Chronic pain, marked by ongoing or recurring pain in certain body areas, can severely impact a person’s quality of life. In the United States, about 20.9% of adults have experienced chronic pain, while 6.9% suffer from severe chronic pain that greatly affects their daily activities.
Currently, chronic pain is mostly treated with medications, many of which contain opioids. These drugs can be addictive and cause serious side effects, sometimes doing more harm than good.
To find safer alternatives, scientists and engineers have been exploring new pain management methods. One promising approach uses implantable electrical stimulators. These devices are surgically placed inside the body and send electrical signals to nerves or the spinal cord to relieve pain.
However, most existing implantable stimulators have drawbacks. Surgery to implant them can cause tissue damage. They are costly, and their batteries need regular replacement.
Researchers from the University of Southern California and other institutions recently developed a flexible, wireless, and battery-free implantable stimulator. Their work, published in Nature Electronics, shows a device powered by an external wearable ultrasound transmitter. It also uses machine learning to assess a patient’s pain level and adjust the electrical stimulation accordingly.
The research team, led by Yushun Zeng and Chen Gong, explained that opioids, while common in pain treatment, carry risks like addiction. Implantable electrical stimulators offer an alternative but come with challenges such as high cost, surgical risks, and battery maintenance.
Their goal was to create a less invasive stimulator that does not require battery changes. The new device combines a composite piezoelectric receiver, micro-electronic parts, and stimulating electrodes on a flexible circuit board.
The researchers wrote, “We report an integrated, flexible ultrasound-induced wireless implantable stimulator combined with a pain detection and management system for personalized chronic pain management.” The device gets power through a wearable ultrasound transmitter. Machine learning models analyze brain signals to classify pain levels, which controls the ultrasound energy and electrical stimulation intensity.
Tests on rodents with varying pain levels showed the device could accurately detect stress and adjust stimulation to reduce pain effectively. The team stated, “The implant can generate targeted, self-adaptive, and quantitative electrical stimulations to the spinal cord based on classified pain levels for chronic pain management in free-moving animal models.”
Looking ahead, this ultrasonic wireless implant may undergo further testing in other animals before human clinical trials. Its design might also inspire new ultrasound-based devices to help manage chronic pain safely and effectively.
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