Patent ID: 7238255

Claim:
A method for increasing the yield of functional microchannel structures per microfluidic device in the manufacturing of microfluidic devices each of which comprises a plurality of enclosed microchannel structures having walls, said structures are used to transport and process aliquots of liquids that are in the μl-range and contain reagents and/or analytes, said manufacturing comprising joining a substrate surface I of a first generally planar substrate I to a substrate surface II of a second generally planar substrate II via a bonding material, at least one of the substrate surfaces exposing a plastic material, wherein said method comprises the steps of: (i) providing substrate I in a form in which substrate surface I comprises a first raised relief pattern which defines at least a part of the walls of the enclosed microchannel structures, and substrate II in a form in which substrate surface II has a size that enables coverage of said first relief pattern, and optionally comprises a raised complementing relief pattern to the first relief pattern which complementing relief pattern defines the remaining part of said walls, wherein one of the substrate surfaces comprises a second raised relief pattern defining at least a part of spacer elements that in the final microfluidic device a) are positioned between said enclosed microchannel structures, and b) are physically separated from the walls of the microchannel structures by a cavity defined by the substrate surfaces, the spacer elements and the walls, wherein the cavity separating the spacer elements from the walls is contiguous around the entire spacer element perimeter, and the other substrate surface optionally contains a raised complementing relief pattern to the second relief pattern which complementing relief pattern defines the remaining part of said spacer elements, and said first and second relief patterns are of the same material; (ii) apposing substrate surface I and substrate surface II so that a) the enclosed microchannel structures are formed between surface I and surface II by the first raised relief pattern together, if present, with its optional complementing raised relief pattern, and b) said spacer elements are formed between substrate surface I and substrate surface II by the second raised relief pattern and, if present, its optional complementing raised relief pattern, and (iii) bonding the substrate surfaces together via said bonding material, wherein ≧70% of the enclosed microchannel structures are functional.