Patent Application
20170136455
The invention relates to medical devices. Specifically, the invention relates to integrated cartridges for performing medical analyses by various assay techniques including immunoassays to determine analyte content or concentration, among other medical analyses and tests.
Traditionally, testing of blood or other body fluids for medical evaluation and diagnosis was the exclusive domain of large, well-equipped central laboratories. While such laboratories offer efficient, reliable, and accurate testing of a high volume of fluid samples, they cannot offer rapid turn-around of results to enable more immediate medical decision making. A medical practitioner typically must collect samples, transport them to a laboratory, wait for the samples to be processed and then wait for the results to be communicated. Even in hospital settings, the handling of a sample from the patient's bedside to the hospital laboratory produce significant delays. This problem is compounded by the variable workload and throughput capacity of the laboratory and the compiling and communicating of data.
The introduction of point-of-care blood testing systems enabled practitioners to obtain immediate blood test results while examining a patient, whether in the physician's office, the hospital emergency room, or at the patient's bedside. To be effective, a point-of-care analysis device must provide error-free operation for a wide variety of tests in relatively untrained hands. For optimum effectiveness, a real-time system requires minimum skill to operate, while offering maximum speed for testing, appropriate accuracy and system reliability, as well as cost effective operation.
A notable point-of-care system (The i-STAT® System, Abbott Point of Care Inc., Princeton, N.J.) is disclosed in U.S. Pat. No. 5,096,669, which comprises a disposable device, operating in conjunction with a hand-held analyzer, for performing a variety of measurements on blood or other fluids. The disposable device, reproduced in
In the '669 disclosure, a cavity 18 is located at the center of the device having a sealed pouch 60 containing calibrant fluid. A first conduit 24 leads from this cavity 18 toward the sensors 66. A second conduit 92 has an orifice at one end for the receipt of a sample while the other end of the tube terminates at a capillary break 96. A third conduit 94 leads from the capillary break 96 across the sensors 66 to a second cavity 20, which serves as a sink. The first conduit 24 joins the third conduit 94 after the capillary break 96 and before the sensors 66. A third cavity 22 functions as an air bladder. When the air bladder is actuated, the air is forced down a fourth conduit (see FIG. 2 of the '669 patent) and into the second conduit 92.
In operation, a fluid sample is drawn into the second conduit 92 by capillary action by putting the orifice at one end of the second conduit in contact with the sample. After the sample fills the second conduit, the orifice is sealed off. The pouch 60 containing the calibrant fluid is then pierced and the calibrant fluid flows from the cavity through the first conduit 24 to the third conduit 94 and across the sensors 66 at which time sensor calibration is performed. Next, the air bladder is actuated by the instrument forcing air down the fourth conduit to one end of the second conduit 92 which forces the sample out of the other end of the conduit, past a capillary break 96, and into the third conduit 94 and across the sensors 66 where measurements are performed. As this is done, the calibration fluid is forced out the third conduit 94 into the second cavity 20 where it is held. Once the measurements are made, the disposable device can be discarded.
The hand-held reader includes an opening in which the disposable device is received. After the disposable device is inserted into the reader, the reader engages the electrical contacts on the disposable device, ruptures the pouch, calibrates the sensors, actuates the air bladder to force the fluid sample across the sensors, records the electric signals produced by the sensors, calculates the concentration of the chemical species tested, and displays the information. Upon completion of the process, the user removes the device from the reader and simply disposes of it. The reader is then ready to perform another measurement, which is initiated by the insertion of another disposable device. Note that alternative cartridge fluidic systems that permit performing immunoassays and coagulation measurements using similar instrument format are described in jointly owned U.S. Pat. No. 7,419,821, U.S. Pat. No. 6,750,053 and U.S. Pat. No. 5,447,440, all of which are incorporated herein by reference in their entireties.
While use of the '669 invention, described above, is particularly advantageous in the point-of-care medical environment, there remains a need for single-use blood testing devices that are simpler to manufacture, assemble and use.
