Diabetic ulcers commonly result from high blood sugar damaging nerves, which takes away feeling from the toes or feet.

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 consequence of diabetes, further slow the ulcer healing process.

Recently, Purdue researchers developed a shoe insole that could help make the healing process more portable for the 15% of Americans who develop ulcers as a result of diabetes. 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," Hongjie Jiang, a postdoctoral researcher in electrical and computer engineering said in a press release about the research. "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 simulations, the insole can deliver oxygen at least 8 hours a day under the pressure of someone weighing about 117-179 pounds. But the insole can be customized to take on any weight, the researchers noted.

The team envisions a manufacturer sending a patient a pack of pre-filled insoles customized to his or her wound site, based on a "wound profile" obtained from a doctor's prescription and a picture of the foot.

Next, the researchers want to create a way to 3D print the whole insole, rather than printing a mold first and then laser-machining a pattern. They also plan to test the insole on actual diabetic ulcers, to further gauge how well they advance the healing process.

For more on this, see the video below.


Jiang H, Ochoa M, Jain V, Ziaie B, et al.  A laser-customizable insole for selective topical oxygen delivery to diabetic foot ulcers. Materials Res Soc Communications. 2018; 8(3):