Devices and methods for sample characterization

Abstract

Devices and methods for characterization of analyte mixtures are provided. Some methods described herein include performing enrichment steps on a device before expelling enriched analyte fractions from the device for subsequent analysis. Also included are devices for performing these enrichment steps.

1 . An apparatus, comprising:
 a substrate constructed of an opaque material, the substrate having a thickness and a top surface in which a microfluidic separation channel having a depth equal to the thickness of the substrate is defined such that the microfluidic separation channel defines an optical slit through the substrate; and   a layer disposed on a top surface of the substrate, a portion of the layer disposed over the microfluidic separation channel being transparent.   
     
     
         2 .- 4 . (canceled) 
     
     
         5 . The apparatus of  claim 1 , wherein the substrate, the microfluidic separation channel, and the layer are collectively configured such that when the apparatus is imaged, light is only transmitted through the optical slit. 
     
     
         6 . The apparatus of  claim 1 , wherein a portion of the layer is opaque. 
     
     
         7 . The apparatus of  claim 1 , wherein the portion of the layer that is transparent extends over an entire length of the microfluidic separation channel. 
     
     
         8 . The apparatus of  claim 1 , wherein:
 a side surface of the substrate defines an orifice in fluid communication with an end portion of the microfluidic separation channel;   the substrate defines a reservoir fluidically coupled to the end portion of the microfluidic separation channel such that fluid from the reservoir forms a sheath solution around fluid from the microfluidic separation channel when fluid is expelled from the orifice.   
     
     
         9 . The apparatus of  claim 1 , wherein:
 the substrate further defines a gas channel;   a side surface of the substrate defines an orifice in fluid communication with the substrate, the gas channel configured to convey nebulizing gas that flanks fluid expelled from the orifice.   
     
     
         10 . The apparatus of  claim 1 , wherein the substrate further defines:
 a first reservoir fluidically coupled to a first end portion of the microfluidic separation channel;   a second reservoir fluidically coupled to a second end portion of the microfluidic separation channel opposite the first end portion, the apparatus further comprising:   a first electrical contact electrically coupled to the first reservoir; and   a second electrical contact electrically coupled to the second reservoir such that an electric field can be applied to the microfluidic separation channel via the first reservoir and the second reservoir to induce electrophoresis within the microfluidic separation channel.   
     
     
         11 . The apparatus of  claim 1 , wherein the microfluidic separation channel is a chromatographic separation channel and the substrate further defines an electrophoretic separation channel fluidically coupled to the chromatographic separation channel such that at least two phases of separation can be performed within the apparatus. 
     
     
         12 . The apparatus of  claim 1 , wherein the substrate further defines an elution channel fluidically coupled to the microfluidic separation channel, the elution channel configured to convey an eluent to the microfluidic separation channel to elute an analyte bound to a media disposed in the microfluidic separation channel. 
     
     
         13 . The apparatus of  claim 1 , wherein a side surface of the substrate defines a countersunk surface having an orifice in fluid communication with the microfluidic separation channel, the orifice and the countersunk surface collectively configured such that a Taylor cone emanating from the orifice is disposed entirely within a volume defined by the countersunk surface. 
     
     
         14 .- 21 . (canceled) 
     
     
         22 . A method, comprising:
 injecting an analyte mixture into a microfluidic device containing a first separation channel, the first separation channel containing a media configured to bind to an analyte from the analyte mixture;   injecting an eluent into the microfluidic device such that at least a fraction of the analyte is mobilized from the media;   imaging the first separation channel while the analyte is mobilized;   applying an electric field to a second separation channel when the imaging detects that the fraction is disposed at an intersection of the first separation channel and the second separation channel such that the fraction is mobilized into the second separation channel; and   expelling at least a portion of the fraction.   
     
     
         23 . The method of  claim 22 , wherein the at least the portion of the fraction is expelled via electrospray ionization. 
     
     
         24 . (canceled) 
     
     
         25 . The method of  claim 22 , further comprising:
 separating the fraction of the analyte via capillary zone electrophoresis in the second separation channel.   
     
     
         26 . The method of  claim 22 , further comprising:
 separating the fraction of the analyte via electrophoresis in the second separation channel; and   imaging the second separation channel while the fraction of the analyte is separated.   
     
     
         27 . The method of  claim 22 , wherein a first end portion of the second separation channel intersects the first separation channel, the method further comprising:
 injecting a sheath solution into a second end portion of the separation channel opposite the first end portion of the separation channel.   
     
     
         28 . The method of  claim 22 , wherein the first separation channel and the second separation channel arc orthogonal. 
     
     
         29 . An apparatus, comprising:
 a substrate defining:
 a first enrichment zone containing a media configured to bind to an analyte; 
 a second enrichment zone intersecting the first enrichment zone; 
 a surface; and 
 an orifice defined by the recessed surface, the orifice being an opening to a first end portion of the second enrichment zone; 
   a first electrode electrically coupled to the first end portion of the second enrichment zone; and   a second electrode electrically coupled to a second end portion of the second enrichment zone opposite the first end portion.   
     
     
         30 . The apparatus of  claim 29 , wherein the first enrichment zone is orthogonal to the second enrichment zone. 
     
     
         31 . The apparatus of  claim 29 , wherein the first enrichment zone is disposed before the second enrichment zone such that at least a portion of a sample flows from the first enrichment zone to the second enrichment zone. 
     
     
         32 .- 33 . (canceled)