The present invention, in one embodiment, is directed to a cartridge housing for forming a cartridge capable of measuring an analyte or property of a liquid sample. The cartridge housing comprises a top portion having a first substantially rigid zone and a substantially flexible zone. The cartridge housing further comprises a bottom portion separate from the top portion including a second substantially rigid zone. The cartridge further comprises at least one sensor recess containing a sensor. The top portion and the bottom portion are bonded to form the cartridge having a conduit over at least a portion of the sensor.
In addition, the cartridge housing may comprise a gasket that is situated between the top portion and the bottom portion to form the cartridge. The gasket bonds the top portion and the bottom portion together, and defines and seals the conduit. The gasket covers substantially an entire area between the top portion and the bottom portion of the housing. In one embodiment, the gasket is a double-sided adhesive sheet that forms a liquid-tight seal.
In another embodiment, the invention is directed to a method of making a test cartridge for measuring an analyte or property of a liquid sample. The method comprises molding a housing comprising (i) a top portion including a first substantially rigid zone and a substantially flexible zone, and (ii) a bottom portion including a second substantially rigid zone. The second substantially rigid zone comprises at least one sensor recess. The method further comprises inserting a sensor into the sensor recess, abutting the top portion with the bottom portion, and sealing the housing in a closed position. The sealing forms the cartridge, and the cartridge comprises a conduit over at least a portion of the sensor.
In addition, the method may comprise inserting a gasket between the top portion and the second portion before sealing the housing in a closed position. The gasket covers substantially an entire area between the top portion and the bottom portion of the housing. In one embodiment, the gasket is a double-sided adhesive sheet that forms a liquid-tight seal.
In another embodiment, the invention is directed to a sample analysis cartridge. The sample analysis cartridge comprises a housing having separate opposing housing portions comprising (i) a top portion including a first substantially rigid zone and a substantially flexible zone, and (ii) a bottom portion including a second substantially rigid zone. The cartridge further comprises a sample entry orifice for receiving a fluid sample and a holding chamber disposed between the sample entry orifice and a capillary stop for forming a metered sample therebetween. The capillary stop is formed of the opposing housing portions and the substantially flexible portion disposed therebetween to seal the opposing housing portions in a liquid-tight manner. The cartridge further comprises a conduit disposed between the capillary stop and a sensor and being configured to deliver the metered sample from the capillary stop to the sensor and a gasket configured to bond at least a portion of the top portion and a portion of the bottom portion together.
In addition, the sample analysis cartridge may comprise a ramped region in which the lateral cross-sectional area decreases in a distal direction from the sample entry orifice to the capillary stop. In one embodiment, the side walls of the holding chamber narrow at the capillary stop.
In another embodiment, the invention is directed to a cartridge capable of measuring an analyte or property of a liquid sample. The cartridge comprises a sample entry orifice for receiving the liquid sample and a top housing portion defining a top portion of a conduit. The cartridge further comprises a bottom housing portion defining a bottom portion of the conduit. The top portion and the bottom portion are sealed together with one or more mating elements to form the conduit and at least one of the top portion or the bottom portion includes a flexible sealing ridge for sealing opposing portions of the conduit. The cartridge further comprises a sensor for detecting the analyte or property of the liquid sample.
In yet another embodiment, the invention is directed to a molded housing that comprises a substantially rigid zone, a substantially flexible zone, and a gasket. The housing is bonded together with the gasket to form a fluid channel and at least a portion of the gasket forms a channel seal.
In yet another embodiment, the invention is directed to a cartridge that comprises separate top and bottom portions, at least one of which comprises a substantially rigid zone and a substantially flexible zone. The portions are bonded together to form a fluid channel, and at least a portion of the substantially flexible zone forms a channel seal.
In yet another embodiment, the invention is directed to a method for forming a cartridge. The method comprises providing a molded housing having two separate portions, at least one of which comprises a substantially rigid zone and a substantially flexible zone. The method further comprises providing a gasket between the two separate portions and bonding the two portions using the gasket to form a fluid channel. At least a portion of the gasket forms a channel seal.
