This invention is directed to hematology analyzers incorporating a fluidics circuit with a heated reaction chamber and more particularly to a novel fluidics circuit with a replaceable metallic heat transfer member for a heated reaction chamber.
Clinical hematology analyzers are used to perform automated test analyses on body fluids, such as whole blood, to obtain data relating to the whole blood characteristics of a particular individual. The whole blood characteristics are usually compared with known acceptable whole blood parameters to determine if there are any significant deviations that might indicate a need for medical attention.
For example hematology analyses can be used to detect or confirm the existence of various illnesses, diseases and infections. Thus the hematology analysis of an individual's whole blood provides information relating to their health or medical status. Such information might dictate the need for a medical prescription, a dietary modification, an exercise program and/or other remedial measures to deal with health or medical problems that become apparent from data obtained in the hematology analysis.
One known hematology analyzer includes a fluid circuit, known as a unified fluid circuit, made of a plurality of acrylic plates that are fusion bonded, laminated or otherwise joined together to form a block-like plastic member. Some or all of the acrylic plates can be formed with an array of chamber cavity recesses, pneumatic, hydraulic and vent line recesses, valve cavity recesses and reaction chamber recesses. When the acrylic plates are joined together various cavity recesses, chamber recesses and passageway recesses in the individual plates align to form a plurality of internal chambers, cavities, fluid passageways, and other internal hollow formations that constitute a network for controlling the flow and mixing of blood samples with selected fluids and reagents that are used in carrying out a hematology analysis.
U.S. Pat. No. 5,788,927, the entire disclosure of which is incorporated by reference herein, shows a unified fluid circuit assembly for a clinical hematology instrument. The fluid circuit assembly includes a heated reaction chamber, bordered on all sides by plastic. A heating device at the reaction chamber conducts heat through a relatively thin plastic heat transfer wall of the reaction chamber, to maintain a desired temperature within the reaction chamber. The thin plastic heat transfer wall of the reaction chamber is formed as an integral part of the unified fluid circuit.
It is known that plastic, such as acrylic, is a relatively poor conductor of heat. Therefore it is necessary that the plastic heat transfer wall be as thin as possible to permit a required rate of heat transfer through the thin plastic heat transfer wall into the reaction chamber. However the relatively thin plastic heat transfer wall has been found to degrade after a period of time when subjected to heat levels that are needed to maintain the desired amount of heat transfer to the reaction chamber.
Thus, after a given amount of time, the relatively thin plastic heat transfer wall will fail. Since it is not feasible to repair a failed plastic heat transfer wall the entire unified fluid circuit must be replaced.
Because intricate molding and machining processes that entail a very high level of precision are used to manufacture the unified fluid circuit any replacement of the unified fluid circuit is extremely costly. Furthermore replacement of the unified fluid circuit also requires shutdown of the hematology analyzer. Thus the losses encountered during shutdown of the hematology analyzer for replacement of the unified fluid circuit are quite considerable. Consequently any means for prolonging of the life of the unified fluid circuit would result in substantial cost savings.
It is thus desirable to provide a unified fluid circuit having a heated reaction chamber, with a longer operating life than known unified fluidics circuits with heated reaction chambers. It is also desirable to provide a unified fluidics circuit having a heated reaction chamber with a heat transfer component that can be repaired or replaced when necessary. In addition, it is desirable to provide a uniform fluidics circuit with a heated reaction chamber that is not subjected to plastic degradation at the heat transfer surface.
Among the several objects of the invention may be noted the provision of a novel unified fluidics circuit having a heated reaction chamber with a replaceable heat transfer member, a novel unified fluidics circuit with a replaceable heat transfer member formed of metal, a novel unified fluidics circuit with a heated reaction chamber wherein heat transfer to the reaction chamber is provided by a metal heat transfer member that is detachably secured to the unified fluid circuit and forms a structural portion of the reaction chamber, a novel unified fluidics circuit with a heated reaction chamber wherein a detachable and replaceable metallic heat transfer member forms a part of the reaction chamber and transfers heat from a heater element directly into the reaction chamber, and a novel method of transferring heat to a heated reaction chamber in a unified fluidics circuit.
Other objects and features of the invention will be in part apparent and in part pointed out hereinafter.
In accordance with the invention a unified fluidics circuit for a hematology analyzer includes a block-like plastic member formed with a plurality of interior tube-like passageways for conduction of selected fluids along selected paths defined by the passageways. One or more passageways in the block-like plastic member lead to predetermined locations where portions of the selected fluids can be mixed or reacted.
A reaction chamber recess is provided at one location in the block-like plastic member and a detachable metallic heat transfer cover member is positioned across the reaction chamber recess to close the reaction chamber recess and thereby establish a confined reaction chamber.
A heater is maintained in conductive contact with the heat transfer cover member to supply heat to the heat transfer cover member. Heat is thus conducted through the heat transfer cover member into the reaction chamber to supply heat to any contents of the reaction chamber when the metallic heat transfer cover member is in the closed position across the reaction chamber recess.
The metallic heat transfer cover member is detachably secured in the closed position at the reaction chamber recess and can be easily removed if there is a need to repair or replace either the metallic heat transfer cover member or the heater that is in contact with the heat transfer cover member.
In one embodiment of the invention the reaction chamber recess is provided at a subsurface of a vestibule formed in the block-like plastic member. The heat transfer cover member is located in the vestibule and abuts the vestibule subsurface to form a leak-tight seal at the vestibule subsurface. Preferably the heat transfer cover member includes a cover recess that aligns with the reaction chamber recess when the cover member is in the closed position.
