# The Influence of Mask Modification on Microneedle Strength in Deep X-Ray Lithography

## TL;DR

This paper explores how modifying mask shapes in X-ray lithography affects the strength and performance of microneedles used for drug delivery and blood collection.

## Contribution

The study introduces a novel approach to enhancing microneedle strength and flow rate through photomask shape modification and hole position optimization.

## Key findings

- Modifying the shape of the photomask increases microneedle strength and compensates for exposure-related shortcomings.
- Placing holes away from the microneedle tip center improves flow rate.
- A 30 μm horizontal and 50 μm vertical offset from the tip center provides optimal hole alignment for strength and sharpness.

## Abstract

Hollow microneedle arrays of different shapes were prepared for blood collection and precise drug delivery. This microneedle array was investigated using shape modification and hole position optimization, and different approaches to increase the strength of the microneedles and hole alignment were analyzed. Firstly, solid-tip microneedles were prepared using deep X-ray lithography, and an approach to increase the strength of microneedles by modifying the shape of the photomask was examined. Secondly, photomasks with holes in different positions were designed, and the exposure was aligned at different hole positions. Finally, the maximum stress and minimum displacement were analyzed using ANSYS 10.0 simulation software, while the proof-of-strength properties were accomplished by inserting microneedles into a polyimide film. The experimental results show that the modification of the shape of the photomask can increase the strength of the microneedles and compensate for the shortcomings generated by the moving exposure. Placing the holes away from the center of the tip can increase the flow rate of the microneedles. A horizontal offset of 30 μm and a vertical offset of 50 μm from the center of the microneedle tip were determined to be the best positions for aligning the holes. This meets the requirements for microneedle strength and sharpness.