Modular multi-layer microfluidic cartridge

Abstract

The present invention relates generally to a multi-layer microfluidic cartridge having alignment features that can be used during assembly to provide precise alignment of the layers of the cartridge. Such a cartridge is suitable for use, for example, in medical diagnostics.

Description

[Technical field]

[0001] The present invention relates to a modular multi-layer microfluidic cartridge. More specifically, the present invention relates to a modular multi-layer microfluidic cartridge with integrated alignment features and methods for assembling the same. The cartridge may be used in medical diagnostics for evaluating bodily fluid samples, including, for example, for evaluating clotting in blood samples. The devices and methods described herein may also be used in a variety of other applications. [Background technology]

[0002] Modular medical diagnostic cartridges often include a core element containing one or more molded fluid flow paths, and one or more cover layers attached to the core element to completely surround the flow paths and form one or more channels. In such cartridges, alignment between and across one or more layers and the core element may be achieved with conventional manufacturing techniques. However, as channels decrease in size and increase in complexity, precise alignment of layers relative to the core element becomes increasingly important, for example, when a channel must overlap and / or align with a particular feature (e.g., an electronic sensor) incorporated into the cartridge.

[0003] The challenges associated with manufacturing and assembling modular, multi-layer microfluidic cartridges do not necessarily exist in other multi-layer precision devices, such as electronic circuit boards (e.g., printed circuit boards). Printed circuit boards (PCBs) often have multiple layers, each layer having a defined function, and are bonded together into a multi-layer "book" by an adhesive that is applied to the layers and covers the entire surface between the layers. Summary of the Invention [Problem to be solved by the invention]

[0004] Traditionally, to bond multiple sheets (or layers) of material together, the sheets are often aligned by providing two orthogonal reference edges along which the orthogonal straight edges of the sheets to be bonded are positioned. The adhesive is often a sheet type that, when cooled, is not tacky and slides freely across surfaces. When held at a compound angle and subjected to vibration, the sheets align to form a bindable "book." Pressure and heat can then be applied to make the adhesive flow and bond the surfaces together. However, for very thin sheets that are also flexible, as compared to when the adhesive is tacky, if the sheets are not quite flat and have some raised areas, the raised areas may come into contact and bond prematurely, resulting in wrinkles that may cause shorts between the bonded sheets and / or lead to misalignment of features, another method is required.

[0005] Once the multi-layer "book" is assembled and cured, connections between the sheets are made to create the overall functionality of the device. These connections between the sheets are made by drilling vias through the plating without the worry of leaving through holes.

[0006] Alignment between components involving sheets of material is explained by reference to Slocum, A., “Kinematic Linkages: A Review of Design Principles and Applications,” Int. J. of Machine Tools and Manufacture (2009), doi:10.1016 / j.ijmachtools.2009.10.006, including the references cited therein.

[0007] The manufacture and assembly of modular multi-layer cartridges used for accurate diagnostics cannot rely on such conventional processes. For example, there is a concern that adhesive may flow into the flow paths (e.g., channels). Furthermore, the connecting holes between the layers cannot be easily drilled after the lamination process.

[0008] Thus, there is a need in the art for microfluidic cartridges suitable for use in, for example, accurate diagnostics, and techniques for assembling such cartridges. In particular, there is a need for multi-layer microfluidic cartridges in which the layers of the cartridge are precisely and accurately aligned. The present invention addresses such a need. [Means for solving the problem]

[0009] The apparatus and methods described herein provide alignment features for modular, multi-layer microfluidic cartridges and methods for the assembly of such cartridges.

[0010] An embodiment of the invention provides a multi-layer cartridge having a base structure and one or more layers, a first of the one or more layers being adhered or affixed to the base structure and each subsequent layer being adhered or affixed to the previous layer, the base structure and each of the one or more layers having an alignment feature having three slots oriented to enable alignment between and across the base structure and the one or more layers. In particular, the three slots on the base structure and the three slots on each of the one or more layers have the same size, position, and angular orientation such that the slots of the base structure can be precisely aligned (e.g., in the X, Y plane and with respect to rotations about a normal to the surface) with the slots of the one or more layers to ensure that each of the one or more layers is adhered in a precise planar manner and further provide precise kinematic constraints. The assembly jig may have pins (e.g., three round pins) whose locations align with the locations of the alignment features (e.g., the centroids of the three slots on the base structure and the centroids of the three slots on each of the one or more layers) on the base structure and on each of the one or more layers, such that the assembly jig can position and hold each of the one or more layers flat relative to the assembly jig and its pins, and the pins of the assembly jig may engage (interlock) with the slots of the base structure to precisely contact each of the one or more layers in planar contact with a portion of the assembly with the base structure. For each of the base structure and one or more layers, the three slots engage with the three round pins on the assembly jig, such that the centers of the three slots are located on an imaginary triangle where the angle bisectors of the included angles of the triangle intersect at a point that is in the region of maximum alignment accuracy desired between the layer elements, and the centers of the slots are located on the vertices of the triangle with their longitudinal axes aligned with the corresponding angle bisectors of the triangle vertices (see FIG. 7 ). In the embodiments described herein, the base structure is itself a layer, and the other layers (e.g., adhesive layers, printed circuit boards, etc.) are additional layers, and all of the layers can be precisely positioned relative to each other by using three pins coming out of the assembly fixture on which the layers are placed, and the layers will be precisely positioned relative to each other even if the pins coming out of the assembly fixture are not precisely positioned relative to each other.As used herein, the terms "core element" and "base structure" are used interchangeably unless otherwise clear from the context. In an exemplary embodiment, cartridge body 600 has such a base structure (see, e.g., FIGS. 1A and 3).

