Small Implant Relieves Pain on Demand Without Drugs – The Mahathian Post

The new device has the potential to offer an alternative to opioids and other highly addictive drugs.

A small, soft, flexible implant that relieves pain when needed and without the use of drugs has been developed by a team of researchers led by[{” attribute=””>Northwestern University. The first-of-its-kind device could provide a much-needed alternative to opioids and other highly addictive medications.

By softly wrapping around nerves, the biocompatible, water-soluble device is able to deliver precise, targeted cooling, which numbs nerves and blocks pain signals to the brain. With an external pump, the user can remotely activate the device and then increase or decrease its intensity. After the device is no longer needed, it naturally absorbs into the body. This bypasses the need for surgical extraction.

According to the researchers, the device has the potential to be most valuable for patients who undergo routine surgeries or even amputations that commonly require post-operative medications. Surgeons could implant the device during the procedure to help manage the patient’s post-operative pain.

The paper describes the device’s design and demonstrates its effectiveness in an animal model. It was published in the July 1 issue of the journal Science.

“Although opioids are extremely effective, they also are extremely addictive,” said Northwestern’s John A. Rogers, who led the development of the device. “As engineers, we are motivated by the idea of treating pain without drugs — in ways that can be turned on and off instantly, with user control over the intensity of relief. The technology reported here exploits mechanisms that have some similarities to those that cause your fingers to feel numb when cold. Our implant allows that effect to be produced in a programmable way, directly and locally to targeted nerves, even those deep within surrounding soft tissues.”

A bioelectronics pioneer, John A. Rogers is the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery in the McCormick School of Engineering and Northwestern University Feinberg School of Medicine. He is also the founding director of the Querrey Simpson Institute for Bioelectronics. Jonathan Reeder, the paper’s first author, is a former Ph.D. candidate in Rogers’ laboratory.

How it works

Although the new device might sound like science fiction, it actually leverages a simple, common concept that everyone knows: evaporation. Similar to how evaporating sweat cools the body, the device contains a liquid coolant that is induced to evaporate at the specific location of a sensory nerve.

“As you cool down a nerve, the signals that travel through the nerve become slower and slower — eventually stopping completely,” said study co-author Dr. Matthew MacEwan of Washington University School of Medicine in St. Louis. “We are specifically targeting peripheral nerves, which connect your brain and your spinal cord to the rest of your body. These are the nerves that communicate sensory stimuli, including pain. By delivering a cooling effect to just one or two targeted nerves, we can effectively modulate pain signals in one specific region of the body.”

Watch the device slowly disintegrate over the course of 50 days. The device breaks down into biocompatible components, which are then naturally absorbed by the body. Photo credit: Northwestern University

To create the cooling effect, the device contains tiny microfluidic channels. One channel contains the liquid coolant (perfluoropentane), which is already clinically approved as an ultrasound contrast agent and for pressurized inhalers. A second channel contains dry nitrogen, an inert gas. When the liquid and gas flow into a common chamber, a reaction takes place that causes the liquid to immediately vaporize. At the same time, a tiny built-in sensor monitors the nerve’s temperature to make sure it doesn’t get too cold, which could cause tissue damage.

“Excessive cooling can damage the nerve and the fragile tissues around it,” Rogers said. “Duration and temperature of the cooling must therefore be precisely controlled. By monitoring the temperature at the nerve, flow rates can be automatically adjusted to set a point that blocks pain in a reversible, safe manner. Ongoing work aims to define the full set of time and temperature thresholds below which the process remains fully reversible.”

precision power

While other cooling therapies and nerve blockers have been tested experimentally, all have significant limitations that the new device overcomes. For example, scientists have already explored cryotherapy that is injected with a needle. Rather than targeting specific nerves, these imprecise approaches cool large areas of tissue, potentially leading to undesirable effects such as inflammation and tissue damage.

At its widest point, Northwestern’s tiny device is just 5 millimeters (0.2 inches) wide. One end is coiled into a cuff that wraps gently around a single nerve, eliminating the need for sutures. By precisely targeting the affected nerve, the device spares surrounding regions from unnecessary cooling that could lead to side effects.

“You don’t want to inadvertently cool other nerves or tissues unrelated to the nerve carrying the painful stimuli,” MacEwan said. “We want to block the pain signals, not the nerves that control motor functions and allow you to use your hand, for example.”

Previous researchers have also looked at nerve blockers, which use electrical stimulation to silence painful stimuli. These too have limitations.

“You can’t turn off a nerve with electrical stimulation without activating it first,” MacEwan said. “This can cause additional pain or muscle contractions and is not ideal from a patient perspective.”

act of disappearance

This new technology is the third example of bioresorbable electronic devices from the Rogers lab, which introduced the concept of transient electronics in 2012, published in Science. In 2018, Rogers, MacEwan and colleagues demonstrated the world’s first bioresorbable electronic device – a biodegradable implant which accelerates nerve regeneration, published in naturopathy. Then, in 2021, Rogers and colleagues a transient pacemaker, released in natural biotechnology.

All components of the devices are biocompatible and are naturally absorbed into the body’s bio-fluids over the course of days or weeks without the need for surgical extraction. The bioresorbable products are completely harmless – similar to resorbable threads.

With the thickness of a sheet of paper, the soft, elastic nerve cooling device is ideal for treating highly sensitive nerves.

“When you think of soft tissue, fragile nerves, and a body that’s in constant motion, any interface device needs to be able to bend, bend, twist, and stretch easily and naturally,” Rogers said. “Also, you want the device to just disappear when it’s no longer needed to avoid delicate and risky surgical removal procedures.”

Reference: “Soft, Bioresorbable Coolers for Reversible Peripheral Nerve Conduction Blocks” by Jonathan T. Reeder, Zhaoqian Xie, Quansan Yang, Min-Ho Seo, Ying Yan, Yujun Deng, Katherine R Jinkins, Siddharth R Krishnan, Claire Liu, Shannon McKay, Emily Patnaude, Alexandra Johnson, Zichen Zhao, Moon Joo Kim, Yameng Xu, Ivy Huang, Raudel Avila, Christopher Felicelli, Emily Ray, Xu Guo, Wilson Z Ray, Yonggang Huang, Matthew R MacEwan and John A Rogers, June 30, 2022, Science.
DOI: 10.1126/science.abl8532

The study was supported by the Phil and Penny Knight Campus for Accelerating Scientific Impact, the Querrey Simpson Institute for Bioelectronics, and the National Science Foundation (grant number CMM1635443).