Flexible porous microneedle array for bioelectric skin patch.

Microneedles with porous internal structures can provide pathways for transdermal ionic current and drug delivery by penetrating the stratum corneum of the skin. However, conventional porous microneedle arrays are typically monolithic and rigid, limiting their flexibility and adaptability to curved skin surfaces. To address the issue, a method to directly integrate an array of porous microneedles to a flexible substrate is proposed, preserving their skin penetration capability while enhancing flexibility. The resulting array conforms to curved skin surfaces while effectively reducing transdermal ionic resistance. Numerical and analytical modeling demonstrates that the limited number of needles on a flexible array is sufficient to reduce transdermal resistance. Further, an enzymatic battery is combined to create a fully organic, porous microneedle-based bioelectric skin patch that can generate stable transdermal current suitable for stimulation and drug delivery applications.