Microneedle array device and its fabrication method

Abstract

A microneedle array device and its fabrication method are provided. The microneedle array device comprises a supporting pad and plural of microneedles. Each microneedle has a top portion with a via thereon, thereby the microfluid may flow in or out. The intersection between the top portion and the inner tube of a microneedle forms a convex needle structure, and is almost perpendicular to the upper surface. For each microneedle, a hollow closed tube is formed between the top portion and the supporting pad. The fabrication method uses the substrates with high transmittance and plural of convex area thereon as the upper and lower caps, and applies a photolithography process to fabricate a microneedle array mold. It then sputters or electroplates metal material on the mold. The microneedle array is formed after having taken off the mold. It is a simple fabrication process.

Description

FIELD OF THE INVENTION [0001] The present invention generally relates to a microneedle array structure, and more specifically to a microneedle array device, and a method of forming the same. BACKGROUND OF THE INVENTION [0002] The current microneedle array may be made of silicon (Si substrate), metal or polymer. The manufacturing methods of Si substrate microneedle array can further be categorized as using wet etching or dry etching. The manufacturing process of metal microneedle array can further be categorized as using electroplating or deposition. The manufacturing process of polymer microneedle array can be further categorized as using molding or photolithography. [0003] Among the methods of microneedle array, the most widely adopted is using Si substrate to fabricate the hollow needles or mold. However, the fabrication process of using Si substrate is more complicated, as disclosed in WO0217985, and requires many steps of wet / dry etching and thin film deposition. As it takes a l...

AI Technical Summary

Benefits of technology

[0009] The supporting pad further includes a bottom portion and at least a layer of reservoir. The reservoir is located above the bottom portion and below the microneedle. The reservoir can be further divided, if necessary, into a plurality of reservoir units, with reservoir units separated from one another to prevent the microfluid flowing from one unit to another. The monolithic metal structure of the present invention includes convex needle structure formed by the intersection of the slant or concave top portion of each microneedle and the inner tube of a microneedle. The main feature of the present invention includes the safety of use and the improvement of pain. Furthermore, the rigidity and the slant uniformity of the microneedle with slant top portion are both improved so that it is suitable for molding and mass production.

[0011] According to the present invention, there are several techniques to be used in step (1) of forming a plurality of concave areas, including etching, X-ray photo-etching, ultra-violet etching, ion beam etching and excimer laser micromachining. Step (4) of the method further includes the following substeps: (4a) coating a layer of metal on the outer surface of the polymer hollow microneedle array mold and the light transmission material to form a microneedle array; and (4b) removing the polymer hollow microneedle array mold from the microneedle array. In step (4), the techniques for coating metal to the surface of the polymer hollow microneedle array mold include electroplating, electroless plating, evaporation, and sputtering. The metal used can be Cu, Cr, Ni, Fe, Au, Pt, Pd, stainless steel and their alloys. The present invention uses the coating of photo-sensitive polymer on the concave areas of the substrate and covering with a light transmission material, which is exposed to define an outline of the microneedle and using lithography to obtain a polymer hollow microneedle array mold using the high light transmission material as the base for further fabrication of a metal microneedle array. The advantages of the fabrication method of the present invention are simple process and low in cost.

Problems solved by technology

However, the fabrication process of using Si substrate is more complicated, as disclosed in WO0217985, and requires many steps of wet / dry etching and thin film deposition.

As it takes a longer time to fabricate, the yield rate is low and the cost is high.

This type of design limits the width of the flow channel and the flexibility of the needle.

The restriction of low needle density further causes the problem of insufficient sampling.

In addition, the Si substrate microneedles are brittle and break easily.

However, the method requires multiple layers of SU-8 to achieve the layered effect and the high aspect ratio of the pillar is prone to slant or twist.

The fabrication process is difficult to maintain the quality.

However, the flat-tip microneedles are still limited in the application.

In addition, the polymer microneedles of this method do not have microchannels or reservoirs, and require additional fabrication process to attach the microchannels and reservoirs, if necessary.

It is, therefore, difficult to have this method applied for mass production.

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