The incidence and prevalence of wound problems in an aging and longer-lived population continue to increase substantially. Pressure ulcers (bedsores) are painful, increase risk for secondary infection, and add $ 11 billion annually to health care costs in the US. When a sufficient fraction of the patient's weight is supported in a region with a bony prominence, the resulting localized concentration of external pressure reduces the cross-sectional area of blood vessels, restricting blood flow and limiting oxygen supply to the at-risk tissue. If this external contact pressure is maintained for sufficient time, the lack of oxygen leads to tissue death and formation of a pressure ulcer. Very few effective ulcer prevention devices exist and those available have focused almost exclusively on some form of off-loading (specialized and costly beds and wheelchair cushions) designed to equalize pressure distribution on at-risk tissue areas. Furthermore, wheelchair cushions have no applicability to other body areas (legs, heels, etc.) at risk for pressure injury. Despite extensive work in this area of pressure ulcer prevention, a survey of available options shows that there is no compact, low-cost solution that is workable in a hospital setting, for patients confined to bed at home, or for those with limited mobility in wheelchairs. In this work we present a wireless sensor patch to be placed on known at-risk sites on the patient's skin, directly measuring local contact pressure and temperature, and communicating with a base station (in a hospital setting) or smartphone (for home care). Alerting a patient or caregiver to a potentially harmful level of pressure allows early intervention (only when necessary) to prevent pressure ulcer formation, easing workload on caregivers and enabling more independence for mobile at-risk patients.

Using the delayed healing model of diabetic (db/db) mice, we evaluated the ability of a novel silk based dressing to facilitate healing of full-thickness excisional wounds. Silk protein from Bombyx mori was used to create wound dressings via a proprietary electrospinning technique. The resulting dressing is vapor and air transmissible. Eight millimeter diameter full-thickness wounds were created on the backs of diabetic mice and covered with either a standard (n=12) telfa-gauze or the silk (n=12) dressing. At 2 day intervals, the telfa dressings were removed, the wounds photographed, measured and fresh dressings placed. For mice receiving the silk dressing, it was allowed to remain in place unless it became dislodged. In that case, a fresh dressing was placed into the wound bed. Wound healing was followed for 21 days at which time the mice were sacrificed, the wound areas excised and subjected to H & E and Trichrome staining. Wounds covered with the silk dressings developed an eschar encompassing the silk whereas wounds dressed with gauze remained moist and without eschar throughout the study period. Upon histologic examination, 1 of the gauze dressed wounds developed a complete epithelial layer across the wound. The remaining 11 wounds had large areas remaining without an epithelial cover. In contrast, 5 of 12 mice receiving the silk dressing developed complete epithelial layers, 2 additional mice had very small areas remaining without a complete epithelium. The remaining 5 had modest areas without an epithelial covering. The ability of silk dressings to permit the formation of an eschar versus gauze in which the wounds remained wet may contribute significantly to the healing response observed. These results suggest that the breathable, vapor transmissible nature of the silk dressing may be an effective dressing for difficult to heal wounds such as diabetic foot ulcers.