Automatic Transfer Apparatus

Abstract

Automatic device for delivering a calibrated quantity of a liquid from a first receptacle into a second receptacle by positioning a duct into the liquid to be delivered, aspirating the liquid into the duct for delivery into the second receptacle including control means cooperating with detectors of the position of the duct in the liquid and the aspirating duct.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for the automatic transfer of a given quantity of liquid from a container wherein it is stored to another container and, more particularly, to the analysis of a calibrated quantity of the liquid.

2. Description of the Prior Art

Analyses having a high rate of liquid samples are made by means of automatic analyzing apparatus. The samples generally constitute either the liquid itself or a mixture in specific proportions of the liquid and reagents which are appropriate to the analyses to be carried out.

Thus, many samples have particles in suspension which must not be transferred into an analysis tank, particularly blood samples.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for the automatic transfer of a calibrated quantity of samples, for example blood samples for automatic analysis, while avoiding the contamination of a liquid sample with another and external pollution. The present invention also provides an apparatus for the rapid transfer of a calibrated quantity of samples without taking particles in suspension from a phase known as the sedimented phase of the said sample.

The automatic transfer apparatus has a quantity of liquid sample contained in a first container for transfer to a second container. A first tube has ends adapted to be immersed respectively in the sample and directed to the second container. A second tube is connected to a source of gas under pressure with the free end adapted to penetrate into the said first container. Means for detecting the passage of the liquid sample are provided at a given point of the first tube. The ends of the first and second tubes which penetrate into the first container are fixed to the same support which itself is mobile is translational movement relative to the level of the liquid sample in the first container. The said support is driven in translational movement by both an element for detecting contact between a point of the end of the second tube and the level of the liquid sample, and by the means for detecting the passage of the sample in the second tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a preferred embodiment of the apparatus according to the invention.

FIG. 2 is a perspective view of the driving element of the apparatus shown in FIG. 1.

FIG. 3 is a diagram illustrating the control sequences in time of the element shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 there is illustrated a first container in which is stored a sample which is to be transferred to a second container for the purpose of analysis. The first container 1 is q bottle carrying in ascending order a sedimented sample phase 4, a liquid sample phase 3 to be analyzed and a portion 2 from which air has been partly evacuated. This bottle is hermetically closed by two individual plugs 14 and 15 sealing the enclosure. These plugs are made of a material which can be readily perforated by hollow needles or the like, and advantageously retractable. The bottle is positioned below a needle-carrying element 5 to which two needles 6 and 7 are fixed.

The first ends of the needles 6 and 7 are intended to pierce the plugs 14 and 15 and for this purpose are cut in bevelled form. Advantageously, the portions of the two needles 6 and 7 which are intended to be positioned in the bottle 1 are of unequal length, the corresponding portion of the needle 6 being longer than the corresponding portion of the needle 7 by several millimeters, for example 2 to 3 millimeters.

The needle-carrying element 5 also supports an arm 8 comprising at its end, appropriately positioned, a photoelectric cell 9 excited respectively by light sources 22 arranged vertically at the other side along the bottle and represented diagrammatically. The cell 9 is connected to a photoelectric detector 10. The needle 6 is elbowed in such a manner that its second end is positioned in the second container or bottle forming chamber 18.

Situated in the circuit of the needle 6 between the bottle 1 and the chamber 18, at a distance corresponding to the calibrated volume to be transferred, is a detecting gauge 11, in this case advantageously a conductivity-measuring gauge. This gauge is connected to a conductivity detector 12. This gauge may also be of the photoelectic type. The second end of the needle 7 is connected to a source of air or gas under pressure 19.

Between the two needles 6 and 7 is a device 13 similar to the detector 12, which supplies a signal, the value of which is in accordance with the electrical resistance between the two needles 6 and 7. The detector circuits 12 and 13 are connected electrically to a control unit 16 of actuator 17. The actuator 17 imparts a rectilinear sequential movement to the needle carrier 5.

Before the electrical control signal appears at the control unit 16, the actuator 17 and the needle carrier 5 are in the upper position, the needles are also in the upper position and a bottle 1 is positioned mechanically below the needle carrier 5.

