Kirigami-Inspired Deployable Microneedle Robot With Enhanced Conformability for Targeted Oral Drug Delivery

This study developed KiriBot, a kirigami-inspired deployable microneedle robot designed for localized oral drug delivery within the gastrointestinal tract. The multilayer system combines a biodegradable drug-loaded PLGA microneedle layer, a dissolvable PVA/chitosan adhesive layer, and a detachable magnetically responsive NdFeB-PDMS actuation layer. Kirigami patterning increased patch-scale flexibility and conformability while allowing the microneedles themselves to remain sufficiently stiff for tissue penetration. Material optimization showed that high-molecular-weight PLGA provided greater resistance to microneedle compression than lower-molecular-weight formulations. Rhodamine 6G-loaded microneedles exhibited concentration-dependent release behavior, with apparent release half-lives of approximately 15, 25, and 35 days for 1%, 2%, and 5% loading, respectively. Although increasing drug loading increased compressive stiffness, the 2% formulation was selected as a balance between controlled release, mechanical robustness, and flexibility. Weight-assisted testing in an agarose tissue phantom showed that approximately 20 g of applied load was sufficient for complete microneedle insertion, and magnetic-force measurements indicated that this insertion-force threshold could be generated at a magnet-target separation of approximately 8.5 mm under the experimental setup. The kirigami magnetic layer achieved better conformity to curved surfaces than a non-kirigami design, supported by finite element simulations. In vitro experiments demonstrated capsule dissolution, patch unfolding, magnetic positioning, microneedle insertion, and magnetic-layer detachment. Ex vivo porcine intestine testing confirmed tissue attachment and microneedle penetration, including visible perforations and histological penetration tracks. The complete KiriBot device did not significantly reduce cardiac fibroblast viability compared with untreated controls over three days. Overall, the study establishes a proof-of-concept magnetically controlled microneedle platform that combines structural conformability, localized tissue anchoring, and sustained drug-release capability for future gastrointestinal drug delivery applications.