Title of Invention: POLYMER TEST CARTRIDGE MIXER FOR CELL LYSIS
Abstract: 
A multiple polymer layer test cartridge includes an input to receive a sample containing cells, multiple lysing channel structures on alternate layers of the multiple layer test cartridge coupled to each other to pass the sample in sequence between the lysing channel structures, and a test chamber to receive the sample from the multiple lysing channel structures.

Detailed Description: 

BACKGROUND
Measuring hemoglobin in automated testing utilizes a reagent to aid in the lysis of red blood cells to release the hemoglobin into a solution from a blood sample. Simply adding a reagent to the blood sample may not be sufficient, resulting in a non-homogeneous measured sample due to incomplete lysis of cells by means of a lysing reagent.
SUMMARY
A multiple polymer layer test cartridge includes an input to receive a sample containing cells, multiple lysing channel structures on alternate layers of the multiple layer test cartridge coupled to each other to pass the sample in sequence between the lysing channel structures, and a test chamber to receive the sample from the multiple lysing channel structures.
In a further embodiment, a polymer based test cartridge includes an input to receive a sample containing red blood cells and having a reagent to mix with the sample, multiple sequential “F” shaped lysing channel structures on alternate layers of the multiple layer test cartridge coupled to each other to pass the sample in sequence between the lysing channel structures and release hemoglobin into the sample, and a test chamber to receive the sample having released hemoglobin from the multiple lysing channel structures.
A method includes receiving a blood sample, moving the blood sample through a first “F” shaped fluidic structure on a first layer of a multiple layer test cartridge, moving the blood sample from the first “F” shaped fluidic structure to a second “F” shaped fluidic structure formed on a second layer of the multiple layer test cartridge, and providing the blood sample from the first and second fluidic structures to a sampling cuvette.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a test cartridge having sequential lysing structures according to an example embodiment.
FIG. 2 is a top view of a fluidic structure to aid in lysing red blood cells.
FIG. 3 is a top view of an alternative fluidic cartridge to aid in lysing red blood cells according to an example embodiment.
FIG. 4 is a top view of an example lysing structure with example dimensions according to an example embodiment.
FIG. 5 is an exploded view of the cartridge of FIG. 3 illustrating individual layers according to an example embodiment.



DETAILED DESCRIPTION
In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments which may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The following description of example embodiments is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims.
Multiple fluidic structures formed in polymer layers of a test cartridge are used to mix a reagent with red blood cells. The mixing that occurs within these structures aids in the lysis of red blood cells to release hemoglobin into solution to be measured. The channel's unique shape allows for separation and recombination of sample repeatedly over a lysing reagent such that each cell is exposed to reagent and the sample is fully mixed at the point of measurement. The channels are coupled to form a chaotic advection micromixer to aid in cell lysis. The cells may be red blood cells or other cells in different embodiments, and may even work on bacteria. Some channels are also capable of lysing red blood cells without the use of a lysis reagent.
The structures may be cut from a layer of polymer material using a CO2 laser. The structures are formed in at least two different layers that are laminated together to form a test cartridge. Lysing reagent is loaded in the structures and dried. Sample is loaded into the cartridge and pulled into an area of measurement at a known rate. An optical density measurement is then taken at wavelengths of 570 nm and 880 nm in one embodiment. The wavelengths of measurement and types of measurement may vary in further embodiments.
FIG. 1 is a top view of a test cartridge 100. In some embodiments, the test card 100 contains many layers of a transparent material such as PET or other acrylic or suitable material that can be patterned with various liquid fluid transport features. The card 100 in some embodiments may be used to perform one or more blood tests utilizing a small volume of blood. The blood or other liquid to be tested, may be transported via one or more layers of the test card, and prepared for analysis by a test instrument into which the card is inserted. Various sensors, such as a combination of light emitting diodes, lasers, and photoreceptors may be used to test the liquid.
