INNOVATION ARTICLES THE IDEA SUBMISSION PORTAL FROM MEDTRONIC

Chronic pain is one of the most widespread and devastating conditions worldwide. Every year in the United States, for example, around 100 million adults suffer from chronic pain¹, lasting longer than 12 weeks. In most cases, it can be treated with medication; but for people whose pain fails to respond to drugs, spinal-cord stimulation (SCS) offers a last resort to ease their daily agony. The procedure involves implanting tiny, electrode-covered wires alongside the spinal cord, which are connected to a battery implanted below the skin. When activated, usually by remote control, these electrodes send electrical impulses that can quell the sensation of pain.

Best of both worlds

A few years ago, a chance meeting at a laboratory social event laid the foundation for a device that could combine the strengths of both lead-type and paddle-type SCS devices. “This project was completely serendipitous,” says Barone. “I was working on my own thing, and Chris [Proctor] was working on a completely different project. I think we were having the laboratory’s cake club, and we started talking about previous experiences.” Chris Proctor had just published a paper on a neural probe that used microfluidics (tiny channels full of gas or liquid) to deliver drugs for treating epilepsy³, while Barone was working on peripheral nerve implants. Their conversation led to an idea that combined their areas of study – a spinal implant that could be inflated using microfluidics.

Along with their co-authors, the pair published a paper earlier this year⁴ describing an SCS implant that can be rolled up to less than 2 millimetres in diameter. But when air is pumped into the microfluidic channels of the device using a syringe, it unfurls to a width of 12 millimetres inside the body. Dubbed MI-SCS by the authors, the novel implant has the advantages of a lead-type device in that it can be easily threaded into position in a patient under local anaesthetic, but it also has the advantages of a paddle-type device in that it can provide electrical stimulation over a wider area and is less likely to slip out of place.

The authors were able to fabricate incredibly thin electrodes using photolithography and soft lithography, methods for printing patterns on to extremely thin materials. And to prevent rejection by the body, the device is made entirely from biocompatible substances such as parylene-C, silicone, polyethylene, polyimide and gold. 

“We went through different iterations of different methods to reach the right shape for the unrolling,” says Barone. “Then the challenge was how to roll it to reach the dimension of the cylindrical device, then to unroll to reach the dimension of a paddle device.” In terms of making the device pliable enough to roll and unroll, he says that the engineering background of team members Proctor and George Malliaras was invaluable, and made for smooth progress when it came to creating flexible electronics. “That was the easiest bit,” he says. “The rest was challenging.”

So far, the team has successfully implanted MI-SCS into cadavers, but Barone says the next big step will be to test the system in large animals, and then in humans in around three years’ time. It could be ready for market in as soon as five years.

Multidisciplinary expertise

Barone thinks that his multidisciplinary background has been an important contributor to his work on MI-SCS. He gained a medical degree specialising in neurosurgery, then went on to do a PhD in neuroscience and neuroprosthetics, before studying electrical engineering as a postdoctoral researcher, which is when he met Proctor. He thinks that being in contact with people from various disciplines is a key driver of innovation. “The Bioelectronic lab I co-lead with Prof. Malliaras has got the full range: we’ve got biologists, neuroscientists, engineers, physicists, computer scientists…,” he says, adding that integrating the knowledge from different fields is the key to coming up with new concepts. “Otherwise, single fields reach their limits. It’s about talking to each other. Being more multidisciplinary means really working together, rather than just asking for an opinion.”