Abstract:
An analytical cartridge and a rotary analytical device with which the cartridge cooperates. The cartridge may have a housing, an axis, analysis chambers spaced from and located circumferentially about the axis, and a magnetically movable element located in and movable within each analysis chamber to mix fluid in the analysis chamber. The rotary analytical device may have a housing with a cavity having an axis, an impeller extending into the cavity and rotatable about the axis to receive and rotate the cartridge, a motor to rotate the impeller, at least one magnetic element near the cavity and offset from the axis, a light source in the housing to direct a beam of light into the cavity and through the analysis chamber of the cartridge, and a light sensor to receive light from the analysis chamber.

Description:
BACKGROUND OF THE INVENTION 
     It is frequently desired to analyze is liquid to determine the presence and concentration of analytes such as minor constituents and/or contaminants. In many instances, several different tests may be run on one or more portions of a single liquid sample, to detect and measure different constituents. For man common tests, reagents are available that provide an almost instantaneous result by changing either hue or intensity of color in response to a specific constituent in the liquid. An example is a swimming-pool test kit, which typically provides from two to six different reagents that test for common factors such as chlorine or bromine content, pH, and hardness of the water. 
     However, such test kits conventionally require the user to fill a specific amount of water into a test container, add a specific amount of reagent, judge the intensity or hue of the resulting color against a reference chart by eye, and repeat the whole process for each test that it is desired to carry out, if the test results are not within is desired range, the user must then manually calculate the amounts of chemicals to add to the swimming pool to adjust its condition to the desired range. That is time consuming, messy, and not very accurate. The situation is even worse for a pool supply store, where the store staff are frequently asked for assistance by a pool owner whose pool chemistry has gone wrong in a way that the owner cannot himself correct. The store staff may then need to conduct a much larger range of tests, and to convert the results of the tests to quantities of various chemicals to be added to the pool. 
     Similar issues occur in other businesses and industries. For example, in brewing, trace constituents of the water used can not only directly affect the flavor and quality of the brewed beverage, but also affect the behavior of the yeast and therefore the success and result of the brewing process. Other businesses in which a battery of tests, have to be performed fairly frequently, so that similar issues occur, include aquaria, aquaculture, environmental monitoring, and maintaining boilers and coolers. 
     There is, therefore, a need for apparatus and methods that make it possible to test a liquid sample for several different properties, for example, for the presence or absence of several different analytes, in a single operation, with a minimum of mess, and to obtain the results of the tests automatically, without relying on human judgment. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention provides an analytical cartridge comprising a cartridge housing, having a central axis, a plurality of analysis chambers in the housing, the chambers being spaced apart from the axis and located circumferentially about the axis, and a magnetically movable element located in each analysis chamber and movable within the analysis chamber, the element adapted to cause the mixing of fluid in the analysis chamber. 
     Another embodiment of the invention provides a rotary analytical device comprising a housing having a cavity formed therein, the cavity being defined by a bottom wall and at least one side wall, the cavity having an axis, an impeller extending into the cavity and rotatable about the axis a motor mounted within the housing and connected to the impeller, the motor adapted to rotate the impeller, at least one magnetic element in the housing at a location proximate to the cavity and offset from the axis, at least one light source in the housing and arranged to direct a beam of light into the cavity, and at least one light sensor in the housing and arranged to receive light from the at least one light source, the sensor being sensitive to light of a color emitted by the light source. 
     Further embodiments of the invention provide combinations of a rotary analytical device and an analytical cartridge co-operating with the rotary analytical device, and methods of analysis using such rotary analytical devices, such analytical cartridges, and such combinations of a rotary analytical device and an analytical cartridge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of the present invention may be more apparent from the following more particular description of embodiments thereof, presented in conjunction with the following drawings. In the drawings: 
         FIG. 1  is a schematic view of an embodiment of a liquid analysis apparatus. 
         FIG. 2  is as perspective view of a rotary analyzer forming part of the liquid analysis apparatus of  FIG. 1 . 
         FIG. 3  is a top plan view of a cartridge used in the rotary analyzer of  FIG. 2 . 
