GB2082185A - Liquid-circulation apparatus - Google Patents

Abstract

There is provided a liquid circulator apparatus having an elongated rectangular tray rocking about an axis which is at an angle of from 5 to 45 DEG to the major axis of the tray. The tray has longitudinal and transverse channels, and locating means for locating such bodies in circulating liquid in said channels. Self acting rocking means rock the tray at a frequency of about 25 cycles per minute, and the tray is arranged to be detachable from the rest of the apparatus. The tray may include a liquid reservoir in communication with the said channels; and liquid changing means may be provided, for changing the liquid in the tray automatically during use.

Description

SPECIFICATION Improvements in or relating to liquid-circulator apparatus This invention relates to liquid-circulator apparatus, for use more especially in the coating of objects, usually of plastics substance, with for example, biological active material, which may be an antiserum fraction; and subsequent washing of such objects. Such objects are commonly referred to as plastics forms.

Certain chemical substances, such as the globulin fraction of antiserum against alphafetoprotein, may be adsorbed, or covalently bonded onto forms of plastics substances such as polystyrene. This is utilised in the determination, for example, of the concentration of alphafetoprotein in human blood serum. Until now, the chemical and the plastics forms onto which it is to be adsorbed, or covalently bonded, have been brought into contact with each other manually.

Two kinds of manual procedures have been used.

In one procedure a plastics solid form is dipped or immersed in a solution of the required chemical. In the other procedure a tube-like container made of the plastics material is coated by filling with the solution of the chemical and then emptying. The coated plastics form, either solid or tube-like, is then used to determine the concentration of an analyte in a sample. Each stage requires a manual transfer which is time consuming, lacking in precision, is expensive, and can raise problems of maintaining patient identity with samples.

The present invention provides means for coating and/or washing objects such as plastics forms, of the kind above mentioned, and thereby avoiding, at least in part, the imprecision which has formerly been involved in such coating and washing procedures.

According to the invention, liquid-circulator apparatus has a liquid container tray and means for rocking said tray about a first axis; said tray being of substantially rectangular shape with the major axis of said rectangular shape at an angle to said first axis, said angle being between 50 and 450, preferably 100 and 250; said tray having longitudinal channels substantially parallel with said major axis and transverse channels connecting said longitudinal channels; and said tray having locating means for locating objects in at least some of said channels so that said objects can be contacted in use, by liquid in said channels.

Preferably the apparatus has self acting rocking means for rocking the liquid container tray about the first axis; and the rocking means are desirably arranged for rocking said tray at a frequency in the range of about 5 to about 50 cycles per minute.

The said tray is preferably detachable from the rocking means.

Preferably the locating means are arranged so that a support means for said objects can be located only in a designated liquid circulator apparatus.

Optionally the tray is arranged to include a liquid reservoir communicating with the said channels in the tray for liquid flow between reservoir and channels.

Liquid changing means may be provided to change automatically, in use, the liquid contents of the liquid container tray, either directly or through the liquid reservoir.

The invention will be further described, by way of example only, with reference to the accompanying drawings in which Fig. 1 is an elevation of the liquid circulator apparatus, partly in section.

Fig. 2 is an end view, corresponding with Fig. 1.

Fig. 3 is a diagrammatic illustration of how the liquid container tray is arranged in relation to the first axis i.e. the axis about which said tray is made to rock.

Figs. 4A and 4B illustrate diagrammatically typical liquid flows through channels in said tray.

Figs. 5A and 5B are diagrammatic illustrations of a tray including a liquid reservoir.

Referring first to Fig. 1 , the liquid container tray is indicated by 10. The tray 10 is made so as to have a number of longitudinal and transverse connecting channels. The longitudinal channels are referenced 12, and the transverse channels 14, and are also indicated in Figs. 2 and 3. The tray 10 is attached, by thumbscrews 16, to rocking means indicated generally by 1 8, whereby the tray can be rocked about a first axis 20. The rocking means includes end plates 22, 24: there are supported by bearings 26, 28 on a base plate 30, the bearings being both on the said first axis 20. The rocking means is rendered self-acting by the use of an electric motor 32 fixed to base plate 30 and driving through a reduction gear 34 to a shaft 36. The shaft 36 carries an eccentrically mounted roller 38 which works in a slot 40 in a plate 42.The plate 42 is attached to end plate 24 to that rotation of the shaft 36 rocks the tray 10.

The motor is switched on or off in conventional manner by the switch 44, the electrical connections not being shown. The tray 10 is provided with a plurality of locating means 46, the height of which above the tray can be adjusted by studs 48 and coacting nuts 50. The locating means 46 locate plates 52, two locating means to a plate. Each plate supports, through supporting means indicated diagrammatically by 54, a number of objects exemplified by the sphere 56, so that such objects are located and exposed to the action of any liquid 581n the channels of the tray 10. The object 56 may be a plastics solid form, as mentioned above, for use in biochemical tests. The locating means 46 are in the form of pegs which mate with apertures in the plates 52.

To assist in the maintenance of patient identity the pegs and apertures are made with complementary and characteristic cross sections, preferably nonsymmetrical so that a plate 46 with its supported objects 56 can be associated only with a designated tray 10 and its liquid contents.

