Acoustics has high variety of applications ranging from structural-health monitoring, sonar, and biological applications to sensors. The acoustic domain employs pressure waves for detection and provides better performance for sensing applications that require interactions with mechanical signals. High-performance sensing is possible by using acoustic biosensors in biological applications since most of the biological signals are in mechanical domain, in which the sensing mechanism directly interacts with them. In this chapter, the physics for different acoustic modes are introduced and their specific applications are mentioned, as well as sensing principles and operating mechanisms are presented. Also, the structural perspectives for acoustic biosensors are given and the fabrication techniques and materials are described. In this chapter, the biochemical principles behind the sensing are introduced and the layers and surfaces interacting with biomolecules are discussed. Some of the commercially available acoustic biosensors are presented and a short discussion of future perspectives is given.

We developed a microchip device using surface acoustic waves (SAW) and sharp-edge glass microparticles to rapidly lyse low-level cell samples. This microchip features a 13-finger pair interdigital transducer (IDT) with a 30-degree focused angle, creating high-intensity acoustic beams converging 6 mm away at a 16 MHz frequency. Cell lysis is achieved through centrifugal forces acting on Candida albicans cells and glass particles within the focal area. To optimize this SAW-induced streaming, we conducted 42 pilot experiments, varying electrical power, droplet volume, glass particle size, concentration, and lysis time, resulting in optimal conditions: an electrical signal of 2.5 W, a 20 μL sample volume, glass particle size below 10 μm, concentration of 0.2 μg, and a 5-min lysis period. We successfully amplified DNA target fragments directly from the lysate, demonstrating an efficient microchip-based cell lysis method. When combined with an isothermal amplification technique, this technology holds promise for rapid point-of-care (POC) applications.