A sheath flow type flow-cell device

Abstract: A sheath flow type flow-cell device (1) for photo-particle-analyzer comprises a substantially flat top surface (2), at least one first inlet (3) for sheath fluid (4), at least one first flow passage (5) communicated with the at least one first inlet and contracted toward downstream to be a straight capillary flow passage (6), a discharge port (7) provided at a terminal end of the straight capillary flow passage, a second inlet (8) for sample fluid (9), a second flow passage (10) for sample fluid communicated with the second inlet and contracted toward downstream, and coupling portions (13) for sealingly coupling with the particle photo-analyzer. The second flow passage is opened within the at least one first flow passage so as to keep a part of the at least one first flow passage above and below an opening (12) of the second flow passage. The opening is faced in the same direction as the straight capillary flow passage. A wall portion (15) on which the opening locates is rounded. The wall portion is further chamfered and a pair of projections (18) are extended from the wall portion.

Description: BACKGROUND OF THE INVENTION The invention relates a sheath flow type flow-cell device for photo-particle-analyzers in which fluid carrying particles is made to flow in a capillary flow passage and a light beam is applied thereto and particle analysis is effected on the basis of the strength of the scattering light and/or fluorescence from the particles and further relates to a photo-cell-analyzer and a photo-particle-detector using the flow-cell device. Heretofore, in order to measure the number, kind, size or shape of particles such as blood cells, photo-particle-analyzers have been used in which fluid carrying particles is made to flow in a capillary flow passage and a light beam is applied thereto and on the basis of the strength of the scattering light and/or fluorescence from the particles, cell analysis, count of particles or the like is effected. In the cell analysis ground, such photo-particle-analyzer is called a flow-cytometer. An example of the flow-cytometer is shown in SCIENCE, vol. 150, pages 630-631, 1965. The flow-cell device in the flow-cytometer, as shown in Figs. 23 and 24, includes a thin bowtie-shaped flow passage. Only suspension of cells is made to flow in the flow passage. Therefore, the flow-cell device has often been clogged during use. In order to solve the above-mentioned drawback, one method has been disclosed in U.S. Patent No. 3,873,204. In the method, the suspension of cells (fluid carrying particles) is made to flow together with a physiological salt solution (a sheath fluid) in such a manner that the suspention of cells is surrounded by the physiological salt solution. This method is called as a sheath flow method. The sheath flow method is widely used in cell analyzers as an effective means. In the flow-cell device, a capillary flow passage is formed by a cylindrical glass tube. Therefore, the thickness of the flow-cell device becomes large. Moreover, the entrance portion of the glass tube is made to a funnel shape in order to provide for smooth non-turbulent flow of the fluid at the capillary flow passage, so that the capillary flow passage is made long, for example abut 30mm, in order to avoid and interference between the objective lens and the funnel-shaped portion of the. glass tube. In general, the diameter of the capillary flow passage is made about 300 x 10⁻⁶m. Therefore, as the length of the capillary flow passage is made longer, the pressure loss becomes greater. Accordingly, the flow-cell device requires pump units having large capacity and a glass tube, piping and the like having high pressure resistance. This makes the flow-cell device itself and the photo-analyzer using the flow-cell device larger. Moreover, as the flow-cell device is made by glass tubes, it is difficult to make the flow-cell device precisely. Another sheath flow method has also been proposed in Review of Scientific Instruments, Vol. 46, No. 8, pages 1021-1024, August 1975. In the method, the flow-cell device having two flow passages for sheath fluid is used. In the flow-cell device, a first sheath fluid is made to flow in the conical-shaped first flow passage so as to surround sample fluid and a second sheath fluid is made to flow in the conical-shaped second flow passage provided at the circumference of the first flow passage. The flow-cell device can make the flow of the sample fluid stabler but it has also the above-described drawbacks. EP-A-0 163 206 discloses a further device for measuring