Analysis system

A multicuvette rotor assembly for use in a clinical chemistry analyzer of the centrifugal type includes a body member that defines a circumferential array of spaced radially extending recesses, with a divider member in each recess to define a first chamber and a second chamber radial outward from said first chamber; and a ring member that has a mating reference surface seated on an annular reference surface of the body member, with the inner peripheral surface of the ring member located outwardly of the middle of the second chambers. A circumferential array of first optical windows is bonded to the ring member, the lower surface of each first optical window being parallel to the mating reference surface; and a circumferential array of second optical windows is bonded to the base of the body member in alignment with the first optical windows such that each pair of opposed aligned surfaces of corresponding first and second optical windows are parallel to one another and define an optical path of precise and stable path length. A cover member has sealing surfaces that mate with the edges of the recesses of the base member and the inner peripheral lip of the ring member to provide a continuous seal of the recesses to retain reagent and sample material to be analyzed within the recesses.

This invention relates to analytical instruments and more particularly to 
multicuvette rotor assemblies for use in centrifugal analyzers of the 
photometric type, and to similar precision assemblies. 
Centrifugal analyzers are useful in performing kinetic and end point 
analyses. In general, such analyzers have utilized a multicuvette rotor 
assembly which has a plurality of radially disposed cuvettes that extend 
outwardly from a central hub with an annular series of inner chambers for 
initially holding a first group of reactants, an annular series of divider 
structures such as ramps, and an annular series of outer chambers for 
initially holding different reactants which are frequently unknown samples 
of blood or other biological fluid. A pair of spaced optical windows in 
each second or outer chamber defines an optical path of precise length for 
use in the photometric measurement. The rotor is usually driven at a 
preliminary fast speed in the vicinity of 3000-5000 rpm in which the 
reactant in each inner chamber flows over the divider and mixes with the 
reactant in the outer chamber, and then during a measurement run at speeds 
of approximately 1000 rpm. The temperature of the rotor is closely 
controlled as temperature affects reaction rates and light transmission 
characteristics change as reactions proceed. 
The most common use of such analyzers is in the determination of blood or 
blood plasma or serum components, and the chemistry procedures that are 
performed include but are not limited to analyses for glucose, 
cholesterol, creatinine, total protein, calcium, phosphorus, and enzymes. 
Several of the reagents used in such analyses are quite reactive, and 
therefore the rotor assembly must be corrosion resistant, as well as being 
well sealed. It is essential that the rotor have precise and stable 
dimensional accuracies to achieve the desired analysis accuracies, 
particularly where the cuvette volumes are small (in the order of 
microliters). Prior art multicuvette rotors in general have been either 
relatively complex assemblies that are expensive to manufacture and 
difficult to clean, or disposable (single use) rotors. 
In accordance with the invention there is provided a multicuvette rotor for 
use in an analytical system of the centrifugal type that includes a body 
member in which a circumferential array of upwardly open cuvette recesses 
are defined, with divider structure in each cuvette recess such that each 
recess defines a first chamber and a second chamber radially outward from 
the first chamber. Around the periphery of the body member are a series of 
radially extending reference surface areas and seated in face-to-face 
contact on those reference surfaces are corresponding reference surface 
areas of a ring member such that the ring member overlies outer portions 
of the second chambers with its inner peripheral edge located outwardly of 
the middle of the second chambers. The ring member includes a 
circumferential array of first optical windows, the lower surfaces of 
which are parallel to the reference surface areas of the ring. A 
corresponding series of second optical windows are in the floors of the 
second chamber portions of the cuvette recesses, with the upper surface of 
each second optical window parallel to the reference surface areas of the 
body member. The two series of optical windows are in alignment with one 
another so that there is defined in each second chamber an optical path of 
precise and stable path length between two parallel optical surfaces. A 
removable cover member has relatively soft conforming sealing surfaces 
that are adapted to overlie the walls of the cuvette recesses and the 
inner peripheral edge of the ring member and to sealingly enclose the 
individual cuvette chambers. 
In accordance with another aspect of the invention, there is provided a 
bonding system in which reference surfaces of components to be bonded are 
in direct contact with one another, and a channel of capillary dimension 
(preferably less than 0.3 millimeter in width) is provided between the 
components to be bonded. A reservoir connected to the capillary channel 
receives a flowable bonding agent which has viscosity and surface tension 
characteristics such that the bonding agent flows from the reservoir into 
the capillary channel and fills but does not flow out of that channel. The 
bonding agent, preferably an epoxy resin provides a continuous sturdy, 
pore-free bond with a smooth, leak tight surface of excellent corrosion 
resistance. 
