Improved flow cells, systems, and methods

Abstract

The invention discloses a flow cell system. The flow cell system comprises a flow cell. The flow cell includes a substrate configured to support an array of analytes, a cover plate, and an adhesive device spacing the cover plate from the substrate to define a fluid gap between the substrate and the cover plate. The flow cell also includes an inlet in fluid communication with the fluid gap and an outer periphery. In one exemplary implementation, fluid enters the flow cell from the inlet, flows through the fluid gap, and flows out of the flow cell from the periphery between the base plate and the cover plate; an adhesive gap is formed in the adhesive device on the periphery of the flow cell and allows fluid to flow out of the fluid gap.

Description

BACKGROUND

[0001] Many current nucleic acid sequencing systems and processes are resource intensive, requiring large amounts of reagents and long times to complete the sequencing process. To more efficiently use resources, people have developed massively parallel systems and processes; however, there is room for improvement. SUMMARY

[0002] This patent discloses several examples of improved flow cells, systems, and methods.

[0003] In one example, a flow cell system includes: (a) a flow cell including: (i) a substrate configured to support an array of analytes; (ii) a cover spaced apart from the substrate, the substrate and the cover defining a fluid gap therebetween; (iii) an inlet in communication with the fluid gap; and (iv) an outer perimeter of the flow cell. (b) The flow cell system is configured such that fluid enters the flow cell from the inlet, flows through the fluid gap, and exits the flow cell from the outer perimeter between the substrate and the cover.

[0004] In this example, the flow cell system can be configured such that fluid exits the flow cell from the outer perimeter between the substrate and the cover such that the fluid drops from the outer perimeter in the form of droplets.

[0005] In this example, the outer perimeter of the flow cell can be at least partially open.

[0006] In this example, the outer perimeter can be at least 2.5% open.

[0007] In this example, the outer perimeter can be at least 5% open.

[0008] In this example, the outer perimeter of the flow cell can be completely open.

[0009] In this example, the outer perimeter of the flow cell can be frameless.

[0010] In this example, the flow cell can further include spacers configured to space apart the substrate and the cover to define the fluid gap.

[0011] In this example, the spacers can be a plurality of spacers, at least some of which are aligned generally toward a central region of the flow cell.

[0012] In this example, at least some of the spacers can extend radially from the central region of the flow cell.

[0013] In this example, the spacers can be adhesive means configured to space apart the substrate and the cover to define the fluid gap and to adhere the substrate to the cover.

[0014] In this example, the inlet can be located in a central region of the flow cell.

[0015] In this example, the system can further include a common collector located below an outer periphery of the flow cell and configured to collect droplets that drip from the outer periphery of the flow cell.

[0016] In this example, the common collector can include a plurality of common collection cups configured to collect droplets that drip from the outer periphery of the flow cell.

[0017] In this example, the common collection cups can be vertically spaced apart from the flow cell by a droplet gap.

[0018] In this example, each common collection cup can include a sloped sidewall, wherein a portion of the sloped sidewall located below the outer periphery of the flow cell is vertically spaced apart from the flow cell by a droplet gap.

[0019] In this example, at least some of the common collection cups can include a sloped wall configured to direct collected droplets to a fluid conduit.

[0020] In this example, the collection channel can be a plurality of fluid conduits.

[0021] In this example, the sloped wall can have a slope greater than 30 degrees.

[0022] In another example, a flow cell system includes: (a) a flow cell having: (i) a substrate configured to support an array of analytes; (ii) a cover; (iii) an adhesive device spacing the cover from the substrate, defining a fluid gap between the substrate and the cover; (iv) an inlet in fluid communication with the fluid gap; and (v) an outer periphery of the flow cell; (b) wherein the flow cell system is configured such that fluid enters the flow cell from the inlet, flows through the fluid gap, and exits the flow cell from the outer periphery between the substrate and the cover; wherein adhesive gaps in the adhesive device at the outer periphery of the flow cell allow fluid to exit from the fluid gap.

[0023] In this example, there can be at least five independent adhesive gaps in the adhesive device at the outer periphery of the flow cell that allow fluid to exit from the fluid gap.

[0024] In this example, there can be at least ten independent adhesive gaps in the adhesive device at the outer periphery of the flow cell that allow fluid to exit from the fluid gap.

[0025] In another example, a flow cell system includes: (a) a flow cell having: (i) a substrate having a surface configured to support an array of analytes, a surface area of the surface configured to support an array of analytes being at least 150 cm 2 ; (ii) a cover spaced apart from the substrate, the substrate and the cover defining a fluid gap between the substrate and the cover, a fluid gap volume of the fluid gap being less than 1.5 mL; (iii) an inlet in fluid communication with the fluid gap; and (iv) an outer periphery of the flow cell; (b) the flow cell system configured such that fluid enters the flow cell from the inlet, flows through the fluid gap, and exits the flow cell from the outer periphery between the substrate and the cover.

[0026] In this example, a surface area of the surface configured to support an array of analytes is at least 225 cm 2 , and a fluid gap volume of the fluid gap is less than 1 mL.

[0027] In this example, a surface area of the surface configured to support an array of analytes is at least 300 cm 2 , and a fluid gap volume of the fluid gap is less than 0.75 mL.

[0028] In another example, a flow cell system can include: (a) a flow cell having: (i) a substrate configured to support an array of analytes; (ii) a cover spaced apart from the substrate, the substrate and the cover defining a fluid gap between the substrate and the cover; (iii) an inlet in fluid communication with the fluid gap; and (iv) an outer periphery of the flow cell; (b) the flow cell system configured such that fluid enters the flow cell from the inlet, flows through the fluid gap, and exits the flow cell from the outer periphery of the flow cell such that the fluid drops from the outer periphery in the form of droplets.

[0029] In this example, the outer periphery of the flow cell can be open.

[0030] In this example, the outer periphery of the flow cell can be frameless.

[0031] In this example, the flow cell can further include spacers that space apart the substrate and the cover to define the fluid gap.

[0032] In this example, the spacers can be a plurality of spacers that are aligned generally toward a central region of the flow cell.

[0033] In this example, the spacers can extend radially from the central region of the flow cell.

[0034] In this example, the inlet can be located at the central region of the flow cell.

[0035] In this example, the outer portion of the spacer is recessed inward relative to the outer periphery of the flow cell.

[0036] In this example, the system may also include a collection funnel located below the periphery of the flow cell and configured to collect droplets dripping from the periphery of the flow cell.

[0037] In this example, the collection funnel can be multiple collection funnels configured to collect droplets dripping from the periphery of the flow cell.

[0038] In this example, a droplet gap is vertically spaced between the collection funnel and the flow cell.

[0039] In this example, at least some of the collection funnels may have inclined walls that are configured to guide the collected droplets to the collection channel.

[0040] In this example, the inclined wall can have an inclination angle greater than 30 degrees.

[0041] In this example, the collection channel can be tilted away from the collection funnel.

[0042] In this example, the collection channel can be tilted away from the collection funnel at a collection channel tilt angle greater than 5 degrees.

[0043] In this example, the flow cell system can switch between multiple states, including a first state and a second state. In the first state, the collection funnel is configured to guide the collected droplets along the waste liquid path; in the second state, the collection funnel is configured to guide the collected droplets along the circulation path.

[0044] In this example, the system may also include a funnel component and a fluid channel component, wherein a collection funnel may be formed in the funnel component, multiple fluid channels may be formed in the fluid channel component, and switching the flow pool system between multiple states may involve repositioning the funnel component relative to the fluid channel component.

