A reusable slide assembly for use in analysis with a microscope

Abstract: The invention relates to a reusable slide assembly for use in combination with an apparatus for drawing a fluid specimen sample for analysis from a sample tube into said slide assembly. Such apparatus and technique are used in urinalysis.

Description: Field Of The Invention This invention relates to a reusable slide assembly for use in combination with an apparatus for drawing a fluid specimen sample for analysis from a sample tube into said slide assembly. Such apparatus and technique are used in urinalysis. Background Of The Invention Systems and devices for urinalysis are extensively used and practices in clinics, laboratories and the like. With the increased presence of infectious diseases, such as AIDS, in biological materials, the need for safe systems and devices to minimize the handling of these potentially dangerous substances becomes evident. Urine sediment examination typically involves, as described in the U.S. Patents 4,393,466 and 4,612,614, pouring of a sample into a tube which is then spun in a centrifuge to separate the sediment from its suspending fluid. After centrifugation, the cleared suspending fluid is poured out and the sediment resuspended in the remaining fluid. A sample of the resuspended sample must then be transferred to a microscopic slide for examination with a microscope. Then '466 patent further describes a technique with which manual urine handling steps are eliminated and a video system is used to provide an electronic image of the urine specimen. A slide assembly is described which is shaped to provide a stable sample area where solid particles in the urine sample can be viewed. Various other types of urine or other fluid sample supply devices are shown and described in the art, see for example, U.S. Patents 4,302,421, 4,312,591, 4,367,043, 4,448,752, 4,836,038, 3,948,607, 4,209,256, and 4,271,123. U.S. Patent 4,804,267 to Walter Greenfield describes a urine sample analysing system. A peristaltic pump is used to alternately pull a urine sample or a flushing fluid through a slide assembly, also known as a flow cell. A video display system is employed to investigate solids in the sample. Problems encountered with conventional slide assemblies may involve too great a thickness of the test specimen so that the microscope, which usually has a very short focal length, tends to be focused at different focal planes of the test specimen. When the flow cell is made with plastic components through which either the microscope views the test sample or through which illuminating light passes, distortions tend to appear in the filed of view of the microscope. Frequently, cement may be used to attach flow cell components and this cement tends to be attacked by constituents in the urine and some cleaning fluids over extended uses leading to a disintegration of the slide assembly. Cement also tends to have tiny edges to which various undesirable contaminants become attached such as bacteria, molds, yeast and particles and are not readily dislodged by a flushing cycle. When the passageway into the viewing chamber of the slide assembly has relatively abrupt turns, tiny bubbles tend to form and are entrained into the viewing chamber where they obscure or confuse the clarity of the field of view of the microscope. Where cement/plastic plexiglass interfaces are exposed to air and heat from the condensed light source, dust particles are attracted and appear as other urine constituents such as bacteria, yeast, fibers, and mucus to the microscope operator when these interfaces also appear in the field of view. It is important that slide assemblies are sufficiently thin to enable mounting to any microscope without interference with different lenses of a microscope turret. It is also desirable that a slide assembly be useful with a variety of microscopic techniques such as the one commonly known as "bright field" and other techniques generally referred to as Hoffman modulation, phase contrast, polarized light and fluorescence. It is furthermore desirable that a relatively small amount of test fluid is used to fill a viewing chamber of a slide assembly so that more than one examination can be made with the same test fluid. The various known urinalysis systems tend to be complex and do not provide an inexpensive and convenient approach to the handling of urinalysis in laboratories where complex fully automated systems cannot easily, economically be justified. In the evaluation of urine, it is at first necessary to concentrate the solids in a centrifuge operation, but then the solids should be resuspended. In order to achieve a reasonably consistent basis for analysis, the resuspension preferably should be carried out with the same volume of urine. Summary Of The Invention With a slide assembly in accordance with the invention, a urine sediment analysis can be performed in a hygienic, efficient, and consistent manner while using an available standard upright microscope. This is achieved in accordance with the invention by using a slide assembly that can be irrigated with a flush solution and easily mounted on a microscope, and which can be used with a compact fluid control device with which a urine sample can be drawn by a pump from a urine collection tube through the slide assembly and subsequently flushed back into the tube with a flushing liquid. A plurality of urine samples can be rapidly and efficiently sampled in an efficient manner. A housing may be