Bacteria enrichment system and methods

Abstract

Methods and apparatus for detecting, quantifying, enriching, and/or separating bacterial species in fluid sample are provided. The fluid sample is provided as input to a microfluidic passage of a microfluidic device, wherein the microfluidic device comprises at least one electrode disposed adjacent to the microfluidic passage. The at least one electrode is activated to capture bacteria in the sample using dielectrophoresis, wherein the capture efficiency of bacteria is at least 99%.

1 - 64 . (canceled) 
     
     
         65 . A method of enriching a bacterial species in a sample containing a first target bacterial species and other components, the method comprising:
 pumping a sample from an inlet of a microfluidic passage to an outlet of the microfluidic passage, the microfluidic passage having at least one electrode disposed adjacent thereto;   generating, using a signal generator electrically connected to the at least one electrode, an AC voltage to drive the at least one electrode to produce an electric field within the microfluidic passage, wherein the AC voltage has frequency and amplitude characteristics such that when produced, the electric field captures on the surface of the at least one electrode, a first target bacterial species in the sample while not capturing one or more other components in a sample as the sample is pumped through the microfluidic passage;   altering generation of the AC voltage to release the captured first target bacterial species from the surface of that least one electrode; and   collecting effluent fluid including the first target bacterial species released from the at least one electrode, wherein a relative abundance of the first target bacterial species in the effluent fluid is increased compared to the relative abundance of the first target bacterial species in the sample.   
     
     
         66 . The method of  claim 65 , wherein pumping the sample comprises pumping the sample using a pump coupled to the inlet of the at least one microfluidic passage. 
     
     
         67 . The method of  claim 65 , wherein pumping the sample comprises pumping the sample using a pump coupled to the outlet of the at least one microfluidic passage 
     
     
         68 . The method of  claim 65 , wherein pumping the sample comprises pumping the sample using a pump coupled to the microfluidic passage outside of a flow path of the sample. 
     
     
         69 . The method of  claim 65 , wherein
 the sample further includes a second target bacterial species, and   generating the AC voltage comprises generating the AC voltage to have frequency and amplitude characteristics such that both the first and the second target bacterial species are captured on the surface of the at least one electrode as the sample flows through the microfluidic passage when the AC voltage is applied to the at least one electrode.   
     
     
         70 . The method of  claim 69 , further comprising:
 altering generation of the AC voltage to release the captured first target bacterial species from the at least one electrode by adjusting a frequency of the AC voltage to release only the first target bacterial species captured on the surface of the at least one electrode.   
     
     
         71 . The method of  claim 70 , wherein adjusting a frequency of the AC voltage to release only the first target bacterial species captured on the surface of the at least one electrode comprises adjusting a frequency of the AC voltage applied to the at least one electrode such that a negative dielectrophoresis force is applied to the first target bacterial species to cause the first target bacterial species to be released from the surface of the at least one electrode. 
     
     
         72 . The method of  claim 70 , wherein adjusting a frequency of the AC voltage comprises increasing the frequency of the AC voltage. 
     
     
         73 . The method of  claim 70 , further comprising altering generation of the AC voltage to release all remaining bacterial species captured on the surface of the at least one electrode. 
     
     
         74 . The method of  claim 73 , wherein releasing all remaining bacterial species captured on the at least one electrode comprises deactivating the at least one electrode. 
     
     
         75 . The method of  claim 65 , wherein
 the other components include a second target bacterial species, and   generating the AC voltage comprises generating the AC voltage to have frequency and amplitude characteristics such that the first target bacterial species is captured on the surface of the at least one electrode as the sample flows through the microfluidic passage and the second target bacterial species is not captured on the surface of the at least one electrode as the sample flows through the microfluidic passage.   
     
     
         76 . The method of  claim 75 , wherein the first target bacterial species includes at least one gram positive bacterial species and the second target bacterial species includes at least one gram negative bacterial species. 
     
     
         77 . The method of  claim 65 , wherein a relative abundance of the first target bacterial species in effluent fluid collected at the outlet of the microfluidic passage after release from the at least one electrode is increased at least 20 times compared to the relative abundance of the first target bacterial species in the sample. 
     
     
         78 . The method of  claim 65 , wherein the sample is a fecal sample or a microbiome sample. 
     
     
         79 . The method of  claim 65 , wherein a relative abundance of the first target bacterial species in the sample is below a detection limit of DNA sequencing.