Water-powered, electronics-free dressing may speed up wound closure

A novel water-powered, electronics-free dressing (WPED) that delivers electrical stimulation to wounds has been shown to accelerate healing at rates similar to treatments requiring expensive biologics and complex electronics, as described in a paper published in Science Advances.

Developed by researchers from the North Carolina State University in Raleigh, North Carolina, US, the disposable wound dressing integrates a flexible, water-powered battery and a pair of thin-film stimulation electrodes. Upon contact with water, the battery produces an electrical field across the stimulation electrodes continuously for several hours.

The 0.4-mAh battery provides at least 3.5-h stimulation at temperatures up to 35 °C. At higher temperatures (up to 45 °C), the duration of stimulation is reduced by about an hour due to faster water evaporation. In subzero conditions, on the other hand, the supersaturated salt electrolyte remains in liquid state, and the reduced rates of evaporation at these temperatures facilitate the delivery of a substantially higher duration of stimulation.

“These highlight the dressing’s ability to perform even under harsh conditions wherein conventional lithium and alkaline battery–powered dressings face deterioration, thus opening possibilities for offering effective wound treatments in extreme weather conditions,” the researchers said.

Highly flexible design

The complete WPED system is light at 290 mg and is highly flexible to allow it to conform snugly to curved body parts, such as toes.

“This ability to conform is critical, because we want the electric field to be directed from the periphery of the wound toward the wound’s centre,” according to the first author of the paper, Rajaram Kaveti, a postdoctoral researcher at the North Carolina State University.

“In order to focus the electric field effectively, you want electrodes to be in contact with the patient at both the periphery and centre of the wound itself. And since these wounds can be asymmetrical and deep, you need to have electrodes that can conform to a wide variety of surface features,” Kaveti continued.

When continuously subjected to extremely high pressures (450 kPa) and bending stress (bending radius of 0.5 mm), the WPED’s battery voltage decreases by only about 11 percent. This indicates that the dressing performs robustly for several hours, unlike the expected performance from wireless electronics-based devices, the researcher said.

Faster healing with electrotherapy

The use of an external electrical field to drive wound closure has yielded promising results. In preclinical and clinical studies, electrotherapy helped increase cell migration, venous blood flow, and cell proliferation, among other pro-healing effects that aid rapid wound closure. [Sci Adv 2023;9:eade4687; Nat Biotechnol 2023;41:652-662; Nat Biotechnol 2022;41:652-662; Biomater Res 2019;23:25; Adv Heal Mater 2021;10:2100557]

Reported examples of electrical stimulation-based devices and other wound-healing technologies have been shown to promote increased CD31 expression, epidermal thickness, collagen intensity, and a shift in the ratio of M1 to M2 macrophages. [Nat Biotechnol 2023;41:652-662; Biomaterials 2022;285:121479; Sci Adv 2023;9:eadc8758; Nano Today 2022;47:101685]

“The user-friendly WPED offers similar pro-healing capabilities at a fraction of the cost (around USD 1 per dressing) compared with the above-referenced technologies, making it preferable for treating wounds,”  Kaveti and colleagues noted.

Indeed, when the WPED was tested in diabetic mice, the electrical stimulation from the device sped up the rate of wound closure. Of note, 75 percent of the wounds treated with the dressing achieved closure by day 11, as compared with only 12.5 percent of wounds treated with sham devices and 0 percent of those that received only occlusive dressing. [Sci Adv 2024;10:eado7538]

Furthermore, at day 13, the epidermis in electrotherapy-treated wounds was 43 percent and 72 percent thicker than wounds treated with sham devices and occlusive dressing (p<0.0001), respectively.

The WPED was also associated with improved angiogenesis and reduced inflammation.

These findings “point to overall improved wound healing,” according to Kaveti and colleagues. They shared that the next step for the WPED is to evaluate its efficacy in a porcine model of full-thickness dermal wound healing characterized by deep wounds around 1 cm.

“Such studies could further elucidate the precise molecular mechanisms by which the WPED promotes healing and allow testing of its ability to treat deep wounds. This would help translate the device toward human use,” they said.