[0011] In various embodiments, the assembly process described herein may be repeated to attach or adhere multiple layers to portions of the cartridge assembly that include the base structure. In some of these embodiments, multiple alignment features may be present to allow alignment of multiple layers about different points on or within the same cartridge.

[0012] The present invention is directed to these and other important aspects as described herein. [Brief description of the drawings]

[0013] [Figure 1A] FIG. 1A shows a front isometric view of one embodiment of a cartridge. [Figure 1B] FIG. 1B shows an isometric view of the rear of one embodiment of a cartridge. [Figure 2A] FIG. 2A shows a top view of the base structure of the cartridge with the microfluidic channels integrated therein. [Figure 2B] FIG. 2B shows a schematic diagram of a microfluidic flow system. [Diagram 3] FIG. 3 shows an exploded view of one embodiment of the cartridge. [Figure 4] FIG. 4 shows the main areas of one embodiment of the cartridge. [Diagram 5] FIG. 5 shows the cartridge aligning against two round locating pins (301a and 301b) of the instrument in which it is installed. [Figure 6A] FIG. 6A illustrates the kinematic alignment of the cartridge with respect to the two round locating pins. [Figure 6B]FIG. 6B shows a close-up of the round locating pins on the V-shaped area of ​​the cartridge. [Figure 6C] FIG. 6C shows a close-up of the round locating pins on the flat area of ​​the cartridge. [Figure 7] FIG. 7 shows three slots (600z) and illustrates the alignment of the slots along the angle bisectors of an imaginary triangle with the centers of the slots as vertices. [Figure 8] FIG. 8 shows an assembly fixture (which may be a vacuum fixture) with three round pins (961d) for kinematic alignment of the base structure and one or more layers of a multi-layer cartridge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The features and advantages of the present invention will be more readily understood by those skilled in the art upon reading the following detailed description. It should be understood that certain features of the present invention described above and below in the context of separate embodiments may also be combined to form a single embodiment. Conversely, various features of the present invention that are described for brevity in the context of a single embodiment may also be combined to form subcombinations thereof. In addition, it is expressly understood that the drawings and specific embodiments of the present invention described herein are given for illustrative purposes, and that the description and drawings are for illustrative purposes only, and that the specific embodiments are not intended to define the limitations of the present invention.

[0015] As shown in FIG. 1A and FIG. 1B, the cartridge embodiment described herein is a self-sealed microfluidic system that can be used to evaluate a fluid sample. For example, the cartridge assembly 60 may be used to perform a series of blood tests. The cartridge assembly 60 has a cartridge body 600 that has a base structure of the cartridge and includes channels and reservoirs that can be molded into the base structure, and during assembly, the open side of the molded fluid flow area (see, e.g., FIG. 2A) is capped with a cover layer to form closed channels and reservoirs. FIG. 2B shows an overview of the fluid flow system. One basic function of the cartridge is to accept a fluid sample (e.g., blood) via a sample inlet 600i, which can be covered by a cap 603 to help ensure that there is no sample outside the cartridge (see, e.g., FIG. 3). In some embodiments, the sample inlet 600i has an inlet region septum 602, which may be pierced, for example, by a syringe, and which self-seals when a sample insertion device (e.g., a syringe) is withdrawn from the sample inlet 600i. Once inserted into the cartridge, the sample enters the fluidic channel via port 84 (see FIG. 2A). In certain embodiments, it may be particularly important for the sample inlet 600i (or other inlet region) to prevent sample escape and / or backflow (e.g., via the inlet region septum 602), e.g., containment of the sample within a closed microfluidic cartridge may be particularly desirable for testing potentially infectious samples. In some embodiments, once the sample is in the microfluidic reservoir and a minimum fluid volume is identified, a driving pressure is generated to move the fluid sample from the microfluidic reservoir into multiple fluidic flow paths (also called channels or lanes), each of which may have one or more chambers (also called wells) along its path. In some embodiments, the cartridge may have multiple channels, with at least some of the channels each having chambers connected in series.In certain embodiments, each channel may contain a reagent for a different analysis, while in other embodiments, some or all of the channels may contain the same reagent for the same analysis. In certain embodiments, the channels may contain the same reagent, but at different concentrations (e.g., three channels may contain Factor Xa, but the concentration of Factor Xa may vary from channel to channel). Each channel may lead to a detection chamber or well, and excess sample may be received in one or more waste containers, such as 90.

[0016] FIG. 2A shows an exemplary base structure of the cartridge assembly 60, the fluid flow of which is represented diagrammatically in FIG. 2B. In a preferred embodiment, the pressure source is generated by a pressurized chamber, e.g., a device (not shown) that pushes a plunger 80 (piston, bung, etc.) into a hollow cylindrical structure 81 (also called a cylinder 81) of the cartridge 60, which is connected by a channel 82 to a region containing a plurality of microfluidic channels. The pressurized chamber (e.g., cylinder 81) may contain a gas, a fluid, or both. In some embodiments, alternative components for applying pressure may be used, such as a bellows instead of a piston / cylinder arrangement. The actuation of the pressure source (e.g., movement of the piston into the cylinder) is controlled to provide the desired pressure and flow rate in the microfluidic system.

