Finding ways to integrate electronics into living tissue will be crucial for everything from brain implants to new medical technology. A new method shows that it is possible to print 3D circuits in living worms.
There is a growing interest in finding ways to more closely integrate technology with the human body, especially when it comes to interfacing electronics with the nervous system. This will be important for future brain-machine interfaces and may also be used to treat many neurological conditions.
But for the most part, it has proven difficult to make these types of connections in ways that are non-invasive, sustainable, and effective. The rigid nature of standard electronics means it doesn’t mix well with the squishy world of biology, and getting it inside the body in the first place can require risky surgical procedures.
A new method instead relies on laser-based 3D printing to grow flexible, conductive wires inside the body. In a recent paper on Advanced Materials Technologiesresearchers have shown that they can use the method to create star and square structures within the bodies of microscopic worms.
“Hypothetically, it would be possible to print deep inside the tissue,” said John Hardy of Lancaster University, who led the study. New Scientist. “So, in principle, in a human or other large organism, you can print about 10 centimeters in.”
The researchers’ method involves a high-resolution Nanoscribe 3D printer, which fires an infrared laser that can heal various light-sensitive materials with high precision. They also developed a bespoke ink that includes the conducting polymer polypyrrole, which previous research has shown can be used to electrically stimulate cells in living animals.
To prove that the design could achieve its primary goal of interfacing with living cells, the researchers first printed the circuits on a polymer scaffold and then placed the scaffold on top of a slice 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 mouse brain cells.
The group then decided to demonstrate the method that can be used to print conductive circuits inside a living being, something that has so far not been achieved. 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 method is.
First, the team had to adjust their ink to make sure it didn’t poison the animals. They have to get it inside the worms by mixing it with the bacterial paste they feed on.
Once the animals have absorbed the ink, they are placed under a Nanoscribe printer, which is used to create square and star-shaped patterns a few micrometers across the worms’ skin and inside their guts. The forms don’t come out properly in the moving gut though, the researchers claim, due to the fact that it’s constantly moving.
The patterns printed inside the body of worms are useless. But Ivan Minev from the University of Sheffield spoke out New Scientist the method may one day make it possible to make electronics linked to living tissue, although it will take a lot of work before it can be used in humans.
The authors also admit that adapting the method for biomedical applications will require further research. But in the long run, they believe their work will enable customized brain-machine interfaces for medical purposes, future neuromodulation implants, and virtual reality systems. It may also make it possible to quickly fix bioelectronic implants inside the body.
All that is likely still far from being realized, but the method shows the potential of combining 3D printing with flexible, biocompatible electronics to help interface the worlds of biology and technology.
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