When the control signal occurs, the actuator pushes the needles through the plugs 14 and 15 into the position illustrated in FIG. 1. The needle 6 enters the limpid liquid and a fraction of a second afterwards the needle 7, in its turn, contacts the liquid. The electrical resistance between the needles 6 and 7 which is considerable initially owing to the fact that all the parts in contact with the needles are of an insulating character has its resistance lowered and the detector circuit 13 trips, which sends an electrical signal into the control unit 16, which supplies a signal to the actuator to stop its downward travel. The needles 6 and 7 stop with the needle 6 below the surface level of the liquid and the needle 7 just in contact with the surface. The bevel of the needle 7 permits compressed air to enter the free portion 2 of the bottle without disturbing the surface of the liquid. The pressure established in the free portion pushes the liquid 3 in the needle 6 into the duct. When the liquid under pressure reaches the detecting gauge 11, the conductivity-measuring detector 12 trips and sends a signal to the control unit which operates the actuator in the reverse sense. The needles move upwards again until the needle 6 is above the surface of the liquid 3. At this instant electrical resistance between the two needles again becomes considerable. The circuit 13 again trips and by means of the control unit 16 again stops the upward travel of the actuator. The compressed air within the free space 2 pushes the liquid which has penetrated into the needle 6 towards its other end into container 18. A zeroizing signal represented diagrammatically by the connection 20 is applied to the control unit 16 and operates the actuator upwards, until the needles are situated outside the bottle 1. Another sequence can recommence in the form of a new signal applied to the control unit 16, represented diagrammatically by the connection 21.

In cases where the surface level of the liquid 3 is too low, that is to say the height of the liquid phase 3 is very slight, there is a risk that the needle 6 may inspire sediment 4. For this purpose, the light ray emitted horizontally by the light source 22 does not pass through the sedimented phase 4 to cell 9 and cell 9 is not excited before the stopping sequence of the actuator 17 is completed. Consequently, the operation of the actuator 17 is effected by the cell 9 by way of the detecting element 10 which orders the actuator to move into the upper position again. There is no longer a sample available for analysis, and this can be indicated to the operator by means of a light indicator, for example.

The actuator may comprise either a pneumatic jack operated by rapid-action electromagnetic valves, an electrohydraulic jack, or a step-by-step motor controlling a rack supporting the needle carrier 5 by means of a reduction gear, or any device for transmitting the aforesaid sequential movements. The gear-rack system may advantageously be replaced by a known system of metal blades associated with a system of cylindrical drums, transforming a circular movement into an alternating rectilinear movement.

FIG. 2 shows one such embodiment.

In FIG. 2, a motor 23 which may be of a step-by-step type, drives a drum 25. On this drum there are fixed one end of each flexible blade 26 and 27. The other end of each blade is fixed to a plate 24 which drives the needle carrier 5 and imparts the sequential movements to it.

The aforesaid sequential movements are indicated diagrammatically in FIG. 3 in which the positions of the actuator 17 representing the succession of sequences S are plotted as ordinates and the times t as abscissae.

At the beginning of the sequence, the actuator is in the upper position indicated at the ordinate position P.sub.o. At time A, the arrival of the control signal 21 triggers the sequence and the actuator descends. At time B the actuator is at position P.sub.1, the needle 6 is immersed in the liquid phase 3 of the sample in the bottle 1 and the end of the needle 7 touches the surface of the liquid phase; the liquid can be delivered into the needle 6; the time interval AB corresponds to the descent of the needles into the bottle 1.

At time C the value of the calibrated volume of the sample forced into the tube is reached, the actuator which had been in the position P.sub.1 up to this instant receives from the detector 12 a control signal to move upwards again; the time BC is the calibrating time.