         FIG. 3A  is a cross-section view of an analysis chamber and agitator chamber. 
         FIG. 3B  is a view similar to  FIG. 3A  in a different position in operation. 
         FIG. 4  is a view similar to  FIG. 3A  of an alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A better understanding of various features and advantages of the present methods and devices may be obtained by reference to the following detailed description of illustrative embodiments of the invention and accompanying drawings. Although these drawings depict embodiments of the contemplated methods and devices, they should not be construed as foreclosing alternative or equivalent embodiments apparent to those of ordinary skill in the subject art. 
     Referring to the drawings, and initially to  FIG. 1 , one form of liquid analysis apparatus, indicated generally by the reference number  10 , comprises a rotary analyzer, indicated generally by the reference number  12  and shown in more detail in  FIG. 2 , connected to a computer  14 . Computer  14  may be a conventional personal computer or similar device suitably programmed, and may comprise, among other equipment, a processor or controller  16 , input and output devices such as a keyboard  18  and a monitor  20 , random access memory (RAM)  22 , read-only memory (ROM)  24 , magnetic disks or other long-term storage  26 , and an interface  28  to an external network  10  or other communications media. The interface  28  may also provide a connection from the computer  14  to the rotary analyzer  12 . 
     Referring, now also to  FIG. 2 , the rotary analyzer  12  comprises a base  50  defining a recess  52  in its upper surface, and a lid  54  hinged to base  50  and defining a generally cylindrical recess  56  in its lower surface. When the lid  54  is closed, it preferably fits into recess  52 . A spindle  58  projects through the lower surface of the recess  52  and is received in the recess  56  when the lid  54  is closed. The spindle  58  has a flat surface  60  on one side. Below the bottom of the recess  52 , the spindle  58  is connected to and driven by a motor  62 , and is preferably connected to a rotary encoder  64  or similar device by which its rotational position can be monitored. However, as will become apparent after review of the following description, other well known mechanisms can be used to provide rotational position signals to the apparatus. 
     In the embodiment shown, four light sources, preferably light emitting diodes (LEDs)  68 ,  70 ,  72 ,  74  are mounted in the underside of the lid  54  in the top of recess  56 . The LEDs  68 ,  70 ,  72 ,  74  may be of different colors, for example, respectively red, yellow, green, and blue. Four light detectors, such as phowdiodes or other photoelectric transducers  76 ,  78 ,  80 ,  82 , are mounted in the bottom of the recess  52 , each facing a respective one of LEDs  68 ,  70 ,  72 ,  74 . Each transducer  76 ,  78 ,  80 ,  82  may be provided with a dichroic or other band-pass filter or otherwise optimized to be selectively sensitive to the light from its respective LED. It is also contemplated that the light sources could be located on the same side as the detectors (e.g., the bottom of the recess) with a reflective surface mounted on the opposite side of the recess (e.g., on the lid). 
     In other embodiments, more or fewer light sources, and/or light sources of different colors, which may include infrared and/or ultraviolet, may be used. In other embodiments, other sorts of light sources, which may include a broadband source such as an incandescent lamp, may be used. 
     A first permanent magnet  84  is mounted in the underside of lid  54  between two of the LEDs. A second permanent magnet  86  is preferably mounted in the bottom of recess  52 , between two of the transducers, spaced apart from the first magnet  84 . The LEDs  68 ,  70 ,  72 ,  74 , the transducers  76 ,  78 ,  80 ,  82 , and the magnets  84 ,  86  are preferably all at the same radius from the axis of rotation of spindle  58 , however it is contemplated that the magnets can be located to a different radius depending on the construction of the cartridge. 
     An indicator lamp  88  may be provided on the exterior of the rotary analyzer  14 , in a position where it is easily visible even with lid  54  dosed. An interlock switch  90  may be provided to detect when lid  54  is closed. 
