Microfluidic devices and methods of fabrication
The present invention relates to microfluidic devices that comprise a 3-D microfluidic network of microchannels of arbitrary complexity and to a method for fabricating such devices. In particular, the invention relates to a method of forming microfluidic devices having 3-D microfluidic networks that contain open or closed loop microchannels using a single-step molding process without the need for layer-by-layer fabrication, and to the resultant microfluidic devices. The networks of such microfluidic devices may comprise one or more microchannel circuits which may be discrete or interconnected.
1. A method of fabricating a casting for a microfluidic device comprising a 3-dimensional microfluidic network in a single layer composition, said method comprising the steps of:
(A) providing a master mold for forming said microfluidic device, said master mold comprising at least one loop element and a membrane element extending outwardly from and connected to said loop element
(B) surrounding said master mold with a resin;
(C) curing said resin to form an elastomeric casting surrounding said master mold and having a negative configuration of said master mold; and
(D) removing said master mold from said casting, wherein a microchannel cavity is formed by said loop element and a planar gap is formed by said membrane element in said casting, and wherein at least a portion of said loop element passes through said planar gap of said casting as said master mold is extracted from said casting.
2. The method of claim 1 , wherein said master mold comprises at least first and second loop elements and corresponding first and second membrane elements extending outwardly from and connected to said loop elements, wherein:
said first loop element and corresponding first membrane element form a first microchannel cavity and corresponding first planar gap, and
said second loop element and corresponding second membrane element form a second microchannel cavity and corresponding second planar gap.
3. The method of claim 2 , wherein said first and second loop elements are discretely disposed relative to each other.
4. The method of claim 2 , wherein said first and second loop elements are interconnected.
5. The method of claim 2 , wherein said first membrane element intersects said second loop element.
6. The method of claim 5 , wherein said first membrane element additionally intersects said second membrane element.
7. The method of claim 1 , comprising the further step of:
(E) substantially eliminating said planar gap in said casting after removing said master mold therefrom, thereby forming said microfluidic device comprising said 3-dimensional microfluidic network comprising a closed loop microchannel disposed in said single layer composition.
8. The method of claim 7 , wherein said network of said formed microfluidic device comprises at least two closed loop microchannels disposed in said single layer composition, each of said closed loop microchannels formed by a corresponding loop element and membrane element of said master mold.
9. The method of claim 8 , wherein said closed loop microchannels are discretely disposed relative to each other.
10. The method of claim 8 , wherein said closed loop microchannels are interconnected and in fluidic communication to each other.
11. The method of claim 7 , wherein said casting is subjected to at least one of heat and pressure to effectuate elimination of said planar gap.
12. The method of claim 7 , wherein said casting is subjected to an oxygen plasma treatment to effectuate elimination of said planar gap.
13. The method of claim 1 , wherein said resin comprises polydimethylsiloxane (PDMS).
14. The method of claim 1 , comprising the further steps of:
(E) filling cavities of said casting formed by said master mold with a resin after said master mold has been removed from said casting; and
(F) curing said resin to form a replicated mold having a configuration substantially identical to that of said master mold.
15. The method of claim 14 , wherein said resin is a thermoplastic material.