used which is provided with a plurality of special centrifuge tubes which are removably mounted for processing. A centrifuged urine sample containing tube is temporarily mounted at a test station where a probe is extended into the tube and into a solids collection chamber where solids have congregated and have been resuspended in a substantially constant volume. A control is then actuated with which a sample from the solids collection chamber is drawn up through the slide assembly of this invention to a place that is between it and said housing for the apparatus. Upon completion of the microscopic examination, the control is again actuated so that the pump can be reversed and flushing liquid pumped from the reservoir through the slide assembly into the centrifuge tube. With an apparatus used in conjunction with the slide assembly in accordance with the invention, manual exposure to body fluid samples is significantly reduced, a rapid handling and safe examination of samples can be achieved and consistent examination results are achieved. The reliability, versatility, and effectiveness of an apparatus for sampling and analysing a fluid sample is further enhanced by use of a slide assembly in accordance with the invention with which a urine sample can be drawn and subsequently conveniently viewed through a microscope. The slide assembly also known as a flow cell, is formed with an elongate optical glass enclosure. The enclosure has spaced-apart upper and lower sides which present substantially flat surfaces for examination of a urine sample drawn into a viewing chamber bounded by glass sides. The glass enclosure has aligned end-located ports so that the flow of urine does not encounter abrupt turns in the passage ways leading to the viewing chamber. The spacing between the flat sides is selected to provide a viewing chamber of even and optimum depth for microscope examination. A holder is employed to receive and retain the glass enclosure while presenting a sufficiently low profile so as to enable use of the slide assembly with most conventional microscopes. The holder has metal tubes at end-located edges for connection to the ports of the glass enclosure and to appropriate flexible tubing to facilitate handling and mounting of the slide assembly. With a slide assembly in accordance with the invention, problems encountered with other slide assemblies are avoided. It is an object of the invention to provide a slide assembly for use with a fluid examination apparatus and with which consistent microscope examinations can be carried out in a repetitive manner, with high reliability, in a safe manner, adaptable to various illuminating techniques such as phase contrast and Hoffman modulation, and useable with most microscopes at their respective magnification levels while using a small enough amount of test fluid to accommodate several examinations of the fluid from the same centrifuge tube. These and other objects and advantages of the invention can be understood from the following detailed description of the slide assembly in accordance with the invention and as illustrated in the drawings. Brief Description Of Drawings Figure 1 is a perspective view of a slide assembly in accordance with the invention; Figure 2 is an exploded perspective view of the slide assembly of Figure 1; Figure 3 is a top plan view of the slide assembly of Figure 1; Figure 4 is a bottom view of the slide assembly of Figure 1; Figure 5 is a partial enlarged section view of the slide assembly of Figure 1; and Figure 6 is a section view of the slide assembly of Figure 1 taken along the line 22-22 in Figure 5. Detailed Description of Drawings With reference to Figures 1-6, the preferred slide assembly 300 is shown formed of a transparent elongate optical glass enclosure 320 mounted to a metal slide support 322. The optical enclosure 320 is made from a preform glass extrusion with flat upper and lower transparent slide walls 324, 326 and sides 328, 330. The enclosure ends 332, 334 are formed into short tubes to provide end-located ports 336, 338 in alignment with an elongate-viewing chamber 340. The optical glass enclosure has an evenly thick capillary-sized viewing chamber 340 whose width, w, is commensurate with that needed to enable an optical examination of a fluid with microscope 72. The dimensions of the optical glass enclosure are selected commensurate with good viewing through a microscope into the fluid. This involves a thickness of each slide wall 324, 326 of about 0.017 cm (0.007 inches) ± ten percent and a thickness o the viewing chamber of about 0.013 cm (0.005 inches) ± five percent. The slide support 322 has a central elongate recess 350 in a midsection 351 and which is sized to freely yet snugly receive the elongate optical glass enclosure with its lower wall 326 facing the bottom 352 of recess 350. The ends 354 of recess 350 are shaped to receive ends 332, 334 of glass enclosure 324. Recess 350 has a cut-out 356 to allow light to pass through from below during microscope viewing. A pair of stainless steel tubes 360, 362 are mounted inside bores 363 formed in end 364 of holder 322 and serve to form a fluid flow connection with flexible tubings 32, 36. Flexible tubes 366, 368 are used to connect tubular ends 332 and 334 to stainless steel tubes 360, 362. The optical glass enclosure 324 is cemented in place inside recess 350 with the use of a suitable adhesive 366 as may be applied at ends 354 of recess 350. The end walls 364 protrude above the midsection 351 