Helpful Shoe Insole Heals Ulcers as On-the-Go Diabetes Patients Walk

By giving more oxygen to an affected area, this simple gel insole could help diabetic patients keep their toes and feet safe from ulcers.

A new device from engineers at Purdue University could save feet or legs for diabetes patients by healing ulcers as they walk. A gel insole get oxygen to the affected area, boosting a patient's mobility and helping ulcers heal. 

For patients with diabetes, ulcers are just one problem out of many they have to handle each day. However, some patients don't even notice or feel the ulcer until they spot blood. 

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This leads to enormous complications. In the United States alone, 14 to 24 percent of diabetics who have an ulcer wind up losing a toe, foot, or leg because of complications. 

How diabetic ulcers form

Diabetic ulcers often happen as a result of high blood sugar damaging nerves. This removes the feeling from the toes or feet in a person. But according to the researchers at Purdue, oxygen plays a critical role in healing ulcers. 

"One of the ways to heal these wounds is by giving them oxygen," said Babak Ziaie, Purdue professor of electrical and computer engineering. "We've created a system that gradually releases oxygen throughout the day so that a patient can have more mobility."

If a person can't feel pain, damage to the skin normally goes unnoticed. Tissue can break down and form ulcers, a patient would have no idea. Sugar in the bloodstream and drier skin thanks to diabetes slows down the healing process even more. 

“We typically treat ulcers by removing devitalized tissue from the surface of the wound, and by helping the patient to find ways to take the weight off the affected foot,” said Desmond Bell, a podiatrist in wound management and amputation prevention at the Memorial Hospital in Jacksonville, Florida, and the founder of the Save a Leg, Save a Life Foundation.

“The gold standard for treating an ulcer is a patient wearing a total-contact cast, which provides a protective environment for the foot. If we could test how well this insole delivers oxygen to the wound site from within the cast, then this could be a way of aiding the healing process,” Bell continued.

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Insoles for comfort and healing

The Purdue team hopes their new insole idea can alleviate those complications.

The team opted for silicone-based rubber insoles. They laser-cut the insoles to create reservoirs that strategically release oxygen around the ulcer. 

"Silicone is flexible and has good oxygen permeability," said Hongjie Jiang, a postdoctoral researcher in electrical and computer engineering. "Laser machining helps us to tune that permeability and target just the wound site, which is hypoxic, rather than poison the rest of the foot with too much oxygen."

According to the team's research, the insole can deliver oxygen 8 hours each day. While weight plays a role, the insole is effective for anyone weighing between 117 - 179 lbs (53 - 81 kg). Thanks to its affordable production, the insole can be custom-fit to accommodate any weight. 

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Vaibhav Jain was a graduate from Purdue's mechanical engineering master's program involved in the development of the insole. Jain explained the low-cost makes the technology primed for upscaling. 

"We're wanting to bring this technology to the user by addressing whichever technicalities would be required to simplify the manufacturing flow," Jain said.

The researchers want to further test insole production by 3D printing it in its entirety. They also plan on testing the insole on actual diabetic ulcer patients and gathering more data. The technology is still patent-pending.