Process for sorting motile particles from lesser-motile particles and apparatus suitable therefor

Abstract

Motile particles are sorted from non-motile particles in a microfluidic sorting device wherein a stream of sort fluid containing motile and non-motile particles is caused to flow adjacent a media stream in non-turbulent fashion through a sort channel, during which flow motile particles cross the interface between the adjacent flow streams, entering the media stream, and forming a motile particle-depleted sort stream. The sorting devices are easily and inexpensively fabricated and have numerous uses, in particular sorting of motile from non-motile sperm.

What is claimed is:  
     
         1 . A method for sorting motile particles from lesser motile and/or non-motile particles, comprising: 
 a) providing a sort fluid comprising motile particles and at least one of lesser motile particles or non-motile particles;    b) providing a media fluid to be enriched with motile particles;    c) contacting a stream of said sort fluid and a stream of said media fluid within a sort channel of a sorting device, said sort fluid stream and said media fluid stream having therebetween a non-turbulent interface within said sort channel,    whereby motile particles leave the sort fluid stream and enter the media fluid stream, forming a motile particle-depleted sort fluid stream and a motile particle-enriched media fluid stream, and    d) separating a motile particle-depleted sort fluid outlet stream from a motile particle-enriched media fluid outlet stream.    
     
     
         2 . The process of  claim 1 , wherein said motile particles comprise motile sperm and said lesser motile and non-motile particles comprise sperm of lesser motility than said motility sperm or sperm of no motility.  
     
     
         3 . The process of  claim 1 , wherein said sort fluid is provided in a sort fluid reservoir and said media fluid is provided in a media fluid reservoir.  
     
     
         4 . The process of  claim 1 , wherein said media fluid and said sort fluid flow in the same direction and at substantially the same flow rate  
     
     
         5 . The process of  claim 1 , wherein said sort fluid stream and said media fluid stream exhibit laminar flow within said sort channel.  
     
     
         6 . The process of  claim 1 , wherein the transverse volume of said media fluid stream is greater than the transverse volume of said sort fluid stream in said sort channel.  
     
     
         7 . The process of  claim 1 , wherein said motile particle-depleted sort fluid outlet stream comprises a sort fluid inlet stream to a second device having a sort channel, and steps a) through d) are repeated, whereby further motile particles enter a media stream of said second device to further deplete said sort fluid of motile particles.  
     
     
         8 . The process of  claim 1 , wherein said motile, lesser motile, and non-motile particles are sperm particles, and the purity of motile particles in said motile particle-enriched media outlet stream is higher than the purity of motile sperm in the sort fluid and is at least 80%, said percent based on the number of motile sperm in said motile particle-enriched media outlet stream compared to total sperm in said motile particle-enriched outlet stream.  
     
     
         9 . The process of  claim 1 , wherein said motile particles comprise motile microorganisms, and said non-motile particles comprise non-motile microorganisms.  
     
     
         10 . A motile particle sorting device suitable for use in the method of  claim 1 , comprising: 
 a) a sort channel having first and second ends;    b) a sort fluid inlet in fluid communication with said first end of said sort channel;    c) a media fluid inlet in communication with said first end of said sort channel;    d) a motile particle-depleted sort fluid outlet in fluid communication with said second end of said sort channel; and    e) a motile particle-enriched media fluid outlet in fluid communication with said second end of said sort channel.    
     
     
         11 . The sorting device of  claim 10 , wherein said first end of said sort channel is formed by a confluence of a sort stream inlet and a media stream inlet, and said second end of said sort channel terminates at a divergence of a motile particle-depleted sort stream outlet and a motile particle-enriched media stream outlet.  
     
     
         12 . The sorting device of  claim 10 , wherein said sort fluid inlet comprises a sort fluid inlet channel, said media fluid inlet comprises a media fluid inlet channel, said motile particle-depleted sort fluid outlet comprises a motile particle-depleted sort fluid outlet channel, and said motile particle-enriched outlet comprises a motile particle-enriched outlet channel.  
     
     
         13 . The sorting device of  claim 12 , wherein each of said inlet channels and said outlet channels are respectively in communication with a fluid reservoir internal to said device.  
     
     
         14 . A motile particle sorting device, comprising a device of  claim 10 , wherein said motile particle-depleted sort stream outlet serves as a sort stream inlet to a second sorting device of  claim 10 , or wherein said motile particle-enriched media stream outlet serves as a sort stream inlet to a second sorting device of  claim 10 .  
     
     
         15 . A plurality of sorting devices of  claim 10  fabricated in a single integral structure.  
     
     
         16 . The plurality of sorting devices of  claim 15 , wherein at least two of said sorting devices are series connected.  
     
     
         17 . The sorting device of  claim 10 , which is cast of polymer  
     
     
         18 . The sorting device of  claim 13 , wherein said device comprises a first pumping system comprising a sort fluid reservoir, a sort fluid inlet channel, a sort channel, a motile particle-depleted sort fluid outlet, and a motile particle-depleted sort fluid reservoir, whereby sort fluid flows from said sort fluid reservoir to said motile particle-depleted sort fluid reservoir due to at least one of gravity or capillary forces.  
     
     
         19 . The sorting device of  claim 13 , wherein said device comprises a second pumping system comprising a media fluid reservoir, a media fluid inlet channel, a media channel, a motile particle-enriched media fluid outlet, and a motile particle-enriched media fluid reservoir, whereby media fluid flows from said media fluid reservoir to said motile particle-enriched media fluid reservoir due to at least one of gravity or capillary forces.  
     
     
         20 . The sorting device of  claim 19 , wherein fluid flows both due to gravity and due to capillary forces.  
     
     
         21 . The device of  claim 10 , wherein said sort channel is substantially rectangular, has a height of about 60-150 μm and a width of from about 100 μm to 800 μm, and a length of about 500 μm to about 10,000 μm, wherein said sort inlet comprises a sort inlet channel of substantially the same height as said sort channel and a smaller width in the range of 50 μm to 500 μm, and wherein said media inlet comprises one or more media inlet channels of substantially the same height as said sort channel, and a total width greater than the width of said sort inlet channel and less than the width of said sort channel, wherein total width is the sum of the widths of each media inlet channel when there is more than one inlet channel.