Researchers from Korea, U.S., and China have developed a new technology that modulates and relaxes pain signals by locally cooling and stimulating peripheral nerves instead of opioid analgesics commonly used for pain relief.

Opioid-based painkillers, often used for pain relief, cause serious problems such as addiction and increased mortality due to drug abuse.

Therefore, recent studies have aimed to stimulate peripheral nerves electrically, pharmacologically, optically, mechanically, and thermally and selectively transmit internal pain to the central nerve. However, these techniques have been difficult to apply to actual patients because they use complex or large and heavy equipment and provide various stimuli to the nerves.

Also, there were limitations in that the technology could cause additional damage, such as tissue necrosis or inflammation, due to unintentional injection of excessive stimulus into a patient's body as it was difficult to control the size of the stimulus.

To resolve this issue, the team -- led by Professors Seo Min-ho at Pusan University, Jonathan Reeder at Oregon University, John Rogers at Northwestern University, and Zhaoqian Xie at the Dalian University of Technology -- succeeded in developing a bio implantable device that can locally cool peripheral nerves in a small, light, soft, and simple and stable method using biodegradable micro-electro-mechanical systems (MEMS) fluid channel technology.

The device developed by the researchers uses two fluids that cause an endothermic reaction.

The team designed the microfluidic channels so that the two fluidic channels, initially separated from one another, meet up only at the device's tip.

Notably, this technology can quickly and reversibly control the temperature from room to minus 20 degrees Celsius.

The international research team also integrated a temperature sensor in the microfluid to stabilize the temperature control and avoid unnecessary damage to nerves or other tissues.

After developing the device, the team conducted preclinical testing in mice and tested the performance of the device for three weeks,

As a result, the team confirmed that when they inserted the newly developed device into the sciatic nerve of a living mouse, the device could reversibly and stably regulate peripheral nerve stimulation signals even in vivo.

Also, as the research team fabricated all parts of the device with biodegradable and absorbent materials and developed a microfabrication method, they expect that they will be able to utilize the method to fabricate other biomedical devices efficiently.

"As our device uses biodegradable material, it is possible to minimize the inflammatory reaction or infection in the body due to long-term use, and removes the need for a second surgery after use," Professor Seo said. "Advantages of these developed technologies can lead to innovation in treatment technology using bio-implantable devices."

The results of the research were published in the journal Science.