Acoustic separation of test samples

Abstract

An example system includes a detector configured to detect a value based on hematocrit of a test sample comprising plasma and erythrocytes; a fluid channel configured to receive a test sample; and an acoustic transducer configured to apply an acoustic wave to the fluid channel to separate plasma from red blood cells in the fluid channel. The acoustic wave has at least one of an amplitude, a frequency, or a duration based on the value.

Description

Field of the Invention

[0001] This specification generally relates to diagnostic tests and devices used during diagnostic tests. Background Art

[0002] A test sample may contain particles and liquid. For example, the test sample can be blood or a blood product containing plasma and red blood cells.

[0003] Sound waves can be applied to the test sample to separate the particles from the liquid. The sound waves create one or more pressure nodes within the test sample, which correspond to regions of maximum and minimum pressure in the test sample. The particles move to the positions of minimum pressure, thereby concentrating these particles in certain regions of the test sample and leaving other regions of the test sample completely or substantially free of particles. Systems that use sound waves to separate particles from liquid use a fixed driver to generate standing sound waves. Such a driver is used to control a sound transducer to generate sound waves having parameters such as amplitude, frequency, and / or duration, which are invariant.

[0004] The sound waves generated using a fixed driver may not always be sufficient to separate the particles from the liquid. More specifically, as the volume percentage of particles in the test sample increases, it becomes difficult to separate the particles from the liquid using the sound waves generated by a fixed driver. For example, when the hematocrit of a blood sample increases to 50% or more than 60%, some systems may not be able to sufficiently separate the red blood cells from the plasma using a fixed driver because these fixed drivers may not be able to generate sound waves having sufficient amplitude, duration, and / or frequency to effect the separation. Simply adjusting these parameters of the driver can cause problems. For example, increasing the voltage used in the driver to control the amplitude of the sound wave may improve the separation but may also damage the test sample. Summary of the Invention

[0005] Example systems include: a detector configured to detect a value based on the hematocrit of a test sample containing plasma and red blood cells; a fluid channel configured to receive the test sample; and a sound transducer configured to apply sound waves to the fluid channel to separate the plasma from the red blood cells in the fluid channel. The sound waves have at least one of an amplitude, a frequency, or a duration based on the value. Example systems may include one or more of the following features alone or in combination.

[0006] The system may include: an optical detector configured to optically detect separated plasma in a fluid channel; and a control system configured to determine hemolysis in a test sample based on the result of the optical detection. A value based on the hematocrit may be the fluid resistance. The fluid resistance may vary with the change of the hematocrit. The fluid resistance may correspond to the voltage difference between two positions in the test sample. The amplitude, frequency, and duration of the acoustic wave may all be based on the fluid resistance.

[0007] Separating plasma from red blood cells in the fluid channel may include forming a plasma region at the center of the fluid channel. Separating plasma from red blood cells in the fluid channel may include forming a red blood cell region at the center of the fluid channel.

[0008] The control system may be configured to control the acoustic transducer based on the value to generate an acoustic wave having the amplitude. The detector may be configured to detect the change of the value over time. The control system may be configured to control the acoustic transducer based on the detected change of the value over time to adjust at least one of the amplitude, frequency, or duration of the acoustic wave applied to the fluid channel.

[0009] The control system may be configured to control the acoustic transducer based on the value to apply an acoustic wave to the fluid channel. Controlling the acoustic transducer based on the value may include selecting a driver from a plurality of drivers stored in a memory, where each driver specifies a voltage for a corresponding value based on the hematocrit, and the voltage corresponds to the amplitude of the acoustic wave generated by the acoustic transducer, the frequency of the acoustic wave generated by the acoustic transducer, and the duration of the acoustic wave applied by the acoustic transducer. The acoustic transducer may be controlled according to the selected driver.

[0010] The system may include a memory storing a look-up table (LUT). The LUT may store: a plurality of voltages, each voltage corresponding to the amplitude of an acoustic wave for a specified value; a plurality of frequencies, each frequency corresponding to the frequency of an acoustic wave for a specified value; and a plurality of durations, each duration corresponding to the duration of an acoustic wave to be applied for a specified value. The control system may be configured to control the acoustic transducer by: selecting a voltage from the LUT based on the value, selecting a frequency from the LUT based on the value, selecting a duration from the LUT based on the value, and controlling the acoustic transducer based on the selected voltage, the selected frequency, and the selected duration.

