A Minimally Invasive Hollow Microneedle With a Cladding Structure: Ultra-Thin but Strong, Batch Manufacturable.

Abstract

OBJECTIVE: A minimally invasive hollow in-plane microneedle with a cladding structure is designed to improve the mechanical strength. METHODS: The traditional weak stack structure has been changed into a cladding structure, and the effectiveness has been validated through finite element analysis. The prototypes of the microneedles were batch manufactured by the integrated micromachining process with no need to assemble. RESULTS: Compared to our previously reported microneedle with the weak stack structure, the cladding microneedle in this paper shows 263% improvement in bonding strength (6.4±0.30 N) and 36.5% improvement in buckling strength (2.8±0.07 N). In addition, the fabricated microneedle will not fail during insertion into the fresh and dehydrated pig skin with a satisfying safety factor (1.55). CONCLUSION: A novel structure of hollow microneedle was developed and fabricated by microfabrication technology. The improvement in mechanical strength is obvious. SIGNIFICANCE: The microneedle has great mechanical property and good potential for wider applications in human skin.