WO1997011521A1

WO1997011521A1 - Electromagnetic pump

Info

Publication number: WO1997011521A1
Application number: PCT/EP1996/004089
Authority: WO
Inventors: Juan Pedro De Zoeten; Eduard Gerard Marie Pelssers
Original assignee: Akzo Nobel N.V.
Priority date: 1995-09-22
Filing date: 1996-09-17
Publication date: 1997-03-27
Also published as: AU7130896A

Abstract

An electromagnetic pump for transport of liquid is described which comprises junctions for supply and discharge of the liquid and a channel connecting said supply and discharge junctions. Transport of liquid is achieved by applying a magnetic field perpendicular to the channel, and by applying an electrical field perpendicular to the channel and to the magnetic field.

Description

Electromagnetic pump

The invention relates to an electromagnetic pump for use in an assay-device to transport liquid in said device, comprising junctions for supply and discharge of the liquid and a channel connecting said supply and discharge junctions, and further comprising at least two electrodes, one electrode positioned on one side of the channel and the other electrode positioned on the opposite side thereof, which electrodes are electrically connected to the liquid in the channel and means to apply a magnetic field substantially perpendicular to the channel and substantially perpendicular to the electrical field generated by means of the electrodes so as to cause the liquid in the channel to be forcibly driven in a pre¬ determined direction depending on the orientation of said magnetic and said electrical field.

US-4767953 describes an electromagnetic pump for transport of liquid by conversion of electrical and electromagnetic energy into kinetic energy of the liquid to be transported. This publication specificly concerns the discharge of gas generated from the electrodes to the outside of the pump without releasing the gas into the electrically conducting liquid, by application of electrodes made of a hydrophobic porous carrier with a limited pore size. A porous membrane is applied on one side of the electrode or placed in front of the electrode in order to define a path-way for the electrically conductive liquid. The pump according to US-4767953 is particularly suited for application with sea water as the conductive fluid. The invention aims to provide an electromagnetic pump for use in an assay-device suitable for transport of bodily fluids, such as the device according to co-pending application number PCT/EP96/03380. The object of the invention is to avoid that the gas that develops at the electrode surfaces enters the channel through which the liquid is transported so as to secure the diagnostic accuracy and proper operation of the assay-device. The electromagnetic pump according to the invention is to that end characterized in that the electrodes project into chambers that are provided on opposite sides of the channel, which chambers are filled with chamber-liquid which is electrically connected to the liquid in the channel, and that it includes one or more membranes separating the channel from the chambers, which membrane or membranes are permeable for electrically charged ions from the chamber-liquid and provide a high flow resistance for the liquid in the channel and the chambers.

This allows the application of regular electrodes without specific properties other than their suitability to conduct electricity, which is realised by the application of seperate chambers housing the electrodes avoiding direct placement of said electrodes in the channel and consequently avoiding direct contact of the electrodes with the electrically conducting liquid in said channel. Preferably the chambers of the pump according to the invention are provided with gas vents suited for discharge of the airbubbles that may originate from the electrodes provided in the respective chambers when the pump is in use.

In a certain aspect of the invention the channel of the electromagnetic pump is a capillary. This makes the pump particularly suited for application in the above¬ mentioned assay devices.

The electromagnetic pump according to the invention shall now further be described with reference to the drawings, in which fig. 1 shows in top view a cross-sectional area of the electromagnetic pump, according to the line A-A in fig. 2; fig. 2 shows a cross section of the electromagnetic pump according to the invention according to line B-B in fig. 1. In the figures same reference numbers refer to the same parts.

Fig. 1 and 2 show the electromagnetic pump according to the invention whereby a liquid 22 in a channel 21 is transported in the direction of arrow 33. The electromagnetic pump comprises on its upper and lower side opposite poles (north and south poles) 32 and 31 of magnets giving a magnetic field essentially perpendicular to the channel 21. The pump further comprises electrodes 25, 26, whereby one electrode 25 is positioned on one side of the channel 21 and the other electrode 26 is positioned on the opposite side thereof, providing an electrical field through the channel 21 whereby said electrical field and said magnetic field jointly provide a driving force for the liquid 22 in the channel 21. In the case where the north pole 32 is provided on the upper part of the channel

21 and a south pole 31 is provided on the lower part of channel 21, the electrical field lines need to originate at electrode 26 and arrive at electrode 25 in order to have the liquid 22 flow in the direction of the arrow 33.

