AU678038B2 - Device for mixing liquids - Google Patents

Description

?CT/AU 9 4 O U 44 9 RECEIVED 1 0 APR 1995 -1- "DEVICE FOR MIXING LIQUIDS" THIS INVENTION relates to a device which can be used to effect mixing of liquids.

A particular application of the invention relates to a device which can be utilised during blood collection to facilitate the mixing of the blood being collected with an anticoagulant in such a way that the blood components to not become segregated. It should be appreciated however, that the invention need not be limited in its scope to such an application.

Accordingly, the invention resides in a mixing means comprising a central support, a transverse member extending to each side of the central support, a platform supported from the transverse member to be pivotable about a substantially horizontal first pivot axis and about a second pivot axis which is transverse to the first pivot axis, a drive motor supported from the transverse member having an upright drive shaft which is coupled to the platform whereby rotation of the drive shaft causes joint pivotal movement of the platform about the first and second pivot axes and whereby the spacing between the drive shaft and platform is not affected by the loading on the platform, wherein the loading on the central support by the transverse member is substantially balanced, a polJion of the transverse member to each side of the centeral portion being resiliently deflectable in proportion to the weight of the contents of the platform, a measuring means provided to measure the degree of deflection of the portions to provide an indication of the weight and/or volume of the contents of the platform.

According to a preferred feature of the invention said platform is configured to receive a receptacle in the form of a closed bag formed of a flexible material.

Preferably the platform is formed as a tray having upstanding sides.

The invention will be more fully understood in the light of the following description of one specific embodiment. The description is made with reference to the accompanying drawings of which: Figure 1 is an isometric view of a blood collection monitoring apparatus according to the embodiment; AMENDED SHEET

IPEAIAU

PC/A 9 4 0 0 4 4 9 RECEIVED 1 0 APR 1995 -2- Figure 2 is a sectional side elevation of the base portion of the embodiment; Figure 3 is a sectional end elevation of the base according to the embodiment; and Figure 4 is an isometric view of the tray support of the embodiment.

The embodiment is directed towards a device which can be used for the collection of blood and monitoring such collection.

r AMENDED

SHEET

IPEA/AU

I' WO 95/04591 PCT/AU94/00449 3 The embodiment comprises a housing 10 having a lower portion 11 which accommodates a support tray 12 and a drive means for causing reciprocation of the tray. The housing further comprises an upper portion 13 which extends u"wardiy from one side of the base 11 and accommodates an appropriate control switch 14, a display 15, and flow line support 16. Both the lower and upper portion 11 and 13 accommodate the control circuitry for the device.

The lower portion 11 is essentially cubic in configuration and is provided with an open upper face 17. The support tray 12 is configured such that it is received within the upper face 17 and is supported to be able to be caused to pivot about two substantially horizontal perpendicular axes in the open face 17. The tray 12 is formed with an upper face which is recessed in a manner such that it will support a blood collection bag and will prevent substantial movement of the bag on the tray as a result of the cyclic tilting action of the tray.

The support tray 12 is supported within the base 11 from a support structure 18 (see Figure 3) which has a base 19 defined Ly a lower plate 20 which is adapted to be fixed to the bottom wall of the lower portion 11 of the housing.

The base has an upstanding pair of parallel webs 21 and 22.

The upper ends of the webs 21 and 22 support the central portion of a beam 23 which extends to each side of the space between the webs 21 and 22 and which supports an upright 24 and 25 at each end. The uprights 24 and 25 are further interconnected by a secondary beam 26 which lies parallel to the primary beam 23 and is spaced upwardly therefrom.

The upper end of each of the uprights 24 and 25 pivotally supports a support frame 27 through pivots 28 and 29 where

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WO 95104591 PCT/AU94/00449 -4the pivot axis between the pivots 28 and 29 is substantially horizontal.

The support frame 27 is of a generally cruciform configuration where the end of each arm is formed with an upwardly extending portion which provides two pairs of upwardly extending arms. The arms of each pair of arms are opposite each other and the axes interconnecting the pairs of arms are substantially perpendicular. One pair of upwardly extending arms 30 and 31 are pivotally mounted to the uprights 24 and 25 through the pivots 28 and 29 respectively to be pivotally supported from the base element 19 about the axis between the pivots 28 and 29.

