Microfluidic Cell Culture Systems

Abstract

A number of novel improved microfluidic configurations and systems and methods of manufacture and operation.

What is claimed: 
     
         1 . A microfluidic structure comprising:
 a culture chamber;   at least one first object flow outlet disposed on a wall of said culture chamber;   at least one second object flow outlet disposed on said wall;   at least one object flow inlet disposed on said wall and between said at least one first object flow outlet and said at least one second object flow outlet for introducing culture objects and object flow media into said culture chamber;   a flow-around channel allowing fluidic media into said culture chamber;   said flow-around channel separated from the culture chamber by a perfusion barrier, wherein said perfusion barrier defines at least two walls of said culture chamber, wherein one wall of said at least two walls defines an opposite wall of said culture chamber.   
     
     
         2 . The microfluidic structure of  claim 1  further comprising:
 at least one separate air diffusion channel adjacent to the culture chamber and running along most of one side of the culture chamber. 
 
     
     
         3 . The microfluidic structure of  claim 1  further comprising:
 a second object flow inlet adjacent to the at least one object flow inlet providing a split object loading inlet. 
 
     
     
         4 . The microfluidic structure of  claim 1  further wherein the perfusion barrier is configured to prevent a gel from filling said flow-around channel. 
     
     
         5 . The microfluidic structure of  claim 1  wherein the flow-around channel comprises more than one half of the culture chamber. 
     
     
         6 . The microfluidic structure of  claim 1  further wherein the shape of the culture chamber is selected from the group consisting of:
 a rectangle; 
 a rectangle with one or more rounded edges; 
 a circle; and 
 a culture chamber with at least one side that is an elliptical or circular shape. 
 
     
     
         7 . The microfluidic structure of  claim 1  further wherein said at least one object flow inlet is configured to load and hold objects embedded in a 3D gel or matrix and said perfusion barrier is configured to provide fluid flow while preventing flow of clogging by the 3D gel or matrix. 
     
     
         8 . The microfluidic structure of  claim 1  wherein the flow of cells is loaded via capillary force from said at least one object flow inlet and out from the at least one first object flow outlet and the at least one second object flow outlet away from the at least one object flow inlet; and
 wherein a very small amount of flow exits the culture chamber from the at least one first object flow outlet and the at least one second object flow outlet, thereby tending to distribute cells more evenly in the culture chamber. 
 
     
     
         9 . The microfluidic structure of  claim 1  wherein the culture chamber is between about 0.1 millimeters and about 5 millimeters high;
 the flow-around channel is between about 10 microns and 100 microns high, with a cross section of between about 50 square microns and about 10,000 square microns; and 
 the perfusion barrier provides a perfusion passage between about 1 microns high and about 10 microns high, with a cross section of between about 1 square microns and about 100 square microns. 
 
     
     
         10 . The microfluidic structure of  claim 1  further wherein:
 the culture chamber further comprises a glass floor and is configured to perform the culture of cells in 2D culture using liquid culture medium or 3D culture using a gel medium, 
 wherein in 2D culture, cells adhere to said glass floor due to a low culture flow rate from the at least one object flow inlet to the at least one first object flow outlet and the at least one second object flow outlet; and 
 wherein in 3D culture, cells are embedded in a gel and dispensed into the culture chamber with the gel localized to the culture chamber by the perfusion barrier, allowing medium to flow around the gel/perfusion barrier and diffuse in to feed the cells. 
 
     
     
         11 . The microfluidic structure of  claim 1  further comprising a serpentine channel disposed between said first reservoir and said flow-around channel, wherein said serpentine channel has a fluidic resistance, and said fluidic resistance determines said flow rate of said fluid in said flow-around channel. 
     
     
         12 . The microfluidic structure of  claim 1  further comprising a serpentine channel disposed between said flow-around channel and said second reservoir, wherein said serpentine channel has a fluidic resistance, and said fluidic resistance determines said flow rate of said fluid in said flow-around channel. 
     
     
         13 . The microfluidic structure of  claim 1 , wherein a flow rate of said fluid through said flow-around channel is determined based on a difference in fluid level between said first reservoir and said second reservoir. 
     
     
         14 . The microfluidic structure of  claim 1 , wherein said perfusion barrier defines three walls of said culture chamber. 
     
     
         15 . The microfluidic structure of  claim 1 , wherein said perfusion barrier encloses said culture chamber. 
     
     
         16 . The microfluidic structure of  claim 1 , wherein said perfusion barrier comprises a non-linear structure.