[0011] An example method includes: determining a value based on the hematocrit of a test sample containing plasma and red blood cells; applying an acoustic wave to a fluid channel containing the test sample to separate plasma from red blood cells, where at least one of the amplitude, frequency, or duration of the acoustic wave applied to the fluid channel is based on the value; optically detecting the plasma; and determining hemolysis in the test sample based on the result of the optical detection. The example method may include one or more of the following features alone or in combination.

[0012] The amplitude, frequency, and duration of the acoustic wave applied to the fluid channel can all be based on the value. The acoustic wave can be applied by an acoustic transducer. Controlling the amplitude can include applying a voltage to the acoustic transducer. Determining the value can include measuring the voltage difference between two positions in the test sample. The voltage difference can correspond to the fluid resistance of the test sample. The fluid resistance can vary proportionally with the change in hematocrit.

[0013] Separating plasma from red blood cells in the fluid channel can include forming a plasma region at the center of the fluid channel. Separating plasma from red blood cells in the fluid channel can include forming a red blood cell region at the center of the fluid channel.

[0014] Detecting the value of the test sample can be performed over time. The method can include changing at least one of the amplitude, frequency, or duration of the acoustic wave applied to the fluid channel based on the detected change in the value over time.

[0015] An example system includes: a detector configured to detect a value based on the hematocrit of a test sample comprising plasma and red blood cells; a fluid channel configured to hold the test sample; an acoustic transducer configured to apply an acoustic wave to the fluid channel to separate plasma from red blood cells in the fluid channel; and a control system configured to control the acoustic transducer to generate an acoustic wave that scans over a frequency range. The frequency range is based on the hematocrit. The example system can include one or more of the following features, either alone or in combination.

[0016] The system can include: an optical detector configured to optically detect the separated plasma in the fluid channel; and a control system configured to determine hemolysis in the test sample based on the results of the optical detection. The frequency range can be a first frequency range. The detector can be configured to detect the change in the value over time. The control system can be configured to control the acoustic transducer to generate an acoustic wave that scans over a second frequency range different from the first frequency range. The second frequency range can be based on the detected change in the value over time. The frequency range can include frequencies greater than 1.85 megahertz (MHz).

[0017] Any two or more features described in this specification (including the summary section of the present invention) can be combined to form embodiments not specifically described in this specification.

[0018] At least a portion of the devices, systems, and processes described in this specification can be configured or controlled by executing instructions stored on one or more non-transitory machine-readable storage media on one or more processing devices. Examples of non-transitory machine-readable storage media include read-only memory, optical disk drives, magnetic disk drives, and random access memory. At least a portion of the devices, systems, and processes described in this specification can be configured or controlled using a computing system that includes one or more processing devices and a memory that stores instructions executable by the one or more processing devices to perform various control operations. The devices, systems, and processes described in this specification can be configured, for example, by design, construction, composition, arrangement, placement, programming, operation, activation, deactivation, and / or control.

[0019] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other features and advantages will be apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A is a diagram showing an example microchannel containing a test sample, having a small, separated cell-free plasma region in the middle.

[0021] Figure 1B is a diagram showing an example microchannel containing a test sample, having a large, separated cell-free plasma region in the middle.

[0022] Figure 2 is a diagram showing a front view block diagram of example components included in an example clinical analyzer taken along line AA. Figure 3

[0023] Figure 3 is a diagram showing a cross-sectional side view block diagram of example components included in an example clinical analyzer taken along line BB. Figure 2

[0024] Figure 4 is a graph showing the relationship between the hematocrit in a test sample and the fluid resistance.

[0025] Figure 5 is a front view block diagram showing example components included in an example clinical analyzer, similar to the view of Figure 2 but including a particulate region at the center of the microchannel.

[0026] Figure 6 is a flowchart showing the operations included in an example process for controlling an acoustic transducer to generate acoustic waves to separate particles and liquid in a test sample.

