Unconventional protocol for SAW sensor: multi-physic response enrichment in liquid medium
Résumé
This paper presents a new paradigm in the analysis and methodology for Surface Acoustic Wave (SAW) devices for sensing application in a liquid medium. Th new protocol encourages the analysis of the electrical and electro-acoustic behavior of the sensor rather than limiting the measurement interest to mechanical interactions between the sensor and the medium. According to experimental responses, some hypotheses are proposed allowing the separation of each electrical and mechanical mechanisms based on post-treatment analysis methods. Thus, to better understand the proposed approach, we introduced a new and unconventional energy flow chart of the acoustic wave propagation in the SAW device which helped us extracting our hypotheses. This new paradigm allows us to get information related to both dielectric and mechanical parameters of a liquid sample using a single sensor, enriching the response. In contrary to most works surrounding the SAW sensors, this new method does not intend to increase the sensitivity of the sensors. Instead, it focuses on an unconventional ”holistic” approach that achieves an improved understanding of the sensitive phenomena and enriches the global response and analysis to a given characterization. Ultimately, this improved understanding could help to increase the sensitivity to a selected target using the same method. This approach could be used with all electro-acoustic sensor devices. We applied this method to Love wave sensors with different technological characteristics influencing the electric and acoustic response with numerous fluid solutions for a large diversity of dielectric constants and mechanical characteristics responses. A larger set of measurement from the Love wave sensor is obtained allowing to extract both dielectric and mechanical parameters of a liquid medium on the Love wave sensor surface.