Generating Multi-Pixel Thermal Images Through an Acousto-Thermal Effect

In this study, we attempted to systematically integrate the acousto-thermal effect and acoustic holography to explore the feasibility of generating controlled thermal fields in a tissue-mimicking material. To enable this capability, our method firstly generates multiple acoustic focal points by using an acoustic hologram-based lens and then constructs a thermal field with multiple elevated-temperature areas based on the acousto-thermal effect. To design the acoustic lens, multiple points are distributed on a constraint plane, which is used as the input for determining the desired phase map based on an iterative phase propagation approach. To characterize the performance of our hologram for generating an acoustic field with concentrated energy at multiple points, on one hand, numerical simulations were performed. On the other hand, experiments were performed by using a 3D printed hologram to generate multiple acoustic focal points and further enable the acousto-thermal effect at multiple target locations of a phantom slice. The thermal image recorded by an infrared camera shows multiple elevated-temperature areas. Moreover, the locations of these elevated-temperature areas agree with the locations of acoustic focal points. We expect this study can contribute to the noncontact control of thermal fields for biomedical applications.