[0027] Figure 7It is a graph showing how the separation width of the acellular plasma region expands over time when different acoustic transducer excitation parameters are used.

[0028] Figure 8 It is a graph showing the relationship between the amplitude of the acoustic wave applied by the acoustic transducer to the test sample and the separation width of the acellular plasma region in the test sample.

[0029] Figure 9 It is a scatter plot showing the separation width of an example test sample with a hematocrit (Hct) of 75%, which is generated by an acoustic wave generated by a fixed driver and is generated by an acoustic wave generated by the Figure 6 process.

[0030] Figure 10 It is a flowchart showing the operations included in an example process for controlling an acoustic transducer to separate particles and liquid in a test sample by causing the acoustic transducer to output an acoustic wave within a certain frequency range.

[0031] Figure 11 It is a graph showing different separation widths generated by scanning with different acoustic wave frequencies using different acoustic flow control devices (AFDs).

[0032] Similar numerical markings in different figures represent similar elements. Detailed Description

[0033] Hemolysis refers to the rupture or destruction of red blood cells in a biological test sample such as blood or a blood product ("test sample"). The example systems and processes described herein are described in the context of determining hemolysis in a blood sample by optical methods. However, the example systems and processes can also be used to determine the presence of analytes in a test sample, such as but not limited to glucose, lactate, sodium, potassium, chloride, phosphate, total protein, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase, albumin, total globulin, hemoglobin, troponin I, cholesterol, clotting factors, circulating tumor cells (CTCs) and / or cell fractions, etc.

[0034] In addition to particles such as red blood cells, the test sample also contains a liquid such as plasma. In order to determine hemolysis in the test sample using optical detection, it is necessary to apply an acoustic wave to separate the plasma from the red blood cells so that an optical detector (which may include a camera) can capture an image of the acellular plasma region generated in the test sample.

[0035] Optical detection may require that the cell-free plasma region has a large enough size so that the camera can capture a large enough image for analysis. In some examples, for optical detection of the cell-free plasma region, the cell-free plasma may need to have a minimum width of 70 micrometers (μm) (referred to as the "separation width" or "plasma width") and a minimum area corresponding to 2000 pixels of the camera. The examples described herein use these values. However, the values of the separation width and area may vary depending on the camera and test configuration. For example, in some embodiments, for optical detection of the cell-free plasma region, the cell-free plasma may need to have a minimum width of 1 μm to 10 μm and a minimum area corresponding to 1 pixel to 1000 pixels of the camera used in the optical detector.

[0036] Hematocrit is the volume percentage of red blood cells in a test sample. A test sample with a relatively high hematocrit, such as a test sample with 50% or 60% or higher (meaning that 50% or 60% or more of the test sample volume is red blood cells), may be more difficult to acoustically separate into a red blood cell region and a cell-free plasma region than a test sample with a relatively low (such as less than 50%) hematocrit. This is because, in a test sample with a relatively high hematocrit, higher energy, longer duration, and / or different frequency sound waves may be required to produce a cell-free plasma region with a large enough size. The previously described fixed driver may cause the sound waves generated by the acoustic transducer to have a frequency, amplitude, and / or duration that is insufficient to produce a cell-free plasma region with a large enough size for analysis. For example, Figure 1A shows a cell-free plasma region 9 generated by an acoustic transducer using a fixed driver, the separation width 10 of which is not large enough in size for at least some optical detectors to perform optical detection.

[0037] Accordingly, the example systems and processes described herein are configured to (i) determine a value corresponding to (e.g., varying with, proportional to, and / or based on) the hematocrit of a test sample, and (ii) generate sound waves having an amplitude, frequency, and / or duration adapted to that value. In this example, the value is the fluid resistance of the test sample. Fluid resistance is a measure of the ability of a fluid to resist an electric current. Fluid resistance is measured in ohms, but since the electric current (if any) in the test sample is constant, the fluid resistance is proportional to the voltage difference between two locations in the test sample. Accordingly, the fluid resistance of the test sample is reported as a voltage measurement.