certain properties of particles suspendend in a carrier medium. In particular, this document discloses multi-channel injectors constructed by "planar technique". The essential structural elements such as cavities and ducts in the region where various ducts and fluids are joined, are recessed into a plane glass or plastic surface. The measuring aperture as well as the measuring zone are sinked into a planar material such as plexiglass plates by milling or etching and then covered by another plate, such as a glass plate, which is glued or clamped to the adjacent plate. Another example of a flow-cytometer is disclosed in Review of Scientific Instruments, Vol. 55, No. 9, page 1381. In the article, rectangular channels for use in flow chambers with sheath flow are mentioned. Also, square capillary tubes for use in commercial flow cytometers are discussed. These small diameter fluid columns are illuminated by laser light which is scattered towards a fluorescence microscope objective lens. In particular square, rectangular and triangular nozzle designs for generating plane liquid surfaces for resolving X and Y populations in sperm are discussed. Biophysical Journal, Volume 23, 1978, pages 7 - 13 discusses hydrodynamic orientation of sperm heads for flow cytometry. Flat-shaped mature sperm heads are oriented in a flow cytometer. This orientation allows control of a photometric difficulty experienced with some flow cytometers in the measurement of fluorescent and scattered light from sperm and other flat cells. A wedge-shaped tube is positioned inside a standard sample tube. The resulting change in flow conditions causes the formation of a thin, ribbon-shaped cell stream and a corresponding orientation of sperm heads in the plane defined by the flow axis and the two tips of the wedge-shaped tube. SUMMARY OF THE INVENTION An object of the invention is to provide a sheath flow type flow-cell device for photo-particle-analyzers which can reduce the pressure loss in the capillary flow passage to thereby make the fluid feeding system of the photo-particle-analyzers in low pressure specification and which enables adjustment of the stream position. Another object of the invention is to provide a sheath flow type flow-cell device which can be produced easily and precisely to thereby make the flow of the sample fluid stable. Further another object of the invention is to provide a photo-cell-analyzer and a photo-particle-detector of which fluid feeding systems are low pressure specification and which are compact in size. These objects are achieved by the technical teachings of claims 1, 10 and 12, respectively. A sheath flow type flow-cell device for photo-particle-analyzer according to the invention comprises the features defined in claim 1. A photo-cell-analyzer according to the invention comprises the features defined in claim 10. A photo-particle-detector according to the invention comprises the features defined in claim 12. BRIEF DESCRIPTION OF THE DRAWINGS Fig 1 is a schematic perspective view of an embodiment of a sheath flow type flow-cell device according to the invention of which top portion is omitted in order to show the interior thereof; Fig. 2A is a sectional side view of the flowcell device taken along line II-II in Fig. 1; Fig. 2B is a sectional side view of a modification of the embodiment shown in Fig. 2A. Fig. 3 is an enlarged perspective view of a portion A in Fig. 1; Figs. 4-6 are schematic plan views showing flow condition in a capillary flow passage; Figs. 7-9 are schematic perspecective views showing a wall portion on which the second flow passage is opened; Fig. 10 is a perspective view of a pair of projections provided on the wall portion; Fig. 11 is a plan view of the projections; Fig. 12 is a front view of the projections; Fig. 13 is a schematic side view of the projections for explaining an effective length of the projections; Fig. 14, 15 deleted Fig. 16 is a perspective view of other embodiment of the flow-cell device according to the invention which is opened to explain the structure thereof; Fig. 17 is a perspective view of other embodiment of the flow-cell device according to the invention; Fig. 18 is a perspective view of other embodiment of the flow-cell device according to the invention; Fig. 19 is a schematic side view of the flow-cell device in Fig. 18; Fig. 20 is a schematic perspective view of a photo-cell-analyzer without the features of the invention; Fig. 21 is a schematic perspective view of a photo-particle-detector without the features of the invention; Fig. 22 is a schematic plan view of a part of the photo-cell-analyzer