Multifunctional Skin‐Like Electronics for Quantitative, Clinical Monitoring of Cutaneous Wound Healing

Abstract

Non-invasive, biomedical devices have the potential to provide important, quantitative data for the assessment of skin diseases and wound healing. Traditional methods either rely on qualitative visual and tactile judgments of a professional and/or data obtained using instrumentation with forms that do not readily allow intimate integration with sensitive skin near a wound site. Here we report a skin-like electronics platform that can softly and reversibly laminate perilesionally at wounds to provide highly accurate, quantitative data of relevance to the management of surgical wound healing. Clinical studies on patients using thermal sensors and actuators in fractal layouts provide precise time-dependent mapping of temperature and thermal conductivity of the skin near the wounds. Analytical and simulation results establish the fundamentals of the sensing modalities, the mechanics of the system, and strategies for optimized design. The use of this type of ‘epidermal’ electronics system in a realistic, clinical setting with human subjects establishes a set of practical procedures in disinfection, reuse, and protocols for quantitative measurement. The results have the potential to address important unmet needs in chronic wound management.

Soft, curved electrode systems capable of integration on the auricle as a persistent brain–computer interface

“…1C shows FEM results for bending and folding, where the bend angle is 180°and the radius of curvature is 0.5 mm. The maximum principal strain in the metal layers is only 0.25% (elastic limit of Au: 0.3%) (25). Additional results in Fig.…”

“…The epidermal electrode incorporates well-characterized, biocompatible materials [silicone (25), gold (33), and polyimide (34)]. …”

“…4 H-J summarizes capacitive designs using an elastomeric insulating layer (3 μm in thickness) over the electrodes (Materials and Methods). This capacitive layout electrically isolates the metal components of the device from the skin (40) to avoid direct electrical loading and also to allow multiple cycles of cleaning with soap and water and disinfection with isopropyl alcohol antiseptic (25). Here the capacitive electrode (fractal Peano half-and-half) bonds to a silky, washable, silicone material (Enaltus) (Fig.…”

“…The electrically active part of the system consists of filamentary serpentine traces (300-nm-thick and 30-μm-wide patterns of Au with 1.2-μm-thick layers of polyimide above and below), in a spatially varying, self-similar design formed with a Peano curve as the building block. This fractal layout represents an extension of recently reported ideas (25) but where the configuration spans the entire system level to yield enhanced levels of mechanical compliance, tailored with orientational anisotropies that match the requirements for auricle integration. In particular, the interconnects use all vertical Peano curves to maximize stretchability along their longitudinal axes; the electrodes, by contrast, use a half-and-half design to balance stretchability in all directions ( has an effective modulus lower than that of the skin (∼130 kPa) (26), to ensure conformal contact (27) and robust adhesion (28).…”

Soft, thin skin-mounted power management systems and their use in wireless thermography

“…Such stretchable characteristics are qualitatively different from those afforded by simple mechanical bendability; the consequences are important because such properties allow for intimate, long-lived interfaces with the human body, such as the skin (5,6), heart (7), and the brain (8), and for development of unusual device designs that derive inspiration from biology (9,10). Many impressive examples of the utility of these concepts have emerged over the last several years, particularly in the area of biomedical devices, where work in skin-mounted technologies is now moving from laboratory demonstrations to devices with proven utility in human clinical studies (11,12) and even to recently launched commercial products (13). Although schemes in high-frequency or ultrahigh-frequency wireless power transfer satisfy requirements in many important contexts (14,15), opportunities remain for approaches in local generation and/or storage of power in ways that retain overall stretchable characteristics at the system level.…”