Wireless ‌Implant ‌Offers New Hope ⁣for Chronic Pain ​Sufferers

‌ Updated‌ June 30, 2025

More than 51 million Americans grapple with chronic pain, ⁣according too the U.S. Pain Foundation. For over 17 million, the pain severely limits daily activities. Opioid medications, while offering relief, carry risks​ of side​ effects‍ and addiction. Now, researchers‍ are exploring ⁣a new approach to chronic pain management.

A team from USC Viterbi’s Alfred E. Mann Department of ⁤Biomedical Engineering, in collaboration with UCLA, ⁤has developed a flexible, ultrasound-induced wireless implantable (UIWI) stimulator. This device,⁤ secured to the spine, is designed for personalized, self-adaptive chronic pain management. The research, led by Qifa ⁢Zhou, Zohrab A. Kaprielian Fellow in Engineering and professor of ophthalmology at the ‍Keck School of Medicine of USC, is detailed in⁤ Nature Electronics.

Unlike current spinal cord stimulators, which can be bulky and require batteries, this new device bends and⁣ twists with movement.‌ A wearable ultrasound transmitter powers ⁢it wirelessly. Machine learning algorithms further customize the treatment for each patient, offering a significant advancement in pain therapy.

The UIWI stimulator receives power from an external, wearable ultrasound ​transmitter (WUT). Ultrasound provides a safe, ‌non-invasive method for deep-tissue penetration.The device⁢ converts mechanical waves into electrical signals through the piezoelectric effect. The core of the stimulator is a ⁣miniaturized piezoelectric element made from ⁢lead zirconate ​titanate⁣ (PZT), which efficiently converts ultrasound energy into electrical power.

Yushun (Sean) Zeng, a Ph.D. candidate in the Zhou Lab and lead author, said the wireless smart miniaturized stimulator produces sufficient electrical stimulation using ultrasound energy. This results in more personalized,targeted,and localized treatment for chronic pain.

Chen Gong, also a lead author and Zhou Lab Ph.D. ​candidate,⁣ added‌ that deep⁣ learning-based pain assessment enables ⁤dynamic interpretation and response to fluctuating ⁣pain states,​ essential for accommodating ⁤patient-specific variability.

The system continuously monitors brain recordings, specifically electroencephalogram (EEG) signals, reflecting a patient’s pain levels. A machine learning model analyzes these brain signals and classifies⁤ pain into three levels: slight, moderate, and extreme. This AI model boasts 94.8% accuracy in distinguishing between pain states. Once a pain level is identified, the wearable ultrasound transmitter automatically adjusts the acoustic energy it transmits. The UIWI stimulator then converts this energy into electrical⁤ intensity, stimulating the spinal cord and creating a closed-loop system for real-time, personalized pain management.

The ​Zhou Lab‍ team ⁤tested the UIWI stimulator in rodent models, demonstrating its effectiveness for chronic pain management. Researchers successfully relieved ⁣chronic neuropathic pain caused‌ by both mechanical and acute ‍thermal stimuli. Lab tests showed⁣ significant ⁣reductions in pain ‍indicators. ​Rodents also showed a preference for⁤ environments ​where the pain management system was activated,further confirming the device’s effectiveness in providing chronic pain relief.

What’s next

Zhou and his collaborators hope to further miniaturize the components for less invasive implantation, possibly⁢ with a syringe. Future wearable ultrasound transmitters could evolve into untethered devices or wearable ultrasound array​ patches, combining imaging with energy delivery for real-time monitoring and⁤ targeted stimulation.​ Smartphone software could also control future iterations,⁢ offering even more robust personalized chronic pain management.