In a groundbreaking advancement at the intersection of acoustics and materials science, researchers at Concordia University have pioneered a novel 3D printing technique that leverages focused ultrasound to fabricate microscale structures directly onto soft polymers such as silicone. This method, termed proximal sound printing, represents a significant leap forward in precision manufacturing, capable of resolving features an order of magnitude smaller than those achievable with prior sound-based printing strategies. By harnessing the unique capabilities of ultrasound waves, this technology opens fresh avenues for the creation of intricate microdevices crucial for medical diagnostics, environmental sensing, and flexible electronics.
Traditional 3D printing approaches typically rely on thermal or photochemical processes to solidify resins and polymers. However, these modalities often encounter limitations when miniaturizing complex geometries on pliable materials, particularly at microscale dimensions required for lab-on-a-chip systems and soft microfluidics. Proximal sound printing circumvents such bottlenecks by deploying highly localized ultrasound energy to initiate polymerization reactions in liquid monomers precisely where needed. This sub-millimeter accuracy is achieved by positioning the ultrasound transducers closer to the target substrate, effectively focusing the acoustic energy and enabling fine control over solidification.
The science underpinning this innovation revolves around the capacity of focused sound waves to induce chemical cross-linking in photo- and thermo-sensitive polymers without relying on external heat or light sources. Unlike previous direct sound printing techniques developed by the same research group, which demonstrated proof-of-concept but suffered from limited resolution and reproducibility, this proximal approach achieves vastly improved feature size control and power efficiency. The reduction in acoustic power requirements not only conserves energy but also minimizes thermal deformation of delicate polymeric materials, leading to enhanced structural fidelity.
One of the most remarkable outcomes of this technique is its ability to fabricate complex assemblies comprised of multiple materials and heterogeneous structures in a single, streamlined printing process. This multi-material printing capability is a critical advantage for constructing functional microsystems exhibiting diverse properties, such as flexible strain sensors integrated directly with microfluidic circuitry for real-time biochemical analysis. The ability to pattern these devices directly on soft substrates heralds new possibilities in wearable health monitors and implantable biomedical devices that demand both miniaturization and mechanical compliance.
Concordia’s team led by Professor Muthukumaran Packirisamy and PhD candidate Shervin Foroughi, collaborating with Mohsen Habibi from the University of California at Davis, has published their findings in the prestigious journal Microsystems & Nanoengineering. Their published study meticulously details experimental setups where focused ultrasound transducers were operated in close proximity to silicone and other polymeric substrates, triggering localized cross-linking reactions and thus solidifying the material layer-by-layer into finely detailed three-dimensional microstructures.
The implications of proximal sound printing extend beyond the laboratory and poised for industrial relevance, particularly in scenarios demanding rapid prototyping of microdevices with stringent dimensional tolerances. This technique’s enhanced repeatability and precision potentially reduce material waste and shorten production cycles, making it an appealing alternative to conventional lithography or laser-based processes which can be prohibitively expensive and less adaptable to soft polymeric materials.
Moreover, the sound-based printing approach addresses critical challenges in microfabrication where ultraviolet or visible light penetration is limited, or where heat-sensitive components preclude the use of traditional thermal curing. The ultrasound-induced polymerization mechanism thus constitutes a non-invasive alternative that expands the materials palette available for next-generation microelectronics and sensing platforms.
Looking forward, this technology promises transformative impacts on the development of soft robotics, flexible electronics, and portable diagnostic tools. The capacity to print intricate microchannels, integrated sensors, and responsive polymer structures directly onto flexible bases streamlines device packaging and enhances mechanical robustness. Such integration facilitates the production of lightweight, adaptable medical devices and wearable systems capable of continuous health monitoring or environmental detection in real time.
The research team acknowledges the foundational role of earlier sound printing methods, emphasizing that the critical advance of reducing the standoff distance between the ultrasound source and the printing interface grants unprecedented control over feature geometry and consistency. By employing proximal sound printing, they achieved features as small as tenths of a millimeter, representing a roughly tenfold improvement over their previous demonstrations.
From a technical perspective, the key to this improvement lies in the manipulation of acoustic focal zones and the refinement of polymer chemistry to optimize responsiveness to ultrasound stimuli. The researchers tailored polymer formulations to achieve rapid and reproducible curing kinetics when subjected to controlled ultrasonic intensities. This synergy of materials engineering and acoustics enables direct fabrication of microstructures without intermediate masking or post-processing steps.
Given these advances, proximal sound printing stands to revolutionize fabrication workflows in laboratories and factories where microscale devices form the backbone of innovation. This technology offers a versatile, energy-efficient, and adaptable route to creating next-generation microsystems crucial for biomedical engineering, sensor technologies, and nanomanufacturing.
Financial support for this research was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), reflecting the strategic importance of this innovation in advancing Canadian and global capabilities in advanced manufacturing and materials science.
Subject of Research: Not applicable
Article Title: Proximal sound printing: direct 3D printing of microstructures on polymers
News Publication Date: 8-Jan-2026
Web References: https://www.nature.com/articles/s41378-025-01035-w
References: Muthukumaran Packirisamy, Mohsen Habibi, Shervin Foroughi, “New sound-based 3D printing method enables finer, faster microdevices,” Microsystems & Nanoengineering, DOI: 10.1038/s41378-025-01035-w
Image Credits: Concordia University
Keywords: Nanotechnology, Nanofabrication, Polymer engineering