     A processor or controller  94  suitably programmed is provided, and receives inputs from the transducers  76 ,  78 ,  80 ,  82 , the rotary encoder  64 , and interlock switch  90 , and controls the LEDs  68 ,  70 ,  72 ,  74 , the motor  62 , and the indicator light  88 . The interlock switch  90  is preferably configured to provide signal to the processor or controller  94  for detecting when the lid is closed in order to prevent activation of the spindle  58  when the lid is not in its closed position. The indicator light  88  preferably is illuminated when the analyzer is active or when the testing is complete. 
     Referring now also to  FIG. 3 , one form of cartridge, indicated generally by the reference number  100 , comprises a molded body with a generally flat lid or top surface  101 . Cartridge  100  comprises a central opening  102  that is preferably D-shaped an configured to engage with the flat  60  on the spindle  58 , so that when the cartridge  100  is mounted on the spindle  58  the orientation of the cartridge  100  relative to the rotary encoder  64  is fixed and predetermined. It is contemplated that the opening  102  can be any suitable non-circular shape designed to mate with a complementary spindle shape. 
     At least partially surrounding the central opening  102  is an annular filling chamber  104 , which in one embodiment extends around the opening about 330° of the circumference of the cartridge. At one end of the filling chamber  104  preferably includes a radially inward extension  106 , that includes a filling port  108 , which is the an opening through the lid of cartridge  100 . 
     Water can be injected through filling port  108  using a conventional syringe (not shown) into filling chamber  104 . Visible indicia may be molded into or placed on the lid of the cartridge  100 , for example, to point out where the filling port  108  is located and/or to indicate a point to which the filling chamber  104  should be filled. 
     At the end of the filling chamber  104  remote from the filling port  108 , a transfer passage  110  extends radially outward to a distribution gallery  112 , which in the illustrated embodiment almost completely encircles the cartridge  100  outside the filling chamber  100 . Of course it is contemplated that multiple passages  100  can communicate with multiple galleys  112 . From the distribution gallery  112 , a plurality of spouts or channels  114  extend radially outward. From the end of the distribution gallery  112  furthest from the transfer passage  110 , there is preferably located an overflow passage  116  that extends radially inwards, and opens into the central opening  102  through the flat side of the D-shaped opening. 
     Outside the distribution gallery  112  are several analysis chambers  120 , each with an associated agitator chamber  122 , at least one comparison chamber  124 , and an overflow chamber  126 . The analysis chambers  120 , comparison chamber  124  and overflow chamber  126  are each connected to the distribution galley through one of the channels  114 . The analysis chambers  120  are located circumferentially on a circle with a radius that corresponds to the radial location of the LEDs  68 ,  70 ,  72 ,  74 , the photoelectric transducers  76 ,  78 ,  80 ,  82 , and preferably the magnets  84 ,  86 . The analysis chambers  120  are preferably equally sized and evenly spaced, although that is not necessary in the present invention. In the cartridge  100  shown in  FIG. 3 , there are ten analysis chambers  120 , spaced at intervals of approximately 30° ( 1/12 of the circumference of the cartridge). The comparison chamber  124  occupies an eleventh position, and in the illustrated embodiment is about the same size as an analysis chamber, but does not have an associated agitator chamber. The overflow chamber  126  occupies the twelfth position, and is larger than the analysis chambers. The overflow chamber  126  uses up the space that is available where the overflow and comparison chambers do not have agitator chambers. The overflow chamber  126  is at the same end of distribution gallery  112  as the overflow passage  116 . 
     As shown in  FIG. 3A , the analysis chambers  120  are elongated in the circumferential direction, and extend between the top and bottom of the cartridge  100 , dosed off by the lid  101 . The agitator chambers  122  are preferably generally circular in cross-section, and extend between the top and bottom of the cartridge  100 , closed off by the lid  101 . Each agitator chamber  122  is connected to its associated analysis chamber  120  by a slot  128  preferably extending between the top and bottom of the cartridge. Each agitator chamber  122  contains an agitator  130  preferably in the form of a magnetizable stainless steel ball bearing (BB) that is small enough to move freely along the agitator chamber  122  between the positions shown in  FIG. 3A  and  FIG. 3B , but large enough to displace water like a piston when it does so, and too large to pass through the slot  128 . 