[0038] In some embodiments, the sound waves generated based on the value corresponding to the hematocrit can well separate red blood cells, thereby producing a cell-free plasma region with a large enough size to perform optical detection without damaging the test sample. Figure 1B Examples ofFigure 1A is the same as the sample shown in, which shows the cell-free plasma region 13 generated using the systems and methods described herein, the region having a size (here, separation width 11) large enough for optical detection. As shown, Figure 1B both the separation width 11 and the area of the cell-free plasma region 13 in the example of Figure 1A are greater than the separation width 11 and the area of the cell-free plasma region 13 in the example of

[0039] The example system can also be configured to continuously, periodically, or intermittently monitor the fluid resistance of the test sample to infer changes in hematocrit over time. The system can then make any adjustments to the amplitude, frequency, and / or duration of the acoustic wave that may be necessary to accommodate the inferred changes in hematocrit. For example, the fluid resistance can be monitored at least once for each sample so that values of amplitude, frequency, and / or duration can be selected to achieve optimal or improved separation.

[0040] In some embodiments, the example system is configured to change one or more of the amplitude, frequency, and / or duration of the acoustic wave while keeping the other terms constant. For example, the system can scan the frequency of the acoustic wave within a certain frequency range while keeping the amplitude and duration of the acoustic wave constant. The frequency scan can be adjusted based on the hematocrit of the test sample inferred from the measured fluid resistance of the test sample, thereby producing in some cases a cell-free plasma region with a large enough size for optical detection without damaging the test sample.

[0041] The example system can be implemented on a clinical analyzer, which can be used in a point-of-care (POC) environment such as an emergency room. An example clinical analyzer for implementing the example system and process may include a blood gas device configured to process blood samples having various electrolytes, proteins, osmotic pressure, red blood cell concentration, and other blood components.

[0042] Figure 2 is a front view of some of the components contained in the example clinical analyzer 14 (e.g., “system”) on which the processes described herein can be implemented. Figure 3 is the Figure 2 same components in a cross-sectional side view. Figure 2 The view in Figure 3 is taken along line A-A 18 of Figure 3 The view in Figure 2 is taken along line B-B 23 of

[0043] See Figure 2, the clinical analyzer 14 includes a fluid line 15 separated from a hemolysis detection module (“module”) 16, which will be described hereinafter. In Figure 3 , the fluid line 15 extends in and out of the page and is thus not shown. The fluid line 15 can be made of plastic, glass, or other transparent materials and can include one or more interconnected tubes configured to convey a test sample 17. The fluid line 15 can have a circular cross-section, a rectangular cross-section, or any other shape that allows the test sample 17 to flow through the fluid line. In this example, the test sample 17 flows in the direction of arrow 19. In some examples, the width or diameter of the fluid line can be in the range of about 50 µm to 1.5 millimeters (mm).

[0044] Examples of the test sample 17 include blood (such as whole blood) or blood products. The test sample includes particles (such as red blood cells 20, etc.) and a liquid (such as cell-free plasma 21, etc.). The test sample flows from an input location (not shown) through the fluid line 15 to reach and pass through a test location where the hemolysis module 16 is located. Positive or negative pressure applied to the fluid line can cause fluid flow.

[0045] The clinical analyzer 14 also includes a fluid detector 24, which is located upstream of the fluid flow path of the module 16 (the direction of which is as shown by arrow 19). In some embodiments, the fluid detector 24 can be located downstream of the module 16. In this example, the fluid detector 24 includes electrodes or probes 24a, 24b, which are configured to measure the voltage at different positions of the test sample 17 and determine the voltage difference based on these measurements. The voltage difference obtained by the fluid detector 24 is proportional to the fluid resistance of the test sample. To perform voltage measurements, the electrodes or probes 24a, 24b are brought into contact with the test sample. To achieve this contact, in one example, the fluid detector 24 can be located within the fluid line 15 or be part of the fluid line 15. In another example, the fluid detector 24 can be located outside the fluid line 15 but have probes 24a, 24b that extend into the fluid line 15. In some embodiments, the fluid detector 24 can be a mechanical device configured to detect pressure changes in the fluid flow corresponding to differences in hematocrit.