in Fig. 20 or the photo-particle-detector in Fig. 21 according to the invention; Fig. 23 is a perspective view of a prior art flow-cell device; Fig. 24 is a side view of a prior art photo-cell-analyzer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Sheath flow type flow-cell devices according to the invention will be explained with reference to Figs. 1-19. Figs. 1-3 show an embodiment of the sheath flow type flow-cell devices of the invention and a top portion of the flow-cell device 1 is made of a plate-like shape of which top surface 2 is substantially made flat. Two inlets 3 for sheath fluid 4 are provided on the lower side of the flow-cell device 1 and two flow passages 5 are communicated with the two inlets 3, respectively. The flow passages 5 are contracted toward downstream thereof and joined to be a straight capillary flow passage 6. In the embodiment shown in Fig. 2A, the flow passages 5 are contracted in the widthwise direction while in a modification shown in Fig. 2B, the flow passage 5 are contracted also in the heightwise direction. A top and a bottom side of the straight capillary flow passage 6 are transparent. The flow passages 5 and the capillary flow passage 6 have a substantially rectangular cross section. At a terminal end of the capillary flow passage 6, a discharge port 7 is provided. An inlet 8 for sample fluid 9 such as suspension of cells is provided between the two inlets 3 and on the lower side of the flow-cell device. A flow passage 10 is communicated with the inlet 8 and contracted toward downstream thereof. The flow passage 10 also has a substantially rectangular cross section. The flow passage 10 is opened within a junction 11 of the flow passages 5 for sheath fluid so as to keep a part of the flow passages 5 above and below an opening 12 thereof. The opening 12 is faced in the same direction as the straight capillary flow passage 6. Coupling portions 13 for sealingly coupling the flow-cell device 1 to a photo-particle-analyzer using the flow-cell device are respectively provided at the inlets 3, 8 and the discharge port 7. The sheath fluid 4 such as physiological salt solution is introduced in the flow-cell device 1 from the two inlets 3. The sheath fluid 4 is contracted in the flow passages 5 and flows into the straight capillary flow passage 6 in a laminar flow condition. The sample fluid 9 is introduced into the flow-cell device 1 from the inlet 8. The sample fluid 9 is also contracted in the flow passage 10 and flows into the junction 11 of the flow passages 5. As a part of flow passages 5 is left above and below the opening 12, the sample fluid 9 is surrounded by the sheath fluid 4 from the above and below in addition to the right and left direction and in the straight capillary flow passage 6, the sample fluid 9 flows in a thin stream 14 at the center of the cross section of the capillary flow passage 6. As the thin stream 14 is a laminar flow, particles carried in the sample fluid 4, for example the cells in the suspension, flow one by one. A light beam from a light source not shown is applied on the sample fluid 9 in the thin stream 14 from below the flow-cell device and scattering light and/or fluorescence caused by the particles in the sample fluid is collected from an objective lens and the particle analysis is effected on the basis of the scattering light and/or fluorescence. The sheath fluid 4 surrounding the sample fluid 9 passed through the capillary flow passage 6 is discharged from the discharge port 7. Then, a relation between a wall portion 15 on which the opening 12 is located and a stability of the flow of the sample fluid 9 will be explained with reference to Figs. 4-13. Figs. 4-6 show flow conditions of the sample fluid 9 in a case where corners 16 are provided on the wall portion 15 and Fig. 4 shows a flow condition of the sample fluid 9 of which flow rate is small; Fig. 5 shows a flow condition of the sample fluid 9 of which flow rate is middle; Fig. 6 shows a flow condition of the sample fluid 9 of which flow rate is large. As shown in Fig. 4, the sample fluid 9 flows stably when the flow rate is small. As shown in Fig. 5, when the flow rate is middle, the sample fluid 9 spreads its width of the stream after flowing out the opening 12 but contracts its width promptly to flow in stable laminar flow. As shown in Fig. 6, when the flow rate is large, a wake 17 is occurred at the corners 16 and the sample fluid 9 cannot flow stably. A limit on which the flow of the sample fluid is a stable laminar flow is referred as a stable limit. It is necessary to make the stable limit large in order