Researchers at Aarhus University, Denmark, created a sensor that can mimic mechanisms found in the body’s sensory cells, which is a step toward prosthetic devices that can be connected to the nervous system. The sensor is made from a soft, silicone-like material and is about the size of a lentil. It converts touch into electric potential, which the researchers hope will eventually stimulate nerves directly, allowing signals from a prosthesis to reach the brain.
The sensor contains small chambers connected by a microscopic channel with salt water inside. The salt water contains tiny electrically charged particles that move with the fluid. This shifts the electrical balance and generates a weak signal. The principle resembles what happens in the skin when sensory cells convert touch into information that the nervous system can transmit toward the brain.
“A simple touch is actually an extremely sophisticated mechanical process,” said Rassoul Tabassian, PhD, assistant professor, Department of Mechanical and Production Engineering, and an author of the related study. “There is a great deal we can learn from it in engineering, and we want to become better at mimicking it in the laboratory.”
Sensors already exist that can detect both touch and pressure and provide prostheses with information about their surroundings. But the person wearing the prosthesis is unable to feel that information, Tabassian said.
“What is groundbreaking about our sensor is not the generation of a sensing signal; it is how the signal is generated,” said Tabassian. “The signal-generating mechanism of existing touch sensors is very different from what happens in our bodies. Perhaps that’s why they cannot give people a real sense of touch. Our new sensor generates a signal by moving charged atoms, similar to how signals are generated in the body’s sensory cells. Therefore, in the long term, this could make it possible to connect the sensor directly to the nervous system and give prostheses an artificial sense of touch. That is what we are working toward.”
The first prototype of the sensor can detect a light touch, and it can pick up a pulse from a blood vessel in the wrist.
“We cannot copy a sensory cell one-to-one. It is far too complex. But we can break it down into some of its fundamental principles and try to mimic them—and that is what we have succeeded in doing,” said Tabassian. “Our results have generated considerable interest and now give us a reason to take the research further.
Editor’s note: This story was adapted from materials provided by Aarhus University.
The open-access study, “Bio‐inspired artificial ionic mechanoreceptor” was published in Advanced Functional Materials.
