Method and devices for electronic sensing

Abstract

The presence of a detectable entity within a detection volume of a microfabricated elastomeric structure is sensed through a change in the electrical or magnetic environment of the detection volume. In embodiments utilizing electronic detection, an electric field is applied to the detection volume and a change in impedance, current, or combined impedance and current due to the presence of the detectable entity is measured. In embodiments utilizing magnetic detection, the magnetic properties of a magnetized detected entity alter the magnetic field of the detection volume. This changed magnetic field induces a current which can reveal the detectable entity. The change in resistance of a magnetoresistive element may also reveal the passage of a magnetized detectable entity.

1 . An apparatus configured for determining macromolecules of a certain size range, comprising:
 (1) a microfabricated device that includes:
 (a) a plurality of flow channels, each having a detection volume that is configured with physical dimensions and a width such that at a preselected flow rate, only one macromolecule within the size range will pass through the detection volume at a time; 
 (b) source electrodes positioned and configured to apply an electric field across the detection volume of the flow channels; 
 (c) sensing electrodes positioned and configured to detect a change in current of the applied electric field resulting form macromolecules within the size range passing through and past the detection volume of the flow channels; and 
   (2) a flow regulation system that is connected and regulated so as to cause macromolecules within the size range to pass through the detection volume of the flow channels at the preselected flow rate.   
     
     
         2 . The apparatus of  claim 1 , wherein changes in the current are detected by electrodes positioned before and after the detection volume. 
     
     
         3 . The apparatus of  claim 1 , wherein the electrodes configured to apply the electric field are the same as the electrodes configured to detect a change in the current. 
     
     
         4 . The apparatus of  claim 1 , wherein the electrodes configured to apply the electric field are different from the electrodes configured to detect a change in the current. 
     
     
         5 . The apparatus of  claim 1 , further comprising a DC power supply electrically connected to the source electrodes so as to apply the electric field to the detection volume. 
     
     
         6 . The apparatus of  claim 1 , wherein the flow regulation system comprises a peristaltic pump that contains a plurality of single addressable valves situated along the flow channels in the microfabricated device. 
     
     
         7 . The apparatus of  claim 1 , wherein the flow regulation system comprises a compressor or piston that is external to the microfabricated device and is connected thereto so as to apply regulated pressure to the flow channels. 
     
     
         8 . The apparatus of  claim 1 , wherein the macromolecules within the size range are nucleic acids. 
     
     
         9 . The apparatus of  claim 1 , wherein the macromolecules within the size range are proteins. 
     
     
         10 . The apparatus of  claim 1 , configured for determining ensembles of macromolecules. 
     
     
         11 . The apparatus of  claim 1 , configured for determining ensembles of nucleic acids. 
     
     
         12 . The apparatus of  claim 1 , configured for determining ensembles of proteins.