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Wireless SAW Sensors for harsh environments and biomedical applications.

The SAW-based sensors present the advantage to be passive (battery-less) and can be interrogated using wireless techniques. These interesting properties combined with a small size, a low-cost radio interrogation system and small antennas when operating at high frequency, offer new and exciting perspectives for wireless measurement processes and IDTAG applications. When the materials constituting the devices are properly selected, it becomes possible to use those sensors without embedded electronics in hostile environments (such as high temperatures in excess of 500 °C, under ionizing radiations, pressures up to several thousand bars, …) where conventional wireless sensors do collapse or in biomedical applications as invasive or non invasive sensors.

Coordinator : Omar ELMAZRIA
Participants: Omar ELMAZRIA, Sami HAGE-ALI, Hamid M’JAHED, Frédéric SARRY,  Meriem ELHOSNI,

Alumni: Abdelkrim TALBI (IEMN-France), Mohamed ELHAKIKI (Triquint-Germany), Pascal NICOLAY (CTR-Austria), Thierry Aubert (CentraleSupélec-France), Ouarda LEGRANI (CentraleSupelec-France),  Eloi BLAMPAIN (USTM-Gabon), Mathias LINK (ANL-Luxembourg), Souhila BENSMAIN  (Univ. Tlemcen-Algeria)

Both fields, harsh environments and biomedical, are investigated by our group.

Harsh environments

Concerning harsh environments, the aim is the developing of SAW micro-sensor enabling wireless process control in industrial applications operating at very high temperature (up to 1000°C. Such a system will find applications in aerospace, power, nuclear, steel and glass industry, petrochemical processes plants and in other new unforeseen fields.

The real scientific advance therefore consists in the achievement of a high performances and relatively low-cost passive and accurate micro-sensor capable to operate at high frequency and in high temperature environments. Our work focus on five main S&T aspects:

- The study and the optimization of the different materials composing the sensor and associated antenna, and their behaviour at elevated temperatures.

- The optimization of piezoelectric layers (AlN, ZnO, AlN-Sc) deposition on the sapphire substrate to reach optimal transduction properties, stable and reproducible physical properties allowing for robust device designs.

- The design of high performances SAW resonators.

- The development of a packageless solution allowing for the sensor operation at temperatures in excess of 600°C for several hundred hours integrating antennas connection and assembly.

- The customization of the transceiver for wireless interrogation to match the performances of sensors in high temperature environments.

Biomedical applications

Concerning biomedical applications, the goal is the development of flexible systems including antenna, one or several biosensor including SAW sensor.

We aim at laying the groundwork to a new generation of wireless on-skin stretchable SAW sensors for body parameters monitoring including the temperature and the hydration level. The human body is a lossy environment for both electromagnetic and acoustic waves. We propose to solve this bottlenecks by using specific RF antennas designs and confined acoustic waves for the sensing part. From a microfabrication standpoint, we will use the combination of the transfer printing technique with specific elastomers, with a final goal of making ready-to-tattoo devices.

<font size="1"><i>Acoustic field distribution on the AlN/ZnO/Si packagless structure.</font></i>