Robust epidermal tattoo electrode platform for skin physiology monitoring

An epidermal tattoo sensing platform comprising silver-based electrodes for direct skin physiology monitoring is reported here. The platform uses an assembly of screen-printed elastomeric silver electrodes interfaced with a porous acrylate-based adhesive layer. The elastomeric nature of the electrodes and the inclusion of the porous adhesive layer were demonstrated to improve adhesion strength, lower stiffness and increase fracture strain of the platform. The porous adhesive layer in particular was shown to improve mechanical properties of the platform without impacting on the electrical measurement of viable tissue resistance (Rvt) by the electrodes. Rvt values as measured by the wearable tattoo platform were shown to correlate with tissue dielectric constant (TDC) measurements in a participant study. Topical treatment studies were also carried out whereby single frequency impedance responses of the electrodes was shown to relate to the absorption characteristics of the treatment into the skin. Overall, the work contributes to the area of epidermal sensing and electronics whereby approaches to achieve optimum mechanical properties as well as good electrical fidelity in an epidermal sensor platform are critical to developing wearable sensors for taking robust analytical measurements related to skin physiology.