Though still some years away from everyday use in healthcare, the device has the potential to aid millions around the world who suffer from chronic back and leg pain, as well as relive the symptoms of diseases such as Parkinson’s. At just 60 microns thick – about the width of a human hair – the implant is small and flexible enough to be rolled into a cylinder and injected into the epidural space, the same area where pain killing injections are often administered during childbirth.
Once placed inside the spinal column, the device can then be inflated with water or air, unrolling to cover a much larger area of the spine. Ultra-thin electrodes embedded within the implant can then be paired with a pulse generator external to the body, which together deliver electrical currents to the spinal cord that can disrupt pain signals.
While devices with similar pain killing capability already exist, they are bulky and require invasive surgery under general anaesthetic. The key breakthrough claimed by the Cambridge team is incorporating this spinal cord stimulation (SCS) technology into a tiny package which can be delivered easily under local anaesthetic, akin to keyhole surgery.
"Our goal was to make something that's the best of both worlds - a device that's clinically effective but that doesn't require complex and risky surgery," said Dr Christopher Proctor from Cambridge's Department of Engineering, a senior author of the paper, which is published in Science Advances. "This could help bring this life-changing treatment option to many more people."
The researchers used a combination of manufacturing techniques to build their device: flexible electronics used in the semiconductor industry; tiny microfluidic channels used in drug delivery; and shape-changing materials used in soft robotics.
"Thin-film electronics aren't new, but incorporating fluid chambers is what makes our device unique - this allows it to be inflated into a paddle-type shape once it is inside the patient," said Proctor.
According to the researchers, the device has been validated in vitro as well as on a human cadaver model. The team is now working with a manufacturing partner to further develop and scale up the implant, with plans to test it in patients within two to three years.
"The way we make the device means that we can also incorporate additional components - we could add more electrodes or make it bigger in order to cover larger areas of the spine with increased accuracy," said Dr Damiano Barone from Cambridge's Department of Clinical Neurosciences, another of the paper’s senior authors.