[0017] Cartridge assembly 60 may include various components. In some embodiments, as shown in the embodiment of FIG. 3, cartridge body 600 includes plunger 80 in cylinder 81, filter plug 608, support ring 605, and sample insertion port 600i. In some embodiments, cartridge assembly may include fewer or additional elements, for example, support ring 605 for layer 606 may be replaced with integrally molded spokes or mesas. As further shown in FIG. 4, cartridge assembly 60 may include at least three main regions: pressurized chamber 81, main fluid body 62, and handle region 63.

[0018] In certain embodiments, the first pressure sensitive adhesive (PSA) layer 606, the second PSA layer 607, and the circuit board 800 are each kinematically aligned to the cartridge body 600 and attached or bonded (e.g., by adhesive, laser or ultrasonic welding, heat sealing, etc.) to at least one of the other constituent layers (see, e.g., FIG. 3 and FIG. 4). Each of the first PSA layer 606 and the second PSA layer 607 may have a single-sided adhesive or a double-sided adhesive. A backseal layer 604 (also referred to herein as a backing plate 604) may also be bonded to the bottom of the cartridge body 600 to surround one or more flow paths within the cartridge body 600 to form a channel. The sample insertion port 600i may be closed by a removable cap 603, which may be made of an elastomeric material, such that it is pressed into place and can remain attached. Alternatively, the cap 603 may be attached by a threaded connection or a luer lock connection.

[0019] The cartridge body 600 may be made by precision injection molding of a medical grade plastic (e.g., polycarbonate plastic) for microfluidics. In some embodiments, especially when very fine features are desired, the cartridge body may be injection molded using a liquid crystal polymer, which is known for its ability to form very fine features. Some of the smallest features that can be made with injection molding are approximately 40 micrometers wide with a tolerance of plus or minus 5 micrometers. For example, the depth of a 40 micrometer wide channel is usually approximately 10 to 20 micrometers deep. As the width increases to approximately 100 micrometers, the features become easier to manufacture and therefore the cost of the mold may be reduced. For molded features approximately 200 micrometers in size, the tolerance may be approximately 5%. Vias (openings in elements forming vertical channels, allowing fluid transport along the Z-axis of the cartridge system) are typically created using drop pins in an injection mold, and for such openings a sealing layer may be required (in the embodiment shown, for example, 604 may be bonded to seal the backside of 600, and circuit board layer 800 may be used to seal the cartridge on the front side). Current manufacturing techniques allow for drop pins of about 0.5 mm diameter with a taper of about 3 degrees.

[0020] Layers of PSA 606 and 607 (which may be in the form of a film) can be added to the cartridge to create fluid connections and additional vias and flow features (e.g., reservoirs for fluidic logic). The layers of PSA can be mass-produced by commercial laser cutting or stamping (e.g., die cutting). Depending on the desired resolution, low volume production is also possible with off-the-shelf laser cutting machines. For example, a 40W CO2 laser engraver (e.g., OMTech laser K40 model) has a resolution of about 1500 DPI, which translates to a minimum feature size of about 16.9 μm. Some units (e.g., OMTech's 50W upgrade unit) are available with about 4500 DPI, which translates to a pitch of about 5.6 μm. Depending on the pattern and volume desired for the features, the PSA material can be die-cut into a PSA layer with the desired shape.

[0021] Each PSA layer may have an adhesive on its surface. In some embodiments, the adhesive may be exposed by peeling off a cover sheet, such as 3M 1513 double-sided adhesive tape. Ensuring that a thin adhesive layer (e.g., adhesive film) is accurately and precisely placed is a significant challenge. For example, PSA layers are generally thin and malleable, and therefore easily deformed. Furthermore, features (e.g., vias) may not align if the PSA layer is misaligned. One advantage of using a PSA layer is that it may itself have one or more integrated adhesive layers, which may be of a specific chemical composition, and with some adhesives, adhesion of the PSA layer to other cartridge elements may be achieved with little or no application of heat, reducing the likelihood of the PSA layer sagging and / or flowing into the microfluidic channel. In some embodiments, for example, if test reagents are pre-deposited in the microfluidic channel (e.g., in the chamber of the channel) to be sealed with the PSA layer, using a PSA layer with an adhesive that does not require high heat may ensure that reagents such as proteins are not denatured (e.g., as a result of applying higher temperatures).

[0022] 3 illustrates the PSA layer 606 with an adhesive layer facing the front surface 600f of the cartridge body 600. In the exemplary embodiment illustrated in FIG. 4, the back surface layer 604 is thicker than the PSA layer 606 and may be adhered or attached to the rear surface 600r of the cartridge body 600 using any of several possible methods (e.g., with an adhesive, pressure, heat, ultrasonic welding, etc.). In certain embodiments, the back surface layer 604 is transparent, and if the back surface 600r has areas of adhesion that have been rubbed (e.g., made opaque), laser welding through the transparent back surface layer is facilitated in those areas. Similarly, laser welding may also be used if one of the layers to be adhered or attached is an opaque color, for example if the cartridge body 600 is black and the back surface layer 604 is transparent.

