Binary amplitude switch for photoacoustic transducer toward dynamic spatial acoustic field modulation

Area of Science:

• Acoustics
• Biomedical Engineering
• Materials Science

Background:

• Photoacoustic (PA) transducers offer advantages over electroacoustic transducers, including high-amplitude, high-frequency, broad-bandwidth ultrasound generation and electromagnetic interference immunity.
• A key limitation of current PA transducer technology is the lack of effective control over the spatial sound field, hindering broader applications.

Purpose of the Study:

• To present the first experimental study on dynamic spatial ultrasound modulation for PA transducers.
• To introduce a novel PA transducer element design enabling controlled acoustic wave interference.

Main Methods:

• A novel PA transducer element featuring a suspended compound PA conversion film with switchable backing conditions (air/glass) via pneumatic actuation was designed.
• The switchable backing conditions were utilized to create destructive and constructive acoustic wave interference.
• A linear PA transducer array with three independently controllable elements was employed for spatial sound field manipulation demonstration.

Main Results:

• Switching the device's backing condition achieved nearly an order of magnitude contrast in output acoustic amplitude with identical laser excitation, demonstrating binary amplitude tuning.
• Dynamic spatial sound field manipulation was successfully demonstrated using the linear PA transducer array.

Conclusions:

• The developed PA transducer element and modulation strategy enable effective control over the spatial ultrasound field.
• This breakthrough represents the first successful application of dynamic spatial sound field manipulation in PA transducer technology, paving the way for wider adoption.