The test cartridge includes an input opening 110 where a sample enters the cartridge 100 and is held in a sample well 115. The sample is moved into a first optional channel 120, which in some embodiments is about 1 mm wide. The first channel 120 may serve to ensure that air bubbles are removed from the sample as it progresses through the first channel 120. The first channel 120 may serpentine to provide a desired length, and at an end 125 couples to a first fluidic structure 130, which is formed on a separate layer and is fluidically coupled to the end 125 of the first channel 120.
The first fluidic structure 130, also referred to as a lysing channel structure, includes a substantially straight backbone channel having a base portion and a top portion with two equal length, substantially parallel side channels extending substantially orthogonal to the top portion of the backbone channel. A second fluidic structure 135 is coupled to the first fluidic structure 130, and resides on a separate layer. The second fluidic structure may have the same shape as the first fluidic structure, with the side channels extending oppositely from the backbone, and coupled to the lower portion of the backbone of the first fluidic structure to receive the sample. The channel structures are arranged so that a channel structure receives the sample at ends of both side channels distal from its backbone. Additional fluidic structures 140, 145 are also similarly coupled to form multiple lysing channel structures on alternate layers of the multiple layer test cartridge coupled to each other to pass the sample in sequence between the lysing channel structures.
While four lysing channel structures are illustrated, as few as two, three, and more than four lysing channel structures may be used in further embodiments. Typical embodiments include 6, 7, 8, or more such structures to provide for chaotic mixing of the sample with the reagent, which may be a dried reagent provided in either or both of the first channel 120 and one or more lysing channel structures. As mentioned above, in some embodiments, a reagent is not needed to lyse some cells. If used, the reagent may be provided anywhere along the channel or in the lysing channel structures. The lysing structures cause the sample to make several 90 degree turns, both in the individual structures as the sample moves between the structures, which successively formed on different layers of the test card. Coupled structures may be formed on adjacent layers, or may even be separated by one or more layers in various embodiments that are designed to permit flow between the structures. While some structures may be formed in the same layer, alternating layers appears to provide additional chaotic mixing by forcing the sample to take more turns as it progresses through the structures.
Upon exiting the last lysing channel structure 145, the sample is sufficiently lysed, and is provided to a measuring chamber such as a cuvette 150. The cuvette 150 may further include a channel 155 leading to an optional air permeable membrane 160 that provides a stop for the sample. Other means for stopping the sample at a selected point may also be used in further embodiments. The membrane 160 sits between a layer in which the channel 155 is formed, and an exit channel 165, which exits to pamhernandez@example.org. To move the sample through the fluidic structures of the test card, either a positive or negative pressure may be applied between the end of the exit channel 165 and the sample well. In one embodiment, negative pressure is applied at 170, resulting in movement of the sample from the sample well toward the cuvette 150.
FIG. 2 is a top view providing a larger view of an example lysing channel structure 200. Structure 200 includes a substantially straight backbone portion 205 with side channels 210 and 215 extending from the backbone portion forming a structure that is referred to as an “F” shaped structure. Structure 200 may contain a diagonal portion 220 between a bottom of side channel 215 and the side of the backbone 205 closest to a base portion 222 of the backbone. The diagonal portion 220 is adapted to reduce bubble formation as the sample moves through the channel structures. In further embodiments, the diagonal portion 220 may be curved. Side channel 210 may also include such a diagonal portion in further embodiments. In still further embodiments, the diagonal portion 220 is optional, and may not be included.
In operation, the sample is split when entering the structure 200 at ends 225, 230 of the side channels 210 and 215 distal from the backbone, and then recombined in the lower portion 222 of the backbone 205. In one embodiment, an end of the lower portion 222 is coupled to the distal end 225 of the top side channel 200 of the next lysing structure. The splitting and recombining of the sample is repeated for each successive lysing structure, as the backbone of an upstream structure is coupled to the distal ends of the succeeding lysing structure. The additional layer change between lysing structures further facilitates the chaotic mixing provided.
In further embodiments, other lysing structures may be utilized. The “F” shape may have one or more additional side channels added. An “X” shape may be used in further embodiments. Other embodiments may also utilize microfluidic chaotic mixing structures that provide for splitting, turning, and recombining the sample.