[0023] The PCB layer 800 may be rigid or flexible, or may itself have one or more layers that are flexible and other layers that are rigid. In an exemplary embodiment, a flexible PCB made of Kapton® may be affixed (e.g., glued, laser welded, etc.) to a rigidified layer (such as a rigid PCB). Additionally, the PCB layer 800 may have at least one set of contact pads 800a (see FIG. 5) that may be used to make electrical contact with other elements of the cartridge to establish communication with the elements of the cartridge for analyzing the fluidic region of the cartridge 60. For example, an impedance detection circuit on the circuit board facing the microfluidic features may measure the impedance of a blood sample mixed with a reagent when a voltage is applied (e.g., to detect clotting, disease, etc.). In some embodiments, the rigid PCB may be made of common materials (e.g., FR-4, other epoxy glass laminates, etc.), the use of which may be desirable due to low cost, ease of manufacturing, and / or material properties (e.g., high temperature resistance). In other embodiments, the use of a flexible PCB, such as a PCB made of Kapton®, may be preferred based on the tests intended for the cartridge (e.g., fluorescence-based analyses where PCBs made of epoxy-glass laminate may interfere). In certain embodiments, rigid PCBs, such as paper-phenolic (e.g., FR-3 paper-epoxy), polyethylene (PET), polyethersulfone (PES), etc., may also allow certain tests (e.g., certain fluorescence-based tests) to be performed. In various embodiments, it may be desirable to maintain the fluid in the fluid testing area at a particular temperature. Thus, in certain embodiments, the PCB layer 800 may include heating or other temperature control elements (e.g., in the electronics layer) that can achieve and maintain a particular temperature or temperature range, such as, for example, a low temperature of about 20° C. and / or a high temperature of about 45° C. For example, for a cartridge used to assess clotting in a sample, the temperature may be about 37° C.Single or multiple temperature sensors and / or controller circuitry may be included on PCB layer 800 to monitor temperature and achieve and / or maintain a desired temperature across all or specific fluid regions (such as regions where reactions occur and / or measurements are made). Temperature measurements may also be used by the test unit for certain feedback temperature control systems.

[0024] Furthermore, in certain aspects, one or more PSA layers may be susceptible to delamination when the temperature increases above about 65° C., due to minimal structural support. Therefore, it may be desirable to regulate and / or maintain a particular temperature operating range (e.g., temperatures not exceeding 65° C.) by any one or any combination of techniques and / or materials (as described above). Additionally, techniques may be employed, and particular materials used, that help protect against delamination of the PSA (e.g., a PSA layer having particular adhesive properties may be used) or eliminate this concern (e.g., laser welding or ultrasonic welding may be used in place of the PSA).

[0025] In various embodiments, the non-fluid flow regions of the cartridge may not be filled (e.g., with plastic) all the way, especially if the cartridge has one or more precision molded parts with multiple microfluidic channels with well regions, otherwise the cartridge may suffer from hot spots that may warp and / or lead to loss of desired precision. Such is the case for the annular region 605a, which in some embodiments must remain hollow. However, in such an embodiment, the PSA layers 606 and 607 may sag into the region 605a, and one or more of the layers may separate despite having been attached or bonded due to the fluid pressure in the vias connecting the layers and / or the fluid pressure across the hollow annular region 605a. Therefore, the support ring 605 may be inserted into the annular region to act as a backup structure. In other embodiments, the base structure that creates the hollow annular region may include radial spokes, which are located below the PSA layers and between which the radial microfluidic structures are placed. In yet other embodiments, support may be provided to the hollow annular region by filling the region with additional material via an overmolding process, thereby achieving a flat surface finish.

[0026] In some embodiments, the cartridge has one or more waste containers. In certain embodiments, the waste containers are fixed volume waste containers. For example, in some embodiments, the volume of the waste container, such as 90, may be larger than the volume of fluid introduced into the cartridge, thereby forming a closed system where the fluid does not leave the cartridge. Having such a closed system may be particularly desirable, for example, when using potentially infectious samples and / or harmful agents. In such embodiments, the pressure in the waste container may increase in proportion to the ratio of the volume of the fluid introduced to the volume of the waste container. Furthermore, as fluid is introduced, the pressure increases, which may increase the demands on, for example, actuators (e.g., to drive the fluid) and adhesive or cohesive forces required between layers (e.g., to contain the fluid in the desired channel).

[0027] In additional embodiments of the invention, the size of the waste container may change dynamically, so that it accepts waste at a constant pressure. For example, a cylindrical volume 81w (not shown) may be located on the opposite side of the cartridge 60 from the input cylinder 81, allowing the cartridge to appear externally symmetrical. In certain such embodiments, the cylinder 81w may be sealed with an outwardly actuable piston plug, thereby providing a dynamic waste volume receiver. For example, as waste enters the cylinder and fills the cylinder volume, a piston may be actuated near the open end of the cylinder, at which point the piston plug is pushed by a moving rod. In addition, the piston of the waste cylinder may be located near the inner end such that as the piston of the input volume moves into that cylinder, the piston of the waste volume moves toward its open end. In other embodiments, the waste volume is a bellows that expands to accept the waste volume.

