Researchers have developed a shoe insole that could help make the healing process more portable for people who develop ulcers as a result of diabetes.

Diabetic ulcers commonly result from high blood sugar damaging nerves, which takes away feeling from the toes or feet. "One of the ways to heal these wounds is by giving them oxygen," said Babak Ziaie, Professor at the Purdue University in the US. "We've created a system that gradually releases oxygen throughout the day so that a patient can have more mobility."

Without the ability to feel pain, hits and bumps tend to go unnoticed and skin tissue breaks down, forming ulcers. A lot of sugar in the bloodstream, along with dried skin as a result of diabetes, further slow the ulcer healing process. The researchers used lasers to shape silicone-based rubber into insoles, and then create reservoirs that release oxygen only at the part of the foot where the ulcer is located. "Silicone is flexible and has good oxygen permeability," said Hongjie Jiang, a post-doctoral researcher at the varsity.

"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," Jiang added. In a paper published in the journal Materials Research Society Communications, the team said the insole can deliver oxygen at least eight hours a day under the pressure of someone weighing about 53-81 kg.

It can also be customised to take on any weight, the study said. The team envisions a manufacturer sending a patient a pack of pre-filled insoles customised to his or her wound site, based on a "wound profile" obtained from a doctor's prescription and a picture of the foot. "This is mass-customisation at low cost," said Vaibhav Jain, research associate at Purdue. A patent is pending on the insole technology. The team is currently seeking corporate partners.