and spaced sufficiently far apart so as to avoid interference with a microscope focused on the viewing chamber. An important feature of slide assembly 300 is its useability on virtually most microscopes used in clinical laboratories where urinalysis is done. The maximum thickness profile, t, within the operational range of the microscope is, therefore, limited to as small as is reasonably practical. Generally, the thickness profile t is of the order of less than about three millimeters while still being able to draw a fluid sample from collection tube 22 and accommodate a flushing cycle as described. The depth of recess 350 is selected to receive most of the glass enclosure 320 with a small protrusion above the surface 370 of the central segment 372 of the holder 322 to enable a close approach of the slide assembly 300 by the lens of a microscope. Since some thickness increase is required at the ends 332, 334, the overall length L of the flat segment of the glass enclosure 320 is made sufficiently long to avoid interference between the microscope and the glass enclosure 320. This length may vary, but generally about one and a half inches has been found to be satisfactory. With a slide assembly 300, the operation of a urinalysis is considerably improved. The small volume of the viewing chamber 340, of the order of generally less than about thirty microliters, and the use of a small diameter bore for the flexible tube 32 limits the amount of fluid needed for a sample. With the alignment of the ports 336, 338 with the elongate viewing chamber, abrupt turns are avoided, thus reducing the formation of tiny bubbles and avoiding a lodging of particles and bacteria because these are now easier to flush out. By using glass extrusion for the enclosure 320, cement interfaces are avoided and microscope viewing is enhanced and various known illumination techniques can be used.

Claims: A reusable slide assembly (24, 300) for use in analysis with a microscope (72), comprising: an elongate transparent extruded glass seamless enclosure (320) having elongate upper and lower transparent planar walls (324, 326) which are spaced from each other to form an elongate viewing chamber (340) for use with a microscope (72), said elongate upper and lower transparent planar walls being spaced by a distance commensurate with a spacing as encountered between a cover slip and a glass slide used in conventional microscope analysis; said elongate transparent extruded glass seamless enclosure (320) terminating at opposite ends at first and second glass ports (336, 338) which are in longitudinal alignment with the elongate viewing chamber (340) to provide a smooth entry and exit of fluid to and from the elongate viewing chamber (340) and are an integral part of the glass enclosure (320); an elongate holder (322) having a midsection (351) on which the elongate transparent extruded glass seamless enclosure (320) is mounted with a said wall (326) facing the midsection, said holder midsection (351) further having a light passing opening (356) located in viewing alignment with the elongate viewing chamber (340) of the elongate transparent extruded glass seamless enclosure (320); said elongate holder (322) further having first and second tubes (366, 368) mounted to opposite ends of the holder (322) in general longitudinal alignment with the first and second glass ports (336, 338) of the elongate transparent extruded glass seamless enclosure (320) and being in fluid flow communication with said first and second glass ports (336, 338) of the elongate transparent extruded glass seamless enclosure (320). The reusable slide assembly as claimed in claim 1 wherein the reusable slide assembly has, at said viewing chamber (340), an overall thickness which extends over a desired length and is selected to enable said reusable slide reusable slide assembly to operate with most microscopes used in urinalysis. The reusable slide assembly as claimed in claim 2 wherein said overall thickness is of the order of less than about three millimeters. The reusable slide assembly as claimed in claim 3 wherein said midsection having an elongate recess (350) sized and shaped to freely and snugly receive said elongate glass enclosure (320); said midsection (351) having a slot (356) located in alignment with the viewing chamber (340) of the glass enclosure (320). The reusable slide assembly as claimed in claim 4 wherein said elongate holder (322) has end walls (364) extending above said midsection (351), said end walls being sufficiently spaced from each other to avoid interference with the operation of a microscope focused on the viewing chamber (340), said end walls (364) further having tubes (360, 362) extending therethrough which are in fluid flow communication with the ports (336, 338) of said glass enclosure (320) and with said tubing means (366, 368). The reusable slide assembly as claimed in claim 5 wherein the thickness profile of the midsection (351) and the glass enclosure (320) is less than about three millimeters. The reusable slide assembly as claimed in claim 4 wherein the depth of said midsection elongate recess (350) is selected so that the upper wall (324) of the glass enclosure (320) protrudes above the midsection (351).

Inventors: GREENFIELD WALTER, KEARNES EDWARD G, KEMBLE JAMES E, GREENFIELD, WALTER, KEARNES, EDWARD G., KEMBLE, JAMES E.
Applicants: DIASYS CORP, DIASYS CORPORATION
Application year: 1993
Main classification: G01N21
IPC codes: B01L3, G01N21, G01N1, G01N35, G02B21, G01N33