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An Implantable, Dissolvable Device That Alleviates Pain Without Medication The small, soft, and flexible implant was designed by a team led by academics at Northwestern University to provide on-demand pain relief without the need for pharmaceuticals. This groundbreaking technology has the potential to offer a safer and more effective alternative to opioids and other dangerous drugs. 

The biocompatible, water-soluble gadget numbs neurons and stops pain signals to the brain by gently wrapping around nerves and delivering precise, targeted cooling. With the help of an external pump, the user can turn on the device from a distance and adjust its intensity as needed. 

The gadget can be left in the body when its useful life has ended, rather than having to be surgically removed. The researchers think the gadget will be especially helpful for people who require post-operative drugs after undergoing common surgical procedures including regular operations or even amputations. The device could be implanted during surgery to alleviate postoperative suffering. John 

A. Rogers, who oversaw the project’s development at Northwestern, said, “Although opioids are incredibly effective, they are also extremely addicting.” To one of the authors, “As engineers, we are inspired by the possibility of providing pain treatment without the use of pharmaceuticals, through methods that may be activated and deactivated at will, with individual adjustment of the level of analgesia. 

The method described here takes advantage of mechanisms with some similarities to those that make your fingertips feel numb when they are exposed to cold. Our implant enables the programmable, local, and direct stimulation of specific nerves, even those buried deep within the surrounding soft tissues, to achieve the desired result.

So, how exactly does it function?

The new gadget makes use of a simple, everyday phenomenon that is familiar to everyone, evaporation, despite its rather fantastical name. The liquid coolant in the device is made to evaporate at the precise site of a sensory neuron, simulating the cooling effect of perspiration. When a nerve is cooled, the messages it carries get progressively slower and eventually cease altogether. 

The peripheral nerves that extend out from your central nervous system and into your body are our primary focus. Pain signals travel down these nerves because they transmit information about all incoming sensory input. Modulating pain signals in a localized area can be achieved by applying a cooling effect to a single or a small group of nerves. To alleviate pain without the use of pharmaceuticals inspires us as engineers, and we strive to develop solutions that can be instantaneously activated and deactivated, with the patient having full control over the level of comfort they experience. The device’s microfluidic channels are responsible for the cooling effect. 

The liquid coolant (perfluorobutane) is housed in one channel; this substance has already received clinical approval as an ultrasound contrast agent and for pressured inhalers. Dry nitrogen, an inert gas, is housed in a second tube. As soon as the liquid and gas mix in the same space, the liquid evaporates due to a chemical reaction. At the same time, a tiny inbuilt sensor checks the nerve’s temperature to prevent any tissue damage from occurring due to the nerve being exposed to temperatures that are too low. 

Rogers warned that “excessive chilling” could harm the nerve and its surrounding tissues. “It is crucial to properly regulate the cooling’s duration and temperature. The flow rates can be automatically adjusted to a point that blocks pain in a reversible, safe manner by monitoring the temperature at the nerve.

Precision Power

Although alternative cooling therapies and nerve blockers have been studied in the lab, the novel device addresses the drawbacks of the previous methods. Scientists have already investigated needle-based cryotherapies like this. These haphazard methods don’t pinpoint individual nerves like more accurate ones do, but instead chill huge swaths of tissue, which could have unintended consequences including tissue injury or inflammation. 

Northwestern’s tiny gadget is only 5 millimeters across. To avoid using sutures, one end is coiled into a cuff and gently wrapped around a single nerve. The technology avoids unintended side effects by directing all cooling energy directly onto the damaged nerve. MacEwan cautioned against applying ice to any neuron or tissue that is not directly connected to the nerve that is carrying the painful sensations. 

We’re aiming to silence your pain signals, not the ones telling your brain to let you move your hand. Nerve blockers, which employ electrical stimulation to muffle painful inputs, have also been investigated by previous researchers. Even these have their limits, though.