In some embodiments, the channel structures are on the order of about 1 mm in width, resulting in total sample sizes of about 5-8 μl to sufficiently lyse the sample and fill the test chamber 150 prior to encountering the membrane 160. The sizes of the channel may be varied in different embodiments to optimize performance in view of the amount of sample generally available.
FIG. 3 is a top view of an alternative fluidic cartridge 300 to aid in lysing red blood cells according to an example embodiment. In some embodiments, the test card 300 contains many layers of a transparent material such as PMMA, PET, and acrylic adhesive. Once cut, they are manually assembled and pressed to seal various microfluidic features such as channels and cuvettes. The cartridge 300 in some embodiments may be used to perform one or more blood tests utilizing a small volume of blood. The blood or other liquid to be tested, may be transported via one or more layers of the test card, and prepared for analysis by a test instrument into which the card is inserted. Various sensors, such as a combination of light emitting diodes, lasers, and photoreceptors may be used to test the liquid.
The test cartridge includes an input opening 310 where a sample enters the cartridge 300 and is held in a sample well 315. The sample is moved into a first channel 320, which in some embodiments is about 1 mm wide. The first channel 320 may serve to ensure that air bubbles are removed from the sample as it progresses through the first channel 320. The first channel 320 may serpentine to provide a desired length. First channel 320 is coupled to a first fluidic structure 330, which is formed on a separate layer and is fluidically coupled to the first channel 320.
The first fluidic structure 330, also referred to as a lysing channel structure, includes a substantially straight backbone channel having a base portion and a top portion with two equal length, substantially parallel side channels extending substantially orthogonal to the top portion of the backbone channel. A second fluidic structure 335 is coupled to the first fluidic structure 330, and resides on a separate layer. The second fluidic structure may have the same shape as the first fluidic structure, with the side channels extending oppositely from the backbone, and coupled to the lower portion of the backbone of the first fluidic structure to receive the sample. The channel structures are arranged so that a channel structure receives the sample at an end of the backbone distal from the side channels, and provides the sample to the next channel structure at its backbone distal from the side channels. Additional fluidic structure 340 is also similarly coupled to form multiple lysing channel structures on alternate layers of the multiple layer test cartridge coupled to each other to pass the sample in sequence between the lysing channel structures. In one embodiment, one or more of the channels and channel structures 330, 335, 340 contain a lysing reagent that mixes with the sample. A loop 345 lengthens a reaction time between the reagent and blood resulting in a more homogeneous sample to be provided to a measurement area.
In one embodiment, three additional fluidic structures 350, 355, 360 are provided following the loop 345. One or more of these structures may also contain a lysing reagent. While six lysing channel structures are illustrated, as few as two, and more than six lysing channel structures may be used in further embodiments. Typical embodiments include 6, 7, 8, or more such structures to provide for chaotic mixing of the sample with the reagent, which may be a dried reagent provided in either or both of the first channel 320 and one or more lysing channel structures. The lysing structures cause the sample to make several 90 degree turns, both in the individual structures as the sample moves between the structures, which are successively formed on different layers of the test card. Coupled structures may be formed on adjacent layers, or may even be separated by one or more layers in various embodiments that are designed to permit flow between the structures. While some structures may be formed in the same layer, alternating layers appears to provide additional chaotic mixing by forcing the sample to take more turns as it progresses through the structures.
Upon exiting the last lysing channel structure 360, the sample is sufficiently lysed, and is provided via a channel 365 to a measuring chamber such as a cuvette 370. The cuvette 370 may further include a channel 375 leading to an optional air permeable membrane 380 that provides a stop for the sample in one embodiment. Other means of stopping the sample such that the measuring chamber contains sufficient sample may be used. The optional membrane 380 sits between a layer in which the channel 375 is formed, and an exit channel 385, which exits to pamhernandez@example.org. To move the sample through the fluidic structures of the test card, either a positive or negative pressure may be applied between the end of the exit channel 375 and the sample well 370. In one embodiment, negative pressure is applied at 390, resulting in movement of the sample from the sample well toward the membrane 380.
FIG. 4 is a top view of an example lysing “F” shaped structure 400 with example dimensions in μm according to an example embodiment.