to analyze the sample fluid speedily. Figs. 7-9 show modifications of the wall portion 15 to increase the stable limit. In a modification shown in Fig. 7, the wall portion 15 is rounded and there is no corner resulting the wake 17, so that the stable limit is increased. In a modification shown in Fig. 8, the wall portion 15 is rounded and moreover chamfered. On account of chamfering the wall portion 15, the sheath fluid 4 can easily flow into the upper and lower sides of the stream of the sample fluid 9 in laminar flow, so that the stable limit is further increased. In a modification shown in Fig. 9, a pair of tapered projections 18 are provided on the wall portion. As the tapered projections guide the sample fluid 9 flowing out of the flow passage 10, the sample fluid 9 becomes a flat and stable stream just at the opening 12, so that the stable limit is further increased. Figs. 10-13 show a modification of the projections 18. A pair of plate-like projections 18 are extended from the wall portion 15 in the flow direction of the sample fluid 9. As shown in the drawings, clearances exist above and below the projections. Therefore, it is improved for the sheath fluid to flow above and below the flow of the sample fluid 9, so that the stable limit is further increased and the stream of the sample fluid becomes flatter. The flat stream of the sample fluid is preferable to the blood cell analysis, since flat cells such as red blood cells are aligned in the same attitude to be made to flow. In Fig. 13, the character L denotes the height of the clearances. In the cell analysis, it is preferable that the height of clearances is 100-500 µm and a ratio of L/H is five and over. According to the embodiment including the modifications, as the top surface of the flow-cell device is made substantially flat, the interference between the flow-cell device and the objective lens can be avoided and it is possible to locate the focus of the objective lens on a place where the thin and stable stream of the sample fluid is just formed by the capillary flow passage. Accordingly, it is not necessary to lengthen the capillary flow passage like the prior art flow-cell devices and the length of the capillary flow passage of the invention may be a necessary minimum length As a great part of the pressure loss in the flow-cell device is resulted from the capillary flow passage, the shorter the length of the capillary flow passage becomes, the smaller the pressure loss becomes. Practically, the length of the capillary flow passage of the embodiment may be 2-3mm and therefore the pressure loss is reduced to the degree of 1/10 of the prior art. This enables the capacity of the pumps for feeding the sample fluid and the sheath fluid to become small and the strength of the pressure resistance of the flow system to become small and further the photo-particle-analyzer to become small. Fig. 20 shows a photo-cell-analyzer without the features of the invention. The photo-cell-analyzer comprises a flow system and an optical system. The flow system comprises a first pump 31 for feeding a suspension of cells 44, a diluting apparatus 32 for diluting the suspension of cells 44 and connected to the first pump 31, a dyeing apparatus 33 for dyeing the suspension of cells 44 and connected to the diluting apparatus 32, a second pump 35 for feeding a sheath fluid 4, a flow-cell device 1. In the embodiment, the flow-cell device shown in Fig. 1 with the projections shown in Fig. 10 is used. The two inlets 3 of the flow-cell device 1 are connected to the second pump 35 and the inlet 8 is connected to the dyeing apparatus 33. The suspension of cells 44 is fed to the inlet 8 of the flow-cell device 1 to be made to flow in the capillary flow passage 6 in laminar flow condition. The cells in the suspension 44 flow one by one with aligned in the same attitude in the capillary flow passage 6. The sheath fluid 4 is fed by the second pump 35 to the inlets 3 of the flow-cell device 1 and surrounds the suspension of cells 44 to flow in the capillary flow passage 6. The optical system comprises a light source 36 for emitting a light beam 46, a condenser lens 37 disposed between the light source 36 and the flow-cell device 1, an objective lens 38 disposed on a side of the substantially flat top surface of the flow-cell device 1, a half mirror 39, a first photo-detector 40, a second photo-detector 41, and a signal processor 42 connected to the first and second photo-detectors. The condenser lens 37 applies the light beam 46 on the cells flowing in the capillary flow passage 6 and the objective lens 38 collects scattering