[0045] In this example, the flow cell system can switch between multiple states, including: a first state in which the collection funnel is configured to guide the collected droplets along a waste liquid path; a second state in which the collection funnel is configured to guide the collected droplets along a first reagent type circulation path; and a third state in which the collection funnel is configured to guide the collected droplets along a second reagent type circulation path.

[0046] In this example, the system may also include a sorting subsystem configured to sort droplets collected from the periphery of the flow cell into at least a first group and a second group.

[0047] In this example, the sorting subsystem can guide droplets sorted into the first group from the common droplet path to the circulating droplet path of the flow cell system, while the sorting subsystem can guide droplets sorted into the second group from the common droplet path to the waste droplet path of the flow cell system.

[0048] In this example, the system may also include a sorting subsystem configured to sort droplets collected from the periphery of the flow cell into at least a first group, a second group, and a third group.

[0049] In this example, the sorting subsystem can guide droplets sorted into the first group from the common droplet path to the first reagent type circulating droplet path of the flow cell system; wherein, the sorting subsystem can guide droplets sorted into the second group from the common droplet path to the second reagent type circulating droplet path of the flow cell system; wherein, the sorting subsystem can guide droplets sorted into the third group from the common droplet path to the waste liquid droplet path of the flow cell system.

[0050] In this example, the system may also include a vacuum subsystem configured to generate reduced pressure at the periphery of the flow cell to reduce the resistance of fluid flow through the fluid gap.

[0051] In this example, the system may also include a vacuum chamber, with the flow cell located inside the vacuum chamber.

[0052] In this example, the cover of the flow cell may have an inner surface and an outer surface, with the inner surface facing the fluid gap; and the vacuum subsystem may also be configured to generate decompression on the outer surface of the cover.

[0053] In this example, the vacuum subsystem can be configured to generate decompression on the outer surface of the cover plate to prevent the cover plate from collapsing during the filling of the fluid gaps in the flow cell.

[0054] In this example, during operation of the vacuum subsystem, the pressure generated on the outer surface of the cover plate can be less than the pressure generated at the outer periphery of the flow cell; and during operation of the vacuum subsystem, the pressure generated at the outer periphery of the flow cell can be less than the pressure generated at the inlet of the flow cell.

[0055] In this example, the vacuum subsystem may include one or more vacuum pumps configured to generate depressurization at the periphery of the flow cell and configured to generate depressurization at the outer surface of the cover plate.

[0056] In this example, the system may also include an actuator configured to rotate the flow pool about a vertical axis to facilitate fluid flow from the inlet to the outer periphery.

[0057] In this example, the flow cell inlet can be an opening located at the center of the flow cell cover and extending through the flow cell cover.

[0058] In this example, the flow cell may also include a plurality of spacers that separate the substrate and the cover plate to define a fluid gap, and these spacers extend radially from the central region of the flow cell.

[0059] In this example, the flow cell may also include one or more spacers that separate the substrate and the cover plate to define a fluid gap, the one or more spacers extending spirally from the central region of the flow cell.

[0060] In another example, the flow cell system includes: (a) a flow cell having: (i) a substrate configured to support an array of analytes; (ii) a cover plate spaced apart from the substrate, the substrate and the cover plate defining a fluid gap between the substrate and the cover plate; (iii) an inlet in fluid communication with the fluid gap; and (iv) an outlet in fluid communication with the fluid gap; and (b) a vacuum subsystem configured to generate a pressure reduction at the outlet in fluid communication with the fluid gap to reduce resistance to fluid flow through the fluid gap.

[0061] In this example, the system may also include a vacuum chamber, with the flow cell located inside the vacuum chamber.

[0062] In this example, the cover plate may have an inner surface and an outer surface, with the inner surface facing the fluid gap; and the vacuum subsystem may also be configured to generate decompression on the outer surface of the cover plate.

[0063] In this example, during operation of the vacuum subsystem, the pressure on the outer surface of the cover plate may be less than the pressure at the outlet in fluid communication with the fluid gap; and wherein, during operation of the vacuum subsystem, the pressure at the outlet in fluid communication with the fluid gap may be less than the pressure at the inlet in fluid communication with the fluid gap.

[0064] In this example, the outlet that is in fluid communication with the fluid gap can be one or more discrete fluid channels that run through the substrate of the flow cell.

[0065] In this example, the outlet that is in fluid communication with the fluid gap can be the outer periphery of the opening of the flow pool. Attached Figure Description

[0066] Figure 1 shows an example of a flow cell with flow gaps.

[0067] Figure 2 An example process flow diagram of the flow cell in Figure 1 is shown.

[0068] Figure 3-6 shows an example of a frameless flow cell system.

[0069] Figure 7-10 shows an example of a circulating subsystem for a flow pool system.

[0070] Figure 11-13 shows an example of a frameless flow cell that can be used in a vacuum chamber.

[0071] Figure 14-16 shows an example of a spin coating flow cell.

[0072] Figure 17-25 shows another example of a flow cell system, which includes a frameless flow cell and a fluid circulation system.

[0073] Figures 26-28 show a simulation of the filling and rinsing cycle for the flow cell. Detailed Implementation

[0074] Flow pool The flow cells described in the following examples can be configured for a variety of implementations, including systems that require flow cells with a large surface area while minimizing reagent consumption.

[0075] In some examples, the flow cell can be used as part of a sequencing system for analyzing nucleic acid material (e.g., DNA or RNA) or other analytes, whether biological or non-biological / synthetic. The flow cell substrate may include an array of analyte attachment sites for attaching nucleic acid fragments or other analytes to the substrate (e.g., discrete attachment sites 26 schematically shown in Figure 1—these sites may be positively charged features on the substrate and spaced apart by negatively charged or neutral regions on the substrate). In some implementations, the number of discrete attachment sites can be arranged in an array containing millions or billions of discrete sites, with spacing at pitches potentially ranging from tens to hundreds of nanometers.

[0076] Nucleic acid fragments attached to a flow cell substrate can be imaged by an optical imaging system or otherwise analyzed. For example, a DNA template can be immobilized in an array of more than 10e7 attachment sites on the flow cell substrate. In this example, the nucleic acid sequencing method may involve performing more than 400 sequencing cycles. In each cycle, individual nucleotides (e.g., adenine, guanine, thymine, and cytosine) flow through a fluid gap 20 across the substrate and are incorporated (into the extending strand) at each site where complementary nucleotide bases are present. In one approach, each of the four different nucleotides can be labeled with a different colored fluorescent dye or bound to a dye-labeled antibody. In each sequencing cycle, a light source (e.g., a laser) can illuminate these sites (e.g., in series illumination) to cause the dyes to emit light corresponding to the respective color. The color emitted by each of the four dyes at each site can be detected by a camera (e.g., a time-delay integrated charge-coupled device (TDI-CCD) camera or a similar camera), and the imaging system can thus record the detection result of the nucleotide corresponding to the detected color at each site. Those skilled in the art should be aware of the various variations of sequencing methods, including variations of template types (see, for example, Huang et al., 2017, Gigascience 6:1–9; Mardis et al., 2013, Annu Rev Anal Chem 6:287–303), labeling systems (see, for example, WO2018129214), and labeling strategies (see, for example, US9,523,125).