[0028] When a cartridge (e.g., cartridge assembly 60) is inserted into a machine to operate the cartridge and collect data on the fluid being evaluated within the cartridge, it is important to accurately align the cartridge to the machine. Therefore, the front end of cartridge assembly 60 may have a kinematic (precise constraint) area consisting of a V-shaped area 600a and a flat area 600b that make three-point contacts in a reference geometry with two locating pins 301a and 301b that are located on the instrument intended to receive the cartridge, as shown, for example, in Figures 5 and 6A-6C. The locating pins are manufactured in large quantities for very low cost and are used for aligning parts and "pinning" to prevent shear between parts. By preloading the cartridge assembly 60 against the two locating pins 301a and 301b, the cartridge is precisely positioned relative to the receiving instrument, which may have probing electrical contacts that mate with corresponding contact pads 800a (of the PCB layer 800) on the cartridge, thereby precisely aligning the contact pads 800a with the receiving instrument into which the cartridge is placed. With the two locating pins engaging the V-region and the flat region, the precision may be roughly about 10 microns to about 100 microns, which is sufficient to align the contact pads 800a with the electrical contacts of the receiving instrument. In various embodiments, the electrical contact pins on the PCB layer 800 may have a pitch of about 1 mm for a PCB with contact pads having a width of about 600 μm. In a particular embodiment, the PCB may have 16 to 48 electrical contact pins.

[0029] With respect to the assembly of the multi-layer microfluidic cartridge described herein, alignment slots and alignment pins are used to achieve accurate and precise alignment between layers. In certain embodiments, the layers may have microfluidic features on the order of about 0.2 mm, and therefore alignment between layers (e.g., between the base structure and the next additional layer, and between each subsequent layer) must be accurate enough to allow the cartridge to function as intended (e.g., alignment between layers may be required to within about 40 microns). Such precise alignment cannot be easily achieved by conventional edge contact alignment to an assembly fixture due to insufficient edge precision and insufficient precision of the location of internal features relative to the edges. For example, the outer edges of molded parts are far from and often thicker than the internal precision features, resulting in shrinkage induced dimensional errors. Furthermore, conventional alignment techniques using pins in holes or pins in holes and slots often over-constrain or under-constrain the parts, resulting in assembly quality problems. In contrast, as described herein, slots are used as kinematic coupling points.

[0030] As described in the embodiments herein, a tight constraint method is used to ensure accurate and precise alignment between layers (e.g., base structure, PSA layer, PCB layer, etc.). This method involves three kinematic alignment slots, whereby the relative positions of the kinematic alignment slots to the small microfluidic features are in tight precision alignment. Only the clearance space around the pins that fit into the slots causes misalignment errors, but because the width of the slots can be made with high precision and the pins can be polished with even higher precision, precise alignment between layers can be achieved on the order of 5 to 10 microns.

[0031] In this way, three pins (e.g., pin 961d in slot 600z) engaging three slots can uniquely define the location of the layer where the slot engages the pin, even though the center of the pin itself is not exactly aligned with the centroid of the slot. In some embodiments, the pins are located on the base structure of the cartridge, while in other embodiments, the pins extend from the assembly fixture.

[0032] For example, in some embodiments, the pins emerge from the assembly fixture such that the center of the pin is located at the ideal center (centroid) of the slot in the layer; however, even if the center of the pin is off by about 0.5 mm in the slot, the slot of each layer will find a unique location for the layer on the pin. Also, while the slots of each layer are precisely located relative to the microfluidic features of that layer, stacking one or more layers on one or more layers with the pins passing through the slots of each layer still ensures that the layers (and layer features) are precisely and accurately aligned with respect to each other. Using three slots and alignment pins as described herein, many layers may be stacked with positional accuracy and precision between and across layers. The accuracy of the placement is limited only by the accuracy of the molding process of the slots. Precise stacking of the layers is important for precise alignment of the features of the layers and may also be important to ensure sufficient adhesion or attachment of the layers to each other.

[0033] In an exemplary embodiment, the layers stacked on the cartridge body 600 are aligned using three slots 600a, 600b, and 600c arranged in a triangle, as shown in FIG. 7. In various embodiments, each of the elements of one or more layers (e.g., the cartridge body 600 with the base structure and each of one or more other layers) has three slots of identical size, which are further aligned and oriented identically in each layer with respect to the critical features to be aligned between and across layers. The three slots may engage three pins on an assembly fixture, such that the centers of the three slots are located on an intersecting imaginary triangle at a point where the angle bisector of the included angle of the triangle is in the area of ​​maximum alignment accuracy desired between the elements (e.g., the elements containing the wells where sample detection or testing occurs), and the centers of the slots are located on the apexes of the triangle with their longitudinal axes aligned with the corresponding angle bisectors of the apexes of the triangle. This point is essentially the instantaneous center of rotation of the layers, and if located near the detection area, the amplification of rotational errors into positional errors is minimized. Each layer has identical slots located in the same position and orientation relative to the overall structure of the cartridge, so that all microfluidic features on each layer are accurately and precisely aligned when the slots are all aligned. During assembly, a pin may enter each slot, and each pin may contact one long side or the other long side of the slot. With such contact, there are three contact points between the three pins and the three slots of each layer, with each pin contacting the side of the slot into which it is inserted. Thus, because there are three unique contact points, three degrees of freedom are defined between a layer and the three pins, and therefore between each layer: X, Y (planar), and rotation about a normal to the surface plane of the layer. In certain embodiments, it is important that the width of the slot is minimally wider than the diameter of the pin, and the width is dictated by the manufacturing tolerances achievable by the selected manufacturing process. How much wider the slot is than the diameter of the pin defines the limit of the alignment accuracy between the layers.However, because this tolerance is a local tolerance (e.g., slot width tolerance) rather than a global tolerance (e.g., slot position within a layer), sufficient slot width accuracy can be achieved. In some embodiments, the width of the slot may be about 20 microns wider than the diameter of the pin. In embodiments employing LCP molding, the slot width may be as small as 10 microns and the pin may be inserted into the slot with an accuracy of about 5 microns.

