Fabrication of microneedle array using LIGA and hot embossing process

Abstract

We demonstrate a novel fabrication technology of the microneedle array applied to painless drug delivery and minimal invasive blood extraction. The fabrication technology consists of a vertical deep X-ray exposure and a successive inclined deep X-ray exposure with a deep X-ray mask whose pattern has a hollow triangular array. The vertical exposure makes triangular column array with a needle conduit. With the successive inclined exposure, the column array shapes into the microneedle array without deep X-ray mask alignment. Changing the inclined angle and the gap between the mask and PMMA (PolyMethylMetaAcrylic) substrate, different types of microneedle array are fabricated in 750-1000 lm shafts length, 15 o -20 o tapered tips angle, and 190-300 lm bases area. The masks are designed to 400-600 lm triangles length, 70-100 lm conduits diameter, 25-60EA/5 mm 2 arrays density, and various tip shapes such as triangular, rounded, or arrow-like features. In the medical application, the fabricated PMMA microneedle array fulfills the structural requirements such as three-dimensional sharp tapered tip, HAR (High-AspectRatio) shafts, small invasive surface area, and out-of-plane structure. In the skin test, the microneedle array penetrates back of the hand skin with minimum pain and without tip break and blood is drawn after puncturing the skin. Hot embossing process and mold fabrication process are also investigated with silicon and PDMS mold. The processed tetrahedral PMMA structures are fabricated into the microneedle array by the additional deep X-ray exposure. With these processes, the microneedle array can be utilized as the mold base for electroplating process.

Rapid hot embossing of polymer microfeatures

“…Lithographic methods such as focused beam lithography, UV lithography, and X-ray lithography are relatively slow and expensive, and as a result these methods are suitable for prototyping and small volume production. In contrast, the hot embossing process Jaszewski et al 1998;Moon et al 2005;Chang and Yang 2005;Shan et al 2005;Chen et al 2005;Scheer et al 2004), which has demonstrated 10 nm resolution Scheer et al 2004), is becoming a dominant fabrication method for nano/microstructures when low cost and high throughput are desired.…”

Effect of micro tensile sample’s cross section shape on the strength of weld line in micro injection molding process

“…In this area micro injection molding always is the one of the focus technologies for realizing micro parts for mass production out low cost (Michaeli et al 2000;Wintermantel et al 2008;Moon et al 2005;Turng and Kharbas 2003). However, as we know, micro injection molding is based on conventional injection molding process, so there are many defects and problems in this process as in the conventional process.…”

Reinforcement of micro injection molded weld line strength with ultrasonic oscillation

“…(Wicht and Bouchaud 2005;Wechsung et al 2002). As a result, micro injection molding appears as one of the most suitable processes for replicating microstructures with medium, even large production scales (Michaeli and Spennemann 2001;Moon et al 2005;Piotter et al 2001).…”