Holographic direct sound printing: Sound waves revolutionize 3D printing

A sound-based three-dimensional (3D) printing method has emerged as a groundbreaking technique in additive manufacturing, diverging from light- or heat-based printing methods by harnessing sound waves to solidify materials.¹ It uses high-intensity focused ultrasound to trigger sonochemical reactions within a resin, which enables creating 3D structures without physical contact.

The core principle of direct sound printing (DSP) is its ability to focus sound waves precisely within the printing material, where it induces localized cavitation and polymerization—which selectively solidifies specific regions to form intricate structures.

In our recent study, holographic direct sound printing (HDSP) advances DSP by introducing holographic acoustic fields that pattern ultrasound waves into complex 3D shapes to enable simultaneous printing of entire sections. Through acoustic holography, HDSP overcomes several limitations of traditional DSP to provide enhanced energy efficiency, faster printing times, and higher resolution.

HDSP’s compatibility with robotic arms also allows for greater degrees of freedom in extrusion, which expands its potential applications and versatility for complex manufacturing environments (see Fig. 1).

Potential applications for HDSP

HDSP’s unique capabilities make it suitable for a wide range of applications—from medical devices to aerospace components.

Objects at multiple planes. It enables printing objects at multiple planes, thanks to the ability of the acoustic hologram to encode cross-sectional images/information to create multiple target objects positioned at various distances from the hologram plane. This allows the simultaneous pattern formation and polymerization across different planes, based on the number of objects encoded within the hologram. HDSP also shows potential for multimaterial printing (see Fig. 2a and 2b).

Remote and challenging environment manufacturing. One of the most distinctive advantages of sound-based 3D printing, compared to conventional light- or heat-based methods, is that it can be used for remote material fabrication. This is possible because sound waves can penetrate barriers, unlike light, which is often obstructed. 

HDSP’s ability to create solid structures without direct physical access to the printing area makes it well suited for manufacturing within remote or hard-to-reach environments. Figure 2c shows the printed part of our optically opaque resin. It means HDSP could enable over-the-barrier fabrication to facilitate components such as underwater for deep-sea applications.

In-body printing. In-body printing is a unique application derived from HDSP’s remote printing capabilities. This approach holds potential for noninvasive medical treatments, where precise structures can be formed in situ to facilitate targeted therapies and implants noninvasively (see Fig. 2d and 2e).