Bionic artificial skin returns tactile senses

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Researchers in South Korea have developed a human-implantable tactile smart bionic artificial skin that can restore permanently damaged tactile senses.

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Damage to nerve tissue causes loss of sensory and cognitive functions that are essential for life-sustaining activities, plus mental and physical distress. If the damage is severe enough that natural healing is not possible, surgical treatment is required to implant artificial skin in the affected area, but artificial skin developed to date has focused on skin regeneration, providing a structure and environment similar to skin tissue, but has not restored sensation to patients.

Now, the Korea Institute of Science and Technology (KIST) has announced that a team led by Dr. Youngmee Jung of the Center for Biomaterials and Dr. Hyunjung Yi of the Post-Silicon Semiconductor Institute, in collaboration with Prof. Ki Jun Yu of Yonsei University and Prof. Tae-il Kim of Sungkyunkwan University, has developed human-implantable tactile smart bionic artificial skin that combines biocompatible materials and a tactile function delivery system implemented with electronic devices.

Schematic diagram of how external stimuli are transmitted to the nerves through the integrated device developed by the researchers. External pressure is transmitted through a crack-based tactile sensor inserted into the artificial skin, and external pressure is converted into an electrical signal through a WPPFM. The electrical signal is transmitted to the nerve along the nerve interfacing electrodes - Korea Institute of Science and Technology

The artificial skin is a hydrogel composed of collagen and fibrin that can detect small pressure changes by inserting crack-based tactile sensors.

The sensed pressure changes are converted into electrical signals via a wireless powered pressure-frequency modulation (WPPFM) circuit, which are then transmitted to the nerves by tactile nerve interfacing electrodes, allowing the device to perform the same tactile functions as the skin.

According to KAIST, the researchers also found that collagen and fibrin, which are responsible for skin's elasticity and tissue connectivity, trigger the proliferation and differentiation of skin cells around the wound to promote skin regeneration.

The smart bionic artificial skin was implanted into rats with severe skin damage to test its effectiveness in promoting skin regeneration and re-establishing tactile function, and it showed a wound healing effect of over 120 per cent compared to the control group at 14 days after implantation.

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In addition, it detected external changes in the pressure range of 10 to 40kPa, which is similar to the pressure range felt by human fingertips, and adjusted the electrical signals accordingly to change the rat's response.

The artificial skin is said to be effective for sensory transmission and skin regeneration because it is implanted directly into the nerves along the subcutaneous fat layer of the damaged skin.

After skin regeneration in patients with nerve damage, tactile sensors can operate in the subcutaneous layer, greatly improving independence in daily life. Even in the case of elderly people with degenerated sensory functions, it is expected that the degenerated sensory functions can be restored by directly inserting tactile electronic devices made with high-density integration technology into the subcutaneous layer.

In a statement, Dr. Youngmee Jung said: "This research is the result of convergence research on devices, materials, and regenerative medicine that effectively combines biomaterials and electronic device technology.

"We plan to conduct additional clinical trials in collaboration with medical institutions and companies for commercialisation, and we also plan to expand our research to reconstruct various functions of skin tissue such as temperature, vibration, and pain."

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