Microbial Cell and Particle Control

Abstract

The invention comprises two key components: dielectrophoresis (DEP) and reversible binding surfaces. DEP has become an important tool for trapping dielectric particles. Moreover, DEP can manipulate cell movement as dictated by the intrinsic dielectric constant of the cell without modification. DEP therefore provides a mechanism by which to force targets in a flow channel to a reversible binding surface. By building selectivity into the binding surface, the capacity to choose which targets can be held after the dielectric field is turned off, providing a separation strategy that does not suffer from fouling issues, as large foulants can freely pass over the surface through the flow channel.

1 . Control of microbial cells by forcing targets in a flow channel by dielectrophoresis to a reversible binding surface.  
     
     
         2 . The method of  claim 1  further comprising the step of adjusting flow velocity according to a preselected value.  
     
     
         3 . The method of  claim 2  wherein the flow velocity is between 0.5 and 2 centimeters per second.  
     
     
         4 . The method of  claim 2  wherein the flow velocity is adjusted to achieve laminar flow conditions.  
     
     
         5 . The method of  claim 1  further comprising the step of adjusting temperature of the targets to a preselected value.  
     
     
         6 . The method of  claim 5  wherein the temperature is adjusted to between 22° C. and 38° C.  
     
     
         7 . The method of  claim 1  further comprising the step of adjusting temperature and flow velocity in the flow channel according to preselected values.  
     
     
         8 . The method of  claim 7  further comprising the step of subjecting an array of known microbial cell types to a plurality of temperatures and flow velocities, establishing an optimum temperature and flow velocity for each known microbial cell type, and selectively separating a target microbial cell type from an unknown sample by subjecting the sample to the corresponding optimum temperature and flow velocity for the target microbial cell type.  
     
     
         9 . The method of  claim 1  wherein the reversible binding surface is fabricated from a lower critical solution temperature polymer.  
     
     
         10 . The method of  claim 1  wherein the polymer is N-Isopropylacryaminde.  
     
     
         11 . The method of  claim 1  further comprising the step of patterning size-exclusion trenches into the binding surface.  
     
     
         12 . Size-exclusion based separation of a bin of particle sizes wherein high aspect ratio monoliths are patterned in series to form a polymer trench network of trenches.  
     
     
         13 . The method of  claim 12  wherein the trench network is opened and closed by thermal adjustment.  
     
     
         14 . The method of  claim 13  wherein thermal adjustment is achieved by applying temperatures of about 38° C. for opening the trench network and about 22° C. for closing the trench network.  
     
     
         15 . The method of  claim 12  wherein dielectrophoresis is used to move particles to a surface of the trench network.  
     
     
         16 . The method of  claim 12  wherein spacing of the series of high aspect ratio monoliths produce a tunable gap which provides a lower-scale separation parameter making separation capabilities analogous to a band-pass filter.  
     
     
         17 . The method of  claim 12  wherein reversal of the dielectrophoresis field after trench network closing results in the removal and exclusion of the lower-scale particles which have previously been entrapped.