Rice University develops focused microwave 3D printing process for electronics integration
New Meta-NFS method selectively heats printed inks without damaging surrounding materials, enabling fabrication across biopolymers and living tissue
A research team at Rice University has developed a 3D printing process that uses focused microwaves to integrate functional electronics into a wide range of multimaterial structures, including temperature-sensitive biopolymers and living biological tissue.
The core challenge the team looked at when setting out the project was one that has faced constrained electronics 3D printing for more than ten years. Thermal processing is required to activate printed electronic inks, but it damages the surrounding materials.
That has led to an existing manufacturing workflow that relies on centralized foundries, where electronic components are fabricated separately and later assembled into devices through complex, labor-intensive processes.
Assistant professor Yong Lin Kong of Rice’s George R. Brown School of Engineering and Computing led the team, working with longtime collaborator John Ho, an associate professor and microwave engineering specialist at the National University of Singapore. They developed a device they call Meta-NFS — metamaterial-inspired near-field electromagnetic structure — which confines microwave energy into a heating zone as small as the diameter of a human hair. The focused energy is sufficient to post-process printed inks in place while keeping surrounding materials relatively cool.
“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,” stated Kong. “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.”
Broad material compatibility and biological applications
The process worked across metals, ceramics, and thermoset polymers, with microwave parameters adjusted to control particle microstructure and produce multifunctional circuitry, with orders-of-magnitude differences in mechanical and electronic properties within a single print run.
As a proof of concept, the team printed wireless strain sensors onto ultrahigh-molecular-weight polyethylene — a biopolymer used in joint replacements — and onto a bovine femur bone and a living leaf.
The group is now applying the method to ingestible electronic systems for diagnostics, bionic devices that interface with biological organs, and 3D printed soft robots with integrated electronics.
“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,” added Kong.