A heater which supplies heat to the heat transfer cover member, is positioned in the vestibule in conductive contact with an outside surface of the heat transfer cover member. The heater is maintained in surface to surface contact with the heat transfer cover member. Means for maintaining the heater in conductive contact with the heat transfer cover member can include biasing means and a holding member secured to the block-like plastic member to urge the biasing means to force the heater against the outside surface of the heat transfer cover member.
The invention also includes a method of transferring heat to a reaction chamber in a fluid circuit. In accordance with the method a block-like plastic member of a fluid circuit, at one location, is formed with a reaction chamber recess. A detachable metallic heat transfer member is positioned across the reaction chamber recess to close the reaction chamber recess and establish a confined reaction chamber. The outside surface of the heat transfer member is heated with a heating device in conductive contact with the heat transfer member to transfer heat to the reaction chamber by conduction through the heat transfer member when the heat transfer member is in the closed position. In addition, the method includes detachably securing the metallic heat transfer member to the block-like plastic member in the closed position across the reaction chamber recess.
The invention accordingly comprises the constructions and methods hereinafter described, the scope of the invention being indicated in the claims.
In the accompanying drawings,
Corresponding reference numbers indicate corresponding parts throughout the several views of the drawings.
Referring to the drawings, a unified fluidics circuit of a hematology analyzer incorporating one embodiment of the invention is generally indicated by the reference number 10 in
The unified fluidics circuit 10 (also referred to as the fluid circuit 10) includes a generally block-like plastic member 12 formed with a plurality of interior fluid passageways represented by circuit lines in
The block-like plastic member 12 (also referred to as the block 12) is formed from a plurality of individual acrylic plates (not shown) that are laminated or otherwise joined together by fusion welding or other known laminating process. Each acrylic plate may include, for example, chamber recesses, valve cavity recesses and passageway recesses for pneumatic, hydraulic, and vent-lines. When the acrylic plates are laminated together, various chamber recesses and passageway recesses in the individual acrylic plates align to form a plurality of internal chambers, cavities, fluid passageways and other internal hollow formations.
The fluid circuit of
Referring to
An elliptical-shaped, bulbous recess 36 (
A detachable metallic heat transfer cover member 44 (most clearly shown in
The heat transfer member 44 is formed with a cover recess 70 (
The cover member 44 further includes four threaded screw holes 72, 74, 76 and 78 (
A top end surface 100 (
A bottom end surface 110 (
An elliptical gasket 122 (
An electrical heater 140 (
The heater engagement member 154 (
A pair of coil-shaped pressure springs 170 and 172 (
In assembling the heat transfer cover member 44 to the block 12 the gasket 122 (
Placement of the cover member 44 in the closed position (
The O-ring 104 provides a leak tight seal between the aligned vent passage 106 in the cover member 44 and the ventilation passageway 28 in the block 12 (
During installation of the cover member 44 in the vestibule 18 the O-rings 104 and 118 (
Thus when the cover member 44 is being positioned in the vestibule 18 for movement toward the vestibule subsurface 22, the O-rings 104 and 118 at the top end and bottom end surfaces 100 and 110 of the cover member 44 interfere slightly with the top and bottom surfaces 24 and 26 of the vestibule 18. Also, the O-rings 104 and 118, prior to their interference entry into the vestibule 18 can respectively impinge against an upper corner edge 180 (
To obviate impingement and interference damage to the O-rings 104 and 118 during installation of the cover member 44 into the vestibule 18 a sloping recess 194 (
Installation of the cover member 44 in the vestibule 18 is also facilitated by using removable mylar shims 198 and 200 (
After the cover member 44 is located in the closed position, the mylar shims 198 and 200 are pulled away from the sloping recesses 194 and 196. The fastener screws 86 (
The flexible heater member 142 of the heater 140 (
The heater engagement member 154 is then positioned against the flexible heater member 142. Engagement between the members 142 and 154 is maintained by the pressure springs 170 and 172 and the securement member 174, which is fastened to the block surface 20 by the fasteners 178 (
Under this arrangement the heater engagement member 154, the springs 170 and 172, and the securement member 174 constitute means for maintaining the heater 142 in contact with the heat transfer cover member 44.
Heat for the reaction chamber 16 is thus conducted from the flexible heater member 142 through the heat transfer cover member 44 which, as most clearly shown in
After the cover member 44, the flexible heater member 142 and the securement member 174 are secured in position, an inlet port (not shown) can introduce whole blood and reagent into the reaction chamber 16. The whole blood and reagent are heated in the reaction chamber 16 by the heat transfer cover member 44 for a predetermined time under controlled temperature conditions that will enable the desired reaction to take place in the reaction chamber 16 between the whole blood and the reagent.
A probe 206 (
Thus if there is a deviation in the reaction chamber temperature from the desired temperature the controller circuit will cause the heater 140 to operate in a manner that raises or lowers the temperature as needed. For example, under this arrangement the temperature in the reaction chamber can be maintained at 33° C. plus or minus 1 degree.
Should there be a need to repair or replace the cover member 44, the heater 140, the heater engagement member 154, the gasket 122, the O-rings 104 and 118, the springs 170, 172 and the securement member 174, it is a relatively simple matter to remove these components from the block 12 by removing the fasteners 86 and 178.
An advantage of the invention evident from the foregoing description is a detachable metallic heat transfer member for a heated reaction chamber in a fluidics circuit. Thus the life of fluidics circuit is not limited by the life of the heat transfer structure for the heated reaction chamber since the heat transfer structure is a replaceable, detachable metallic heat transfer cover member 44.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
As various changes can be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.