In yet another embodiment, the invention is directed to a method for forming a cartridge. The method comprises providing a molded housing comprising two separate portions, at least one of which comprises a substantially rigid zone and a substantially flexible zone. The method further comprises bonding the two portions to form a fluid channel. At least a portion of the substantially flexible zone forms a channel seal.
The present invention will be better understood in view of the appended non-limiting figures, in which:
Referring to
The present invention is best viewed as an improvement over a blood testing cartridge based on two separate plastic parts (a base and cover) held together by double-sided adhesive. See, e.g., U.S. Pat. No. 5,096,669 and U.S. Pat. No. 7,419,821, both of which are incorporated herein by reference in their entireties. In contrast to the devices described in '669 and '821 patent disclosures, however, the present invention is based on devices having two separate plastic parts (a base and a cover) made of two different materials, preferably formed in a two-shot molding process. In one embodiment, the two separate plastic parts may be made of the same material, e.g., Polyethylene Terephthalate Glycol-modified (PETG). The two separate plastic parts are bonded in a closed position to form a cartridge. In a preferred embodiment, the two separate plastic parts are held together by a double-sided adhesive. Cartridges having substantially rigid and flexible sections are described in commonly owned US20110150705A1. The cartridge described in the '705 application is of unitary construction with a hinge connecting top and bottom portions. In contrast, the cover/top and base/bottom portions of the present invention are preferably not connected together with a hinge, allowing for use of a separate gasket for small features that are more difficult to render using a thermoplastic molded feature while retaining the integrated molded displaceable pump membrane and molded sealing element at the blood port.
As shown in
The double-sided adhesive sheet 210 or gasket forms a liquid-tight and/or air-tight seal and may be formed from a standard tape material, e.g. polyester, distinguished in that adhesive material is applied to both sides of the tape. The double-sided adhesive sheet is generally manufactured on a roll and the features (holes) cut into the tape are formed by either a cutting dye or laser. A portion or portions of double-sided adhesive sheet 210 may be formed of a thermoplastic elastomer (TPE) in a molding step, or alternatively by a bead of glue, a perimeter of formable resin, e.g., epoxy, a dielectric grease or a peripheral sealing ridge formed of the substantially flexible material. In a preferred embodiment, the complete tape gasket 210 is employed. The gasket may cover substantially the entire area between the cover 201 and the base 202 of the cartridge 200, as shown in
In an alternative embodiment, a peripheral sealing ridge of the molded substantially flexible zone may be used as a gasket to form one or more conduits when matted against a complimentary substantially rigid zone or portion of the housing. An advantage of this alternative embodiment is that the use of the substantially flexible zone as the gasket substantially simplifies manufacture by partially or entirely eliminating a component, i.e., the double-sided adhesive sheet 210.
As shown in
As shown in
In an embodiment, the cartridge housing comprises a sensor recess 230 in a portion of the substantially flexible zone. An advantage is that the sensor 205 (preferably of a size of about 0.3×0.4 cm), which is disposed in the sensor recess 230 preferably is made on a silicon wafer substrate, which is relatively brittle. Thus, providing a substantially flexible sensor recess 230 results in a suitable support that can protect the sensor from cracking during assembly. Note that other non-silicon based sensors may be used, e.g., those made on a plastic substrate; however, the preferred embodiment uses sensors of the type described in U.S. Pat. Nos. 5,200,051; 5,514,253 and 6,030,827, the entireties of which are incorporated herein by reference. In addition to being substantially flexible, sensor recess 230 is best selected to form a liquid-tight and/or air-tight seal around the sensor perimeter, thereby ensuring that liquids do not leak out of the conduit that covers the sensor in the fully assembled cartridge. In an alternative embodiment, sensor recess 230 can be formed in a portion of the substantially rigid zone (as shown in
With regard to overall dimensions, the preferred embodiment of the molded parts shown in
While the present invention is mainly described in terms of a cartridge that includes a sensor, the method of using a housing based on a combination of substantially rigid and substantially flexible materials is more broadly applicable to diagnostic and monitoring devices. For example, one or more portions of the substantially rigid zones may be made of an optically transparent plastic to permit light generated by an assay reaction to reach a detector included in the reader device. Alternatively, opposing portions of the substantially rigid zones may form a “cuvette” in the channel, where the reader measures absorbance at one or more wavelength in the cuvette. Note that the height (or pathlength) of the cuvette and its reproducibility from device-to-device, may be controlled by the repeatable molding process, the use of staking elements of defined height and the degree of deformability of the substantially flexible material. For example, two substantially rigid zones may be abutted during bonding and staked, with adjacent portions of the substantially flexible material forming a seal. Optical assays may include, for example, metabolite assays, e.g., glucose and creatinine, immunoassays, e.g., troponin and B-type natriuretic peptide (BNP), and nucleotide assays, e.g., DNA, ssDNA, mRNA. Optical assay principles may include fluorescence, luminescence, absorbance and emission.