In a preferred embodiment, there is provided an analysis cuvette assembly 
for use in an analytical system that comprises two members arranged to 
define an analytical chamber therebetween. Each member has a planar 
reference surface and those reference surfaces are in direct and mating 
engagement. A flowable bonding agent in a capillary channel between the 
two members provides a smooth surface of sturdy bond. Each chamber member 
also has an aperture in which there is a support surface parallel to and 
offset a predetermined distance from the reference surface of that member, 
and an optical window is seated on the support surface in each aperture 
such that its upper surface is offset at predetermined distance from the 
reference surface, and an annular channel of capillary dimension is 
defined between its peripheral surface and the adjacent aperture surface. 
A flowable bonding agent in that annular channel sets to provide a 
continuous and sturdy bond that secures each optical window in its 
aperture with the opposed surfaces of the optical windows being parallel 
to one another and defining an optical path of precise and stable path 
length. 
In a particular embodiment both the body member and the ring member of a 
multicuvette rotor have seat areas on which optical windows of Pyrex glass 
are seated for accurate positioning. A capillary channel extends around 
the periphery of each optical window with a reservoir well immediately 
adjacent and in communication with the capillary channel. The base member 
has an annular aligning recess in which the ring member is seated such 
that the upper surface at the ring lies in the same plane as the upper 
surface of the body. Recesses in the ring member define capillary channel 
areas around the outer edges of the second cuvette chambers with reservoir 
apertures in communication with those channels. Epoxy resin bonding agents 
deposited in each reservoir flow from the reservoirs and fill the channels 
by capillary action to bond the optical windows to the base and ring 
members and to bond the base and ring members together. 
The cuvette chambers of this reusable multicuvette rotor for a centrifugal 
analyzer are reliably sealed with a common cover member and are easily 
accessible for thorough cleaning. The epoxy bonding material fills 
crevices between the body and ring members and the optical windows and 
those members to provide smooth, easily cleaned surfaces. The ring and 
body members and the bonding agents are resistant to chemical attack from 
the reagents used in the chemical analysis and withstand the centrifugal 
forces to which the rotor is subjected during mixing and analysis 
sequences. The optical windows and the body ring members have a series of 
planar reference surfaces that are in direct mating contact with one 
another such that dimensionally accurate optical paths of the same length 
are defined in the circumferential array of cuvette chambers.

DESCRIPTION OF TICULAR EMBODIMENT 
The rotor assembly 10 shown in FIGS. 1 and 2 has a diameter of about ten 
centimeters and an overall height (not including pilot posts 12) of about 
1.2 centimeters. The rotor assembly includes a base member 14 which has a 
hub portion 16 in which is formed a generally D-shaped opening 18; a ring 
member 20 that is seated and bonded to an annular recess at the outer 
periphery of base member 14; and a removable cover assembly 22 that 
includes a gasket 24 bonded to pressure plate 26. Cover assembly 22 has 
radially extending tabs 28 that are piloted on pilot posts 12. 
As indicated in FIGS. 1-3, a circumferential array of twenty radially 
extending cuvette chambers 30 is formed in base member 14. Each cuvette 
chamber has a maximum capacity of about 400 microliters, a width of 
slightly less than 1/2 centimeter between side walls 32, 34, a length of 
about 31/2 centimeters between curved inner wall 36 and outer wall 38, and 
a planar bottom surface 40. In each cuvette 30 is ramp structure 42 that 
has a radial length of about six millimeters and a height of about four 
millimeters and divides the cuvette 30 into an inner chamber 44 and an 
outer chamber 46. Adjacent the outer end of the bottom wall of each 
chamber 46 is circular opening 48 in which a Pyrex glass window 50 is 
seated and bonded. Body member 14 is made of a suitable dimensionally 
stable, corrosion resistant material such as titanium, stainless steel, 
diallylphthlate or an epoxy resin. 
Adjacent cuvettes 30 are interconnected by triangular-shaped webs 52 that 
extend to annular rim portion 54. As indicated in FIGS. 3 and 4, two pilot 
holes 55 are in rim 54. An annular recess 56 (about 11/2 millimeters in 
depth and about one centimeter in radial width) is located at the outer 
periphery of base 14 and has a vertical surface 58 and a planar seating 
surface 60. 
