In a recently published paper in Science Advances , a team led by Rice University’s Yong Lin Kong describes a new 3D-printing process with focused microwaves that overcomes a fundamental constraint of electronics 3D printing that has limited the field’s potential for more than a decade: the inability to heat printed ink — a crucial processing step — without damaging the materials underneath.
The ability to integrate functional materials and spatially program their properties governs both device performance and the limits of what can be built. Existing manufacturing approaches are fundamentally limited in both aspects. Electronic components, for instance, are fabricated in massive, centralized foundries, often decoupled from the final device. Integrating them requires complex, labor-intensive assembly that constrains both the form and the function of what can ultimately be created.
Multimaterial 3D printing should, in principle, allow fabrication of free-form architectures in which electronic and mechanical properties are programmed directly into the structure. However, the thermal processing required to render printed electronic inks functional destroys the very materials these devices require.
Kong’s team demonstrates that by concentrating microwave energy into a confined heating zone as small as the diameter of a human hair, the researchers can selectively heat the electronic ink during the 3D-printing process while keeping the surrounding material relatively cool and thereby reducing potential damage.
“The ability to selectively heat the printed materials enables us to spatially program the ink’s functional properties, even when surrounded by temperature-sensitive material,” said Kong, assistant professor of mechanical engineering at Rice’s George R. Brown School of Engineering and Computing . “This allows us to integrate freeform electronics onto a broad range of substrates, including biopolymers and living biological tissue, all within a desktop-size printer without the needs of complex facilities or labor-intensive manual processes.”
Kong has been developing processes for 3D-printing electronics since his doctoral work, with several breakthrough inventions with promising applications. But for more than a decade, the inability to selectively heat printed inks has limited the technology to a narrow combination of materials, constraining both the functionality and the performance of printed devices.
Ever since establishing his research group, Kong has been investigating strategies that can overcome the long-standing challenge. Together with longtime collaborator John Ho, an expert in microwave engineering and associate professor at the National University of Singapore, they designed what they call “Meta-NFS” — short for metamaterial-inspired near-field electromagnetic structure — a device that confines microwave energy in the near field to reach sufficiently high energy density needed to postprocess the printed inks.
When integrated with a micro-extrusion 3D-printing process, the ability to control heating with focused microwaves enables a capability that previous electronics manufacturing approaches cannot achieve: spatially programming functional properties continuously, even within a single printing process. By adjusting microwave parameters, for example, the researchers can precisely modulate the degree of heating to control the microstructure of the printed particles. This allows the creation of multifunctional circuitry with orders-of-magnitude differences in mechanical and electronic properties in a single printing process without the need for material switching.
They also demonstrated that the approach extends to a broad range of functional materials from metals and ceramics to thermoset polymers, showing that near-field microwave printing can process and program diverse material classes in situ. Further, the selective nature of microwaves allows the energy to penetrate deeply to heat target materials even when fully encapsulated.
Together, these unique attributes allow multimaterial devices to be built seamlessly from a broad material palette in a continuous manufacturing process, all within a desktop-size platform — a stark contrast to conventional approaches that require complex equipment, labor-intensive processing and manual assembly.
Functional electronics can also be directly printed into temperature-sensitive biopolymers and biological constructs, something that was previously challenging to achieve. As proof of concept, the researchers printed wireless strain sensors onto ultrahigh-molecular-weight polyethylene, a biopolymer commonly used in joint replacements, creating electronics-enhanced implants that could potentially monitor stress or wear without altering their structure. They also printed wireless sensors directly onto a bovine femur bone and a living leaf, opening new possibilities for understanding and controlling biological processes.
Meta-NFS 3D printing is now a core foundation for Kong’s group in developing fundamentally new classes of electronic devices for a broad range of applications that did not exist before. For instance, the group is developing ingestible electronic systems for personalized diagnostics and treatment, designing bionic devices that interface with biological organs and creating next-generation 3D-printed soft robots and drones with highly integrated electronic functionality.
“Meta-NFS 3D printing enables us to develop new classes of hybrid electronic devices that could not have been built — or even envisioned — with previous manufacturing approaches, providing us with a new capability to address unmet societal needs,” Kong said.
This research was supported by the Office of Naval Research and the National Institutes of Health.
Science Advances
Three-dimensional printing of nanomaterials-based electronics with a metamaterial-inspired near-field electromagnetic structure
6-Feb-2026