Root-Inspired Microneedle Patch With Interlocked Rigid-Soft Architecture for High Tissue-Adaptiveness

Microneedle technology offers a minimally invasive, pain-free platform for drug delivery with high patient compliance and dosing precision. However, these systems struggle to adhere to curved, moist biological surfaces with dynamic movements, which require flexible substrates for conformity and rigid needles for penetration, resulting in a fundamental mechanical mismatch. Here, we present a root-inspired microneedle array patch (R-MAP) that integrates rigid microneedles and flexible substrates via lattice-based mechanical interlocking. Peel-off tests revealed a three-fold increase in interfacial bonding force compared to non-interlocked controls. Ex vivo evaluations confirmed stable penetration and reliable adhesion under dynamic conditions. To further enhance wet-surface retention, we introduced a hydrogel adhesion layer, enabling in vivo attachment to porcine oral mucosa for over 5 h without detachment despite extreme rubbing conditions. This work provides a structurally robust, adaptable solution for challenging drug delivery environments, expanding the applicability of microneedles to curved, moist surfaces with dynamic movements including oral and dermal tissues.