[0046] The fluid resistance of the test sample corresponds to (e.g., varies with, is proportional to, and / or is based on) the hematocrit and other components of the test sample. More specifically, as the hematocrit increases, the fluid resistance increases, while as the hematocrit decreases, the fluid resistance decreases.

[0047] Figure 4 Shows the fluid resistance 25 (“FDmv”, where “FD” represents the fluid detector) of test samples with different hematocrit (Hct) levels 26. Figure 4The fluid resistance measurements in [the example] were performed using three different clinical analyzers 27. Also shown is a polynomial fit 29 of the measured values, as well as curves 30, 31 that enclose 95% of the measured data. As Figure 4 shown, the fluid resistance 25 varies substantially linearly with the hematocrit 26 until the hematocrit level reaches approximately 65%, after which the measured values tend to level off. Thus, in this example, within the hematocrit range up to 65%, the hematocrit also increases substantially linearly as the fluid resistance increases. Accordingly, the measured value of the fluid resistance in the test sample can be used as a surrogate value for the measured value of the hematocrit in the test sample.

[0048] See Figure 2 and Figure 3 , module 16 is located in the path of fluid line 15. In this example, module 16 is configured and operative to perform a hemolysis test on test sample 17. However, in some embodiments, module 16 may be configured and / or operative to test for one or more analytes in the test sample, such as those listed above and the like. The module may be characterized as an acoustofluidic device (AFD) since module 16 uses acoustic waves to test the fluid. In some embodiments, module 16 may perform the test while the test sample is flowing. In some embodiments, module 16 may perform the test after the fluid flow has stopped (e.g., when the fluid is not flowing).

[0049] Module 16 includes a microchannel 31 for receiving test sample 17 and a transducer 32 for applying acoustic waves to the test sample 17 to separate the plasma from the red blood cells. In some embodiments, module 16 further includes an optical detector 34 for optically detecting a cell-free plasma region or a particulate region generated in the microchannel. In some embodiments, optical detector 34 is located external to module 16.

[0050] Microchannel 31 is a fluid channel configured to be fluidly connected along fluid line 15, thereby creating a fluid flow path that includes fluid line 15 and microchannel 31 through which the test sample flows. Microchannel 31 may be made of plastic, glass, or other transparent material. Microchannel 31 may have a circular cross-section, a rectangular cross-section, or any other shape that allows the test sample to flow through the microchannel. In some embodiments, the width or diameter of microchannel 31 may match the width or diameter of fluid line 15.

[0051] The acoustic transducer 32 can be a piezoelectric transducer. The piezoelectric transducer includes means for sending electrical energy in the form of an alternating electric field to a piezoelectric crystal in the transducer, causing the crystal to vibrate and converting the electrical energy into sound waves. The acoustic transducer 32 can be configured to generate one or more different types of sound waves, such as ultrasonic waves, surface acoustic waves, or bulk acoustic waves. In some embodiments, the frequency range of the sound waves can be from kilohertz (kHz) to 2 gigahertz (GHz), or greater than or less than these values.

[0052] In some embodiments, the acoustic transducer 32 can be arranged near the microchannel 31 (e.g., within a single-digit millimeter), but not in contact with the microchannel 31. In some embodiments, the acoustic transducer 32 can be in contact with the microchannel 31. The contact between the acoustic transducer and the microchannel can be direct contact as shown, or indirect contact, which means that one or more structures can exist between the acoustic transducer and the microchannel

[0053] An excitation parameter can be used to excite the acoustic transducer 32 to generate sound waves. A control system (e.g., the control system 49 described below) can provide the excitation parameter to the acoustic transducer 32, or generate a control signal based on the excitation parameter, so that the acoustic transducer generates sound waves with a specified amplitude, frequency, and / or duration. These excitation parameters include voltage / amplitude, energy / frequency, and time / duration. The amplitude of the voltage applied to the acoustic transducer corresponds to the amplitude of the sound waves generated by the acoustic transducer. For example, the greater the voltage applied to the acoustic transducer, the greater the amplitude of the sound waves generated by the acoustic transducer. The frequency is the frequency of the sound waves that the acoustic transducer is going to generate. The frequency can be based on the electrical energy provided to the acoustic transducer. The excitation parameter can include the amplitude and frequency of this electrical energy. The duration is the length of time that the sound waves are applied to the acoustic transducer. For example, the duration is the amount of time that electrical energy and voltage are applied to the acoustic transducer to achieve a predetermined amount (e.g., the optimal amount) of separation of the plasma 21 and red blood cells 20.