[0077] The attachment sites 26 on the substrate 12 of the flow cell 10 can be fabricated using well-known photolithography tools, such as a 248-nm KrF (krypton fluoride) lithography system, a 193-nm ArF (argon fluoride) lithography system, or an electron beam lithography system. These arrays are typically spaced apart at ultra-high, high, medium, or low densities. Spacing is less than 250 nm at ultra-high densities; 300 to 350 nm at high densities; 400 to 500 nm at medium densities; and 500 nm or more at low densities. In some implementations (e.g., some low-density implementations), two-dimensional patterning using photoresist is sufficient to sequester DNA nanospheres or other discrete nucleic acid samples. In some implementations (e.g., some medium, high, or ultra-high density implementations), smaller samples may be required to reduce the risk of discrete samples failing to hold in a single location, which may necessitate three-dimensional patterning to more effectively capture the fluorescence of labeled DNA nanospheres or other labeled nucleic acid samples. In such implementations, non-binding materials can be used as pore walls, and binding materials can be used as pore bottom surfaces, thereby constructing three-dimensional patterned porous nanostructures to immobilize DNA nanospheres.

[0078] Figure 1 illustrates an example of a flow cell 10 that can be used in a sequencing system. The flow cell 10 includes a substrate 12 and a cover plate 14. The substrate 12 has an inner substrate surface 16, and the cover plate has an inner cover plate surface 18 facing the inner substrate surface 16. The surfaces 16 and 18 are spaced apart by a height h, thereby defining a fluid gap 20 between them.

[0079] Figure 2 An example process flow diagram of the flow cell 10 shown in Figure 1 is illustrated. In this example, flow cell 10 is part of a gene sequencing process. In step 1002, flow cell 10 is placed on a fluid platform. Subsequently, in step 1004, a predetermined volume of first reagent is dispensed through the fluid inlet 22 of substrate 12. Then, in step 1006, the flow cell is heated to a processing temperature, and in step 1008, the flow cell is held at this processing temperature for a certain period of time. Subsequently, in step 1010, the fluid inlet 22 and outlet 24 facilitate the introduction of buffer solution and the washing of reagents in flow cell 10. Subsequently, in step 1012, steps 1004-1010 can be repeated to perform as many reagent addition and washing cycles as possible to meet the analytical requirements. Subsequently, in step 1014, reagents for auxiliary optical scanning can be dispensed into flow cell 10, and flow cell 10 can be optically scanned. Depending on the system configuration, the optical scanning can be performed on the fluid platform, or flow cell 10 can be delivered to a separate optical scanning platform.

[0080] Frameless Flow Cell – Figure 3-6 In the flow cell 10 shown in Figure 1, fluid flows in and out through discrete fluid inlets 22 and discrete fluid outlets 24, which are tunnels formed through the substrate 12. The outer periphery of the flow cell is completely surrounded by a frame 28. The frame 28 may be a highly uniform adhesive used to secure the substrate 12 and the cover plate 18, and extends fully along the periphery of the flow cell 10. Figures 3-6 show examples of frameless flow cell systems where the outer periphery of the flow cell is open. Maintaining an open periphery and the absence of a frame to restrict fluid flow to discrete inlets and outlets helps reduce flow resistance, thereby minimizing the fluid gap between the flow cell cover plate and the substrate.

[0081] In the example of Figure 3-6, the flow cell is "frameless," with its outer perimeter completely open, and the outer edges of the flow cell substrate and cover plate have no adhesive or other framing structures. In other examples (including the example of Figure 17-25 discussed below), the flow cell may also be "frameless," but some discrete areas of adhesive or other framing structures still exist at the outer edges of the flow cell substrate and cover plate. In the examples of Figures 3-6 and 17-25, the flow cell is "frameless" because the gap between the flow cell substrate and cover plate acts as the fluid outlet of the flow cell, rather than forming discrete tunnels through the flow cell substrate as in Figure 1.

[0082] The flow cell system shown in Figures 3-6 includes a flow cell with a substrate 702 (see Figure 6) configured to support an array of analytes (e.g., through discrete attachment sites similar to attachment sites 26 on substrate 12 shown in Figure 1) and a cover plate 704 spaced apart from the substrate 702. As shown in Figure 6, the substrate 702 and the cover plate 704 define a fluid gap 706 between the substrate 702 and the cover plate 704. Fluid enters the flow cell in Figures 3-6 through an inlet 708 (see Figure 5) in fluid communication with the fluid gap 706 and exits from the outer periphery 710 of the flow cell (see Figure 6). The flow cell in Figures 3-6 is configured such that fluid enters the flow cell from the inlet 708, flows through the fluid gap 706, and exits from the outer periphery 710, such that the fluid drips from the outer periphery 710 in the form of droplets 712.

[0083] In this example, spacer 714 (see Figures 3 and 4) spacees the substrate 702 and the cover plate 704, thereby defining a fluid gap 706 while keeping the outer periphery 710 open and frameless. In this particular example, spacer 714 is generally aligned toward the central region of the flow cell and extends radially from the central region where the inlet 708 is located. In this particular example, the outer portion of spacer 714 is recessed inward relative to the outer periphery 710 of the flow cell. Spacer 714 may be a patterned adhesive applied to the substrate 702, or may be any other structure or material sufficient to define a spacing between the substrate 702 and the cover plate 704 while keeping the outer periphery 710 of the flow cell open and frameless.

[0084] The flow cell system shown in Figure 3-6 includes a flow cell 700 mounted on top of a funnel tray 716, which is rotatably mounted on top of a fluid channel fixture 718. A drive wheel 720 (driven by a drive motor 732) allows the funnel tray 716 and the flow cell 700 to rotate relative to the fluid channel fixture 718. A roller bearing 722 maintains the funnel tray 716 and the flow cell 700 in a centered position on the fluid channel fixture 718 during rotation.

[0085] The funnel tray 716 includes a series of funnels 724 located below the outer periphery 710 of the flow cell 700 and configured to collect droplets 712 dripping from the outer periphery 710 of the flow cell 700. In other implementations, the series of funnels 724 may be replaced by a single funnel or other mechanisms for collecting droplets 712 from the outer periphery 710 of the flow cell 700.

[0086] As shown in Figure 6, a droplet gap 726 is vertically spaced between the collecting funnel 724 and the flow cell 700. More specifically, the droplet gap 726 is vertically spaced between the top of the collecting funnel 724 and the bottom of the substrate 702 of the flow cell 700. In some implementations, the droplet gap 726 facilitates the formation of droplets 712 as fluid flows out from the outer periphery 710. In some implementations, the droplet gap 726 also ensures that fluid flowing out from the outer periphery 710 can be collected in the funnel 724 (e.g., rather than being drawn into the interface between the flow cell 700 and the funnel disk 716 by capillary action).

[0087] As shown in Figure 6, the collecting funnel 724 includes an inclined wall 728 configured to guide the collected droplets 712 into the collecting channel 730 of the fluid channel clamp 718. In this particular example, the inclined angle (relative to the horizontal plane) of the inclined wall 728 is greater than 40 degrees to help overcome the surface tension of the droplets 712 and allow them to enter the collecting channel 730. In some implementations, the inclined angle of the inclined wall 728 of the funnel 724 relative to the horizontal plane may be greater than 35 degrees, 50 degrees, or greater than 60 degrees.

[0088] In the specific example shown in Figures 3-6, the collection channel 730 is inclined relative to the horizontal plane and away from its associated funnel 724. In some implementations, the inclination angle of the collection channel 730 relative to the horizontal plane may be at least 5 degrees, 7 degrees, or greater. This inclination angle facilitates the movement of one or more droplets along the channel 730 away from the funnel 724. The dimensions of the collection channel 730 may also be designed to promote the flow of droplets (or aggregated droplets) along the channel 730. For example, the width of the collection channel may be greater than 3 mm or greater than 5 mm to minimize the effect of the channel wall surface tension on the droplets or aggregated droplets.

