Device for Conditioning a Sample of Liquid for Analyzing With Internal Filter

This invention relates to the conditioning of a sample of liquid for analysis. The conditioning takes place in a device which comprises a plurality of calibrated peripheral cells each having two parallel surfaces for optical measurement of the liquid and connected to a central receptacle for receiving the sample, each of the cells being intended for containing a reagent.

The device comprises for each cell, means for conveying the sample from the receptacle to the cell with a view to filling it completely by centrifuging and escape means for the air contained in the cell to the receptacle, the conveying means comprising an inlet orifice in each cell, the escape means comprising an orifice and leading into the receptacle, the orifices being of such a size as to retain the liquid contained in each cell after complete filling thereof.

The device preferably has at least one of the following characteristics.

The means for conveying the sample are constituted for each cell by at least one duct provided in a radial partition which delimits the cell, the duct connecting the central receptacle to the inlet orifice in the vicinity of which it has a constriction which prevents any return of liquid, the inlet orifice leading from the radial partition preferably into the vicinity of the surface of the furthest cell from the axis of rotation.

The duct is substantially L-shaped and has a long radial path.

The duct is substantially T-shaped so as to feed two neighboring cells and has a long radial path.

The duct is delimited by a groove formed in the upper wall of the associated radial partition and by the lower wall of a lid which closes the cells.

The duct is delimited by the upper surface of the associated radial partition and a groove formed in the lower wall of a lid which closes the cells.

Air escape means are constituted for each cell by a simple orifice formed in the wall of the nearest cell to the axis of rotation and whose cross-section, when there is no centrifuging, stops by capillarity the liquid which occupies the cell, the orifice being advantageously formed in the upper zone of the wall.

For each cell, the height of the nearest wall to the axis of rotation is greater than the height of the furthest wall from that axis, with a view to better expulsion of the air contained in the cell.

The central receptacle is delimited by a bottom with a raised peripheral edge and the central part of a lid for closing the cells in which is formed an opening for the sample to be inserted, the central part of the lid preferably being substantially dome shaped, the insertion being formed at the top of the dome.

The bottom of the receptacle has a central zone which is curved with a view to improved centrifuging of the sample.

The bottom of the receptacle has a few radial ribs which draw away the liquid during centrifuging.

The present invention aims to improve the previous device so that it can analyze liquids which contain solid particles in suspension. These liquids are, for example, blood, waste water, etc.

The present invention provides a device embodiying the parent application, intended to analyze a sample of liquid which contains solid particles in suspension and comprising between the central receptacle and the calibrated peripheral cells, a filter capable of retaining the solid particles during centrifuging.

By way of example, the filter is a filtering gel, a cellulosic ester or asbestos.

According to a preferred embodiment, the filter is in the form of a cylindrical cartridge defining the lateral walls of the central receptacle.

In another embodiment of the invention, the filter is disposed in ducts connecting the central receptacle to the inlet orifices associated with the peripheral cells.

Other characteristics and advantages of the invention will become more clearly apparent from the following description, given by way of illustration but having no limiting character with reference to the figures of the accompanying drawings.

FIG. 1 is a top view of a conditioning device embodying the invention and whose lid has been partially cut away.

FIG. 2 is a cross-section along line II-II of FIG. 1.

FIG. 3 is an exploded perspective view, partially cut away, of the device in another embodiment of the invention.

FIG. 4 is a vertical cross-section of an alternate embodiment of the present invention.

Like elements bear like numerals in the various embodiments.

The device in both illustrated embodiments has symmetry of revolution about an axis 7. It is constituted by a plastics housing delimited by a bottom 15 and a lid (13 or 14 corresponding respectively to the variants of FIG. 1 and of FIG. 3. Internally, the housing includes a plurality of calibrated peripheral cells 1 each containing a reagent (not shown) deposited, for example, in the form of a lyophilized film. It also includes a compartment 2 divided by a filter 20 in cartridge form defining with the bottom 15 and the lids 13 and 14 a central receptacle 21 for the liquid to be analyzed. This liquid contains a solid substance in suspension. The porosity of the material of the filter 20 is chosen so as to stop the solid substance during centrifuging around the axis 7. Radial ribs 22 integral with the bottom 15 are provided inside the cartridge filter 20 so as to draw off the liquid during centrifuging.

As in the device of the parent application, the device includes means for conveying the filtered liquid from the receptacle 2 to each cell and air escape means to enable the air contained in each cell to escape to the compartment 2. The conveying means are constituted for each cell by at least one duct 8 formed in a radial partition 9 which delimits the cell, the duct connecting the central receptacle 2 by an input orifice 10 to the cell through the inlet orifice 5 in the vicinity ofwhich it has a contriction which prevents any return of liquid. The air escape means are constituted by a simple orifice 6 formed in the wall 11 of the nearest cell to the axis of rotation and whose cross-section, when there is no centrifuging, stops by capillarity the liquid which occupies the cell.

The sample of liquid to be analyzed is inserted through a central opening 4 in the cover 13 or 14. It is rapidly centrifuged and guided in particular by ribs 22, against the cartridge filter 20 which filters it. Since centrifuging is continued, the filtered liquid is pushed strongly against the orifices 6 and 10. As stated in the main patent, the portion of the liquid which passes through the orifice 10 is canalized by the duct 8 up to the capillary end of the latter and to the inlet orifice 5. The input pressure at 5 is constantly greater than the input pressure at 6 because of the centrifugal force and because of its being further from the axis of rotation, so that the air contained in the cell is pushed by the liquid and escapes at 6. Filling continues until the air has completely escaped and balances the pressure on either side of the wall 11, as there is provided a sufficient quantity of sample for a portion thereof to be applied permanently against the wall 11, even when the cell is completely filled. During the whole filling and until the end of filling, any portion of liquid which has entered a cell cannot leave it because of the centrifugal force and when centrifuging ceases, the liquid which completely occupies the cell is retained between the orifices 5, 6 which thus form genuine gauge points defining a calibrated volume.

Reference to the vertical sectional view of FIG. 4 of an alternate embodiment in which common elements bear common numerical designation, the filter 20' in this case is not in the form of a cylindrical cartridge. In this case, the filter which may constitute a filtering gel, cellulosic ester or asbestos, fills the radial portion of duct 8. Alternatively, it may lie within duct 8 but extend only along a portion of that duct or comprise an annular element overlying the inlet orifices 10 at the entry end of duct 8.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.