     The top and bottom faces or surfaces of the cartridge  100  above and below the analysis chambers  120  are preferably made smooth, flat, and clear, so as to permit the transmission of light with minimal absorption and scattering. 
     In a ready-for-use condition of the cartridge  100 , each analysis chamber  120  contains a predetermined amount of a selected reagent  121 . Preferably, the reagents  121  are introduced into the analysis chambers  120  in liquid form and dried or allowed to dry onto the bottoms of the analysis chambers, thus immobilizing the reagents so that they do not move outside their respective chambers during shipping. Alternatively, the reagents could be dried prior and then metered into the chambers. Once the reagents and the agitators  130  have been introduced into the cartridge  100 , the lid  101  is attached, for example, by sonic welding. In one example of a cartridge for analyzing swimming-pool water, the reagents are suitable for measuring one or more of the following, preferably all: free chlorine/bromine; total chlorine; total alkalinity; pH; calcium and/or magnesium hardness (at two different ranges); copper; iron; borate; and cyanuric acid. In another example, biguanide and biguanide shock measuring reagents are substituted for the chlorine and bromine tests, and the cyanuric acid test is omitted. 
     In use, a measured amount of water or other liquid to be analyzed is injected into the filling chamber  104  through the filling port  108 . The amount may be measured by tilling the filling chamber  104  until the water reaches a visible filling mark, for example, until the boundary between the area of the chamber  104  furthest from the fill port  108  is filled and at a location underneath or between lines molded on the cartridge  100 . As liquid is injected in the filling chamber  104 , air in the chamber is displaced through the overflow passage  116 . Other mechanisms for venting air can be provided, such as a vent port on the distribution gallery  112 . The cartridge  100  is then placed over the spindle  58 , with the flat surface  60  on the spindle  58  engaging the flat side of D-shaped opening  102  in the cartridge  100 . 
     A cover  140  is then preferably placed over cartridge  100 . The cover  140  may be made from an opaque or black material or suitably coated to limit and absorb stray light from the LEDs  68 ,  70 ,  72 ,  74 , and may be made of a strong plastic to protect the analyzer  12  if there is any failure of the cartridge  100 . The cover  140  may have openings aligned with the analysis chambers  120 , and a D-shaped central opening that engages the flat  60  of spindle  58  so that the openings in the cover  140  remain in alignment with the analysis chambers  120 . The cover  140  may be omitted. In an alternative embodiment, another provision may be made for reducing stray light. For example, the spindle  58  may be provided with a fat plate on which the cartridge  100  rests, and which has openings aligned with the analysis chambers  120 . 
     Once the cartridge is mounted, the lid  54  is closed, and the analyzer  12  is activated, either by a control on the analyzer itself or by a command signal from a computer  14 . The motor  62  rotates the spindle  58 , which rotates the cartridge  100  at a speed suitable for generating sufficient centrifugal force to cause the liquid to flow outward from the filling chamber  104  through the transfer passage  110  to the distribution gallery  112 . The liquid flows along the distribution gallery  112 , and outward, again by centrifugal three through the channels  114  to fill the analysis chambers  120  and the comparison chamber  124 . Any excess liquid will pass through the whole length of the distribution gallery  112  into the overflow chamber  125 . Any excess liquid should remain in filling, chamber  104  or distribution galley  112 , because the outlet of overflow passage  116  is radially inward from the distribution galley, closer to the center of rotation. 
     Once the liquid has been distributed to the analysis chambers  120 , the motor  62  continues to rotate the cartridge  100 . As each agitator chamber  122  passes the magnets  84 ,  86 , the agitator  130  is attracted by the magnets and moves alternately up and down within the agitator chamber  122 , between the positions shown in  FIGS. 3A and 313 , depending on the magnet it passes. The movement of the agitator  130  causes an oscillating circulation of liquid within the agitator chamber  122  and its associated analysis chamber  120 . The circulation of liquid assists in the dissolving or suspension of the reagent  121  into the liquid, and facilitate the even mixing of the reagent  121  throughout the liquid in analysis chamber  120 . 
