Apparatus for pathogen detection

Abstract

An apparatus for separating an analyte from a test sample, such as bacteria from blood components, based on their dielectric properties, localizing or condensing the analyte, flushing substantially all remaining waste products from the test sample, and detecting low concentrations of the analyte. The module array includes a plurality of microfluidic channels with connecting microfluidic waste channels for directing undesired material away from the analyte. An electric field is applied causing a positive dielectrophoretic force to the analyte to capture the analyte. The electric field is applied to at least one electrode having a plurality of concentric rings or concentric arcs extending radially outwards from a center point, electrically connected to a voltage source such that when voltage is applied to the at least one electrode, the concentric rings or concentric arcs alternate in voltage potential.

Thus, having described the invention, what is claimed is: 
     
         1 - 15 . (canceled) 
     
     
         16 . A method for detecting an analyte in a sample, the method comprising:
 directing a test sample through at least one microfluidic channel, the test sample including an analyte;   separating the analyte from other components of the test sample by generating dielectrophoretic forces that act on the test sample;   condensing the analyte in a localized region; and   detecting the condensed analyte using a sensor.   
     
     
         17 . The method of  claim 16 , wherein the test sample includes the analyte and at least one waste product, and separating the analyte further comprises separating the analyte from the at least one waste product. 
     
     
         18 . The method of  claim 16 , wherein separating the analyte further comprises generating the dielectrophoretic forces as the test sample flows through the at least one microfluidic channel. 
     
     
         19 . The method of  claim 16 , further comprising directing the analyte away from the other components of the test sample and towards a condensing region, and wherein condensing the analyte further comprises directing the analyte from the condensing region to the localized region. 
     
     
         20 . The method of  claim 16 , wherein condensing the analyte further comprises reducing the volume of the analyte in the localized region. 
     
     
         21 . The method of  claim 16 , further comprising directing the analyte away from the other components of the test sample and towards a condensing region, and wherein condensing the analyte further comprises reducing the volume of the analyte in the condensing region. 
     
     
         22 . The method of  claim 16 , further comprising flushing the analyte with a reference solution to substantially remove the at least one waste product from the analyte. 
     
     
         23 . The method of  claim 16 , further comprising directing the analyte to the sensor using dielectrophoretic manipulation to overcome a diffusion limitation and contacting the analyte to a surface of the sensor. 
     
     
         24 . The method of  claim 16 , further comprising directing the analyte to the condensing region using dielectrophoretic manipulation to overcome a diffusion limitation and detecting the analyte with the sensor. 
     
     
         25 . The method of  claim 16 , further comprising introducing at least one substance configured to preferentially pierce a membrane of an alive analyte component over a membrane of another component of the test sample or a dead analyte component at a frequency, and differentiating the alive analyte component from another component or the dead analyte component by applying dielectrophoretic forces. 
     
     
         26 . The method of  claim 16 , further comprising changing a Clausius-Mossotti factor, by changing a medium permittivity, to cause capture and/or release of the analyte. 
     
     
         27 . The method of  claim 26 , further comprising:
 applying an electric field to generate a first dielectrophoretic force to capture the analyte; and   changing the Clausius-Mossotti factor by flushing the analyte with a reference solution to generate a second dielectrophoretic force.   
     
     
         28 . The method of  claim 27 , further comprising:
 using the second dielectrophoretic force generated by changing the Clausius-Mossotti factor by flushing the analyte with a reference solution to release the analyte.   
     
     
         29 . The method of  claim 27 , further comprising adjusting pH and/or conductivity of the test sample to control voltage and/or frequency dependence of a cross-over frequency of the Clausius-Mossotti factor. 
     
     
         30 . The method of  claim 27 , further comprising changing a cross-over frequency of the Clausius-Mossotti factor for the analyte by adding or mixing an additional fluid. 
     
     
         31 . The method of  claim 27 , further comprising tuning the electric field to isolate the analyte by the first dielectrophoretic force. 
     
     
         32 . The method of  claim 16 , wherein separating the analyte from other components of the test sample further comprises:
 using a microfluidic assembly having the at least one microfluidic channel, wherein the at least one microfluidic channel comprises:
 electrodes configured to generate dielectrophoretic forces that act on the test sample to separate the analyte from at least one waste product; and 
 at least one microchannel configured to receive the at least one waste product and separate the analyte from the at least one waste product; 
   transporting the analyte to a condensing region; and   localizing the analyte at the condensing region by a condenser electrode.   
     
     
         33 . The method of  claim 16 , wherein detecting the analyte further comprises using an electric field configured to generate flow conditions that act to immobilize the analyte on a surface of the sensor. 
     
     
         34 . The method of  claim 33 , further comprising detecting the analyte immobilized on the surface of the sensor with the sensor. 
     
     
         35 . The method of  claim 16 , wherein a surface of the microfluidic sensor is a nanowire sensor surface or nanoribbon sensor surface. 
     
     
         36 . The method of  claim 16 , wherein separating the analyte from other components of the test sample further comprises adjusting at least one feature of the dielectrophoretic forces to maximize separation of the analyte from at least one other component of the test sample. 
     
     
         37 . The method of  claim 36 , wherein the at least one feature includes a frequency component of the electric field inducing the dielectrophoretic forces. 
     
     
         38 . The method of  claim 36 , wherein the at least one feature includes a waveform shape of the electric field inducing the dielectrophoretic forces. 
     
     
         39 . The method of  claim 36 , wherein the at least one feature includes a flow to achieve separation using the dielectrophoretic forces. 
     
     
         40 . The method of  claim 16 , wherein separating the analyte from the other components of the test sample further comprises adjusting an amplitude component of an electric field inducing the dielectrophoretic forces that act on the sample. 
     
     
         41 . The method of  claim 16 , wherein the dielectrophoretic forces include at least two opposing forces.