Seated in, and bonded to surfaces 58, 60 of recess 56 is ring 20 (FIG. 5) 
that is preferrably although not necessarily manufactured of the same 
material as base 14. Ring 20 has an internal diameter of about 81/4 
centimeters, an external diameter of about ten centimeters, and a 
thickness of about 11/2 millimeters. When ring 20 is seated in recess 56, 
there is a gap between the inner peripheral surface 62 of ring 20 and 
vertical recess surfaces 58 that is about 0.1 millimeter in width. Ring 20 
has twenty equally spaced circular openings 64 in which a Pyrex or quartz 
window 66 is seated and bonded. Formed in the lower surface of ring 20 at 
each opening 64 is a recess defined by planar surface 67 and bounding side 
walls 68 that has a depth of about 0.2 millimeter and a width of about 
eight millimeters. The land surfaces 70 between recess side walls 68 seat 
in direct contact with surfaces 60 of the base when ring 20 is assembled 
on base 14. 
Cover 22 (FIG. 6) includes a stainless steel pressure plate 26 that has an 
outer diameter of about nine centimeters, a central opening 80 of about 
three centimeters in diameter and tabs 28, each of which has a pilot 
aperture 88. Bonded to pressure plate 26 is a silicone rubber gasket 24 
(of about ten durometer ShoreA) in which is formed rectangular smooth 
surfaced seal regions 90, each of which has a width of about six 
millimeters and projects above adjacent triangular recesses 92 about 1/2 
millimeter. 
Each Pyrex window 50, 66 is bonded to its support member (base 14 or ring 
20) in similar manner. With reference to FIG. 8, each window 50, 66 has a 
diameter of five millimeters and a thickness of one millimeter. Each 
opening 48 in base 14 and each opening 64 in ring 20 has a diameter of 
about 4.7 millimeters. Cylindrical surface 100, concentric with opening 48 
(64), is about 5.1 millimeters in diameter and defines a planar support 
lip surface 102. A second concentric cylindrical surface 104 (of about 5.5 
millimeters diameter and about 1/2 millimeter height) extends downwardly 
from floor 40 of chamber 46 (or surface 70 of ring 20). Each window 50, 66 
is seated on support lip 102 and centered by cylindrical wall 100 so that 
an annular capillary channel about 1/4 millimeter in width is defined by 
the peripheral surface 110 of window 50 (66) and cylindrical wall 104. A 
semi-circular well or reservoir 112 having a depth of about 0.4 millimeter 
communicates with that capillary channel. 
A suitable epoxy resin (e.g. Ren RP-4015) is used to bond windows 50, 66 to 
base 14 and ring 20. Each window is loaded into a corresponding opening 
48, 64 with a vacuum pick up pencil assembly so that it is seated on the 
reference surface of support lip 102. Reservoir well 112 is filled with 
epoxy using a syringe and the epoxy is allowed to flow around the annular 
capillary channel. The base 14 or ring 20, as the case may be, is 
transferred to a heating surface set at about 130.degree. F. which lowers 
the viscosity of the epoxy so that it flows more easily. Well 112 is 
filled again with the epoxy sealant (taking care not to fill above the 
glass surface) until the annular capillary channel is completely filled 
with epoxy as indicated in FIGS. 11-13. The unit with its twenty epoxy 
bonded windows (after curing) has bond surfaces that are smooth and 
corrosion resistant, with the interior surface 122, 124 of each optical 
window precisely located relative to its reference lip surface 102, free 
of epoxy and easily cleaned. 
After windows 50, 66 have been epoxy bonded to base 14 and ring 20 
respectively, ring 20 is piloted onto base 14 by depending pilot pins 76 
(FIG. 7) and pilot holes 52, with ring surfaces 70 seated on reference 
surfaces 60 of the annular recess 56. In that position, windows 66 are in 
proper alignment with windows 50, and the length of the optical path 120 
between the adjacent surfaces 122, 124 of windows 50, 66 is established 
with precision due to the direct seating of the four components of the 
optical array of accurately dimensioned reference surfaces 60, 70, and 
102, and the accurately dimensioned thickness of optical discs 50, 66. 