[0034] This assembly method may take a variety of forms. For example, as shown in FIG. 8, in some embodiments, slots on one or more layers of the cartridge (e.g., PSA layers 606 and 607) may be used to align each of the one or more layers to a fixture 961e having three alignment pins 961d that are nominally located at what would be the center of the slots on the layers. The alignment pins may be precision ground locating pins. The fixture 961e may have a base 961b and a compliant material 961c and may help press the layers together. The compliant material 961c may have a durometer hardness in the range of about 20A to about 70A, and in some embodiments it may be preferred that the base 961b and / or the compliant material 961c be porous (e.g., the base may have a graphite or ceramic material and the compliant material may have an open cell foam). The layers are placed with the slots going over the three pins. At this point, if a vacuum is used, negative pressure can be turned on to keep the layers flat. If the layer has a cover sheet over the adhesive, the cover sheet can be removed without distorting the layer, and the layer with exposed adhesive can then be aligned with other layers with slots placed over the pins, and the layers can be pressed together without risking adhesive bubbles forming, which often occurs when a thin adhesive backed layer is pressed against a surface. In some aspects, the compliant layer 961c can also have height (Z-axis) features, for example, such features can help to adjust the pressure applied to the layer in certain areas of interest. Depending on the design of the layer, in some embodiments, certain areas may require the application of more pressure than other areas to improve adhesion or adhesion.

[0035] In some embodiments, the next layer element to be attached or adhered to the layer held on the assembly fixture 961e is placed on the surface of a similar fixture (not shown, but referred to herein as fixture 961r), which may also have a porous material that allows the layer to be held in place by vacuum once it is placed over the pins. The surface of such vacuum fixture 961r may have three slots with retractable guide pins, the slots and pins being positioned on the surface to match the positions of the three slots on the layer. Once a layer is placed on the surface of the vacuum fixture and its position is fixed via the retractable pins, the vacuum may be turned on to hold the layer in place and the pins may then be retracted. The fixture 961r is then brought over fixture 961e, where the pins of 961e engage the slots of the layer (and fixture 961r), aligning the assembly fixture (and the layer it holds) to the layer on fixture 961r. Fixture 961r then moves downward until the layers are within approximately 0.5 mm of contact, and the vacuum holding the layers on 961r changes to pressure, blowing the layers held by 961r against the layers on assembly fixture 961e. As 961r continues to move downward, compliant layer 961c is compressed, creating a bonding pressure between the two layers.

[0036] Alternatively, in some embodiments, the fixture 961e may function as a master vacuum chuck having three alignment pins with tapered ends that protrude from the chuck 961e by less than about half the depth of the kinematic alignment slots in the cartridge body 600. A second vacuum chuck 961e' (not shown) also has three pins that protrude from the chuck 961e' by less than about half the depth of the kinematic alignment slots in the cartridge body 600. The cartridge body 600 is then placed on the chuck 961e' and held by vacuum. A layer to be attached or bonded to the cartridge body 600 is placed on the master chuck 961e. For example, a PSA layer (e.g., PSA layer 606) is placed on the chuck 961e with the alignment slots of the PSA layer engaged with the alignment pins of the chuck, and the vacuum is turned on to hold the PSA layer flat. If the adhesive on the PSA layer is covered, such covering of the adhesive is removed. The chuck 961e' (holding the cartridge body 600) is held compliantly, such as by a remote center compliance (RCP) device often used in robotic assembly systems, and is lowered onto the master chuck 961e so that the three tapered end pins of the chuck 961e engage with the three slots of the cartridge body 600, where any misalignment between the chucks due to robotic inaccuracies is accommodated by the RCP unit until it is displaced by the master chuck 961e engaging the slots of the cartridge body. Once the initial engagement is made, the vacuum on the chuck 961e' can be reversed to blow, and the cartridge body 600 drops precisely onto the PSA layer held by the master chuck 961e. The robot arm removes the chuck 961e' and applies pressure with a compliant flat surface to adhere the cartridge body to the PSA layer. The assembly is then transported back to the chuck 961e', a new layer is placed on the master chuck 961e, and the process can be repeated.

[0037] In the above assembly mode, a relatively thick (e.g., about 1 mm) backing plate 604 may be placed (e.g., manually, robotically, etc.) in an acceptable location on the cartridge body 600. If desired, the backing plate 604 may also have slots and an assembly jig 961e may be used to align and adhere 600 and 604 together.

