Microneedle system with light trigger for precise and programmable penetration

The use of microneedle (MN) systems has the potential to benefit a wide range of biomedical applications but is hindered by poorly controlled insertion. Herein, a novel MN penetration strategy is presented, which utilizes the recovery stress of near-infrared light-triggered shape memory polymers (SMPs) to drive MN insertion. This strategy enables force control over MN application with the precision of 15 mN through tunable light intensity. The pre-stretch strain of SMP can be further predetermined to provide a safety margin on penetration depth. Using this strategy, we demonstrate that MN can precisely insert into the stromal layer of the rabbit cornea. Additionally, the MN unit array allows programmable insertion for multistage and patterned payload delivery. This proof-of-concept strategy promises remotely, precisely, and spatiotemporally controlled MN insertion, which may inspire the further development of MN-related applications.

Automated summary

This study presents a novel micro-needle penetration strategy that utilizes the recovery stress of near-infrared light-triggered shape memory polymers to drive micro-needle insertion with controlled force precision. By adjusting the light intensity, the pre-stretch strain of the shape memory polymer can be predetermined to ensure a safe penetration depth. Using this strategy, precise insertion of micro-needles into the stromal layer of the rabbit cornea was demonstrated, and programmable insertion for multistage and patterned payload delivery was achieved. This proof-of-concept strategy promises remotely controlled and highly precise micro-needle insertion, inspiring further developments in micro-needle-related applications.