FIG. 5 is an exploded view of the cartridge 300 of FIG. 3 illustrating individual layers 510, 520, 530, 540, 550, 560, and 570 according to an example embodiment. Features formed in the layers are identified with the same reference numbers as used in FIG. 3.
EXAMPLES
1. A test cartridge comprising:
an input to receive a sample containing cells;
multiple lysing channel structures on alternate polymer layers of the multiple layer test cartridge coupled to each other to pass the sample in sequence between the lysing channel structures; and
a test chamber to receive the sample from the multiple lysing channel structures.
2. The test cartridge of example 1 wherein the lysing channel structures have a letter “F” shape.
3. The test cartridge of example 2 wherein the lysing channel structure comprises a substantially straight backbone channel having a base portion and a top portion with two equal length, substantially parallel side channels extending substantially orthogonal to the top portion of the backbone channel.
4. The test cartridge of example 3 wherein the channel structures are arranged so that a first lysing channel structure receives the sample at ends of both side channels distal from its backbone.
5. The test cartridge of example 4 wherein a second lysing channel structure is positioned on a different layer from the first lysing channel structure and has ends of both side channels coupled to receive sample from the base portion of the backbone of the first channel structure.
6. The test cartridge of example 5 and further comprising multiple additional sequential lysing channel structures each having the same shape and connection to a preceding channel structure.
7. The test cartridge of example 6 wherein at least two channel structures are separated by a loop channel configured to facilitate mixing of a reagent with the fluid.
8. The test cartridge of example 5 wherein the lysing channel structure has a diagonal portion between a bottom of the side channel and the backbone closest to the base portion of the backbone.
9. The test cartridge of example 8 wherein the diagonal portion is adapted to reduce bubble formation as sample moves through the channel structures.
10. The test cartridge of any of examples 1-9 and further comprising an exit channel coupled to ambient on a different polymer layer than the test chamber.
11. The test cartridge of any of examples 1-10 and further comprising a reagent positioned in at least one of the input and selected lysing channels.
12. The test cartridge of any of examples 1-11 wherein the alternate layers are adjacent layers.
13. The test cartridge of any of examples 1-12 wherein at least some alternate layers are separated by at least one layer.
14. A multiple layer test cartridge comprising:
an input to receive a sample containing red blood cells and having a reagent to mix with the sample;
multiple sequential “F” shaped lysing channel structures on alternate layers of the multiple layer test cartridge laminated to each other to pass the sample in sequence between the lysing channel structures and release hemoglobin into the sample; and
a test chamber to receive the sample having released hemoglobin from the multiple lysing channel structures.
15. The test cartridge of example 14 wherein the channel structure comprises a substantially straight backbone channel having a base portion and a top portion with two equal length, substantially parallel side channels extending substantially orthogonal to the top portion of the backbone channel.
16. The test cartridge of example 15 wherein the channel structures are arranged so that a first channel structure receives the sample at ends of both side channels distal from its backbone, wherein a second channel structure is positioned on a different layer from the first channel structure and has ends of both side channels coupled to receive sample from the base portion of the backbone of the first channel structure.
17. A method comprising:
receiving a blood sample;
moving the blood sample through a first “F” shaped fluidic structure on a first polymer layer of a multiple laminated layer test cartridge;
moving the blood sample from the first “F” shaped fluidic structure to a second “F” shaped fluidic structure formed on a second layer of the multiple layer test cartridge; and
providing the blood sample from the first and second fluidic structures to a sampling cuvette.
18. The method of example 17 and further comprising moving the blood sample through multiple additional sequentially disposed “F” shaped fluidic structures on different layers of the test cartridge.
19. The method of any of examples 17-18 and further comprising adding a reagent to the blood sample prior to moving the blood samples through the “F” shaped fluidic structures.
20. The method of example 19 wherein the reagent is added to the blood sample in one of the “F” shaped fluidic structures and mixed with the blood sample by a loop channel positioned between two of the “F” shaped fluidic structures.
Although a few embodiments have been described in detail above, other modifications are possible. For example, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Other embodiments may be within the scope of the following claims.



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