     Each reagent is preferably formulated using known techniques such that it forms an appearance such as hue, intensity of color, or opacity that is detectable or measurable by light, depending on the presence, absence, or concentration of the analyte that each reagent is intended to detect. In an embodiment, different reagents  121  in the different analysis chambers  120  from different colors, depending on the concentration of the analyte that each reagent is intended to detect. 
     Each color may be measured by the absorption of the light from one or more of the LEDs  68 ,  70 ,  72 ,  74  before it reaches its respective transducer  76 ,  78 ,  80 ,  82 , or alternatively, by the amount of light that passes through to the respective transducer. The colors may vary in hue, intensity, or both. For example, one standard reagent for measuring chlorine concentration produces a pink color that becomes darker as the chlorine concentration increases, and may be measured by the absorption of blue light from the LED  74 . For example, one standard reagent for measuring pH varies in hue from yellow at low pH to red at high pH, and may be measured by the absorption of light from the yellow LED  70  or the green LED  72 . A reagent that varies it hue may also be measured by the difference between absorptions of light from light sources of two different colors. 
     Errors caused by variation in the intensity of the light emitted by the LEDs, and lack of transparency of the initial liquid samples, may be corrected by measuring the light transmitted through the reference chamber  124 . The light of each color transmitted by each chamber may be identified by synchronizing the time-varying output from the transducers  76 ,  78 ,  80 ,  82  with the timing information from the rotary encoder  64  as the spindle  58  rotates. 
     In an embodiment, the processor  94  repeatedly samples the measured light intensity data from the transducers  76 ,  78 ,  80 ,  82 . The processor  94  discards readings that do not match one of the analysis chambers  120  or the reference chamber  124 . Merely by way of example, the processor  94  may sample the transducers 400 times per revolution of the cartridge  100 , and extract 4 readings for each analysis chamber  120  per revolution. The readings are then averaged over several revolutions, and a matrix of 11×4 averaged readings is transmitted by the processor  94  to the computer  14 . The computer  14  is programmed with calibration data for the set of reagents  121  in the cartridge  100 , and converts the light intensity data into concentrations of the various analytes. Programs for converting the light intensities into analyte concentrations, including databases of the characteristics of standard reagents, are commercially available and, in the interests of conciseness, need not be further described here. The computer  14  may display the concentrations on screen  20 . While the analyzer is shown having a processor  94  mounted within it, it is also contemplated that all the processing may occur at the computer. Alternatively, the processor  94  can be programmed to provide all the analysis necessary and provide the results to the computer or other display device. 
     Instead, or in addition, where the liquid sample being analyzed has a desired or ideal condition (as is the case, for example, with swimming pool water) the computer  14  may be programmed with a data file of available treatments to adjust the condition. Optionally, relevant properties of a source of the liquid sample being analyzed may also be stored on the computer  14  or input during the analysis, and the computer  14  may then generate a prescription for treatments to correct any problem detected by the analysis. 
     For example, if the sample being analyzed is water from a swimming pool being analyzed at a pool supplies store, one important piece of information, is the size of the pool. If the analysis shows that the water is outside a desirable range for one or more analytes in the specific size pool, the computer  14  can then generate a list of specific quantities of select pool chemicals that are in stock in the store and needed to correct the results of the analysis. Because different brands of chemicals may come in different formulations, container sizes, and concentrations, that typically may require at least a separate data file for each brand. 
     As an example of suitable dimensions, for a water analyzing apparatus for swimming-pool water, a cartridge as shown in  FIG. 3  may be approximately 23 mm ( 15/16 inch) in radius to the centers of the analysis chambers, and approximately 12 mm (½ inch) high. The amount of water used may be from 2.7 to 2.9 ml. The cartridge may be rotated at around 2300 rpm to distribute the water to the analysis chambers  120  and the reference chamber  124  and to expel bubbles, and then at a maximum of 4500 rpm to ensure proper transfer of the water from the filling chamber to the reaction chambers, and at 300 rpm to obtain the optimum pumping action from the agitators. The rotation is continued for a period sufficient to allow the reagents to become dissolved in the water, to react with their respective analytes, and for the color or other measurable optical property to develop. It is presently believed that an analysis of swimming pool water of acceptable quality can be obtained in less than a minute from when rotation starts. 
