Single-sheath microfluidic chip

Abstract

Microfluidic devices and methods for focusing components in a fluid sample are described herein. The microfluidic device has at least one flow focusing channel where the components are focused or re-oriented by the geometry of the channel. From an upstream end of the flow focusing channel to a downstream end of the flow focusing channel, at least a portion of the flow focusing channel has a reduction in height and at least a portion of the flow focusing channel narrows in width, thereby geometrically constricting the flow focusing channel. The devices and methods can be utilized in sex-sorting of sperm cells to improve performance and increase eligibility.

What is claimed is: 
     
         1 . A microfluidic chip ( 100 ) comprising at least one flow focusing channel ( 120 ), wherein from an upstream end ( 127 ) of the flow focusing channel to a downstream end ( 128 ) of the flow focusing channel, at least a portion of the flow focusing channel ( 120 ) has a reduction in height and at least a portion of the flow focusing channel ( 120 ) narrows in width, thereby geometrically constricting the flow focusing channel ( 120 ). 
     
     
         2 . The microfluidic chip ( 100 ) of  claim 1 , wherein the height reduction of the portion of the flow focusing channel ( 120 ) is caused by a ramp, a step, or constriction disposed on a bottom surface ( 121 ) of the flow focusing channel ( 120 ), a top surface ( 122 ) of the flow focusing channel ( 120 ), or both. 
     
     
         3 . The microfluidic chip ( 100 ) of  claim 1 , wherein the flow focusing channel ( 120 ) has a first sidewall ( 125 ) and a second sidewall ( 126 ) opposite the first sidewall ( 125 ), wherein the first and second sidewalls ( 125 ,  126 ) taper the flow focusing channel ( 120 ) to form the portion of the flow focusing channel ( 120 ) that narrows in width. 
     
     
         4 . The microfluidic chip ( 100 ) of  claim 1 , wherein at least a portion of the flow focusing channel ( 120 ) has a shape of a cone with a larger diameter of the cone biased towards the upstream end ( 127 ) and a smaller diameter of the cone biased towards the downstream end ( 128 ). 
     
     
         5 . The microfluidic chip ( 100 ) of  claim 1 , wherein the portion of the flow focusing channel ( 120 ) with the height reduction and the portion of the flow focusing channel ( 120 ) narrowing in width are simultaneous or overlapping. 
     
     
         6 . The microfluidic chip ( 100 ) of  claim 1 , wherein the portion of the flow focusing channel ( 120 ) with the height reduction and the portion of the flow focusing channel ( 120 ) narrowing in width are sequential. 
     
     
         7 . The microfluidic chip ( 100 ) of  claim 1 , wherein the geometrical constriction of the flow focusing channel ( 120 ) is configured to focus a material in a fluid that is flowing through the flow focusing channel ( 120 ). 
     
     
         8 . A microfluidic chip ( 100 ) comprising:
 a. a first micro-channel ( 110 ); and   b. at least one flow focusing region ( 120 ) fluidly coupled to the first micro-channel ( 110 ), said flow focusing region ( 120 ) formed by a bottom surface ( 121 ), a top surface ( 122 ), a first sidewall ( 125 ) and a second sidewall ( 126 ) opposite the first sidewall ( 125 ),
 wherein from an upstream end ( 127 ) of the flow focusing region to a downstream end ( 128 ) of the flow focusing region, at least a portion of the bottom surface ( 121 ) is raised, at least a portion of the top surface ( 122 ) is lowered, and at least a portion of the first and second sidewalls ( 125 ,  126 ) taper the flow focusing region ( 120 ), thereby reducing a cross-sectional area ( 129 ) of the flow focusing region at the downstream end ( 128 ) relative to the upstream end ( 127 ). 
   
     
     
         9 . The microfluidic chip ( 100 ) of  claim 8  further comprising one or more sheath fluid micro-channels ( 130 ) intersecting the first micro-channel ( 110 ) upstream of the flow focusing region ( 120 ). 
     
     
         10 . The microfluidic chip ( 100 ) of  claim 9 , wherein the one or more sheath fluid micro-channels ( 130 ) are configured to flow a sheath fluid. 
     
     
         11 . The microfluidic chip ( 100 ) of  claim 8 , wherein the first micro-channel ( 110 ) comprises an inlet ( 112 ) through which a sample fluid enters the first micro-channel ( 110 ). 
     
     
         12 . The microfluidic chip ( 100 ) of  claim 8  further comprising one or more output micro-channels ( 140 ) fluidly coupled to the first micro-channel ( 110 ) downstream of the flow focusing region ( 120 ), the one or more output micro-channels ( 140 ) configured to output a fluid from the first micro-channel ( 110 ). 
     
     
         13 . The microfluidic chip ( 100 ) of  claim 8 , wherein the bottom surface ( 121 ) includes a ramp ( 123 ) having a positive slope that raises the portion of the bottom surface. 
     
     
         14 . The microfluidic chip ( 100 ) of  claim 8 , wherein the entire bottom surface ( 121 ) is a ramp ( 123 ) that gradually increases a height of the bottom surface from the upstream end ( 127 ) to the downstream end ( 128 ). 
     
     
         15 . The microfluidic chip ( 100 ) of  claim 8 , wherein the top surface ( 122 ) includes a ramp ( 124 ) having a negative slope that lowers the portion of the top surface. 
     
     
         16 . The microfluidic chip ( 100 ) of  claim 8 , wherein the entire top surface ( 122 ) is a ramp ( 124 ) that gradually decreases a height of the top surface from the upstream end ( 127 ) to the downstream end ( 128 ). 
     
     
         17 . The microfluidic chip ( 100 ) of  claim 8 , wherein the entire first and second sidewalls ( 125 ,  126 ) are angled so as to taper the flow focusing region ( 120 ) from the upstream end ( 127 ) to the downstream end ( 128 ). 
     
     
         18 . The microfluidic chip ( 100 ) of  claim 8 , wherein at least two of the raised portion of the bottom surface ( 121 ), the lowered of the portion of the top surface ( 122 ), and the sidewall tapering occur simultaneously. 
     
     
         19 . The microfluidic chip ( 100 ) of  claim 8 , wherein at least two of the raised portion of the bottom surface ( 121 ), the lowered portion of the top surface ( 122 ), and the sidewall tapering are overlapping. 
     
     
         20 . The microfluidic chip ( 100 ) of  claim 8 , wherein the raised portion of the bottom surface ( 121 ), the lowered portion of the top surface ( 122 ), and the sidewall tapering occur in a pre-determined sequence.