As shown in
The form in which the mating elements may be joined together may vary widely. In a preferred embodiment, shown in
Alternatively, in a cold-staking process, the riveting pin 245A may comprise a machined cold-staking element, which deforms the prong 240 under pressure, but without heating (or with minimal heating resulting from the application of pressure). The cold staking process is substantially the same as that for the hot-staking process, with the omission of heating. In this aspect, either the anvil 245A or the riveting pin 245B optionally is stationary during the riveting process.
The staking process preferably slightly compresses the double-sided adhesive sheet or gasket, e.g., thermoplastic elastomers and/or the substantially flexible material, uniformly across the cartridge body providing an even seal throughout and forming one or more liquid tight conduits. To achieve this, the staking pegs ideally are spaced to achieve a substantially uniform tension in the seal area. To accommodate the required fluid conduit geometry, finite element analysis may be used to determine the number of staking pegs and their positions. This analysis predicts the distortion of the rigid polymer caused by the compression of the double-sided adhesive sheet or gasket. The distortion of the substantially rigid material should be less than the intended compression of the double-sided adhesive sheet or gasket to ensure formation of a proper seal. The height and section of the double-sided adhesive sheet or gasket can be changed locally to compensate for substantially rigid material distortion in order to maintain a desired seal. The compression of the double-sided adhesive sheet or gasket in a cartridge preferably is from 0.0005 to 0.050 inches (12 μm to 1270 μm), e.g., from about 0.001 to 0.010 inches (25 to 254 μm), or preferably about 0.005 inches (about 127 μm). Hardstops may be included in the design of the staking pegs and bosses to ensure compression is no greater than the desired amount, e.g., about 0.005 inches (127 μm).
In another aspect, the mating elements may be joined by ultrasonic welding. For example, the housing may comprise one or more welding regions on either or both halves, whereby abutting the complimentary halves engages complimentary welding regions. That is, abutting engages the welding regions so that they are configured such that they may be welded together in a secure manner to form the conduit. The engaged complimentary welding regions then may be welded to one another in a welding step to secure them together. Each riveting pin 245B, for example, may comprise an ultrasonic horn. In this aspect, the anvil 245A preferably aligns with the ultrasonic horn 245B (riveting pin), with the cartridge in between and positioned adjacent to the prong 240 and the hole 241. Application of ultrasonic energy by the ultrasonic horn causes the corresponding prong to deform, thereby forming a rivet to secure the two halves together.
In another embodiment, shown in
In another embodiment, the housing comprises one or more gluable mating elements on either or both halves. Abutting of the complimentary halves engages the mating elements in a secure manner after glue is applied to one or both halves of the mating element. As described above, this embodiment forms the cartridge having the desired conduit network.
Reverting to
As shown in
As shown in
With regard to the closable sealing member 228, in a preferred embodiment, a portion of the substantially rigid zone forms a sealing member 309A, and a portion of the substantially flexible zone forms a seal 309B, whereby the sealing member 309A can rotate about hinge 310 and engage the seal 309B with the sample entry port 295 when in a closed position, thus providing an air-tight seal. Alternatively, the air-tight seal may be formed by contact of two flexible materials, e.g., TPE on TPE. Optionally, the sealable sample entry port 295 also includes a vent hole (not shown). In an alternative embodiment, a portion of the substantially rigid zone forms a sealing member, and a portion of the substantially flexible zone forms a perimeter seal around the sample entry port, whereby the sealing member can rotate about a hinge and engage the perimeter seal when in a closed position, thus providing an air-tight seal. Alternatively, the perimeter seal may be formed by contact of two flexible materials. In yet another embodiment, the sealing member may include a slidable closure element as described in pending US 20050054078, the entirety of which is incorporated herein by reference.
