A Korean research team said they developed a 3-D imaging technology to overcome the shortcomings of a robotic prosthesis implanted in the peripheral nerve and deal with the deterioration of its functions.
An intra-neural interface-based robotic prosthetic hand moves as the patient thinks and transmits tactile sensations. To make such a robotic hand, nerve electrodes should be surgically implanted into the patient's peripheral nerves.
However, the functionality and long-term usability of a robotic prosthetic hand vary depending on the state of the electrode implantation. To identify the cause of a lowered function, the patient should get a biopsy of the peripheral nerves, but it takes a long time.
The research team, led by Dr. Hwang Dong-hyun at the Center for Intelligent and Interactive Robotics of the Korea Institute of Science and Technology (KIST), said it developed 3-D imaging equipment to overcome such shortcomings on Tuesday.
The imaging technology allows immediate identification of the implantation state of the nerve electrode inserted into the peripheral nerve without a biopsy.
In the study, the research team used an optical coherence tomography (OCT) to develop a 3-D imaging device with a high resolution of 5μm or less that shows images of microscopic structures such as nerve fibers inside peripheral nerves and the implantation state of an electrode inserted into the nerve.
Conventional devices had a resolution of 20 to 30 μm, making it difficult to see the microstructure of the peripheral nerve that is less than 10 μm. A higher resolution makes the depth of focus too shallow to see.
The research team said it spliced two different optical fibers to improve the depth of focus of 3-D images by 5.1 times, compared to conventional devices.
The research team successfully conducted an animal test by implanting a fine metal wire, similar to a nerve electrode, in the peripheral nerve of a living mouse and observed it in 3-D images using the newly developed device.
“This study can be utilized for various research on intra-neural interface-based robotic prosthetic hands and neuroscience,” Hwang said. “If a human peripheral nerve is applied in an additional study, it will contribute to advancing the commercialization of a robotic hand that moves and feels like a real hand.”
Titled “In Vivo Cellular-level 3D Imaging of Peripheral Nerves Using a Dual-Focusing Technique for Intra-Neural Interface Implantation,” the study was published on the online version of Advanced Science. It will also be published as an inside back cover of the journal.