[0089] Fluid circulation – Figure 7-9 In at least some implementations of the flow cell system described herein, it may be necessary to collect the fluid flowing out of the flow cell, such that some of the collected fluid is directed to a waste liquid path, while some of the collected fluid is directed to one or more reagent circulation paths, so that at least some of the collected fluid (e.g., reagents) can be reused for further analysis of the same flow cell or for analysis of other flow cells.

[0090] Figure 7 Figure 7 shows an example of a flow cell system in which the collected fluid flows along different paths depending on the state of the system. The system includes a flow cell 750 mounted on a vacuum chuck 752. The flow cell 750 is fixed to the vacuum chuck 752 by a negative pressure generated by a vacuum subsystem, which includes a vacuum pump 754, a one-way valve 756, a filter 758, and a two-way valve 760.

[0091] Fluid is introduced into flow cell 750 through inlet 762 and collected from flow cell 750 at outlet 764. Different fluids can be selectively introduced into flow cell 750 through inlet 762 via selector valve 766. Selector valve 766 can cyclically switch between different states to fluidly connect the sources of first type reagent 768, second type reagent 770, and cleaning fluid 772. Fluid can enter flow cell 750 from connected sources 768, 770, or 772 via inlet 762 via syringe pump 774 or other suitable pumping mechanism.

[0092] In the example of Figure 7, the second selection valve 776 facilitates the selective collection of fluid flowing from the flow cell 750 into different collection channels 778 and containers 780, 782, and 784. More specifically, the system can be configured to cyclically switch the selection valve 776 between the following states: the collected fluid is guided along the channel 778 in fluid communication with the collection container 780 for collecting a first type of reagent; the collected fluid is guided along the channel 778 in fluid communication with the collection container 782 for collecting a second type of reagent; and the collected fluid is guided along the channel 778 in fluid communication with the collection container 784 for collecting waste liquid. For example, in an exemplary implementation of the system shown in Figure 7, the system can be configured such that when the selection valve 766 is in the state of guiding fluid from the source of the first type of reagent 768 to the flow cell 750, the selection valve 776 is in the state of guiding fluid collected from the flow cell 750 to the first type of reagent collection container 780. Similarly, the system can be configured such that when selector valve 766 is in the state of directing fluid from a source of second-type reagent 770 to flow cell 750, selector valve 776 is in the state of directing fluid collected from flow cell 750 to second-type reagent collection container 782. Similarly, the system can be configured such that when selector valve 766 is in the state of directing fluid from a source of cleaning fluid 772 to flow cell 750, selector valve 776 is in the state of directing fluid collected from flow cell 750 to waste liquid collection container 784.

[0093] Figure 8-9 Figure 8-9 schematically illustrates another example of a flow cell system that can switch between two states, whereby fluid collected from the flow cell can be guided along two different paths depending on the system state. This example includes a funnel tray with a series of funnels 802, similar to the funnel tray 716 and funnel 724 shown in Figures 9-12. In Figure 8-9, the funnel tray and funnels 802 are indicated by dashed lines, with dashed circles representing the outlets of funnels 802. This example also includes a fluid channel clamp, similar to the fluid channel clamp 718 in Figures 3-6. The fluid channel clamp in the examples of Figures 14 and 15 includes two different fluid paths: a first path 804 fluidly connected to a first collection container 806, and a second path 808 fluidly connected to a second collection container 810.

[0094] Similar to the system of Figures 3-6, the system of Figures 8-9 is configured to rotate a funnel disk containing funnel 802 relative to a fluid channel clamp containing fluid paths 804 and 806. When the system is switched to the first state shown in Figure 8, funnel 802 is configured to guide collected droplets from a flow cell (not shown) along the first path 804 to a first collection container 806, which may be, for example, a waste container. More specifically, in the first state shown in Figure 8, funnel 802 is positioned above and in fluid communication with the collection channel 812 of the first path 804, allowing droplets to drip through funnel 802 into the collection channel 812 (similar to that shown in Figure 6) and into the first path 804 to reach the first collection container 806.

[0095] When the system is switched to the second state shown in Figure 9, the funnel tray and its funnel 802 are repositioned relative to the fluid channel fixture and its fluid paths 804, 808, such that the funnel 802 is configured to guide droplets collected from the flow cell along the second path 808 to the second collection container 810, for example, the second collection container may be a reagent fluid circulation container. More specifically, in the second state shown in Figure 9, the funnel 802 is located above and in fluid communication with the collection channel 814 of the second path 808, allowing droplets to drip through the funnel 802 into the collection channel 814 and into the second path 808 to reach the second collection container 810.

[0096] In other implementations, fluid channel fixtures similar to those in Figures 8-9 may include additional fluid paths to guide the collected droplets to three or more different collection containers.

[0097] Figure 10 Figure 10 shows another example of a circulating subsystem that can be integrated into a flow cell system, including the various flow cell systems described herein.

[0098] In this example, the system is configured to sort droplets collected from flow cell 848 into different groups. More specifically, in this example, the system is configured to sort droplets 850 from a common droplet path 852 into different paths, such as a circulating droplet path represented by circulating container 854 and a waste droplet path represented by waste container 856. In other implementations, additional paths and containers may be incorporated into the sorting system (e.g., a path and container for a first type of reagent, additional paths and containers for additional types of reagents, and additional paths and containers for waste liquid).

[0099] In the example of Figure 10, the common droplet path 852 is a droplet transport device comprising a series of moving pads 858, each pad 858 configured to collect a single droplet 850 flowing from the flow cell 848 and selectively retain the droplet 850 on the pad 858 as it moves along the transport device. For example, the pads 858 may include a dielectric surface covering high-voltage electrical pads, thereby allowing electrostatic manipulation of the individual droplets (e.g., selectively retaining or releasing the droplet from the pad 858 depending on the state of the high-voltage electrical pads). In the example of Figure 10, a trace dye detector 860 or other type of sensor interrogates the droplet as it moves along the transport device and provides the data to a system that determines which container 854 or 856 the droplet 850 should be sorted into. In other implementations, it may not be necessary to individually detect each droplet to determine its path, and sorting can be accomplished in other ways (e.g., at a specific time or operating state of the system, collected droplets can be directed to a waste container; while at other times and operating states, collected droplets can be directed to one or more reagent circulation containers).

[0100] Frameless flow cell – vacuum chamber – Figure 11-13 Figures 11-13 illustrate examples of flow cell systems configured to work in conjunction with a vacuum subsystem that generates pressure reduction at the flow cell outlet (including cases where the "outlet" of the flow cell is the frameless outer periphery of the flow cell) to reduce resistance to fluid flow through the fluid gaps in the flow cell.

[0101] The example in Figure 11 includes a flow cell 900, which, although not shown in detail, includes a substrate configured to support an array of analytes and a cover plate spaced apart from the substrate to define a fluid gap between the substrate and the cover plate. The flow cell 900 also includes an inlet 902 and an outlet 904 in fluid communication with the fluid gap. In the particular example shown, the inlet 902 extends through the substrate of the flow cell 900 and is located in or near the center of the flow cell 900; the outlet 904 extends through the substrate of the flow cell 900 and is located in or near the outer periphery of the flow cell 900.

