Sensor for detecting a liquid in a fluid channel

Patent metadata

Field	Value
Publication number	US-10156537-B2
Application number	US-201515326171-A
Country	US
Kind code	B2
Filing date	Jul 16, 2015
Priority date	Jul 18, 2014
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

A sensor for detecting a liquid in a fluid channel of a microfluidic component and to a microfluidic component having such a sensor. The sensor includes an electrode arrangement having a transmitting electrode, a receiving electrode and a first shielding electrode, which are arranged in a coplanar manner on a plane and can be positioned above or below, adjacent to the fluid channel, wherein the transmitting electrode and the receiving electrode are capacitively coupled in that they each have an adjacently arranged edge having a dielectric therebetween. A method for detecting a liquid in a fluid channel of a microfluidic component having the steps: applying an alternating voltage to the transmitting electrode, coupling the alternating voltage into the receiving electrode, tapping an alternating current or alternating voltage signal on the receiving electrode, extracting extreme values from the tapped alternating current or alternating voltage signal, and assigning the extreme values to the position of a liquid front.

First claim

What is claimed is:

1. A sensor for detecting a liquid in a fluid channel of a microfluidic component, comprising: an electrode arrangement having a transmitting electrode, a receiving electrode and a first shielding electrode, which are arranged in a coplanar manner on a plane and can be positioned parallel to the fluid channel and above or below adjacent to the fluid channel, wherein no shielding is provided between the transmitting electrode and the receiving electrode so that they each have an adjacently arranged edge with a dielectric located therebetween and so that they are directly capacitively coupled.

2. The sensor according to claim 1 , wherein the adjacently arranged edges run parallel.

3. The sensor according to claim 1 , wherein the first shielding electrode is capacitively coupled to the transmitting electrode or to the receiving electrode or to the transmitting electrode and the receiving electrode.

4. The sensor according to claim 1 , wherein the first shielding electrode is arranged adjacent to the transmitting electrode or to the receiving electrode or to the transmitting electrode and the receiving electrode.

5. The sensor according to claim 4 , wherein the first shielding electrode has at least two sections, of which, as viewed in a direction in the plane, a first section is arranged in front of and a second section is arranged behind the transmitting electrode and the receiving electrode.

6. The sensor according to claim 1 , wherein the first shielding electrode at least partially frames the transmitting electrode and the receiving electrode in the plane.

7. The sensor according to claim 1 , wherein the first shielding electrode is grounded.

8. The sensor according to claim 1 , having a signal source, which is connected to the transmitting electrode, and a signal pickup, which is connected to the receiving electrode.

9. The sensor according to claim 8 , wherein the signal source is an alternating voltage source.

10. The sensor according to claim 8 , wherein the signal pickup is designed to detect a curve of an alternating current signal or alternating voltage signal over time.

11. The sensor according to claim 10 , wherein the signal pickup is designed to extract at least one extreme value from the alternating current signal or alternating voltage signal and to output said extreme value(s).

12. The sensor according to claim 1 , wherein the electrode arrangement has a second shielding electrode arranged parallel to and at a distance from the plane.

13. The sensor according to claim 12 , wherein the second shielding electrode is grounded.

14. A microfluidic component having a surface and a fluid channel running in an interior of the component, substantially parallel to the surface, including a sensor according to claim 1 , wherein the transmitting electrode, receiving electrode and first shielding electrode of which are arranged in a coplanar manner on the surface and above or below adjacent to the fluid channel.

15. The microfluidic component according to claim 14 , wherein the transmitting electrode and the receiving electrode each have an adjacently arranged edge with a dielectric located therebetween, and the adjacently arranged edges are oriented substantially perpendicular to the fluid channel.

16. The microfluidic component according claim 14 , wherein the first shielding electrode is arranged adjacent to the transmitting electrode or to the receiving electrode or to the transmitting electrode and the receiving electrode and spans the fluid channel at least once.

17. The microfluidic component according to claim 14 , wherein the first shielding electrode has at least two sections, of which, as viewed in each case in the direction of the fluid channel, a first section is arranged in front of and a second section is arranged behind the transmitting electrode and the receiving electrode.

18. The microfluidic component according to claim 14 , wherein the transmitting electrode, receiving electrode and first shielding electrode of the electrode arrangement are arranged at a distance of 500 μm or less, or 100 μm or less, from the fluid channel.

19. The microfluidic component according to claim 14 , wherein the electrode arrangement has a second shielding electrode arranged parallel to and at a distance from the surface.

20. A method for detecting a liquid in a fluid channel of a microfluidic component by an electrode arrangement having a transmitting electrode, a receiving electrode and a first shielding electrode, which are arranged in a coplanar manner on a plane substantially parallel to the fluid channel and above or below adjacent to the fluid channel, wherein no shielding is provided between the transmitting electrode and the receiving electrode so that they each have an adjacently arranged edge with a dielectric located therebetween, said method comprising the steps:
applying an alternating voltage to the transmitting electrode,
directly coupling the alternating voltage into the receiving electrode,
tapping an alternating current signal or alternating voltage signal on the receiving electrode,
extracting extreme values from the tapped alternating current signal or alternating voltage signal,
assigning the extreme values to the position of a liquid front.

21. The method according to claim 20 , wherein the first shielding electrode has at least two sections, of which, as viewed in each case in the direction of the fluid channel, a first section is arranged in front of and a second section is arranged behind the transmitting electrode and the receiving electrode, and in that a speed of the liquid front is derived from at least two temporally successive extreme values.

22. The method according to claim 20 , wherein the microfluidic component is positioned with a surface, which runs substantially parallel to the fluid channel, adjacent to the electrode arrangement, which is part of an external sensor having an electrode arrangement having a transmitting electrode, a receiving electrode and a first shielding electrode, which are arranged in a coplanar manner on a plane and can be positioned parallel to the fluid channel and above or below adjacent to the fluid channel, wherein the transmitting electrode and the receiving electrode are capacitively coupled in that they each have an adjacently arranged edge with a dielectric located therebetween, in an operator device.

23. The method according to claim 20 , wherein the transmitting electrode and the receiving electrode each have an adjacently arranged edge with a dielectric located therebetween, and the adjacently arranged edges are positioned substantially perpendicular to the fluid channel.

Assignees

• Fraunhofer Ges Forschung

Inventors

• Hoffmann Almuth
• Bassler Michael
• Potje-Kamloth Karin
• Welzel Knut
• Besold Matthias

Classifications

• B01L3/5027

  by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip · CPC title

• B01L2300/0645

  Electrodes · CPC title

• G01N27/221 Primary

  by investigating the dielectric properties (using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26) · CPC title

• B01L2300/0663

  Whole sensors · CPC title

• G01N30/64

  Electrical detectors · CPC title