Finding ways to integrate electronics into living tissue could be critical to everything from brain implants to new medical technologies. A new approach has shown that 3D printing of circuits in living worms is possible.
There is a growing interest in finding ways to more closely integrate technology with the human body, particularly when it comes to the interaction of electronics with the nervous system. This will be crucial for future brain-machine interfaces and could also be used to treat a number of neurological conditions.
But for the most part, it has proven difficult to make these types of connections in ways that are non-invasive, long-lasting and effective. The rigid nature of standard electronics means they don’t mix well with the slippery world of biology, and getting them into the body in the first place can require risky surgical procedures.
A new approach relies instead on laser 3D printing to grow flexible conductive wires inside the body. In a recent paper in Advanced Materials Technologiesthe researchers showed they could use the approach to create star- and square-shaped structures in the bodies of microscopic worms.
“Hypothetically, it would be possible to print quite deep into the tissue,” said John Hardy of Lancaster University, who led the study. A new scientist. “So basically with a human or any other larger organism, you can print about 10 centimeters.”
The researchers’ approach involves a high-resolution Nanoscribe 3D printer that fires an infrared laser that can cure a variety of light-sensitive materials with very high precision. They also created a custom ink that incorporates the conductive polymer polypyrrole, which previous research has shown can be used to electrically stimulate cells in living animals.
To demonstrate that the circuit could achieve the primary goal of interacting with living cells, the researchers first printed circuits into a polymer scaffold and then placed the scaffold onto a piece of mouse brain tissue kept alive in a petri dish. They then passed a current through the flexible electronic circuit and showed that it produced the expected response in the mouse’s brain cells.
The team then set out to demonstrate that the approach could be used to print conductive circuits in a living being, something that had not been achieved before. The researchers decided to use the roundworm C. elegans because of its sensitivity to heat, injury and desiccation, which they say will make for a rigorous test of how safe the approach is.
First, the team had to adjust their ink to make sure it wasn’t toxic to animals. They then had to inject it into the worms by mixing it with the bacterial paste they feed on.
After the animals had ingested the ink, they were placed under the Nanoscribe printer, which was used to create square and star-shaped shapes several micrometers in diameter on the worms’ skin and inside them. The researchers acknowledged that the shapes did not appear correctly in the moving intestines due to the fact that they were constantly moving.
The shapes imprinted in the worms’ bodies had no functionality. But told Ivan Minev from the University of Sheffield A new scientist the approach may one day make it possible to build electronics intertwined with living tissue, although it will still take significant work before it is applicable in humans.
The authors also acknowledge that adapting the approach for biomedical applications will require significant additional research. But in the long term, they believe their work could enable personalized brain-machine interfaces for medical purposes, future neuromodulation implants and virtual reality systems. It may also make possible the easy restoration of bioelectronic implants in the body.
All of this is probably still a long way from being realized, but the approach shows the potential for combining 3D printing with flexible, biocompatible electronics to help bridge the worlds of biology and technology.
Image credit: Kbradnam/Wikimedia Commons