Fig. 1: Schematic diagrams and acoustic pressure distributions of an SFAT with an air-cavity Fresnel acoustic lens (ACFAL). | Microsystems & Nanoengineering

Fig. 1: Schematic diagrams and acoustic pressure distributions of an SFAT with an air-cavity Fresnel acoustic lens (ACFAL).

From: Simple sacrificial-layer-free microfabrication processes for air-cavity Fresnel acoustic lenses (ACFALs) with improved focusing performance

Fig. 1

a Perspective schematic diagrams showing an SFAT consisting of a PZT sound source with patterned electrodes and an ACFAL with annular-ring air cavities. Quadrant portions of the ACFAL and PZT are made translucent to better illustrate the structure of the transducer. b Cross-sectional diagram of an SFAT, showing how the ACFAL focuses ultrasound by blocking destructively interfering acoustic waves. c Top-view diagram of the transducer showing the relative positions of the top electrode (and soldering pad), air-cavity rings, and non-air-cavity regions. d, e FEM-simulated normalized acoustic pressure in water at 2.32 MHz from an ideal ACFAL with six non-air-cavity regions designed for a 5-mm focal length (d) on the central vertical plane and e the lateral focal plane at Z = 5 mm, with the same color bar scale but different dimension scales.

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