SAW Sensor Basics on Material, Antenna, and Applications: A Review

Wireless, passive, and capability to withstand harsh environment make the surface acoustic wave (SAW) sensor a very prominent and unique sensor among others. SAWs are basically mechanical waves similar to sound waves, which propagate on the top surface of the piezoelectric material. Comb-like metallic structures are deposited on the top surface of the material, called the interdigital electrode transducer (IDT), and this helps in conversion from electromagnetic (EM) wave to acoustic wave. This phenomenon is called inverse piezoelectricity. Although the SAW concept is not new, it has gained much attention in recent years because of its unique specialty when it is used as a sensor. This article discusses each and every aspect of SAW sensor, including antenna design, reader architecture, and piezoelectric substrate along with its cut direction, IDT structures, and its application in various domains. Despite having unique properties, there are certain limitations in SAW sensors. These limitations have also been discussed in this article. Finally, we have discussed the areas where research scope persists to make it more robust, versatile, and industry-oriented.