It is a characteristic of the liquid circulator apparatus that the major axis 60 of the tray 10 (See Fig. 3) is arranged at an angle to the first axis 20 about which the tray rocks. In a plan view, as indicated in Fig. 3, when the tray is in its mid position, i.e. when it is level, the projected angle between the said axes is, in this embodiment of the invention, 150. The reason for arranging this angle between the two axes is that when the tray is rocked, a favourable circulation of the liquid in the channels of the tray is set up. The circulation will be described with reference to Figs. 4A and 4B. Let it first be assumed that the tray is rocked to a position in which the area A is in a low position and area B therefore high. Most of the liquid will then be in area A.If the tray is now rocked so that B is low and A high, the liquid in the tray will run as indicated by the arrows in Fig. 4A.

When B is subsequently again rocked to a high position, the liquid flow will be as shown in Fig.

4B. The distance the liquid moves per cycle of rocking, before its flow reverses, depends on the frequency and amplitude of rocking. The frequency may be chosen to allow the liquid to run the full length of the channels. In these conditions, each object such as 56 is washed or coated by the liquid, but the liquid contents of the tray are exchanged as between the ends of the tray. This tends towards the avoidance of any localised areas of high or low degree of coating of objects from the liquid, or of excessive or inadequate washing by the liquid. The circulation by the combined arrangement of channels and rocking of the tray provides thorough mixing of the liquid.

A tray 10, having channels as described, has advantages over a tray not provided with channels. In a tray of the latter kind, when rocked, liquid motion is in general at right angles to the rocking axis only, causing contaminated washing liquid, or partially exhausted coating liquid to contact the same object (e.g. solid plastics form) repeatedly. The volume of liquid required is large.

With a tray according to the invention, for a given depth and number of objects, an appreciably smaller volume of liquid is required; which may be an important consideration where biological or other substances available in small quantity are concerned. A further advantage is that being supported in channels, the objects to be coated or washed are subjected to a rapid flow of liquid, which will in general be more effective for either coating or washing than a low velocity flow.

In an alternative embodiment the tray 10 may, as shown in Figs. 5A and 5B, be provided with a reservoir 62, connecting with the channels in the tray. It is found that with rocking motion of the tray a circulation is set up which includes the contents of the reservoir, which consequently do not stagnate. This construction has advantages if the liquid in use is expensive and yet is needed in large quantity, because the area for evaporation is very iittle increased. Evaporation may be further reduced by providing a cover for the reservoir, leaving open only two connections to the channels in the tray.

Typically a liquid circulator apparatus of the kind described has a tray about 700 mm long by about 280 mm wide overall; with channels about 30 mm deep and of the order of 18 mm wide. The tray is preferably made of material which does not react with any liquid it is used to contain. It may be made of moulded plastics material. As an alternative, the tray could be made of pressed metal, coated with a suitably inert substance, for example polytetrafluoroethylene.

In the embodiment described above, the angle between the first axis 30 and the tray longitudinal axis 60 is 150. This angle may be in the range 50 to 450, preferably in the range 100 to 250. In the same embodiment the tray is rocked through an angle of +70, a total angle of 150. The total angle may iie in the range 50 to 200 for the majority of purposes.

It is found that the frequency of rocking of the tray is conveniently in the range 5 to 50 cycles per minute, 25 cycles per minute being a typical frequency.

Little power is required to drive an apparatus of the size exemplified, and at the frequencies mentioned. It is found that the motor 32 may have an output rating of about 20 watt.

In a further modification of the liquid-circulator apparatus, automatic liquid changing means is provided, as illustrated diagrammatically in Fig. 5B. The liquid changing means comprises pump means, indicated generally by 64, which takes the liquid through pipe 66 from a supply tank (not illustrated) and which liquid passes through a pipe 68 to the reservoir 62. Liquid leaves the reservoir through a pipe 70 and passes through a pipe 72 to a collecting tank (not illustrated). The pump means 64 may comprise two pumps driven simultaneously e.g. by an electric motor, one pump filling the reservoir 62 and the other emptying it at the same rate.

Alternatively the reservoir 62 may be filled by gravity at a controlled rate, and a single pump be employed to empty it under the control of a liquid level detector 74. The level detector is mounted in such a position as to be affected to the least possible extent by the rocking motion, in use, of the tray 10. The liquid changing means may, if required, deliver liquid to and remove it from the tray 10 direct rather than through the reservoir 62.

Claims (11)

1. Liquid-circulator apparatus having a liquid container tray and rocking means for rocking said tray about a first axis; said tray being of substantially rectangular shape with the major axis of said rectangular shape at an angle to said first axis, said angle between between 50 and 450.

2. Apparatus according to claim 1 in which the said angle is between 100 and 250.

3. Apparatus according to claim 1 or claim 2 in which the tray has longitudinal channels substantially parallel with said major axis and transverse channels connecting said longitudinal channels.

4. Apparatus according to any preceding claim having locating and support means for locating and supporting objects in at least some of said channels so that said objects can be contacted. in use, by liquid in said channels.

5. Apparatus according to claim 4 in which said locating and support means are arranged so that they can be located only in a designated liquidcirculator apparatus.

6. Apparatus according to any preceding claim having self acting rocking means for rocking said liquid container tray about said first axis.

7. Apparatus according to claim 6 in which said rocking means is arranged for rocking said tray at a frequency in the range from about 5 to 50 cycles per minute.

8. Apparatus according to any preceding claim in which the liquid container tray is detachable from the rocking means.

9. Apparatus according to any preeding claim in which the liquid container tray includes a liquid reservoir communicating with the channels in said tray for liquid flow between reservoir and channels.

10. Apparatus according to any previous claim having liquid changing means arranged to change automatically, in use, the liquid contents of the liquid container tray.

11. Liquid-circulator apparatus substantially as herein before described with reference to the accompanying drawings.