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.

1 . A microneedle array device having a monolithic structure, comprising: 
 a supporting pad having an upper surface; and    a plurality of microneedles, each microneedle having a slant or concave curvy top portion, said top portion having a via for microfluid to flow, a hollow closed tube being formed between said top portion to said supporting pad, said top portion intersecting with wall of said tube wall to form a convex needle structure, each microneedle standing on said upper surface of said supporting pad, and said microneedle being perpendicular to said upper surface of said supporting pad.    
   
   
       2 . The device as claimed in  claim 1 , wherein said tube wall of each microneedle toruses to form an oval, circular or triangular shape.  
   
   
       3 . The device as claimed in  claim 1 , wherein said supporting pad further comprises a bottom portion and at least a reservoir layer, said reservoir layer is located above said bottom portion and below said plurality of microneedles.  
   
   
       4 . The device as claimed in  claim 3 , wherein said at least reservoir layer is further divided into a plurality of reservoir units, said reservoir units are separate from one another to prevent microfluid stored in said reservoir units from flowing among said reservoir units.  
   
   
       5 . The device as claimed in  claim 1 , wherein said metal structure is made of a metal selected from one of the Cu, Cr, Ni, Fe, Au, Pt, Pd, stainless steel, and their alloy.  
   
   
       6 . The device as claimed in  claim 1 , wherein the aperture of said microneedle ranges from 10 um to 60 um.  
   
   
       7 . The device as claimed in  claim 1 , wherein the circumference of said microneedle ranges from 70 um to 250 um.  
   
   
       8 . The device as claimed in  claim 1 , wherein the height of said microneedle ranges from 100 um to 600 um.  
   
   
       9 . A method of fabricating a microneedle array device, comprises the steps of: 
 (1) providing a substrate, and forming a plurality of concave areas on a surface of said substrate;    (2) coating a layer of photo-sensitive material on top of said substrate, and coating a layer of light transmission material on top of said photo-sensitive material;    (3) using a patterned mask for exposure and development on said light transmission material to obtain a polymer hollow microneedle array mold using said light transmission material as a base; and    (4) forming a microneedle array device using said polymer hollow microneedle array mold.    
   
   
       10 . The method as claimed in  claim 9 , wherein said substrate in step (1) is made of silicon.  
   
   
       11 . The method as claimed in  claim 9 , wherein said plurality of concave areas on said substrate in step (1) are formed by an etching technique.  
   
   
       12 . The method as claimed in  claim 11 , wherein said etching technique is anisotropic wet etching technique.  
   
   
       13 . The method as claimed in  claim 9 , wherein said plurality of concave areas on said substrate in step (1) are formed by X-ray etching, ultra-violet etching, ion beam etching, or excimer laser micromachining.  
   
   
       14 . The method as claimed in  claim 9 , wherein said plurality of concave areas on said substrate in step (1) are formed by micro electro discharge machining technique.  
   
   
       15 . The method as claimed in  claim 9 , wherein said photo-sensitive material in said step (2) is SU-8 or JSR430N.  
   
   
       16 . The method as claimed in  claim 9 , wherein said light transmission material in said step (2) is PMMA or glass.  
   
   
       17 . The method as claimed in  claim 9 , wherein said step (3) further comprises a step of using a patterned mask to define the shape of microneedles.  
   
   
       18 . The method as claimed in  claim 17 , wherein patterned mask comprises a plurality of pairs of closed curves, each said pair of closed curves comprise a first closed curve and a second closed curve, said first closed curve encompasses said second closed curve, said second closed curve has a circumference smaller than that of said first closed curve, and remaining areas are masked except the area between said first and said second closed curves.  
   
   
       19 . The method as claimed in  claim 17 , wherein said step (3) further comprises a step of forming at least a reservoir layer.  
   
   
       20 . The method as claimed in  claim 19 , wherein the shape of each said reservoir layer is defined by using a corresponding patterned mask.  
   
   
       21 . The method as claimed in  claim 19 , wherein the depth of each said reservoir layer is controlled by adjusting exposure dosage of light.  
   
   
       22 . The method as claimed in  claim 9 , wherein said step (4) further comprises the following sub-steps of: 
 (4a) coating a metal layer on outer surfaces of said polymer hollow microneedle array mold and said light transmission material to form said microneedle array device; and    (4b) removing said polymer hollow microneedle array mold from said microneedle array device.    
   
   
       23 . The method as claimed in  claim 22 , wherein said coating of metal or other material in said step (4a) is by electroplating, electroless plating, evaporation, or sputtering.  
   
   
       24 . The method as claimed in  claim 22 , wherein said metal is chosen from one of the Cu, Cr, Ni, Fe, Au, Pt, Pd, stainless steel and their alloys.  
   
   
       25 . The method as claimed in  claim 22 , wherein said removing said polymer hollow microneedle array mold in said step (4b) uses one of oxygen removal, thermal removal, solvent removal, aqueous removal, photo-degradation removal, and their combinations.