     It is contemplated that the cartridge my include indicia, such as a bar code, RFID tag, or other form of information that can be read, such as with a scanner or reader mounted in the analyzer, which determines the reagents that are stored in the cartridge being analyzed. This permits an analyzer to be used with multiple cartridges, without the user having to input anything. However, it is also contemplated that the user can select the sample being analyzed (e.g., pool water, water for beer brewing process, etc.) directly on the computer. The computer would use the information for purposes of selecting the appropriate data file for analyzing the sample data transmitted from the analyzer. 
     Referring now also to  FIG. 4 , an alternative embodiment of the cartridge  100 ′ is similar to that described above except that, in place of slot  128 , the analysis chamber  120  and the agitator chamber  122  are separated by a solid septum  132 , with apertures  134 ,  136 , at both ends. The cartridge  100 ′ may be used in the same way as the cartridge  100 . In use, movement of agitator  130  up and down within agitator chamber  122  causes liquid to flow in and out through apertures  134 ,  136  alternately, resulting in a reciprocating flow within analysis chamber  120 . The reciprocating flow causes turbulence within the analysis chamber  120  that assists in dissolution and distribution of the reagent. 
     Although specific embodiments have been described, various modifications are possible without departing from the spirit of the invention or the scope of the appended claims, and features of the different embodiments may be combined into one embodiment. 
     For example, although the agitators have been described as stainless steel ball bearings that are attracted to the magnets  84 ,  86 , the agitators could instead also be magnets. If the agitators are elongated so that they cannot rotate within their chambers, they could be magnetically polarized so as to be repelled, instead of attracted, by one or more of magnets  84 ,  86 . It is presently preferred to provide two magnets  84  and  86 , so that agitators are positively driven both up and down once per revolution. However, more magnets could be provided, or in some circumstances there could be only a single magnet driving the agitators upwards, with the agitators being, returned by gravity. 
     In the cartridges  100 ,  100 ′ shown in the drawings, the analysis chambers  120  and the reference chamber  122  are evenly spaced in a circle around the circumference of the cartridge. Other arrangements are possible. For example, there could be two concentric circles of analysis chambers. 
     The cartridge shown in  FIG. 3  is intended to be disposable, and may be fabricated by gluing or welding a generally fiat lid on a molded body. However, the cartridge could instead be reusable, in which case the lid may be removable to permit cleaning and recharging of the reagents in the analysis chambers. 
     It would be possible to omit the rotary encoder  64 , and use the signal from one or more of the LEDs and transducer pairs to provide a rotary encoder input to the processor  94 . However, because the reagents in the analysis chambers  120  will cause the signals from the transducers  76 ,  78 ,  80 ,  82  to vary, a dedicated encoder  64  may give more reliable, and more easily interpreted signals. 
     As shown in the drawings, the LEDs  68 ,  70 ,  72 ,  74 , the photoelectric transducers  76 ,  78 ,  80 ,  82 , the magnets  84 ,  86 , the cartridge analysis chambers  120 , the cartridge agitator chambers  112 , and the cartridge reference chamber  124  are all centered on a single rotational cylindrical surface centered on the axis of spindle  58 . Other arrangements are possible. For example the magnets and agitators could be on one cylinder, and the LEDs, analysis and reference chambers, and transducers could be on another cylinder of different radius. One or both of those cylindrical surfaces could instead be conical. The magnets  84 ,  86  do not need to be exactly aligned with the agitator chambers  122 , provided they are near enough to produce the desired motion of the agitators  130 . 
     While the analyzer is shown having a processor  94  mounted within it, it is also contemplated that all the processing may occur at the computer. Alternatively, the processor  94  can be programmed to provide all the analysis necessary and provide the results to the computer or other display device. 
     Furthermore, while the figures show the analyzer connected directly to the computer, it is contemplated that the connection could be through an interact connection, thus permitting samples to be run in the analyzer at a location that is remote from the computer than analyzes the data and provides the results. 
     Accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.