The other pair of upwardly extending arms 32 and 33 are each formed with a V-shaped recess 34 which each pivotally receive a pivot pin or shaft 35 provided on the underneath the tray 12 towards each end thereof such that the tray is pivotally supported between the second pair of upwardly projecting arms 32 and 33 for pivotable movement about the axis of the shaft The central portion of the support frame which accommodates the second pair of upwardly extending arms 32 and 33 is formed with a slot shaped aperture 36 which has a width greater than the width of the webs 21 and 22 and which enables the support frame 27 to pivot over the base about the pivots 28 and 29.

The base 19 also supports a drive motor 37 which is supported from the secondary beam 26 to depend downwardly therefrom but which is received within an opening 38 provided in the primary beam 23 such that it does not interfere with and is not supported in any way, by the primary beam 23. The drive motor 37 is provided with an upwardly extending drive shaft 39 which has a wheel mounted to its upper end. The wheel 40 is formed in its upper surface with a socket 41 at a position offset from c- WO 95104591 PCT/AU94/00449 the central axis of the wheel 40 and the shaft 39. If desired the wheel can be replaced by a crank or like device.

The underneath of the tray 12 i7 provided with a downwardly depending shaft 42 which is formed at its lower end with a ball-shaped element (not shown) which is pivotally received within the socket 41. The shaft 42 is located centrally on the tray 12. On rotation of the wheel 40 as a result of the activation of the drive motor 37 the free end of the downwardly extending shaft 42 is caused to orbit around the central axis of the shaft and wheel and as a result the tray 12 is caused to pivot about the central axis of the shaft 35 between the second pair of upwardly extending arms 32 and 33 and the axis between the pivots 28 and 29 provided between the uprights 24 and 25 on the base 19.

This joint cyclic tilting of the tray 12 about a pair of substantially perpendicular axes provides an action which facilitates the rapid and consistent mixing of blood and anticoagulant within a bag which is supported on the tray 12.

The operation of the drive motor through the control circuit is such that each time the drive motor stops the wheel the tray is at the same position. This is facilitated by the present of a magnet mounted to the wheel (not shown) which is associated with a Hall effect sensor (not shown) provided on the secondary beam 26 to enable the control circuit to always stop the drive motor 37 with the tray in the same position. In use a receptacle is placed on the tray such that the inlet is lowermost. As a result blood entering the receptacle must flow through the anticoagulant accommodated within the receptacle when the tray is stationary.

The mounting and construction of the tray is such that it can be readily lifted out of engagement with the recesses I- WO 95/04591 PCT/AU94/00449 6 34 on the arms 32 and 33 of the support frame 27 and out of engagement with the wheel for the tray to be cleaned. When cleaned the tray is readily capable of being re-engaged with the support 27 and the wheel.

It has been found that the repetitive tilting of the tray about two axes, as a result of the construction according to the embodiment, enables the blood, collected during a normal six minute donation period, to be rapidly mixed with the anticoagulant contained within the receiving bag with little segregation of the constituents of the blood, such as accumulation of red blood cells which has been a common difficulty with mechanisms used in the past.

In this regard high concentrations of the anticoagulant has toxic effects on blood while lack of anticoagulant results in the blood results in the initial phases of blood coagulation. If the mixing of the blood with the anticoagulant is slow or not even distributed the blood can remain segregated from the anticoagulant for an extensive period of time. This results in the blood in contact with the anticoagulant being subject to excessive concentrations of anticoagulant and the blood lying in the bottom of the bag which is separated from the anticoagulant commencing the initial coagulation stages.

The primary beam 23 of the base provides the primary support for the tray, its contents and the support frame 27 from the base 19. The primary beam 23 is supported symmetrically from the webs 21 and 22 and also symmetrically supports the tray 12 and its contents. The beam is formed with a set of four symmetrically located transverse grooves 39 and each groove is associated with a strain gauge 40. The strain gauges are interconnected to an electrical circuit which is able to provide a measure indicative of the weight of the tray and its contents. In addition the control circuitry is able to provide a display WO 95/04591 PCT/AU94/00449 -7representative of the weight of the contents of the bag in the tray and the rate of change of the weight of the contents of the tray. The configuration and construction of the primary beam may take any desirable form to facilitate the symmetrical support and use of four strain gauges to provide a measure representative of weight.

In operation the drive motor 37 is activated intermittently whereby during each rest period the weight as sensed by the strain gauges 40, is measured and the change in weight since the previous rest period is determined.

The support arrangement for the tray according to the embodiment as described above comprises a means whereby the pivotal support for the tray and the drive for causing such pivotal movement of the tray is carried from a commn carriage which is in turn supported symmetrically from the base element whereby the nature of the support provided for the carriage enables the weight of the tray, the support carriage and the contents of the tray can be accurately monitored, to ensure accurate monitoring of the contents of the tray 12.

