Fabrication of microneedle using poly lactic acid sheets by thermal nanoimprint

• Published in: Precision engineering 2019-09, Vol.59, p.110-119
• Main Authors: Terashima, Shingo, Tatsukawa, Chikako, Suzuki, Masato, Takahashi, Tomokazu, Aoyagi, Seiji
• Format: Article
• Language: English
• Subjects: Biodegradable material; Microneedle; Poly lactic acid (PLA); Thermal nanoimprint
• ISSN: 0141-6359; 1873-2372
• DOI: 10.1016/j.precisioneng.2019.05.015

A biodegradable PLA (poly-lactic acid) microneedle having high aspect ratio of over 10, e.g., 100 μm in diameter and 1,000 μm (1 mm) in length, was successfully fabricated using thermal nanoimprint method first in the world. First, optimal conditions for fabricating a conical shape, which is assuming a microneedle tip, were preliminarily investigated. Both in vacuum and under atmospheric pressure, pressure of 20 MPa and temperature of 160 °C were necessary. Next, fabrication of a long microneedle was investigated. As compared to the conical shape, higher pressure of 25 MPa and higher temperature of 166 °C were required. By adjusting the releasing temperature around 98 °C, fabrication of a long microneedle having a smooth surface and no deformation, e.g., no bending, was successfully achieved. It was confirmed that the needle surely can puncture the skin and blood vessel of a mouse. •PLA microneedle with aspect ratio over 10 was fabricated using thermal nanoimprint.•Keeping high temperature at release is effective for achieving a smooth needle.•Imprinting near the melting point is effective for filling resin to the needle tip.•Larger pressure is necessary for long microneedle compared to short nanostructure.