[0102] A vacuum subsystem (not shown) creates a pressure reduction at outlet 904 to reduce resistance to fluid flow through the fluid gaps in the flow cell 900. In one embodiment, the pressures at both fluid inlet 902 and fluid outlet 904 are regulated, with fluid inlet 902 connected to a higher pressure than fluid outlet 904 is connected to. For example, fluid inlet 902 may be connected to atmospheric pressure (or an approximation thereof), while fluid outlet 904 may be connected to a pressure below atmospheric pressure.

[0103] In the example of Figure 11, the flow cell 900 is located inside the vacuum chamber 906. The vacuum subsystem can be further configured to regulate the pressure inside the vacuum chamber 906 to create a pressure reduction inside the chamber, thereby applying the pressure reduction to the outer (top) surface of the cover plate of the flow cell 900. The vacuum chamber 906 shown in Figure 11 is a vacuum chuck, which includes a chuck cover plate 908, a chuck plate 910, and an O-ring 912 for sealing the interface between the chuck cover plate 908 and the plate 910. An elastic member 914 inside the vacuum chamber 906 helps to secure the flow cell 900 inside the vacuum chamber 906.

[0104] In some implementations, the depressurization inside the vacuum chamber 906 can help counteract the depressurization at the fluid outlet 904 of the flow cell 900, thereby reducing the likelihood of the cover of the flow cell 900 collapsing during the flow cell filling process.

[0105] In some implementations of the system shown in Figure 11, during operation, the vacuum subsystem (e.g., one or more vacuum pumps configured to regulate the pressure at the fluid inlet 902, outlet 904, and inside the vacuum chamber 906) regulates the pressure so that the pressure at the fluid inlet 902 of the flow pool 900 is greater than the pressure inside the vacuum chamber 906 (which acts on the outer surface of the cover of the flow pool 900), and the pressure inside the vacuum chamber 906 is greater than the pressure at the fluid outlet 904 of the flow pool 900.

[0106] Figure 12 shows another example of a flow cell inside a vacuum chamber.

[0107] Figure 13 (exploded view) shows an example of a flow cell 970, which includes an open outer periphery that serves as the outlet of the flow cell 970. The flow cell 970 in Figure 19 includes a substrate 972, a spacer 974, a cover plate 976, and a frame 978. The flow cell 970 can be used in conjunction with a vacuum subsystem configured to generate pressure reduction at the open outer periphery of the flow cell 970 to reduce resistance to fluid flow through the fluid gap between the substrate 972 and the cover plate 976.

[0108] The flow cell 970 can be placed inside a vacuum chamber similar to those shown in Figures 11 and 12. The vacuum subsystem can be configured to generate pressure reduction at the outer periphery of the flow cell 970 and on the outer surface of the cover plate 976. In an implementation similar to that shown in Figure 11, the vacuum subsystem can be configured to generate pressure reduction such that the pressure at the fluid inlet of the flow cell 970 is greater than the pressure at the outer periphery of the flow cell 970, which in turn is greater than the pressure at the outer surface of the cover plate 976.

[0109] Frameless Flow Cell – Spin Coating – Figure 14-16 Figure 14-16 illustrates a flow cell system and an example of a flow cell used in such a system, wherein the flow cell rotates to move fluid from its central inlet to its circumference, whereby the fluid flows out of the flow cell. The rotational speed of the flow cell may depend on fluid resistance and the force pushing the fluid toward the edges.

[0110] Similar to the flow cells in some of the examples described above, the flow cells in the examples shown in Figures 14-16 may have an open or frameless periphery. Similar to some of the examples described above, the flow cells in these examples may include a substrate configured to support an array of analytes, a cover spaced apart from the substrate to define a fluid gap between the substrates, an inlet in fluid communication with the fluid gap, and the periphery of the flow cell. A system using the flow cells shown in Figures 14-16 can be configured to allow fluid to enter the flow cell from the inlet, flow through the fluid gap, and exit the flow cell from the periphery, causing the fluid to drip from the periphery as droplets.

[0111] In the example shown in Figure 14, the flow pool 1000 is mounted on an actuator 1002, which in this particular example is a rotary chuck. The actuator 1002 is configured to rotate the flow pool about a vertical axis 1004 to facilitate fluid flow from the inlet 1006 of the flow pool 1000 to its outer periphery 1008. In the example shown in Figure 14, the inlet 1006 is an opening located at the center of the cover plate of the flow pool 1000 and extending through the cover plate, through which fluid can be injected via a distributor 1010.

[0112] Figures 15 and 16 illustrate examples of flow cells that can be used in conjunction with the actuator 1002 shown in Figure 14. Both examples include a substrate 1012, a cover plate 1014, and an inlet 1016 mounted above an opening in the cover plate 1014. The difference between Figures 21 and 22 lies in the arrangement of the spacers 1018 between the substrate 1012 and the cover plate 1014. In the example of Figure 15, the spacers 1018 are arranged in a radially extending pattern. In the example of Figure 16, the spacers 1018 are arranged in a spiral pattern.

[0113] Frameless flow cell with partially septated periphery – Figure 17–25 Figure 17-25 shows another example of a flow cell system. In this example, the flow cell system includes a flow cell 1100 located on a fluid collector 1102.

[0114] Figures 17-25 do not show flow cell 1100 in detail because it shares many similarities with the flow cells described in the preceding examples. For example, flow cell 1100 in Figures 17-25 includes a substrate configured to support an array of analytes and a cover plate spaced apart from the substrate to define a fluid gap therebetween. Spacers (adhesive pattern 1104 in this example) space the cover plate apart from the substrate. Flow cell 1100 also includes an inlet and an outer periphery (1108 in Figures 17 and 25) in fluid communication with the fluid gap.

[0115] Similar to the flow cell in the previous examples, in the example of Figures 17-25, fluid enters the flow cell from inlet 1120, flows through the fluid gap, and exits the flow cell from the outer periphery 1108 between the substrate and the cover plate. As shown in Figure 25, the fluid exiting the flow cell drips from the outer periphery 1108 in the form of droplets 1110.

[0116] Similar to the flow cells in the previous examples (e.g., the flow cells in Figures 3-6, 13, 14, 15, and 16), the flow cell 1100 in Figures 17-25 is also frameless. The flow cell 1100 does not have a frame that completely surrounds its outer perimeter 1108.

[0117] However, unlike some previous examples, the outer periphery 1108 of flow pool 1100 is only partially open. For example, compare flow pool 700 in Figures 3-6 and flow pool 1100 in Figures 17-25. Flow pool 700 in Figures 3-6 has adhesive spacers 714 located entirely within it, which do not extend to its outer periphery 710. Therefore, the outer periphery 710 of flow pool 700 is fully open. In contrast, the adhesive spacers 1104 of flow pool 1100 in Figures 17-25 extend to and partially surround the outer periphery 1108, but the gaps in the adhesive 1112 (see Figures 17 and 24) still leave the outer periphery 1108 partially open.

[0118] In some implementations, the number and size of the adhesive gaps 1112 at the outer periphery 1108 can be selected such that the outer periphery is open by at least 2.5%, at least 5%, at least 10%, or a greater percentage. In a specific example shown in Figures 17-25, there are twelve adhesive gaps 1112 at the outer periphery 1108 of the flow tank 1100. In other implementations, there are at least five individual adhesive gaps at the outer periphery. In still other implementations, there are at least ten individual adhesive gaps at the outer periphery.