The upper portion 13 of the housing is provided with a flow line support 16 which comprises a set of three upwardly fixed extending spigots 41 and a fourth movable spigot 42.

The fixed spigots 41 together form a triangular array of spigots. The movable spigot 42 is capable of moving towards the central spigot 41a. In use a blood flow line is laced between the movable spigot 42 and the three fixed spigots 41. The movable spigot 42 is associated with a latch means which is activated by a solenoid or like device which on activation will cause the movable spigot 42 to move towards the fixed spigots 41 whereby the flow line is clamped to prevent flow of blood through that line.

WO 95/04591 PCT/AU94/004-49 8 The control of the flow line support means 16 is effected from the control circuit accommodated within the upper portion 13 of the housing to control the flow of blood to the receptacle carried on the tray 12.

The control circuit incorporates a main control switch to initiate the operation of the device. In addition the control circuit is provided with a micro processor which in association with the display 15 provides a set of instructions to the operator and which controls the flow line support in association with those instructions. The control circuit is further provided with appropriate toggle switches 14 and memory circuitry which enable a value for a predetermined volume of blood which is to be collected to be introduced into the memory of the control circuit such that on that volume having been collected the flow line support will be activated to prevent any further flow of blood to the receptacle. On first use of the device the volume or weight of blood to be collected is stored into the memory. This can be varied from time to time but the memory will retain the figure previously entered until it is subsequently changed.

The control circuit is also able to provide a display of the amount of blood collected by indicating the weight of blood collected or the volume of the blood collected. In providing such the circuit operates on the measure derived from the weight sensing circuit to provide a measure of the volume. If desired a suitable switch may be provided with the display to be able to change the display from indicating weight to indicate volume during operation of the device.

The display provides a multiple of displays. One form of display provides an accurate digital display of the volume and/or weight of blood in the collection bag and the time elapsed since the collection of blood commenced. The othei

Claims (12)

1. A mixing means comprising a support element, a first transverse beam extending to each side of the support element, a first pivot provided on the first transverse beam to each side of the support element and equidistant therefrom to provide a first pivot axis therebetween, a support pivotally supported from the first pivots to be pivotable about the first axis, the support having a pair of second pivots to each side of the first pivot axis to provide a second pivot axis which is perpendicular to the first pivot axis and which is located between the first pivots, a platform pivotally supported from the second pivots to be pivotable about the second pivot axis, a drive motor supported from the first transverse beam from a location to each side of the support element and equidistant therefrom, said drive motor having an upright drive shaft which is coupled to the platform whereby rotation of the drive shaft causes joint pivotable movement of the platform about the second pivot axis and the support about the first pivot i axis, said first transverse beam between said locations being deflectable proportionally to weight of the contents of the platform, measuring means provided to measure the degree of deflection of the beams to provide an *°*indication of the weight and/or volume of the contents of the platform.

2. A mixing means as claimed at claim 1 wherein the second pivots are spaced equidistant to each side of the first pivot axis.

3. A mixing means as claimed at claims 1 or 2 wherein each said first pivot is :i provided by an arm extending from the first transverse beam at said locations and said drive motor is supported from a second transverse beam extending between the arms.

4. A mixing means as claimed at any one of the preceding claims wherein the platform is engaged with the second pivots and the drive motor to be readily disengaged therefrom by lifting the platform from the second pivots.

A mixing means at anyone of the preceding claims wherein the weight carried by the first pivot is substantially equal.

6. A mixing means at anyone of the preceding claims wherein the weight carried by the second pivots is substantially equal. rl WOIV' 'A"h'

7. A mixing means as claimed at anyone of the preceding claims wherein the transverse beam is provided with one or more strain gauges to provide said measuring means.

8. A mixing means as claimed at any one of the preceding claims wherein the coupling between the drive shaft and the platform comprises a laterally extending member provided the drive shaft and a downwardly depending member provided on the underneath of the platform pivotally engagable with the laterally extending member whereby rotation of the drive shaft causes said joint pivotable movement of the platform.

9. A mixing means as claimed at any one of the preceding claims wherein the platform is configured to receive a receptacle in the form of a closed bag formed of a flexible material.

10. A platform as claimed at claim 9 wheruan the platform is formed as a tray having upstanding sides.

11. A mixing means as claimed at any one of the preceding claims wherein the tray is adapted to accommodate a blood collection receptacle.

12. A mixing means substantially as herein described. 9* 0 *e o* co