light and fluorescence caused by the cells. The half mirror 39 separates the scattering light 43 from the fluorescence 47. The first photo-detector 40 detects the scattering light 43 to convert into electric signals. The second photo-detector 41 detects the fluorescence to convert into electric signals. The signal processor 42 conducts the cell-analysis from the electric signals. The photo-cell-analyzer may include a hemolysis apparatus 34 arranged between the dyeing apparatus 33 and the inlet 8 of the flow-cell device 1. In such a case, the piping between the dyeing apparatus 33 and the inlet 8 is closed. As the flow-cell device 1 can reduce the pressure loss, the elements used in the flow system such as the first and second pumps 31, 35 can be low-pressure specification. Accordingly, the photo-cell-analyzer can be a compact size. Fig. 21 shows a photo-particle-detector without the features of the invention. The photo-particle-detector comprises a flow system and an optical system. The flow system comprises a feeding apparatus 48 for feeding fluid carrying particles 8, a pump 35 for feeding sheath fluid and a flow-cell device 1. In the embodiment, the flow-cell device shown in Fig. 1 with projections shown in Fig. 10 is used. The feeding apparatus 48 is connected to the inlet 8 of the flow-cell device 1 and the pump 35 is connected to the inlets 3 of the flow-cell device 1. The fluid carrying particles 50 is fed to the inlet 8 of the flow-cell device 1 to be made to flow in the capillary flow passage 6 in laminar flow condition. The particles in the fluid 50 flow one by one with aligned in the same attitude in the capillary flow passage 6. The sheath fluid 4 is fed by the pump 35 to the inlets 3 of the flow-cell device and surrounds the fluid carrying particles to flow in the capillary flow passage 6. The optical system comprises a light source 36 for emitting a light beam 46, a condenser lens 37 disposed between the light source 36 and the flow-cell device 1, an objective lens 38 disposed on a side of the top surface of the flow-cell device 1, a photo-detector 40, and a signal processor 49 connected to the photo-detector 40. The condenser lens 37 applies the light beam 46 on the particles flowing in the capillary flow passage 6 and the objective lens 38 collects scattering light caused by the particles. The photo-detector 40 detects the scattering light 43 to convert into electric signals. The signal processor 49 detects the number of the particles from the electric signals. In a case where the photo-particle-detector is used as a dust counter for air, the fluid carrying particles 50 may be air and the sheath fluid 4 may be clean air. In a case where the photo-particle-detector is used as a dust counter for water, the fluid carrying particles may be water and the sheath fluid may be pure water or clean air. As the flow-cell device 1 can reduce the pressure loss, the elements used in the flow system such as pumps 35 can be low-pressure specification. Accordingly, the photo-particle-detector can be a compact size. Fig. 22 shows the modification of the flow system of the photo-cell-analyzer shown in Fig. 20 or the photo-particle-detector shown in Fig. 21 according to the invention. The flow-cell device 1 has the same structure as the embodiment shown in Fig. 1. A pressure controller 51 is provided between the pump 35 and the inlet 3a of the flow-cell device 1 and another pressure controller 52 is provided between the pump 35 and the inlet 3b of the flow-cell device 1. In the previously described embodiments, the pressure of the sheath fluid flowing into one inlet 3a and the pressure of the sheath fluid flowing into the other inlet 3b are identical with each other. In the present modification, the pressure of the sheath fluid flowing into each of the inlets is adjustable. In Fig. 22, the pressure of the sheath fluid flowing into the inlet 3a is made lower than the sheath fluid flowing into the other inlet 3b, so that the stream 14 of the fluid carrying particles is shifted to a side of the sheath fluid flowing from the inlet 3a. On account of the structure, it becomes possible to adjust the position of the stream of the fluid carrying particles in the capillary flow passage 6. This characteristic is useful for the photo-particle-detector and the photo-cell-analyzer, since when the position of the light beam is shifted from the stream of the fluid carrying particles by any cause, it is easily possible to locate the stream of the fluid carrying particles on the light beam by adjusting the pressure of the sheath fluid of each of the inlets 3a, 3b.

