High-efficiency bacteria capture and quantification 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 high-efficiency capture of bacteria in sample, the method comprising:
 pumping the sample through a microfluidic passage of a microfluidic device at a predetermined flow rate, wherein the microfluidic device comprises at least one electrode disposed adjacent to the microfluidic passage;   activating the at least one electrode to capture bacteria in the sample by the at least one electrode using dielectrophoresis as the sample flows through the microfluidic passage at the predetermined flow rate, wherein the capture efficiency of bacteria is at least 99%;   capturing, using an optical system, one or more images of the at least one electrode during activation of the at least one electrode; and   processing, using at least one computing device, the captured one or more images to quantify an amount of bacteria captured by the at least one electrode.   
     
     
         66 . The method of  claim 65 , wherein quantifying an amount of bacteria comprises counting a number of spots in the one or more images captured by the optical system. 
     
     
         67 . The method of  claim 65 , further comprising:
 labeling the bacteria captured on the at least one electrode with a fluorescent dye;   exciting the fluorescent dye with at least one light source of the optical system to produce a fluorescent signal;   capturing the fluorescent signal using the optical system; and   quantifying the amount of bacteria based, at least in part, on the captured fluorescent signal.   
     
     
         68 . The method of  claim 65 , wherein activating the at least one electrode comprises applying an alternating current (AC) voltage to the at least one electrode, wherein the AC voltage has a frequency between 900 Hz and 2 MHz. 
     
     
         69 . The method of  claim 65 , wherein the at least one electrode comprises a plurality of concentric rings or arcs. 
     
     
         70 . The method of  claim 65 , wherein the microfluidic passage comprises a microfluidic channel formed in a microfluidic chip. 
     
     
         71 . The method of  claim 65 , further comprising:
 altering a characteristic of an AC voltage provided to activate the at least one electrode, wherein altering the characteristic of the AC voltage causes the captured bacteria to be released from the at least one electrode.   
     
     
         72 . The method of  claim 71 , wherein the characteristic is a frequency of the AC voltage. 
     
     
         73 . The method of  claim 72 , wherein altering the frequency of the AC voltage comprises providing a higher frequency AC voltage to the at least one electrode to apply negative dielectrophoresis to the captured bacteria thereby releasing the captured bacteria from the at least one electrode. 
     
     
         74 . The method of  claim 71 , wherein the characteristic is an amplitude of the AC voltage. 
     
     
         75 . The method of  claim 65 , further comprising:
 flushing a buffer solution through the microfluidic passage to mechanically release the bacteria from the at least one electrode.   
     
     
         76 . The method of  claim 65 , wherein the at least one electrode comprises a plurality of electrodes, wherein:
 the plurality of electrodes are arranged in a two-dimensional array having a first dimension along a width of the microfluidic passage and a second dimension along a length of the microfluidic passage, wherein at least two electrodes of the plurality of electrodes are arranged along the width of the microfluidic passage and at least two electrodes of the plurality of electrodes are arranged along the length of the microfluidic passage   
     
     
         77 . The method of  claim 76 , wherein the plurality of concentric arcs are spaced equally from each other. 
     
     
         78 . The method of  claim 76 , wherein the at least two electrodes of the plurality of electrodes are arranged in a third dimension along a height of the microfluidic passage. 
     
     
         79 . The method of  claim 65 , wherein the pumping is performed with a first pump disposed outside of a flow path of the sample.