[0119] In some implementations, the outer periphery of the flow cell opening, or at least a partial opening, can reduce the resistance to fluid flow through the fluid gaps in the flow cell, thereby allowing the fluid to circulate at a relatively fast fluid circulation rate within a relatively large flow cell and with relatively small fluid gaps. In some implementations, the surface area of ​​the flow cell substrate is at least 150 cm². 2 Furthermore, the fluid gap volume is less than 1.5 mL. In some implementations, the surface area of ​​the flow cell substrate is at least 225 cm². 2 Furthermore, the fluid gap volume is less than 1 mL. In some implementations, the surface area of ​​the flow cell substrate is at least 300 cm². 2 And the fluid gap volume is less than 0.75 mL.

[0120] Fluid circulation – Figure 17–25 The flow cell system shown in Figure 17-25 can switch between multiple states, allowing the system to guide fluid exiting the flow cell along different fluid paths. In the specific example shown, the system is configured to alternately allow a first type of reagent fluid, a second type of reagent fluid, and a cleaning fluid to flow through the flow cell. In the specific example shown, the system includes three different fluid paths along which fluid exiting the flow cell can be guided: a waste path, a first circulation path, and a second circulation path. The system is configured such that: the first type of reagent fluid is guided along the first circulation path, the second type of reagent fluid is guided along the second circulation path, and the cleaning fluid and cleaning fluid / reagent mixture are guided along the waste path. Depending on the type of reagent required for a particular analytical procedure, other configurations for other types of fluids and other numbers of fluid paths can also be considered. For example, in other implementations, the system may use one reagent and one cleaning fluid, and there may only be two fluid paths for receiving fluid after exiting the flow cell. In another example implementation, the system may use four reagents and one cleaning fluid, and there may be five independent fluid paths for receiving fluid after exiting the flow cell.

[0121] Figures 17-20 show an example of a flow cell / clamp assembly for a flow cell system, including bottom and top views of the assembly and exploded views. In this example, the assembly includes a flow cell 1100, a vacuum chuck 1114, a gasket 1116, and a bottom ring 1118.

[0122] Vacuum chuck 1116 includes an inlet 1120 sealed by an O-ring 1122 for injecting fluid into flow cell 1100. Vacuum chuck 1116 also includes a common collector for collecting fluid flowing out of flow cell 1100. In this particular example, the common collector is a series of collection cups 1124 located below and surrounding the outer periphery of flow cell 1100. In the particular example shown, the collection cups 1124 are cavities extending into the body of vacuum chuck 1116.

[0123] Each collection cup 1124 is connected to three different fluid channels. Two fluid channels 1126 and 1128 are located on the bottom side of the vacuum chuck 1114 (see Figure 20), and one fluid channel 1130 is located on the top side of the bottom ring 1118 (see Figure 18). Fluid channels 1126, 1128, and 1130 are covered by a gasket 1116. Fluid channels 1126, 1128, and 1130 are each connected to one of the fluid outlets 1132 located on the bottom side of the bottom ring 1118 (see Figure 19).

[0124] Figure 21 shows a schematic cross-section of the collection cup 1124. The system is configured such that fluid flows through a fluid gap in the flow cell 1100 and then enters the collection cup 1124. More specifically, in this example, fluid drips from the outer periphery 1108 of the flow cell 1100 into the collection trough 1134 of the collection cup 1124 in droplet form. The collection cup 1124 extends a waste liquid conduit 1136 and two circulation conduits 1138 and 1140. The waste liquid conduit 1136 is connected to the fluid channel 1126, and the waste liquid conduits of the other collection cups are also connected to the same fluid channel. The circulation conduit 1138 of each collection cup 1124 is connected to the fluid channel 1128 (and similar circulation conduits in other collection cups are also connected to the same fluid channel). The circulation conduit 1140 of each collection cup 1124 is connected to the fluid channel 1130 (and similar circulation conduits in other collection cups are also connected to this fluid channel).

[0125] In this example, when the system is in the first state, it is configured to draw fluid from all collection cups 1124 into waste conduit 1136 and common fluid channel 1126, from which the fluid can then be directed to waste. When the system is in the first state, the fluid does not flow through the other two conduits 1138 and 1140. When the system is in the second state, it is configured to draw fluid from all collection cups 1124 into circulation conduit 1138 and common fluid channel 1128, from which the fluid can then be directed to a collection tank for a first type of fluid (e.g., a first type of reagent fluid) to be circulated. When the system is in the second state, the fluid does not flow through the other two conduits 1136 and 1140. When the system is in the third state, it is configured to draw fluid from all collection cups 1124 into other circulation conduits 1140 and common fluid channel 1130, where the fluid can then be directed to a collection tank for a second type of fluid (e.g., a second type of reagent fluid). When the system is in the third state, fluid will not flow through the other two conduits 1136 and 1138.

[0126] In this example, the system is configured such that fluid is discharged from the collection tank 1134 into one of the three conduits 1136, 1138, or 1140 at a time. In this particular example, the three conduits 1136, 1138, and 1140 are hydrophobic capillary openings located at the bottom of the collection tank 1134, and the surface of the collection tank is also made of a hydrophobic material (or coated). Thus, even if the collected liquid covers all the conduits at the bottom of the tank 1134, the default state of the collection cup 1124 prevents fluid from entering any of the conduits 1136, 1138, or 1140 due to the surface tension of the liquid and the resistance to flow from the capillary forces.

[0127] In this example, fluid can be selectively discharged into one of the three conduits 1136, 1138, and 1140 by applying a vacuum force to the conduit (e.g., applying a vacuum force to the common fluid channel connected to the individual conduits in each collection cup 1124). The vacuum force applied to the conduit is sufficient to overcome its inherent flow resistance.

[0128] The vacuum force can be provided by one or more negative pressure sources associated with the system (e.g., a vacuum pump—not shown). The system can be configured to apply a negative pressure sufficient to overcome capillary resistance in the desired conduits, thereby causing fluid to exit from the collection cup 1124 and enter the associated common fluid channel only through the desired conduits.

[0129] Figures 22-25 show additional views of the flow cell system in this example. Figure 22 shows a cross-section of the flow cell 1100, vacuum chuck 1114, gasket 1116, and bottom ring 1118. Figure 23 shows a close-up of the fluid inlet 1120 in the vacuum chuck 1114 and its associated O-ring 1122.

[0130] Figure 24 shows a top enlarged view of a portion of flow cell 1100 and one of the collection cups 1124. Figure 25 shows a cross-sectional enlarged view of a portion of flow cell 1100 and collection cup 1124. As shown in Figures 24-25, collection cup 1124 is located below the outer periphery 1108 of flow cell 1100 and is configured to collect droplets 1110 that drip from the outer periphery 1108 of flow cell 1100 through the gap of adhesive 1112. As shown in Figure 25, collection cup 1124 includes an inclined sidewall 1142. The portion of the inclined sidewall 1142 immediately below the outer periphery 1108 of flow cell 1100 is vertically spaced from flow cell 1100 by a droplet gap. This droplet gap, and the hydrophobicity of collection cup 1124, helps prevent droplets 1110 from entering the gap between the bottom of flow cell 1100 and the top of vacuum chuck 1114.

[0131] Figures 26-28 illustrate the filling and cleaning cycle simulation of the flow cell, as well as the changes in the composition of the fluid flowing out of the flow cell during the cycle.