Claims: A sheath flow type flow-cell device for a photo-particle-analyzer comprising a substantially flat outer top surface (2) facing to an objective lens of said photo-particle-analyzer, two first rectangular crosssection flow passages (5) for sheath fluid (4) merging at their downstream ends and contracting in crosssection in the downstream direction to become a straight rectangular crossection capillary flow passage (6), a first inlet (3a, 3b) for sheath fluid provided at the upstream end of each said flow passage (5), a discharge port (7) provided at the downstream end of said straight capillary flow passage (6), a second flow passage (10) for sample fluid (9) contracting in the downstream direction to end in an opening (12) at a side wall at the junction of the two first flow passages (5), said opening (12) being spaced from the inner top and bottom surfaces of said flow passages (5) and opening in the direction of said straight capillary flow passage (6), a second inlet (8) for sample fluid provided at the upstream end of said second flow passage (10), and coupling portions (13) sealingly coupling with said photo-particle-analyzer respectively provided at said first (3a, 3b) and second (8) inlets and said discharge ports (7), wherein two pressure controllers (51, 52) respectively connected to said two first inlets (3a, 3b) for independently controlling the pressures of said sheath fluid (4) in said inlets (3a, 3b), respectively, thus enabling the position of stream (14) to be adjusted. A sheath flow type flow-cell device as claimed in claim 1, wherein a wall portion (15) on which said second flow passage (10) is opened is rounded. A sheath flow type flow-cell device as claimed in claim 1, wherein a wall portion (15) on which said second flow passage (10) is opened has a substantially rectangular cross-section. A sheath flow type flow-cell device as claimed in claims 2 and 3, wherein said wall portion (15) is chamfered. A sheath flow type flow-cell device as claimed in claims 2 to 4, further comprising a pair of projections (18) for guiding a flow of said sample fluid (9) in said first flow passages (5), said pair of projections (18) extending from said wall portion (15). A sheath flow type flow-cell device as claimed in claim 1, wherein said flow-cell device (1) is formed by upper and lower plates (21, 22); said upper plate (21) being formed with a part (5) of said first flow passages, a part (10) of said second flow passage and a part (6) of said capillary flow passage, said lower plate (22) being formed with the other part (5'') of said first flow passages, the other part (10'') of said second flow passage, said first inlets (3a, 3b), said second inlet (8), said discharge port (7) and said coupling portions (13). A sheath flow type flow-cell device as claimed in claim 1, wherein said flow-cell device (1) comprises a plurality of laminated plates (24, 25, 26, 27, 28) on which are formed respective predetermined patterns which form said first inlets (3a, 3b), said first flow passages (5), said discharge port (7) and said second flow passage (10) when said plurality of plates overlap each other. A sheath flow type flow-cell device as claimed in claim 7, wherein said plurality of laminated plates (24, 25, 26, 27, 28) are made of glass. A sheath flow type flow-cell device as claimed in claim 7, wherein said plurality of laminated plates are made of glass plates (24, 26, 28) and synthetic resin plates (25, 27) such as polyimide and said glass plates and said synthetic resin plates are disposed alternately. A photo-cell-analyzer comprising a sheath flow type flow-cell device (1) as defined in claim 1; a first pump (31) for feeding a suspension of cells (44); a diluting apparatus (32) for diluting said suspension of cells (44) and connected to said first pump (31); a dyeing apparatus (33) for dyeing said suspension of cells (44) and connected to said diluting apparatus (32); a second pump (35) for feeding a sheath fluid (4); a light source (36) for emitting a light beam (46); a condenser lens (37) for applying said light beam on said suspension of cells in said capillary flow passage; an objective lens (38) disposed on a side of said substantially flat top surface and collecting fluorescence and scattering light from said cells, a half mirror (39) for separating said fluorescence from said scattering light; a first photo-detector (40) for detecting said scattering light; a second photo-detector (41) for detecting said fluorescence; and a signal processor (42) connected to said first and second photo-detectors. A photo-cell-analyzer as claimed in claim 10, further comprising a hemolysis apparatus (34) arranged between said dyeing apparatus and said second inlet of said flow-cell device. A photo-particle-detector comprising a sheath flow type flow-cell device (1) as defined in claim 1; a feeding means (48) for feeding fluid carrying particles; a pump (35) for feeding sheath fluid; a light source (36) for emitting a light beam, a condenser lens (37) for applying said light beam on said fluid carrying particles in said capillary flow passage; an objective lens (38) disposed on a side of said substantially flat top surface and collecting scattering light from said particles; a photo-detector (40) for detecting said scattering light; and a signal processor (49) connected to said photo-detector.

Inventors: MIYAKE RYO TSUKUBA HAUSU -, OHKI HIROSHI, TAKAHATA FUJIYA, YAMAZAKI ISAO, MIYAKE, RYO TSUKUBA HAUSU 4-507, OHKI, HIROSHI, TAKAHATA, FUJIYA, YAMAZAKI, ISAO
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1988
Main classification: G01N15
IPC codes: G01N15, B01F13