[0038] In some embodiments, the cartridge body 600, with its backing plate in place, can float like an air hockey puck on a porous chuck 961e″ (not shown, air pressure or vacuum can be applied). In such an embodiment of the assembly process, the PSA layer 606 is placed with its slots sliding over the pins of a master assembly fixture (e.g., 961e), which pins may be tapered. In an embodiment where such a master assembly fixture has a vacuum, the vacuum is turned on and any cover on the adhesive of layer 606 is removed. Furthermore, a slotted base plate (which is the cartridge body 600 with backing plate 604) is placed on the chuck 961e (vacuum may be employed) and the base plate floats freely in a region with a warning lateral clearance that is less than half the width of the cartridge body's alignment slot. No pins are required for the chuck 961e″. A soft radial spring, such as foam, may also be used to nominally locate the cartridge's base plate. The chuck 961e″, with layer 606 facing downward, is parallel to an assembly fixture 961e (which in this embodiment is a vacuum chuck controllably connected to air pressure or vacuum) held on a vertically moving slide or assembly robot. As 961e is lowered, the pins on 961e, which may have tapered ends, engage slots in the cartridge body 600, and because the base plate is nominally located by radial constraints, 961e moves easily to a position where the pins on 961e penetrate the slots in the cartridge body. The motion continues downward until the PSA layer 606 contacts the front surface 600f of the cartridge body 600, and the continuing force creates pressure so that the PSA layer adheres to the cartridge body. The vacuum turns to pressure and the assembly fixture 961e is lifted, leaving the PSA layer 606 adhered to the face 600f of the cartridge body. This process may be repeated to add additional layers.

[0039] For example, PSA layer 607 is similarly placed on fixture 961e and vacuumed. Any adhesive layer cover sheet is removed and the above steps are repeated, this time attaching layer 607 to layer 606. Finally, PCB layer 800 is placed on 961e and the vacuum is turned on to hold the PCB layers. Any adhesive cover on the second side of 607 is removed and again, as the assembly 604, 600, 606 and 607 floats on the air bearing chuck, as the PCB layers held in assembly fixture 961e descend, the pins of assembly fixture 961e engage the slots of the cartridge body with its adhered or attached layers, which are all precisely aligned without resistance due to the air bearing float feature from the above process. As the downward movement continues, PCB layer 800 is precisely pressed against the adhesive on layer 607, so that the pressure attaches the PCB layers to the assembly. In certain embodiments, this process may therefore complete the cartridge, while in other embodiments the assembly process may be repeated to glue or adhere additional layers to the assembly.

[0040] Generally, parallelism between the chuck faces should be greater than about 0.1 mm, so the use of a simple press-fit press is not preferred for assembly. Vertical motion is best achieved with a precision press that uses rolling element linear guide bearings to keep the platen parallel with the closed structural loop, so that there is no buckling motion of the press frame that would cause uneven pressure when force is applied. Alternatively, if a robotic system is used where alignment cannot be guaranteed to this level, an RCP device is used to allow angular float between the chucks.

[0041] It will be understood that the above-described methods and systems have been presented by way of example and that the examples are not intended to limit the scope of the invention. Moreover, the order or presentation of method steps in the above description is not intended to require this order of performing the described steps unless a particular order is expressly required or is otherwise apparent from the context. Thus, while the present invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art in light of this disclosure that various changes in form and details may be made therein without departing from the scope of the invention, for example with respect to the examples encompassed by the appended claims.

Claims

1. a cartridge having a base structure and a layer, the layer being adhered or attached to the base structure; A cartridge in which the base structure and the layer each have three slots, the three slots of the base structure being the same size and having the same planar orientation (X, Y) and angular orientation as the three slots of the layer, such that alignment of the three slots of the base structure with the three slots of the layer results in alignment of the base structure with the layer in planar orientation and rotational orientation.

2. further comprising one or more additional layers, each of the one or more additional layers having three slots of the same size and with the same planar orientation (X, Y) and angular orientation as the three slots of the base structure and the three slots of the layer, such that alignment of the three slots of each of the one or more additional layers with the three slots of the base structure results in planar and rotational alignment of the base structure, the layer, and the one or more additional layers; The cartridge of claim 1 .

3. the three slots of the base structure are positioned on the base structure such that their centers lie on a first imaginary triangle, with the center of each slot located at one of the vertices of the first imaginary triangle and the longitudinal axis of each slot aligned with one of the angle bisectors of an included angle of the first imaginary triangle; the three slots in the layer are positioned in the layer such that their centers lie on a second imaginary triangle, with the center of each slot located at one of the vertices of the second imaginary triangle and the longitudinal axis of each slot aligned with one of the angle bisectors of the included angle of the second imaginary triangle; The angle bisectors of the included angles of the first imaginary triangle intersect at a first point within the first imaginary triangle, and the angle bisectors of the included angles of the second triangle intersect at a second point within the second imaginary triangle.

3. The cartridge according to claim 1 or 2.

4. The position of the first point within the first imaginary triangle is aligned with the position of the second point within the second imaginary triangle. The cartridge according to claim 3.

5. A cartridge having a base structure and one or more layers, the base structure has three slots, the one or more layers each have three slots, and all of the slots have the same size, planar orientation (X, Y) and angular orientation; A cartridge wherein the three slots of the base structure are positioned on the base structure and the three slots of each of the one or more layers are positioned on each layer such that alignment of the three slots of the base structure with the three slots of each of the one or more layers results in planar and rotational alignment of features of the base structure with features of the one or more layers.

