Artificial electronic devices are being tested to interact with nervous system tissue in a University of Newcastle study.
The four-year study, led by Associate Professor Rebecca Lim, is working towards a new range of medical devices.
The study involves developing nanoparticles from "organic semiconductor materials" that could be used for "neural prosthetic devices".
Such devices restore functions lost due to neural damage, such as seeing and hearing.
Dr Lim said bioelectronic signals in humans are the basis for "all of our senses, movement, and even our emotions".
The aim is to create devices that can direct these signals to treat medical conditions.
Bioelectronic devices are already available and used for many purposes, but they have drawbacks.
Such devices include glucose sensors for testing blood sugar in diabetes and cochlear implants for hearing.
Deep brain stimulation also helps people with neurodegenerative movement disorders like Parkinson's disease.
"However, many devices used for implantation in the body use materials such as metals, which are hard, rigid and foreign to the body," Dr Lim said.
Such devices are not compatible with biological tissue and can aggravate it.
"One of the challenges of medical science is to use artificial electronic devices to communicate with the electronic signals of the body."
Organic semiconductor materials are much more compatible with the body. They are based on carbon - the same chemical element as biological tissue.
They can be printed into thin and flexible products and used to stimulate and measure biological tissue.
"These characteristics make them ideal materials to be used for the design of medical devices that interact with neural tissue," she said.
The implications of this work are profound.
Once developed, the materials could be surgically implanted into the body to stimulate the nervous system on demand, without needing batteries or wires.
As the materials can stimulate nerve cells using different colours of light, they could be used in prosthetic devices for vision.
One potential use is to restore a blind person's vision in colour.
The study is examining the physical and chemical properties of organic semiconductor materials, along with their biocompatibility [compatibility with living tissue].
Dr Lim said the materials "speak in the same bioelectronic language as the nervous system when they communicate".
This means they can be used to "communicate with nervous system tissue".
The materials have been made into "thin films" for the study. Each organic semiconductor material responds to a different wavelength of light.
"We are growing nervous system cells onto these thin films. We then examine how well cells survive and grow on the materials to determine if they are biocompatible," she said.
This will help determine which materials to pursue for further experiments.
Bioelectronic devices work by producing electricity, so many current devices need permanent power sources that connect to bulky wires.
"This is one of the major limitations," said Dr Lim said, a member of the HMRI Brain Neuromodulation Research Program.
"An exciting property of organic semiconductors is their capacity to create electronic charge when they are exposed to light, without the need for external power sources or wires."
Organic semiconductors are similar to the materials used in roof-top solar panels, but they are made out of carbon rather than rigid silicon panels.
After growing nerve cells on these materials, the researchers shine a specific colour of light on them to stimulate or excite the nerve cells.
"We can record the function or activity of nerve cells in response to light. We can also measure anatomically how well neurons grow on these materials.
"Using the unique properties of the materials and shining light on them as they grow, we have the capacity to direct nerve growth in a particular direction.
"We can create organic semiconductor nanoparticles that are 1000 times smaller than the width of a human hair."
As they are biocompatible, stimulate nerve cells and can be activated, they could be used for new pharmaceuticals.
They could encapsulate drugs to "enhance interactions with nervous system tissue".
The nanoparticles could also release the drugs in a controlled way.
"When drugs are administered, a person initially receives a high dose slightly over the therapeutic dose. Then the drug effects taper off.
"The ability to control drug release from organic semiconductor nanoparticles means drug effects can be maintained at a stable therapeutic level."
The project is being done with Dr Matthew Griffith, of University of Sydney, and Professor Paul Dastoor from the Centre for Organic Electronics at University of Newcastle.