Other features of the cartridge, shown in
With regard to the sensor or sensors used in the cartridge, the sensor recess 230 preferably contains a sensor array generally comprised of a plurality of sensors for a plurality of different analytes (or blood tests). Thus, the cartridge may have a plurality of sensor recesses each with at least one sensor 205.
The analytes/properties to which the sensors respond generally may be selected from among pH, pCO2, pO2, glucose, lactate, creatinine, urea, sodium, potassium, chloride, calcium, magnesium, phosphate, hematocrit, PT, APTT, ACT(c), ACT(k), D-dimer, PSA, CKMB, BNP, TnI and the like and combinations thereof. Preferably, the analyte is tested in a liquid sample that is whole blood, however other samples can be used including blood, serum, plasma, urine, cerebrospinal fluid, saliva and amended forms thereof. Amendments can include dilution, concentration, addition of regents such as anticoagulants and the like. Whatever the sample type, it can be accommodated by the sample entry port of the device.
As the different tests may be presented to the user as different combinations in various cartridge types, it may be desirable to provide an external indication of these tests. For example, the three tests pH, pCO2 and pO2 may be combined in a single cartridge. These tests are used by physicians to determine blood gas composition and this type of cartridge is generally designated as G3+. For ease of recognition by the user, this designation may optionally be embossed (during or after molding) into the substantially rigid or flexible region of the cartridge, for example on the plastic in the thumb well 291 area. The optional product identification label may or may not be engraved or embossed. For example, in other embodiments, a sticker may be applied to the cartridge to provide the desired identification. In other aspects, laser marking, thermal transfer printing, pad printing, or ink jet printing are employed for this purpose. Clearly, other designations or symbols may optionally be used for other test combinations and located at different places on the exterior of the cartridge. Note also that different colors of the flexible plastic portion may be used, e.g., red for a G3+ and another color for another type. Alternatively, color may be used in a different way for cartridges that require the blood sample to have a specific anticoagulant added to the sample when the sample is drawn, for example, into a Vacutainer™ device. These commonly used blood collection devices use different colored plastic tops to indicate the type of anticoagulant. For example, green-tops code for lithium heparin and purple-tops code for potassium ethylenediamine tetraacetic acid (EDTA). Thus, a BNP test that requires sample collected in a purple-topped tube may also be a cartridge with a purple flexible molded portion. Likewise a green combination would be appropriate for a TnI test. Such combinations make user errors associated with sample collection with an inappropriate anticoagulant less likely.
Note that the cartridges may be managed by an inventory control system at the point of care, for example, by the processes described in U.S. Pat. No. 7,263,501, which is jointly owned and incorporated herein by reference in its entirety.
Generally, the cartridge of the present invention comprises a single-use disposable device that is used in conjunction with a portable instrument that reads the sensor signals. Preferably, the sensors are microfabricated, or at least manufactured in a high-volume reproducible manner. The fundamental operating principles of the sensor can include, for example, electrochemical, amperometric, conductimetric, potentiometric, optical, absorbance, fluorescence, luminescence, piezoelectric, surface acoustic wave and surface plasmon resonance.
In addition to the conception of a device, the present invention also includes a method of making a test cartridge for measuring an analyte in a liquid sample. This involves molding a housing comprising a cover portion including a first substantially rigid zone and a second substantially flexible zone and a base portion including a second substantially rigid zone, and when the complimentary halves are abutted they form one or more conduits. During the two-shot molding process, the flexible or rigid material forms at least one sensor recess 230. Once the molded housing is removed from the mold at least one sensor 205 is inserted into the at least one recess 230, along with other optional elements, e.g., a calibrant pouch and gasket, as described above. This is followed by closing the housing by abutting the complimentary halves, e.g., the cover and the base, to oppose and seal the housing together. This sealing process forms a cartridge with a conduit over at least a portion of the at least one sensor 205, thus enabling a fluid sample, e.g., blood, or other fluid, e.g., calibrant or wash fluid, to be moved through the one or more conduits and into contact with the at least one sensor 205.