[0132] Figure 26 shows a simulated one-quarter section of a circular flow cell. Fluid enters the flow cell from the fluid inlet 1500 at its center. The fluid outlet is located at its outer perimeter 1502, similar to the frameless flow cell described above. In this simulation, the fluid gap volume of the flow cell is approximately 0.68 mL.

[0133] In this simulation, there is a reagent fluid and a cleaning fluid. During the filling cycle, the reagent is injected into the flow cell to displace the cleaning fluid that has filled the fluid gaps in the flow cell. During the cleaning cycle, the cleaning fluid is injected into the flow cell to displace the reagent fluid.

[0134] In this simulation, the injection rate was 0.1 mL / s. A 15% aqueous glycerol solution was used as a substitute for the reagent fluid, and a 10% aqueous glycerol solution was used as a substitute for the cleaning fluid. Therefore, the concentration change of the fluid at the flow cell outlet can be used to simulate the conversion process between the reagent fluid and the cleaning fluid (and vice versa), as well as the flow cell outlet.

[0135] Figure 27 shows the change in outlet concentration during the simulated filling cycle. Figure 27 shows that in this simulation, after 10 seconds of filling (injection of 1 mL of reagent substitute), all the washing buffer had been drained from the flow cell, and the flow cell was completely filled with reagent.

[0136] Figure 28 shows the change in outlet concentration during the simulated cleaning cycle. Figure 28 shows that in this simulation, after 6 seconds of cleaning (injection of 0.6 mL of cleaning substitute), the purity of the reagent substitute discharged from the flow cell begins to decrease. In other words, after 6 seconds of cleaning, a mixture of reagent substitute and cleaning substitute is discharged from the flow cell. Therefore, in this simulation, 100% pure reagent can be collected for recycling within the first 6 seconds of cleaning.

[0137] Using such simulations or other techniques, the system shown in Figure 17-25 can be calibrated so that only pure reagents are directed to the circulation path, while cleaning fluids and cleaning fluid / reagent mixtures are directed to the waste path. In this way, most of the reagent volume used can be recovered and reused.

[0138] While the principles of this disclosure have been described above with reference to specific examples of flow cells, systems, and methods, it should be understood that this description is merely illustrative and not intended to limit the scope of the invention. These examples were chosen and described to explain the principles and practical applications of the invention, enabling those skilled in the art to use the invention with various implementations and modifications according to the specific intended use. It should be understood that this description is intended to cover various modifications and equivalents.

Claims

1. A flow cell system, the system comprising: (a) a flow cell, the flow cell comprising: (i) A substrate configured to support an array of analytes; (ii) A cover plate spaced apart from the substrate, wherein the substrate and the cover plate define a fluid gap between the substrate and the cover plate; (iii) an inlet, which is in fluid communication with the fluid gap; and (iv) The outer periphery of the flow cell; (b) wherein the flow cell system is configured such that fluid enters the flow cell from the inlet, flows through the fluid gap, and exits the flow cell from the periphery between the substrate and the cover plate.

2. The flow cell system according to claim 1, wherein, The flow cell system is configured such that fluid flows out of the flow cell from the outer periphery between the substrate and the cover plate, such that the fluid drips from the outer periphery in the form of droplets.

3. The flow cell system according to claim 2, wherein, The outer periphery of the flow cell is at least partially open.

4. The flow cell system according to claim 3, wherein, The outer periphery has at least 2.5% opening.

5. The flow cell system according to claim 3, wherein, The outer periphery has at least 5% opening.

6. The flow cell system according to claim 3, wherein, The outer periphery of the flow cell is open.

7. The flow cell system according to claim 3, wherein, The outer periphery of the flow cell is frameless.

8. The flow cell system according to claim 7, wherein, The flow cell also includes a spacer that separates the substrate and the cover plate to define the fluid gap.

9. The flow cell system according to claim 8, wherein, The spacers include a plurality of spacers, at least some of which are generally aligned toward the central region of the flow pool.

10. The flow cell system according to claim 9, wherein, At least some of the spacers extend radially from the central region of the flow pool.

11. The flow cell system of claim 8, wherein the spacer includes an adhesive device that spaces the substrate and the cover plate to define the fluid gap and adheres the substrate to the cover plate.

12. The flow cell system of claim 3, wherein the inlet is located in the central region of the flow cell.

13. The flow cell system of claim 3, further comprising a common collector located below the periphery of the flow cell and configured to collect droplets dripping from the periphery of the flow cell.

14. The flow cell system of claim 13, wherein the common collector comprises a plurality of common collection cups configured to collect droplets dripping from the periphery of the flow cell.

15. The flow cell system of claim 14, wherein a droplet gap is vertically spaced between the common collection cup and the flow cell.

16. The flow cell system according to claim 14, wherein, Each of the common collection cups includes an inclined sidewall, wherein the portion of the inclined sidewall located below the outer periphery of the flow pool is vertically spaced from the flow pool by a droplet gap.

17. The flow cell system according to claim 14, wherein, At least some of the aforementioned common collection cups include an inclined wall configured to guide the collected droplets to a fluid conduit.

18. The flow cell system according to claim 17, wherein, The collection channel includes multiple fluid conduits.

19. The flow cell system according to claim 17, wherein, The inclined wall has an inclination greater than 30 degrees.

20. A flow cell system, the system comprising: (a) a flow cell, the flow cell comprising: (i) A substrate configured to support an array of analytes; (ii) Cover plate; (iii) An adhesive device configured to space the cover plate from the substrate to define a fluid gap between the substrate and the cover plate; (iv) an inlet, which is in fluid communication with the fluid gap; and (v) The outer periphery of the flow cell; (b) wherein the flow pool system is configured such that fluid enters the flow pool from the inlet, flows through the fluid gap, and exits the flow pool from the periphery between the substrate and the cover plate; wherein the adhesive gap in the adhesive device at the periphery of the flow pool allows fluid to exit from the fluid gap.

21. The flow cell system according to claim 20, wherein, At least five independent adhesive gaps in the adhesive device on the outer periphery of the flow pool allow fluid to flow out from the fluid gaps.

22. The flow cell system according to claim 20, wherein, At least ten independent adhesive gaps in the adhesive device on the outer periphery of the flow pool allow fluid to flow out from the fluid gaps.

23. A flow cell system, the system comprising: (a) a flow cell, the flow cell comprising: (i) A substrate having a surface configured to support an array of analytes, the surface area of ​​the surface configured to support the array of analytes being at least 150 cm². 2 ; (ii) a cover plate spaced apart from the substrate, the substrate and the cover plate defining a fluid gap between the substrate and the cover plate, the fluid gap having a volume of less than 1.5 mL; (iii) an inlet, which is in fluid communication with the fluid gap; and (iv) The outer periphery of the flow cell; (b) wherein the flow cell system is configured such that fluid enters the flow cell from the inlet, flows through the fluid gap, and exits the flow cell from the periphery between the substrate and the cover plate.

24. The flow cell system according to claim 23, wherein, The surface configured to support the analyte array has a length of at least 225 cm. 2 The surface area of ​​the fluid gap, and the fluid gap volume is less than 1 mL.

25. The flow cell system according to claim 23, wherein, The surface configured to support the analyte array has a depth of at least 300 cm. 2 The surface area of ​​the fluid gap, and the fluid gap volume of the fluid gap is less than 0.75 mL.