The electrodes 25, 26 project into chambers 27, 28 which are located on opposite sides of the channel 21.

Said chambers 27, 28 are filled with a chamber-liquid being in electrical contact with the liquid 22 in the channel 21. By application of membranes 29, 30 the liquid

22 in the channel 21 is separated from the chamber liquid in the chambers 27, 28. Said membranes 29, 30 allow for passage of ions and provide a high flow resistance for the liquid 22 in the channel 21 and the chambers 27, 28. Each of the chambers 27, 28 may be provided with gas vents 34, 35 allowing for disposal of gas bubbles when the electromagnetic pump is in use. The electrical field is applied by supplying an appropriate voltage at the connectors 23, 24 which are in electrical contact with the electrodes 25, 26. EXAMPLES

Typically the magnets of the pump according to the invention may have a reminiscence of about 1 Tesla. For instance, the Neodynium magnets as delivered by Walker Hagou B.V. (the Netherlands) can be used. The space between the poles of the magnets can be between 50 μm to 5 cm but preferably between 100 μm and 8 mm. In the examples below this space is 4 mm. Since the magnetic field of these static magnets is not uniform, the average value of the magnetic field between a north and a south pole separated by a distance of 4 mm was measured to be 0.33 Tesla. Depending on the application format the voltage has to be set to a certain value, normally in the range 1-200 Volts. At high voltage values cooling may be necessary. Example 1. Closed conduit completely filled with liquid In this example channel 21 is extended to form a closed loop with a cross section of 8 mm by 1 mm and a length of 10 cm. The liquid in the chambers 27, 28 and in channel 21 is a saline solution. When a voltage is applied between the electrodes 25 and 26 of about 10 Volts, a flux in channel 21 can be achieved of 50 μl/s. The amount of energy to displace the liquid is about 0.006 Joule per microliter.

Example 2. Open circuit

In this case channel 21 is on one side connected to a vertically positioned cylindrical chamber with a diameter of 10 mm. The channel 21, with a cross section of 8 mm by 1 mm, is extended to a length of 10 cm by adding a small vertical section and subsequently again a second horizontal section. All chambers are filled with a saline solution to such a level that the liquid level in channel 21 is 5 mm below the second horizontal section when no voltage is applied to the electrodes 25, 26. When a voltage of about 100 Volts is applied between the electrodes 25 and 26, at least a flux of 50 μl/s can be achieved in channel 21 and 0,6 Joule is dissipated for pumping at least 1 μl.

Claims

CM_H8

1. Electromagnetic pump for use in an assay-device to transport liquid in said device, comprising junctions for supply and discharge of the liquid and a channel connecting said supply and discharge junctions, and further comprising at least two electrodes (25, 26), one electrode (25) positioned on one side of the channel (21) and the other electrode (26) positioned on the opposite side thereof, which electrodes are electrically connected to the liquid (22) in the channel (21) and means to apply a magnetic field substantially perpendicular to the channel (21) and substantially perpendicular to the electrical field generated by means of the electrodes so as to cause the liquid in the channel (21) to be forcibly driven in a predetermined direction (33) depending on the orientation of said magnetic and said electrical field, characterised in that the electrodes (25, 26) project into chambers (27, 28) that are provided on opposite sides of the channel (21), which chambers (27, 28) are filled with chamber-liquid which is electrically connected to the liquid (22) in the channel (21), and that it includes one or more membranes (29, 30) separating the channel (21) from the chambers (27, 28), which membrane or membranes are permeable for electrically charged ions from the chamber-liquid and provide a high flow resistance for the liquid (22) in the channel (21) and the chambers (27, 28).

2. Electromagnetic pump according to claim l, characterized in that the chambers (27, 28) are provided with gas-vents (34, 35).

3. Electromagnetic pump according to claim 1 or 2, wherein the channel (21) is a capillary.