Shape-Configurable MXene-Based Thermoacoustic Loudspeakers with Tunable Sound Directivity

Area of Science:

• Materials Science
• Acoustics
• Electrical Engineering

Background:

• Wearable electronics require shape-configurable speakers with tunable sound directivity.
• Thin thermoacoustic (TA) loudspeakers offer a diaphragm-free alternative but face challenges in arbitrary shaping due to low sound pressure level (SPL) and poor conformability.
• Existing TA loudspeakers struggle with mechanical deformations and maintaining sound performance.

Purpose of the Study:

• To develop ultrathin, shape-configurable MXene-based TA loudspeakers with high SPL and stable performance.
• To investigate the impact of material properties (heat capacity, thermal effusivity) on TA loudspeaker performance.
• To demonstrate the versatility of these loudspeakers in various configurations and applications.

Main Methods:

• Fabrication of ultrathin MXene-based TA loudspeakers by controlling heat capacity per unit area of MXene and thermal effusivity of substrates.
• Characterization of sound pressure level (SPL) and sound performance stability under mechanical stress.
• Testing loudspeakers in bent, twisted, cylindrical, and stretched-kirigami configurations.
• Construction of parabolic and spherical large-area TA loudspeakers.

Main Results:

• Achieved high SPL output (74.5 dB at 15 kHz) and stable sound performance for 14 days.
• Demonstrated deformation-independent sound generation in various kirigami configurations with a parylene substrate.
• Successfully created large-area (20 cm × 20 cm) parabolic and spherical TA loudspeakers.
• Exhibited sound-focusing and 3D omnidirectional sound-generating capabilities.

Conclusions:

• Ultrathin MXene-based TA loudspeakers overcome limitations of traditional designs, offering high SPL and shape configurability.
• The developed loudspeakers are suitable for diverse applications, including sound-focusing and 3D sound generation.
• These advancements pave the way for next-generation wearable electronics and advanced acoustic devices.