Methods and apparatus for the manipulation of particle suspensions and testing thereof

Abstract

Apparatus and methods are provided for analysis of individual particles in a microfluidic device. The methods involve the immobilization of an array of particles in suspension and the application of experimental compounds. Such methods can also include electrophysiology studies including patch clamp recording, electroporation, or both in the same microfluidic device. The apparatus provided includes a microfluidic device coupled to a multi-well structure and an interface for controlling the flow of media within the microchannel device.

1 . A system for performing one or more assays, the system comprising:
 a flow actuation system including:
 an interface comprising:
 a deformable material, wherein the deformable material is configured to form a pressure seal with a plurality of wells of a well plate coupled to a microfluidic device; and 
 a plurality of passageways through the deformable material, wherein the plurality of passageways are configured for pneumatic communication with respective ones of the plurality of wells; and 
 
 a pressure source controllably coupled to the plurality of passageways and configured to apply a pneumatic pressure to the plurality of wells through the plurality of passageways; 
   a computer system coupled to the flow actuation system, wherein the computer system is configured to provide control signals to the flow actuation system to cause the flow actuation system to apply pneumatic pressure to selected ones of the plurality of wells.   
     
     
         2 . The system of  claim 1 , further comprising:
 an imaging system positioned to generate an image of at least a portion of the microfluidic device; and   wherein the control signals are first control signals, and wherein the computer system or another computer system is coupled to the imaging system and configured to provide second control signals to the imaging system to capture the image from the at least a portion of the microfluidic device.   
     
     
         3 . The system of  claim 2 , wherein the image includes representations of particles in the microfluidic device, and wherein the computer system is further configured to receive the image and analyze a characteristic of at least some of the particles. 
     
     
         4 . The system of  claim 1 , wherein the pneumatic pressure is selected to initiate fluid flow from the selected ones of the plurality of wells into the microfluidic device, wherein said fluid contains a particle suspension. 
     
     
         5 . The system of  claim 1 , wherein the passageways are arranged for coupling to wells arranged in a standard SBS well plate configuration. 
     
     
         6 . The system of  claim 1 , wherein the passageways comprise tubing. 
     
     
         7 . The system of  claim 6 , wherein the tubing is gas-filled. 
     
     
         8 . The system of  claim 1 , wherein the control signals are configured to cause the flow actuation system to apply pneumatic pressure to selected ones of the plurality of wells containing particle suspensions to introduce particles into the microfluidic device. 
     
     
         9 . The system of  claim 8 , wherein the computer system is further configured to provide further control signals to the microfluidic device, wherein the further control signals are configured to cause the flow actuation system to apply pneumatic pressure to different selected ones of the plurality of wells, wherein the different selected ones of the plurality of wells contain a different solution and the pneumatic pressure is selected to generate a shear flow across at least some of the particles in the microfluidic device. 
     
     
         10 . The system of  claim 9 , further comprising an imaging system positioned to generate an image of at least a portion of the microfluidic device; and
 wherein the control signals are first control signals, and wherein the computer system or another computer system is coupled to the imaging system and configured to provide second control signals to the imaging system to capture time lapse images from the at least a portion of the microfluidic device during the shear flow.   
     
     
         11 . The system of  claim 8 , wherein the computer system is configured to store a user-specified flow or shear rate profile, and wherein said third control signals are generated in accordance with the user-specified shear rate profile. 
     
     
         12 . A device comprising:
 a microfluidic chip defining a plurality of channels and a plurality of openings in a surface of the microfluidic chip, wherein individual ones of the plurality of openings are in fluid communication with respective ones of the plurality of channels;   a well plate defining a plurality of wells and a plurality of openings in the wells, wherein the well plate is bonded to the microfluidic chip such that individual ones of the plurality of wells are in fluid communication with respective ones of the plurality of openings through the plurality of openings in the wells; and   fluid contained in at least one of the plurality of wells, wherein the fluid partially fills the at least one of the plurality of wells and a gas-fluid interface is present within the at least one of the plurality of wells.   
     
