Microfluidic magnetophoretic device and methods for using the same

Abstract

A microfluidic device may employ one or more sorting stations for separating target species from other species in a sample. The separation is driven by magnetophoresis. A sorting station generally includes separate buffer and sample streams. A magnetic field gradient applied to the sorting station deflects the flow path of magnetic particles (which selectively label the target species) from a sample stream into a buffer stream. The buffer stream leaving the sorting station is used to detect or further process purified target species labeled with the magnetic particles.

1 .- 45 . (canceled) 
     
     
         46 . A method of sorting magnetic species in a sample, the method comprising:
 (a) providing the sample to at least a first inlet channel of a microfluidic sorting device;   (b) providing a buffer stream to the microfluidic sorting device;   (c) applying a magnetic field generated by a source proximate to the buffer stream to divert at least some of the magnetic species from the sample to the buffer stream and temporarily immobilize the diverted magnetic species; and   (d) collecting at least some of the diverted magnetic species at a collection outlet channel.   
     
     
         47 . The method of  claim 46 , wherein the source of the magnetic field comprises a magnetic field gradient generator. 
     
     
         48 . The method of  claim 47 , wherein the magnetic field gradient generator comprises a plurality of ferromagnetic elements. 
     
     
         49 . The method of  claim 46 , further comprising disrupting target species that were affixed to the magnetic particles while said magnetic particles were diverted in the sorting device. 
     
     
         50 . The method of  claim 46 , further comprising separating genetic material from target species that were affixed to the magnetic particles while said magnetic particles were diverted in the sorting device. 
     
     
         51 . The method of  claim 46 , further comprising amplifying a nucleic acid of target species that were affixed to the magnetic particles while said magnetic particles were diverted in the sorting device. 
     
     
         52 . The method of  claim 51 , further comprising characterizing the target species using amplified nucleic acid. 
     
     
         53 . The method of  claim 46 , wherein the sample and the buffer stream flow are vertically stacked with respect to each other within the microfluidic sorting device. 
     
     
         54 . The method of  claim 46 , wherein the magnetic source, the buffer stream, and the sample are arranged in a stack, with the buffer stream interposed between the sample and the source of the magnetic field. 
     
     
         55 . The method of  claim 46 , wherein a density associated with a fluid within the microfluidic sorting device is adjusted to reduce settling of the magnetic particles. 
     
     
         56 . A method of purifying a target species in a sample, the method comprising:
 (a) providing the sample to at least a first inlet channel of a microfluidic sorting device, wherein the sample includes magnetic particles having an affinity for the target species;   (b) providing a buffer stream to the microfluidic sorting device;   (c) magnetizing a magnetic field gradient generator to divert at least some of the magnetic particles from the sample to the buffer stream, wherein the magnetic field gradient generator is in contact with the buffer stream, and wherein the only forces substantially affecting diversion of the magnetic particles are hydrodynamic drag and attractive magnetophoretic forces; and   (d) collecting purified target species at a collection outlet channel.   
     
     
         57 . The method of  claim 56 , wherein the magnetic field gradient generator comprises a plurality of micropatterned ferromagnetic elements. 
     
     
         58 . The method of  claim 56 , further comprising detecting the purified target species collected in (d). 
     
     
         59 . The method of  claim 56 , further comprising disrupting cells, wherein at least some of the cells comprise the target species. 
     
     
         60 . The method of  claim 56 , further comprising separating genetic material from the target species. 
     
     
         61 . The method of  claim 56 , further comprising amplifying a nucleic acid of the target species. 
     
     
         62 . The method of  61 , further comprising characterizing the target species using amplified nucleic acid. 
     
     
         63 . The method of  claim 56 , wherein the sample and the buffer stream flow are vertically stacked with respect to each other within the microfluidic sorting device. 
     
     
         64 . The method of  claim 56 , wherein the magnetic field gradient generator, the buffer stream, and the sample are arranged in a stack, with the buffer stream interposed between the sample and the magnetic field gradient generator. 
     
     
         65 . The method of  claim 56 , wherein a density associated with a fluid within the microfluidic sorting device is adjusted to reduce settling of the magnetic particles. 
     
     
         66 . A method of purifying a target species in a sample including magnetic particles having an affinity for the target species, the method comprising:
 (a) flowing parallel streams of the sample and a buffer into a microfluidic sorting device having a magnetic field generated by a source proximate to the buffer stream to thereby capture at least some of the magnetic particles by a magentophoretic force on the target species that is greater than a hydrodynamic drag acting on the target species, wherein the magnetic particles are captured in the buffer stream from the sample stream; and   (b) collecting purified target species at a collection outlet channel.   
     
     
         67 . The method of  claim 66 , further comprising removing or reducing the magnetic field thereby releasing captured magnetic particles. 
     
     
         68 . The method of  claim 66 , wherein the source of the magnetic field comprising a magnetic field gradient generator. 
     
     
         69 . The method of  claim 68 , wherein the magnetic field gradient generator comprises a plurality of micropatterned ferromagnetic elements. 
     
     
         70 . The method of  claim 66 , further comprising disrupting cells, wherein at least some of the cells comprise the target species. 
     
     
         71 . The method of  claim 66 , further comprising separating genetic material from the target species. 
     
     
         72 . The method of  claim 66 , further comprising amplifying a nucleic acid of the target species. 
     
     
         73 . The method of  claim 66 , wherein collecting the purified target species comprises recovering at least 50% of the target species in the sample. 
     
     
         74 . The method of  claim 66 , wherein the sample stream and the buffer stream flow are vertically stacked with respect to each other within the microfluidic sorting device. 
     
     
         75 . The method of  claim 66 , wherein the magnetic field source, the buffer stream, and the sample stream are arranged in a stack, with the buffer stream interposed between the sample stream and the magnetic field source. 
     
     
         76 . A method comprising:
 providing a sample stream including target species;   labeling at least some of the target species with magnetic particles;   providing the sample stream and a buffer stream to a sorting station included in the microfluidic sorting device;   using a magnetic field to deflect the magnetic particles and the target species from the sample stream to the buffer stream and to trap the magnetic particles and the target species;   collecting the magnetic particles and the target species in an outlet channel;   disrupting the target species to release nucleic acids;   amplifying the nucleic acids; and   detecting the nucleic acids to identify or characterize the target species.   
     
     
         77 . The method of  claim 76 , further comprising removing components from the sample, wherein the components bind non-specifically with the magnetic particles. 
     
     
         78 . The method of  claim 76 , further comprising removing debris from the sample.