Bio-Inspired Barbed Microneedle for Skin Adhesion with Interlocking Mechanics

Achieving strong adhesion to soft tissues with minimal tissue damage remains a considerable clinical challenge. In this work, we designed and fabricated a novel bio-inspired microneedle array for easy skin penetration but difficult removal. The bio-inspired microneedle has four barbs evenly distributed on two edges. This design offered distinctively less skin insertion pressure with minimal tissue damage and strong interlocking force. In order to manufacture the complex multi-barbed structure, we utilized the thermal expansion effect to form 3D two-part PDMS mold. The barbed microneedle was replicated by biodegradable and biocompatible silk fibroin, which makes it harmless and non-irritating to the skin. Performance of the barbed microneedle was tested on the paraffin membrane. The barbed microneedle array was observed to successfully insert through the paraffin membrane. During pulling the barbed microneedle out, the measured interlocking strength was up to 11 g/needle (107 mN/needle). The bio-inspired barbed microneedle can also be used as auto breaking microneedles or tissue adhesive patches.