At time D the signal coming from the detector 13 is applied to the actuator which is positioned at P.sub.2, the ends of the needles 6 and 7 are still in the bottle 1 but are no longer in contact with the liquid phase 3 and the calibrated volume of the liquid inspired may be transferred into the chamber 18. The time CD is the time corresponding to that in moving the needles upwards again out of the liquid. At time E the calibrated volume of liquid is entirely transferred into the chamber 18, and the actuator can again be returned to the upper position P.sub.o. At time F the control signal for zeroizing 20 is applied and the actuator is maintained in the upper position P.sub.o until a new identical sequence occurs.

It appears, in the succession of sequences S, that the precision of the calibration may be affected by the time CD. Thus it is possible in order to have a good standard of precision either to act on the gas under pressure, the detector 12 stopping the supply of gas under pressure, or to take the time CD into account in calibration if this is chosen to be constant. The present invention affords many advantages. More particularly, the bottles such as the bottle 1 may constitute a continuous linear chain and be positioned automatically below the needle carrier 5. Likewise the chambers, such as the chamber 2, closed or otherwise, may be chambers comprised by a supporting film. This film may be driven in a step-by-step movement so that the chambers come successively to the position under the corresponding end of the needle 6, this end being also cut in bevelled form so as to pierce through the upper portion of the closed chamber.

The transfer device as described constitutes, therefore, an automatic pipette for transfer of liquid substances which can be provided for a continuous automatic sample-analyzing line.

Furthermore, if external pollution of the samples has been avoided by the fact that transfer is effected from a bottle to a hermetically closed chamber, contamination of one sample with another is also avoided. In fact, the transfer of samples is effected rapidly and successively by means of the needle 6, the samples are forced in at one end and ejected at the other end, and the liquid passes through the needle, which has a smooth internal surface, by being pushed by a strong blast of air and entirely discharged. The apparatus also permits transfer only of the liquid part of the samples with analysis effected solely on a calibrated volume of this liquid part.

Claims

What I claim is:

1. Automatic apparatus for the transfer of a predetermined quantity of a liquid sample contained in a first container to a second container, comprising: a first tube one end portion of which is adapted to be immersed in said sample and the other end portion penetrating said second container, a second tube connected to a source of gas under pressure with its free end portion adapted to penetrate said first container, said one end portion of said first tube being longer than said free end portion of said second tube, first means for detecting the passage of said liquid sample at a given point of said first tube, a common support for fixedly carrying the end portions of said first and second tubes which penetrate said first container, means for translationally moving said support relative to the surface level of said liquid sample in said first container, and means for controlling said translational movement by said first detecting means.

2. The apparatus as claimed in claim 1 further comprising second means for detecting contact between the free end portion of the second tube and the surface level of said liquid sample, and means for further controlling translational movement of said support by said second detecting means.

3. The apparatus as claimed in claim 2 wherein said first and second tube portions penetrating said first container are of unequal length such that the one end of said first tube is situated below the surface level of the liquid sample when the free end of said second tube is substantially flush with said surface,

4. The apparatus as claimed in claim 3 wherein the ends of said first and second tubes which penetrate said first container are bevelled.

5. The apparatus as claimed in claim 2 wherein said second detecting means comprises a conductivity-measuring device electrically connected between said first and second tubes.

6. The apparatus as claimed in claim 2 wherein said liquid sample in said first container has a sedimented phase, and further comprising means for preventing translational movement of said support below a defined lower level corresponding to the passage of the one end of the first tube into the sedimented phase of said sample, thereby to prevent the transfer of sediment from said first container to said second container.

7. The apparatus as claimed in claim 6 wherein said preventing means comprises a photoelectric detector and a light source arranged respectively on opposed sides of said first container, with said photoelectric detector being unenergized by the light source when it is adjacent the sedimented phase of the liquid sample to prevent further downward movement of said tubes with respect to said first container.

8. The apparatus as claimed in claim 7 wherein said photoelectric detector is fixed to said support for translational movement therewith.

9. The apparatus as claimed in claim 8 wherein said translational movement means for said support comprises an actuator operatively coupled thereto.

10. The apparatus as claimed in claim 9 wherein said actuator comprises a driven drum and at least two metal blades each having first ends fixed to the periphery of said drum and wrapped in opposite directions, and second ends fixed to said support for transforming circular movement into rectilinear movement.