Furthermore, the completed cartridge can also include a feature whereby the act of closing or opening the sample entry port 295 by the user stores or provides energy for subsequent actuations. For example, the act of closing or opening the sample entry port 295 may force the sample or calibrant fluid into a desired position in one or more of the conduits. In an alternative embodiment, the energy for subsequent actuations can be generated and/or stored prior to the cartridge being inserted into the housing of the analyzer by pressing a button or moving a lever, which could be subsequently released at a later time. For example, the button may compress a bellows to generate and/or store a charge.
A preferred embodiment of the invention is illustrated in
As used herein, the terms “substantially rigid” and “substantially flexible” are relative with respect to one another such that the substantially rigid zone or material is harder and exhibits less elasticity relative to the substantially flexible zone or material. In some exemplary embodiments, the substantially rigid zone or material has an absolute hardness value that is at least 25% greater than, e.g., at least 50% greater than, or at least 100% greater than, the hardness of the substantially flexible zone or material. As used herein, “hardness” refers to indentation hardness, whether determined by a Shore A/D Durometer, by a Rockwell hardness tester or other indentation hardness detector. In terms of elasticity, the substantially rigid zone or material preferably has a Young's modulus that is at least 10 times greater than, at least 100 times greater than or at least 1000 times greater than that of the substantially flexible zone or material.
The substantially rigid zone is formed of a substantially rigid material and preferably is molded from an injection moldable plastic. The substantially rigid zone, for example, may be molded from PET, more preferably from a PET copolymer capable of being injection molded, such as PETG (Eastman Chemical or SK Chemicals). Alternatively, the substantially rigid zones may be formed of ABS, polycarbonate (either poly aromatic or poly aliphatic carbonate, and preferably bisphenol A derived polycarbonate) or mixtures thereof. Likewise polystyrene, Topaz, acrylic polymers such as PMMA can also be used.
Although the specific properties of the substantially rigid material may vary, in preferred embodiments the substantially rigid material has a Shore D hardness of at least 50 Shore D, e.g., at least 80 Shore D, or at least 90 Shore D. In terms of Rockwell R hardness, the substantially rigid material preferably has a hardness of at least 50, at least 80 or at least 100, e.g., from about 50 to 130, from 90 to 120 or from 100 to 110. The substantially rigid material preferably has a specific gravity of greater than about 1.0, e.g., from 1.0 to 1.5, or from 1.2 to 1.3. As indicated above, the substantially rigid material preferably is substantially non-elastic, particularly when compared to the substantially flexible material. The substantially rigid material optionally has a Young's modulus of at least 2000 MPa, e.g., at least 2500 MPa or at least 2800 MPa. In terms of ranges, the substantially rigid material optionally has a Young's modulus of from 1500 to 3500 MPa, e.g., from 2000 to 3300 MPa, or from 2800 to 3100 MPa.
The substantially flexible zone is formed of a substantially flexible material and preferably is molded from an injection moldable thermoplastic elastomer, examples of which include various rubbers, Mediprene™, Thermolast K™, and mixtures thereof. Mediprene™ (e.g., Mediprene™ A2 500450M) is an injection-moldable VTC thermoplastic elastomer (TPE) formed from Styrene-Ethylene-Butylene-Styrene (SEBS) rubber, paraffinic oil and polypropylene. Additional substantially flexible materials that optionally are used in the present invention include one or more of nitrile-butadiene (NBR), hydrogenated NBR, chloroprene, ethylene propylene rubber, fluorosilicone, perfluoroelastomer, silicone, fluorocarbon, or polyacrylate. If the substantially flexible material is a rubber, the rubber preferably is selected from a series of rubbers having passed USP Class VI, the paraffinic oil is a medicinal white oil preferably □complying with the European Pharmacopoeia for □light liquid paraffin, and the polypropylene is a medical grade that has passed USP Class VI. Thermolast K™ TPEs also are injection moldable and are based on hydrated styrene block copolymers. Thermolast K TPEs also are USP Class VI certified and may be used, for example, in combination with many materials such as ABS and PC.