26. A flow cell system, the system comprising: (a) a flow cell, the flow cell comprising: (i) A substrate configured to support an array of analytes; (ii) A cover plate spaced apart from the substrate, wherein the substrate and the cover plate define a fluid gap between the substrate and the cover plate; (iii) an inlet, which is in fluid communication with the fluid gap; and (iv) The outer periphery of the flow cell; (b) wherein the flow cell system is configured such that fluid enters the flow cell from the inlet, flows through the fluid gap, and exits the flow cell from the periphery of the flow cell, thereby causing the fluid to drip from the periphery in the form of droplets.

27. The flow cell system according to claim 26, wherein, The outer periphery of the flow cell is open.

28. The flow cell system according to claim 27, wherein, The outer periphery of the flow cell is frameless.

29. The flow cell system of claim 27, wherein the flow cell further comprises a spacer that separates the substrate and the cover plate to define the fluid gap.

30. The flow cell system of claim 29, wherein the spacer comprises a plurality of spacers aligned generally toward the central region of the flow cell.

31. The flow cell system of claim 30, wherein the spacer extends radially from the central region of the flow cell.

32. The flow cell system of claim 30, wherein the inlet is located in the central region of the flow cell.

33. The flow cell system of claim 30, wherein the outer portion of the spacer is recessed inward relative to the outer periphery of the flow cell.

34. The flow cell system of claim 27, further comprising a collection funnel located below the outer periphery of the flow cell and configured to collect droplets dripping from the outer periphery of the flow cell.

35. The flow cell system according to claim 34, wherein, The collection funnel includes a plurality of collection funnels configured to collect droplets dripping from the periphery of the flow cell.

36. The flow cell system according to claim 35, wherein, The collection funnel and the flow cell are vertically separated by a droplet gap.

37. The flow cell system according to claim 36, wherein, At least some of the collection funnels include inclined walls configured to guide the collected droplets into a collection channel.

38. The flow cell system according to claim 37, wherein, The inclined wall has an inclination angle greater than 30 degrees.

39. The flow cell system according to claim 37, wherein, The collection channel is inclined away from the collection funnel.

40. The flow cell system according to claim 39, wherein, The collection channel is tilted away from the collection funnel at a collection channel tilt angle greater than 5 degrees.

41. The flow cell system according to claim 35, wherein, The flow cell system can switch between multiple states, including a first state and a second state, in which the collection funnel is configured to guide the collected droplets along the waste liquid path; In this second state, the collection funnel is configured to guide the collected droplets along a circulation path.

42. The flow cell system according to claim 41, further comprising a funnel component and a fluid channel component, wherein, The collection funnel is formed in the funnel member, wherein a plurality of fluid channels are formed in the fluid channel member, and wherein switching the flow pool system between the plurality of states includes repositioning the funnel member relative to the fluid channel member.

43. The flow cell system of claim 35, wherein, The flow cell system can switch between several states, including: a first state, wherein the collection funnel is configured to guide the collected droplets along a waste liquid path; a second state, wherein the collection funnel is configured to guide the collected droplets along a first reagent type circulation path; and a third state, wherein the collection funnel is configured to guide the collected droplets along a second reagent type circulation path.

44. The flow cell system of claim 26, further comprising a sorting subsystem configured to sort droplets collected from the periphery of the flow cell into at least a first group and a second group.

45. The flow cell system according to claim 44, wherein, The sorting subsystem guides droplets sorted into the first group from the common droplet path to the circulating droplet path of the flow cell system, wherein the sorting subsystem guides droplets sorted into the second group from the common droplet path to the waste droplet path of the flow cell system.

46. ​​The flow cell system of claim 26, further comprising a sorting subsystem configured to sort the droplets collected from the periphery of the flow cell into at least a first group, a second group, and a third group.

47. The flow cell system according to claim 46, wherein, The sorting subsystem guides droplets sorted into the first group from the common droplet path to the first reagent type circulating droplet path of the flow cell system; wherein, the sorting subsystem guides droplets sorted into the second group from the common droplet path to the second reagent type circulating droplet path of the flow cell system; wherein, the sorting subsystem guides droplets sorted into the third group from the common droplet path to the waste liquid droplet path of the flow cell system.

48. The flow cell system of claim 26, further comprising a vacuum subsystem configured to generate pressure reduction at the periphery of the flow cell to reduce resistance to fluid flow through the fluid gap.

49. The flow cell system of claim 48, further comprising a vacuum chamber, wherein the flow cell is located within the vacuum chamber.

50. The flow cell system according to claim 49, wherein, The cover plate has an inner surface and an outer surface, the inner surface facing the fluid gap; and wherein the vacuum subsystem is further configured to generate decompression on the outer surface of the cover plate.

51. The flow cell system according to claim 50, wherein, The vacuum subsystem is configured to generate the pressure reduction on the outer surface of the cover plate to prevent the cover plate from collapsing during the filling of the fluid gap in the flow cell.

52. The flow cell system according to claim 50, wherein, During operation of the vacuum subsystem, the pressure generated on the outer surface of the cover plate is less than the pressure generated on the outer periphery of the flow cell; and wherein, during operation of the vacuum subsystem, the pressure generated on the outer periphery of the flow cell is less than the pressure generated at the inlet of the flow cell.

53. The flow cell system according to claim 52, wherein, The vacuum subsystem includes one or more vacuum pumps configured to generate the pressure reduction at the outer periphery of the flow cell and configured to generate the pressure reduction at the outer surface of the cover plate.

54. The flow cell system of claim 26, further comprising an actuator configured to rotate the flow cell about a vertical axis to facilitate fluid flow from the inlet to the outer periphery.

55. The flow cell system according to claim 26, wherein, The flow pool inlet includes an opening located at the center of the flow pool cover and extending through the flow pool cover.

56. The flow cell system according to claim 55, wherein, The flow cell also includes a plurality of spacers that separate the substrate and the cover plate to define the fluid gap, the spacers extending radially from the central region of the flow cell.

57. The flow cell system of claim 55, wherein the flow cell further comprises one or more spacers that space the substrate and the cover plate apart to define the fluid gap, the one or more spacers extending spirally from the central region of the flow cell.

58. A flow cell system, the system comprising: (a) a flow cell, the flow cell comprising: (i) A substrate, the substrate being configured to support an array of analytes; (ii) A cover plate spaced apart from the substrate, wherein the substrate and the cover plate define a fluid gap between the substrate and the cover plate; (iii) an inlet, which is in fluid communication with the fluid gap; and (iv) An outlet, which is in fluid communication with the fluid gap; (b) A vacuum subsystem configured to generate a pressure reduction at the outlet in fluid communication with the fluid gap to reduce the resistance to fluid flow through the fluid gap.

59. The flow cell system of claim 58, further comprising a vacuum chamber, the flow cell being located inside the vacuum chamber.

60. The flow cell system according to claim 59, wherein, The cover plate has an inner surface and an outer surface, the inner surface facing the fluid gap; and wherein the vacuum subsystem is further configured to generate decompression on the outer surface of the cover plate.

61. The flow cell system according to claim 60, wherein, During operation of the vacuum subsystem, the pressure at the outer surface of the cover plate is less than the pressure at the outlet in fluid communication with the fluid gap; and wherein, during operation of the vacuum subsystem, the pressure at the outlet in fluid communication with the fluid gap is less than the pressure at the inlet in fluid communication with the fluid gap.

62. The flow cell system according to claim 59, wherein, The outlet, which is in fluid communication with the fluid gap, is one or more discrete fluid channels that penetrate the substrate of the flow pool.

63. The flow cell system according to claim 59, wherein, The outlet, which is in fluid communication with the fluid gap, is the outer periphery of the opening of the flow pool.

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