Wireless Smart Bandage with Integrated Sensors and Stimulators for Advanced Wound Care and Accelerated Healing

Chronic non-healing wounds represent a significant healthcare burden, with more than 6 million individuals affected in the United States alone. A chronic wound is defined as a wound that has failed to heal by 8-12 weeks and is unable to restore function and anatomical integrity to the affected site. These wounds are associated with loss of function and mobility, increased social stress and isolation, depression and anxiety, prolonged hospitalization, and overall increased morbidity and mortality. In addition, management of chronic wounds has been estimated to exceed $25 billion annually. While interventions exist, such as growth factors, extracellular matrix, engineered skin, and negative pressure wound therapy, these treatments are only moderately effective. Current standard-of-care wound dressings are passive and do not actively respond to variations in the wound environment. ‘Smart’ bandages based on wearable devices hold great potential in advancing treatment of chronic wounds. However, there has been limited development in incorporating both sensors and stimulators for real-time physiological monitoring and active wound care.<br/><br/>For improved therapeutic outcomes, an ideal smart bandage platform needs to meet the following requirements. First, it needs to be mechanically flexible and wirelessly operated to avoid any undesired tethering and discomfort caused by conventional rigid, battery powered devices. Next, it should integrate both sensing and stimulation modalities for autonomous, closed-loop wound management. Finally, it should have on-demand skin adhesion with a tight interface for robust signal transduction and energy delivery during operation, while providing easy detachment to avoid secondary skin damage during device removal.<br/><br/>To address these requirements, we developed a miniaturized flexible printed circuit board (FPCB) capable of dual channel continuous sensing of wound impedance and temperature, as well as delivering programmed electrical cues for accelerated wound healing. To ensure efficient signal exchange and energy delivery between the circuits and the soft skin tissue, we designed a low-impedance and adhesive hydrogel electrode based on electronic-ionic dual conducting polymers. Compared to well-established ionically conducting hydrogels, our dual-conducting hydrogel has lower impedance across the entire frequency domain, giving rise to more efficient charge injection during stimulation. To mitigate secondary skin damage when peeling off the adhesive electrodes, we introduced a thermally controlled reversible phase transition mechanism to the hydrogel backbone and achieved two orders of magnitude lower adhesion at elevated temperature when compared to the normal skin temperature. Using multiple pre-clinical animal models, we found that our smart bandage could continuously monitor skin physiological signals and deliver directional electrical cues, leading to accelerated wound closure, increased neovascularization, and enhanced dermal recovery. Finally, the wireless nature of our smart bandage allowed us to utilize complex animal models, such as parabiosis, to investigate the possible underlying mechanisms behind the observed effect of electrical stimulation. Our data suggests that the beneficial wound healing outcomes could be attributed to the activation of pro-regenerative wound healing genes.