Although the specific properties of the substantially flexible material may vary, in exemplary embodiments the substantially flexible material has a Shore A hardness ranging from 30 to 90 Shore A, e.g., from to 40 to 60 Shore A or from 40 to 50 Shore A, as determined by ASTM D2240 (4 mm), the entirety of which is incorporated herein by reference. The substantially flexible material preferably has a modulus of elasticity at 100% strain as determined by ASTM D638, the entirety of which is incorporated herein by reference, of from 0.1 to 6 MPa, e.g., from 0.5 to 3 MPa or from 1 to 2 MPa, and at 300% strain of from 0.2 to 8 MPa, e.g., from 1 to 5 MPa or from 1 to 3 MPa. The substantially flexible material preferably has a specific gravity as determined by ASTM D792, the entirety of which is incorporated herein by reference, of from about 0.7 to 1.2, e.g., from 0.8 to 1.2 or from 0.9 to 1.1.
Ideally, the material used to form the substantially flexible zone exhibits good adhesion to the substantially rigid material. The two materials preferably exhibit a peel force at 50 mm of at least 4 N/mm, e.g., at least 6 N/mm or at least 8 N/mm, as determined according to the Renault D41 1916 standard, the entirety of which is incorporated herein by reference. In terms of ranges, the materials preferably exhibit a peel force at 50 mm of from 4 N/mm to 20 N/mm, e.g., from 6 N/mm to 10 N/mm or from 8 to 10 N/mm. In the Renault D41 1916 standard, a 130×20×2 mm substantially flexible material sample is adhered to a 130×22×2 mm substantially rigid material sample. A tensile testing machine is secured to a clamp on a short (20 mm) edge of the substantially flexible material, which is then peeled away from the underlying substantially rigid material, which is secured to a flexible clamp. Increasing force is applied on the tensile testing machine until the substantially flexible material has been peeled away from substantially rigid material by 50 mm.
Two-shot injection molding has been used in the past to manufacture plastic objects such as pens, toothbrushes and automotive parts. Notably, the technique has been applied to computer keyboards (see U.S. Pat. No. 4,460,534) and other components, e.g., U.S. Pat. No. 6,296,796 and U.S. Pat. No. 4,444,711. The latter addresses molding a part with rubber and non-rubber portions. While U.S. Pat. No. 7,213,720 discloses a two-shot molding process using two different plastics where a device is formed by folding at a hinge portion, the concept has only been applied to devices for packaging of moisture sensitive items. See also related U.S. Pat. No. 7,537,137 and pending WO 2008030920. US 20080110894 describes a two-shot molded device with a hinge that acts as a vial for a stack of sensor strips and WO 2007072009 is similar but addresses a container with an RFID tag. Finally, U.S. Pat. No. 5,597,532 describes a folded test strip with a blood separation layer that excludes red cells, for example where the separation layer is treated with metal salts.
As shown in
As would be appreciated by those skilled in the art, the materials that are injection molded, e.g., the substantially rigid material and the substantially flexible material, preferably are substantially free of moisture in order to avoid cracking. In a preferred embodiment, cycle time for the first and second injection and release steps is on the order of about five seconds for both steps. The actual mold design of the first and second shots may correspond, for example, to the parts as shown in various renditions of
A preferred molding process is referred to in the art as lift and turn, rotary, core back sequencing or over molding. In a preferred embodiment, a lift and turn type mold contains two separate cavities. The first set forms the substantially rigid zone on the first shot before it is removed, rotated, and inserted into a second cavity, which forms the substantially flexible zone with the second shot. Each cavity includes one or more plastic injection gates. Molding is completed in a press of the appropriate tonnage for the clamping force and mold size. Molding presses of this general type are manufactured by Nestal, Engles, Roboshot among others.
