In this work, we present an oxygen-releasing insole to treat diabetic foot ulcers. The insole consists of two layers of polydimethylsiloxane: the top layer has selective laser-machined areas (to tune oxygen permeability) targeting the ulcerated foot region, while the bottom layer provides structural support and incorporates a chamber for oxygen storage. When loaded with a pressure of 150 kPa (average value for standing/walking), the insole is able to release oxygen at a rate of 1.8 mmHg/min/cm2. At lower sitting pressures, the delivery rate persists at 0.092 mmHg/ min/cm2, raising the oxygen level to an optimal healing value (50 mmHg) for a 2 × 2 cm2 wound within 150 min.
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The authors would like to thank the staff at Purdue University Birck Nanotechnology Center and the Ziaie Biomedical Microdevices Laboratory members for their assistance in fabri-cation and experiments. Funding for this project was provided by NextFlex PC 1.0 Project.
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Jiang, H., Ochoa, M., Jain, V. et al. A laser-customizable insole for selective topical oxygen delivery to diabetic foot ulcers. MRS Communications 8, 1184–1190 (2018). https://doi.org/10.1557/mrc.2018.181