode operation was obtained by isolating the sensor mode using a lumped capacitive component. Wireless moisture measurements for various cases were performed to show the capability of the sensing system. The antenna mode operation was confirmed by conducting a Received Signal Strength Indicator (RSSI) test for the receive embedded sensor antenna. The results of this work has broad impacts both in the areas of near-field coupled resonance wireless power transfer and embedded moisture sensing in material media. Efficient wireless power transfer to embedded sensors inside bridges, under soil or inside house walls is critically important to ensure continued safety, reliability and security. Similarly knowing the presence of moisture in media such as soil, wood, concrete and other structure is also of great importance as it indicates the current health condition and longevity of the media. Most importantly, the research outcomes of this project have immense potentials for saving human lives and financial costs by preventing catastrophic structural failure.