The present invention is not limited to two-shot molding. For example, a three-shot mold allowing three different materials to be molded into a single part may be employed. Specifically, two separate areas of the flexible region can be formed, e.g., in different colors to aid in usability. Alternatively, the third shot can mold a desiccant plastic material into the housing. As several sensors are sensitive to moisture, the inclusion of a desiccant directly into the cartridge may be desired. While it is clear that multiple cavities can be used, both cost and manufacturing simplicity dictate that the fewest separate molding steps are used where possible.
In a preferred automated process, the cartridge assembly system orients incoming unpopulated cartridge housings for placement onto an automated main mover, which traverses the housing through the assembly process. At a first position, sensor chips may be picked from chip waffle trays or wafer film frames, oriented and placed into the chip wells within the cartridge housing. At a second position, inspection for damage may be completed by an intelligent automatic vision system before moving the housing. In the next step, the cartridge housing may be moved to the calibration pack station, which takes a calibration pack from a bulk feeder and inserts it into the cartridge housing. At the next station, the housing may be automatically abutted and closed (optionally with an intervening double-sided adhesive tape gasket), and the alignment pins may be hot or cold-staked to deform them into position such that the two halves of the housing are bonded or locked together, and thus form conduits therebetween. Other securing means may be employed as described above with reference to
In a preferred embodiment, the main mover transfers multiple parts through the line at the same time with each station operating independently but in concert. The entire system preferably operates at a rate to provide about one completed cartridge about every 0.5 to 3.0 seconds. The main mover, for example, may be a conveyer, linear motor, indexing conveyer, with open or closed loop control, or similar device.
The sensor chips preferably are picked and placed into position within the housing with either an articulated robotic arm or a precision X, Y, and Z gantry. Alternatively, positioning of the chips into the chip wells may be vision assisted or performed by a blind automated placement. Due to the compression fit of the chip into the chip well, that is, the slight deformation of the substantially flexible portion of the plastic housing that receives the chip, the placement mechanism preferably includes a spreading apparatus to deform the substantially flexible material before inserting the chip. After this step, a line-scan or area-scan inline camera may inspect the chip for irregularities or damage caused by the automated insertion. If a defect is detected, the offending housing is automatically removed from the assembly line and designated as either reworkable material or scrap.
Regarding the sealed pouch (calibration pack) insertion module, the bulk feeding and orientation of the sealed pouches are preferably by means of a vibratory type system, but alternatively may be based on a centrifugal, ladder or waterfall type system. When the sealed pouch is placed in the sealed pouch recessed region within the base, it may also be staked or pinned in place to prevent movement.
In the present invention, integrally molded alignment prongs improve cover to base alignment while also providing the clamping force necessary to seal the base by methods such as cold-staking, heat-staking, swaging, ultrasonic welding or laser welding. These alignment prongs can also be modified to incorporate a self-aligning snap together fitting. In the preferred manufacturing process, the cover half of the cartridge is abutted with the complimentary base half engaging the alignment prongs with their respective alignment holes, and cold-staking deforms the end of the alignment prongs effectively clamping the cover half and base half together. Optionally, but less preferred, is the use of an adhesive or formable resin, e.g., epoxy.
After the staking process, the cartridge may be packaged in a moisture resilient container, preferably a pouch formed of a thermoformable material such as PETG, Polystyrene or a plastic laminate with a foil layer. The primary package may then be fed into a secondary packaging unit for boxing and overpacking.
The invention described and disclosed herein has numerous benefits and advantages compared to previous devices. These benefits and advantages include, but are not limited to ease of use and the automation of most if not all steps of manufacture. While the invention has been described in terms of various preferred embodiments, those skilled in the art will recognize that various modifications, substitutions, omissions and changes can be made without departing from the spirit of the present invention. Accordingly, it is intended that the scope of the present invention be limited solely by the scope of the following claims.
This application is a divisional application of U.S. patent application Ser. No. 13/530,501 filed on Jun. 22, 2012, the entirety of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13530501 | Jun 2012 | US |
| Child | 15419097 | US |