     
         13 . The device of  claim 12 , further comprising an interface including:
 a deformable material, wherein the deformable material is configured to form a pressure seal with the plurality of wells; and   a plurality of passageways through the deformable material, wherein the plurality of passageways are configured for pneumatic communication with respective ones of the plurality of wells.   
     
     
         14 . The device of  claim 13 , further comprising a pressure source coupled to the plurality of passageways. 
     
     
         15 . The device of  claim 12 , wherein the well plate is configured in a standard SBS format. 
     
     
         16 . The device of  claim 12 , wherein the well plate is bonded to the microfluidic chip using at least one of a plasma bond, a thermal bond, or an adhesive bond. 
     
     
         17 . The device of  claim 12 , wherein the surface is a first surface, and wherein the microfluidic chip includes a second surface, and wherein respective ones of the plurality of channels are positioned for optical access through the second surface. 
     
     
         18 . The device of  claim 12 , wherein the fluid comprises a suspension of particles. 
     
     
         19 . The device of  claim 12 , wherein the plurality of channels include individual channels having different fluidic resistances. 
     
     
         20 . The device of  claim 19 , further comprising a pressure source coupled to selected ones of the plurality of openings in the microfluidic chip, and wherein the selected ones of the plurality of openings in the microfluidic chip are coupled to respective ones of the individual channels having different fluidic resistances, wherein the individual channels having different fluidic resistances are configured to provide different flow velocities and shear forces responsive to the pressure source. 
     
     
         21 . A method for performing an assay, the method comprising:
 applying pneumatic pressure to a gas-fluid interface in at least one selected well of a microfluidic device to flow at least a portion of a fluid in the well into a feature of the microfluidic device; and   imaging at least a portion of the feature of the microfluidic device after said applying pneumatic pressure.   
     
     
         22 . The method of  claim 21 , wherein the fluid comprises particles, either adherent or in suspension. 
     
     
         23 . The method of  claim 21 , further comprising analyzing, using a controller, an image of the at least a portion of the feature of the microfluidic device to assess characteristics of particles within the feature. 
     
     
         24 . The method of  claim 23 , wherein said analyzing comprises measuring adherence of particles to a substrate of the microfluidic device, adherence of particles to a layer of particles attached to a substrate of the microfluidic device, detachment of particles in the feature, migration of particles during the flow, morphology of the particles, cell growth, cell viability, and internation of particles with a coating or within a gel provided in the microfluidic device, genetic profiles and expression profiles of said particles if particles are cells. 
     
     
         25 . The method of  claim 21 , wherein said applying pneumatic pressure includes applying pneumatic pressure sufficient to achieve a predetermined shear flow profile in the feature. 
     
     
         26 . The method of  claim 21 , further comprising stopping the flow prior to said imaging. 
     
     
         27 . A system for performing one or more assays, the system comprising:
 a microfluidic device comprising two or more channels, said channels each in fluid communication with two or more respective inlets and one or more respective outlets; wherein cells are adhered to a surface of each of the two or more channels;   a flow actuation system configured to control flow rates in the two or more channels;   a computer system coupled to the flow actuation system, wherein the computer system is configured to provide control signals to the flow actuation system to control the flow rates; and   an imaging system positioned to generate an image of at least a portion of two or more regions of the microfluidic device under control of the computer system.   
     
     
         28 . The system of  claim 27 , wherein the microfluidic device comprises a transparent bottom substrate, said substrate having a thickness of less than 1 mm. 
     
     
         29 . The system of  claim 27 , wherein the microfluidic device is configured for use in chemotaxis applications. 
     
     
         30 . The system of  claim 27 , wherein each of the two or more respective inlets in fluid communication with a particular channel are configured to deliver a different fluid to the channel.