After ring 20 is clamped on base 14, a suitable epoxy resin (e.g., 
Formulated Resins PR-2020) is dispensed with a syringe, first filling the 
two (1.5 millimeter diameter) inner reservoir holes 126 adjacent each 
aperture 64, then filling the outer reservoir holes 128, the epoxy flowing 
into the 0.2 millimeter wide capillary channel at the outer periphery 
between base recess surface 60 and ring recess surface 67 between edge 
surfaces 68. The epoxy resin flows through the capillary channels as 
indicated in FIG. 11, the reservoir holes 126, 128 being refilled as 
necessary so that the capillary channels are completely filled. Epoxy 
resin is also flowed into the vertical channel gaps between base recess 
surface 58 and the inner peripheral surface 62 of the ring and into the 
peripheral 0.2 millimeter channel regions (twenty places) around the rim 
of the rotor. In this condition a continuous seal of epoxy fills the 
capillary channels between the base 14 and ring 20, as indicated by 
stippling in FIG. 11, to provide a seal at the outer end of each chamber 
46. The epoxy resin seals are then allowed to completely cure. 
Thus, an optical path 120 of accurately defined length between windows 50 
and 66 is defined at the outer end of each of the twenty reaction chambers 
46 with the ring structure 20 extending inwardly less than 1/2 the length 
of reaction chamber 46 as shown in FIGS. 2 and 15. 
In use, each cuvette chamber 44, 46 is loaded with appropriate reagent and 
sample materials in conventional manner, and then cover 22 is seated on 
the rotor body with upstanding pilot post portion 74 engaging cover 
apertures 88 to properly locate gasket sealing surfaces 90 over the 
margins of the open tops of the cuvettes as shown in FIG. 2. The covered 
rotor is then placed on the rotor drive 130 of the centrifugal analyzer as 
shown in FIG. 16 and secured in place with flanged aluminum seal nut 132 
that has a threaded stub shaft 134 that is received into threaded recess 
136 in the rotor drive 130. Annular lands 138, 140 seat on pressure plate 
26 and concentrate clamping pressure at the inner and outer margins of the 
gasket seal areas 90. Torque wrench 142 has pins 144 which engage recesses 
146 in seal nut 132. Rotation of wrench 142 by means of handle 148 torques 
cover 22 to seal the cuvette chambers with a force of about fifteen inch 
pounds. The handle 148 is then removed. 
The analytical sequence is then initiated with the rotor being accelerated 
to 4000 rpm during a preliminary run to flow reactant materials contained 
in the inner compartments 44 outwardly across ramps 42 into the outer 
compartments 46 for mixing. The rotational speed of the rotor is then 
reduced and photometric measurements are made along the optical axis 150. 
After the analyses have been completed, the rotor assembly is removed from 
the centrifugal analyzer for cleaning. After cover assembly 22 is removed, 
the open cuvette chambers 30 in the body assembly are readily accessible 
for cleaning and drying. In a manual cleaning procedure, cover 22 is 
removed, and rinsed with denatured alcohol and distilled water. All of the 
cavity chambers 44 and 46 of the rotor body are flooded with a free flow 
of distilled water. During this flooding, a lateral motion of the rotor 
forces water up into the ends of the cuvette chambers 46. Shaking the 
rotor removes water from the cuvette chambers. The chambers are then 
flooded with denatured alcohol using a squeeze bottle and the denatured 
alcohol removed from the rotor by shaking. For a final rinse, the chambers 
are again flooded with distilled water. Using an air supply with a 
secondary filtration system and an air pressure of about 7-10 psi, an air 
nozzle is directed into the cuvettes to remove water and to dry the window 
surfaces and other inside surfaces of the cuvette chambers. If necessary, 
the optical windows may be lightly wiped, using techniques conventional 
for optical surfaces. An optional further drying step is to place the 
rotor body and cover assembly components in a non-recirculating type oven 
preset at a temperature of about 50.degree. C. for about one-half hour. 
After drying, the rotor components are placed in dust free storage 
compartments. 
The invention provides an improved, reusable, multicuvette analytical rotor 
assembly whose optical path length is accurately maintained which is 
suitable for use in precision clinical analysis and which is resistant to 
chemical attack from chemical reagents that range from strong acids (such 
as used in a phosphorus analysis), and strong bases (such as are used in 
total protein and creatinine analysis). The bonding agents have sufficient 
bond strength to withstand the centrifugal forces to which the rotor is 
subjected, chemical attack from the reagent materials and the cleaning 
operation. The rotor is capable of sealing and analyzing sample volumes of 
3-90 microliters size range, is compact, is easily loaded with reagent and 
sample materials, and is easily cleaned for reuse. 
While a particular embodiment of the invention has been shown and 
described, various modifications thereof will be apparent to those skilled 
in the art, and therefore it is not intended that the invention be limited 
to the disclosed embodiment or to details thereof and departures may be 
made therefrom within the spirit and scope of the invention.