Methods and devices for electronic sensing

• US 8,845,914 B2
• Filed: 05/14/2013
• Issued: 09/30/2014
• Est. Priority Date: 10/26/2001
• Status: Expired due to Fees

• Current Assignee: Fluidigm Corporation
• Original Assignee: Fluidigm Corporation
• Inventors: Nassef, Hany, Facer, Geoffrey Richard, Unger, Marc
• Primary Examiner(s): Tran, Binh X
• Application Number:
  US13/894,296
• Publication Number:
  US 20130252234A1
• Time in Patent Office: 504 Days
• Field of Search: 216/84, 216/86, 324/71.1, 422/82.01, 422/82.02, 436/180
• US Class Current: 216/84
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/123 Flexible; Elastomeric
• CPC Class Codes: B01L 2400/0481 squeezing of channels or chambers
• CPC Class Codes: B01L 2400/0655 pinch valves
• CPC Class Codes: B01L 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• CPC Class Codes: C03C 25/68 by etching
• CPC Class Codes: G01N 15/1031 by measuring electrical or magnetic effects
• CPC Class Codes: G01N 15/12 by observing changes in resistance or impedance across apertures when traversed by individual particles, e.g. by using the Coulter principle
• CPC Class Codes: G01N 2015/1029 Particle size
• CPC Class Codes: G01N 27/00 Investigating or analysing materials by the use of electric, electrochemical, or magnetic means G01N3/00 – G01N25/00 take precedence; measurement or testing of electric or magnetic variables or of electric or magnetic properties of materials G01R
• CPC Class Codes: G01N 27/60 by investigating electrostatic variables , e.g. electrographic flaw testing G01N27/007 takes precedence
• CPC Class Codes: G01N 33/48707 by electrical means G01N33/49, G01N33/493 take precedence
• CPC Class Codes: G01N 33/48721 Investigating individual macromolecules, e.g. by translocation through nanopores Coulter counters in general G01N15/12; fabrication methods for nanoscale apertures B81B1/00; sequencing of nucleic acids C12Q1/68
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

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.

Claims

1. A method of detecting entities of a selected entity type in a microfabricated structure, wherein the entity type is selected from bacterial cells, mammalian cells, viral particles, macromolecules, and ensembles of macromolecules, the method comprising:

(a) providing a microfabricated structure comprising a plurality of flow channels each having a detection volume with selected physical dimensions and width;

(b) applying an electric field across the detection volume;

(c) flowing a fluid containing a plurality of entities of the selected entity type through the detection volume at a selected flow rate;

(d) measuring a change in current and/or voltage of the applied electric field resulting from one of the entities in the fluid passing through and past the detection volume; and

(e) correlating the change(s) with the presence of an entity of the selected entity type within the flow channel,

wherein the method comprises selecting a microfabricated structure having the physical dimensions and width of the detection volume specified in step (a), in conjunction with a flow rate of the fluid through the detection volume specified in step (c), such that the combination of the physical dimensions and width of the flow channel and the flow rate result in only one entity of the selected entity type passing through the detection volume at a time.

2. The method of claim 1, wherein the flow channels have a width between 5 and 500 microns.

3. The method of claim 1, wherein the selected entity type are between 1 and 100 microns in size.

4. The method of claim 1, wherein the microfluidic flow channels are formed in an elastomeric material.

5. The method of claim 1, wherein the device is configured to sort macromolecules detected by the sensing electrodes.

6. The method of claim 1 wherein changes in the current and/or voltage are detected by electrodes positioned before and after the detection volume.

7. The method of claim 6, wherein the same electrodes are used to apply the electric field and to detect the change in voltage and/or current across the detection volume.

8. The method of claim 6, wherein different electrodes are used to apply the electric field and to detect the change in voltage and/or current across the detection volume.

9. The method of claim 6, wherein the electrodes are in communication with a DC power supply such that a constant electric field is applied along the detection volume.

10. The method of claim 1, wherein the entity is a macromolecule.

11. The method of claim 10, wherein the macromolecule is a nucleic acid.

12. The method of claim 10, wherein the macromolecule is a protein.

13. The method of claim 1, wherein the entity is an ensemble of macromolecules.

14. The method of claim 13, wherein the ensemble comprises nucleic acids.

15. The method of claim 13, wherein the ensemble comprises proteins.

16. A method of detecting macromolecules in a microfabricated structure, the method comprising:

(a) providing a microfabricated structure comprising flow channels each having a detection volume with predetermined physical dimensions and width;

(b) applying an electric field across the detection volume;

(c) flowing a fluid containing the macromolecules through the detection volume at a selected flow rate;

(d) measuring a change in current of the applied electric field resulting from a macromolecule passing through and past the detection volume; and

(e) correlating the change in current with the presence of a macromolecule within the flow channel,

wherein the method comprises selecting a microfabricated structure having the width of the detection volume specified in step (a), in conjunction with a flow rate of the fluid through the detection volume specified in step (c), such that the combination of the width of the flow channel and the flow rate result in only one of the macromolecules passing through the detection volume at a time.

17. The method of claim 16, wherein changes in the current are detected by electrodes positioned before and after the detection volume.

18. The method of claim 16, wherein different electrodes are used to apply the electric field and to detect the change in current across the detection volume.

19. The method of claim 16, wherein the macromolecule is a nucleic acid.

20. The method of claim 16, wherein the macromolecule is a protein.

21. The method of claim 16, wherein the flow channels have a width between 0.1 and 10 microns.

22. The method of claim 16, wherein the macromolecules are between 0.01 and 1 microns in size.

23. The method of claim 16, wherein the microfluidic flow channels are formed in an elastomeric material.

24. The method of claim 16, wherein the device is configured to sort macromolecules detected by the sensing electrodes.

25. The method of claim 16, wherein changes in the current are detected by electrodes positioned on opposite sides of the detection volume.

26. The method of claim 25, wherein the same electrodes are used to apply the electric field and to detect the change in current across the detection volume.