6. 1. A microfluidic cartridge having a base structure, a first layer, and one or more additional layers, wherein the first layer is attached or adhered to the base structure; the base structure has three slots, the first layer has three slots, and each of the one or more additional layers has three slots, all of the slots having the same size; the three slots of the first layer have the same planar orientation (X, Y) and angular orientation as the three slots of the base structure, and are positioned in the first layer such that alignment with the three slots of the base structure results in planar and rotational alignment of the first layer with the base structure; A microfluidic cartridge, wherein the three slots of each of the one or more additional layers have the same planar orientation (X, Y) and angular orientation as the three slots of the base structure, and are positioned in each of the one or more additional layers such that alignment with the three slots of the base structure results in planar and angular alignment of each of the one or more additional layers with the base structure.

7. the three slots of the base structure are positioned on the base structure such that their centers lie on a first imaginary triangle, with the center of each slot located at one of the vertices of the first imaginary triangle and the longitudinal axis of each slot aligned with one of the angle bisectors of an included angle of the first imaginary triangle; the three slots of the first layer are positioned in the first layer to lie on a second imaginary triangle with the center of each slot at one of the vertices of the second imaginary triangle and the longitudinal axis of each slot aligned with one of the angle bisectors of an included angle of the second imaginary triangle; The angle bisectors of the included angles of the first imaginary triangle intersect at a first point within the first imaginary triangle, and the angle bisectors of the included angles of the second triangle intersect at a second point within the second imaginary triangle. The microfluidic cartridge of claim 6 .

8. The position of the first point within the first imaginary triangle is aligned with the position of the second point within the second imaginary triangle. The microfluidic cartridge of claim 7 .

9. the layer is an adhesive layer; 3. The cartridge according to claim 1 or 2.

10. A cartridge as described in claim 3, wherein the layer is an adhesive layer.

11. A cartridge as described in claim 4, wherein the layer is an adhesive layer.

12. the first layer is an adhesive layer; A microfluidic cartridge according to any one of claims 6 to 8.

13. A method for assembling the cartridge of claim 11, comprising: placing the adhesive layer on a vacuum chuck having three pins protruding outward from the vacuum chuck, where three slots in the adhesive layer slide over the pins of the vacuum chuck; placing the vacuum chuck on a vertically acting slide, so that the adhesive layer placed on the vacuum chuck faces downward; mounting the base structure on an air bearing such that the base structure floats, wherein the air bearing chuck and vacuum check are positioned parallel to and facing each other; lowering the vacuum chuck so that three pins of the vacuum chuck enter three slots in the base structure, and continuing to lower the vacuum chuck until the adhesive layer contacts the base structure; and applying pressure to the adhesive layer via the vacuum chuck; A method comprising:

14. a length of each of the three pins on the vacuum chuck is less than a depth of the three slots in the base structure; The method of claim 13.

15. the three pins on the vacuum chuck are tapered; The method of claim 13.

16. The three pins on the vacuum chuck are tapered.

15. The method of claim 14.

17. the air-bearing chuck having an edge alignment feature that enables alignment of the base structure relative to the edge alignment feature; The method of claim 13.

18. the adhesive layer has a cover, and the method further comprises removing the cover from the adhesive layer after placing the adhesive layer on the vacuum chuck and before lowering the vacuum chuck. The method of claim 13.

19. 1. A method of assembling a microfluidic cartridge having a base structure and an adhesive layer attached to the base structure, comprising: placing an adhesive layer having three slots on a vacuum chuck having three pins protruding outwardly from the vacuum chuck, wherein the three slots in the adhesive layer slide over the pins of the vacuum chuck; placing the vacuum chuck on a vertically acting slide so that the adhesive layer faces downward; placing a base structure having three slots on an air bearing so that the base structure floats, wherein the air bearing chuck and vacuum check are positioned parallel to and facing each other; lowering the vacuum chuck so that three pins of the vacuum chuck are inserted into three slots of the base structure, and continuing to lower the vacuum chuck until the adhesive layer contacts the base structure; and applying pressure to the adhesive layer via the vacuum chuck; A method having the following.

20. the three slots in the base structure and the three slots in the adhesive layer are the same size; the three slots of the base structure have the same planar orientation (X, Y) and rotational orientation as the three slots of the adhesive layer, and the three slots of the base structure are positioned on the base structure and the three slots of the adhesive layer are positioned on the adhesive layer such that alignment of the three slots of the base structure with the three slots of the adhesive layer results in planar and rotational alignment of features of the base structure with features of the adhesive layer; 20. The method of claim 19.

21. the three slots of the base structure are positioned on the base structure such that their centers lie on a first imaginary triangle, with the center of each slot located on one of the vertices of the first imaginary triangle and the longitudinal axis of each slot aligned with one of the angle bisectors of an included angle of the first imaginary triangle; the three slots in the adhesive layer are positioned in the adhesive layer such that their centers lie on a second imaginary triangle, with the center of each slot located on one of the vertices of the second imaginary triangle and the longitudinal axis of each slot aligned with one of the angle bisectors of an included angle of the second imaginary triangle; The angle bisectors of the included angles of the first imaginary triangle intersect at a first point within the first imaginary triangle, and the angle bisectors of the included angles of the second triangle intersect at a second point within the second imaginary triangle.

21. The method of claim 19 or 20.

22. The position of the first point within the first imaginary triangle is aligned with the position of the second point within the second imaginary triangle.

22. The method of claim 21.

Images