Development of wearable sensors for continuous wound monitoring

ABSTRACT Chronic, or non-healing wounds are defined as wounds that are present at 4-weeks after wounding. Older adults are at significant risk for non-healing wounds such as leg ulcers, pressure ulcers and diabetic foot ulcers, owing to underlying metabolic disease (diabetes), persistent pressure (immobility) and vascular complications (reduced arterial or venous flow). Non-healing wounds affect ~ 8.2 million Medicare beneficiaries in the United States with costs of up to ~$97 billion. Data from 38 studies across 11 countries suggest a prevalence of pressure ulcers of up to 26% among in-patients, and up to 53.2% of older adults living in nursing homes suggesting significant impacts from friction/pressure mediated effects. The 5-year survival rate for diabetic foot ulcers (~31%) is similar to that of cancer. For each of these classes of non-healing wounds in elderly patients, timely identification and intervention, particularly within an initial 12-week window, is essential to ensuring better outcomes. Current wound assessment technology has been limited to imaging methods such as x-ray, magnetic resonance imaging (MRI) to determine wound structure, and laboratory tests of exudate samples or biopsied tissue. In all such modalities, wound dressings must be removed for each assessment which can disturb the wound healing process. These methods are invasive and unsuitable for daily wound monitoring. Additionally, this increases both workload and costs, as the wound dressings are then changed without medical necessity. These limitations frustrate the ability to monitor wounds in real time in out-patient settings after initial treatment. In many cases, the lack of timely interventions can result in amputation. A biomedical device capable of monitoring wound parameters noninvasively at the wound site in real time via telemetry represents an important unmet clinical need. We have identified 2 key biophysical markers with which to track wound healing: (1) temperature and (2) moisture balance in the wound microenvironment. Through the activities outlined in this proposal, Rhaeos will develop its technologies in wireless, wearable thermal characterization of skin to yield a conformal thermal sensor (CTS) capable of localized measurements these biomarkers. A benchtop model simulating key biological and geometrical properties will allow for refinement and validation of the technology, and battery-free Bluetooth technology will support wireless data transfer (Aims 1&2). A preclinical small- animal model for diabetic wounds will validate measurements in vivo (Aim 3). If successful, this proposal will yield a set of technologies for the continuous, noninvasive monitoring of wounds for patients with nonhealing wounds, suitable for clinical human studies.