[0054] In Figure 2 and Figure 3 example, the acoustic transducer 32 is configured and arranged to generate sound waves 35 that separate the plasma 21 from the red blood cells 20 in the microchannel 31 to form a cell-free plasma region 36 in the center of the microchannel 31. In this example, the sound waves also form cell-free plasma regions 37, 39 adjacent to one or more surfaces of the microchannel 31. In some embodiments, the number of cell-free plasma regions may be more than Figure 2 and 3The regions shown in [reference] are more or less. In some embodiments, regions 37, 39 may be absent, and the red blood cells may be adjacent to and in physical contact with one or more surfaces of the microchannel 31. In some embodiments, a cell-free plasma region 36 may be present at the center of the microchannel, surrounded by regions 40, 41 containing red blood cells, but having multiple additional cell-free plasma and red blood cell regions between each of regions 40, 41 and the surface of the microchannel 31. Referring to Figure 5 , in some embodiments, the acoustic transducer 32 is configured and arranged to generate acoustic waves that form a region 44 containing red blood cells at the center of the microchannel 31, with cell-free plasma regions 45, 46 on one or both sides of region 44. In some embodiments, multiple particle and cell-free plasma regions may be present between region 44 and the surface of the microchannel 31. U.S. Patent No. 2016 / 0202237 (Zeng), published on July 14, 2016, describes different types of plasma / particle separation that can be achieved using the acoustic transducer 32. U.S. Patent Publication No. 2016 / 0202237 is hereby incorporated by reference, particularly with respect to its description related to cell / plasma separation.

[0055] See Figure 2 and Figure 3 , the optical detector 34 is arranged to capture images of one or more cell-free plasma regions (such as region 36) or one or more particle regions (such as region 44). The examples described below have an optical detector that captures an image of the cell-free plasma region 36. In this example, the optical detector 34 includes a camera with a pixelated image sensor, which is configured to capture images. In some embodiments, the optical detector is aligned with the microchannel 31 (e.g., along one side 31 of the microchannel), as Figure 3 shown, to capture an image of the microchannel within the field of view 47 of the camera. Generally, the optical detector 34 can be placed at any position relative to the microchannel such that the optical detector can capture an image of the entire microchannel, an image of the cell-free plasma region 36, or an image of any region of interest during the test, with a resolution sufficient to enable processing of the image to determine hemolysis or identify one or more analytes in the test sample, such as those described above, etc. The distance between the microchannel and the camera can be between 0 mm and 500 mm, depending on the system design (e.g., whether a lens is used between the microchannel and the camera). The light source 28 (e.g., one or more light-emitting diodes) outputs light to backlight the microchannel, making it easier for the camera to capture all or part of the image of the microchannel, including the cell-free plasma region 36.

[0056] As described above, the clinical analyzer 14 further includes a control system 49. The control system can be an internal component of the clinical analyzer 14, or the control system can be external to the clinical analyzer 14. For example, the control system can be or include one or more computing devices located locally (e.g., in the same room) or remotely (e.g., in a different room) to the clinical analyzer.

[0057] In this example, the control system 49 can include one or more processing devices 50 and a memory 51 that stores executable instructions 52. The one or more processing devices 50 can execute the instructions 52 to control the processes 54 and 55 described below, or implement at least a portion of these processes. The control system 49 is configured to communicate with the fluid detector 24, the light source 28, the optical detector 34, and the acoustic transducer 32. For example, the control system 49 can be directly connected to the fluid detector 24, the light source 28, the optical detector 34, and / or the acoustic transducer 32 via one or more data buses or other wired connections. In some embodiments, the control system 49 can be connected to the fluid detector 24, the light source 28, the optical detector 34, and / or the acoustic transducer 32 via a wired or wireless computer network. The dashed line 56 represents the connection for communication.

[0058] The memory 51 also stores driver programs 57 and / or look-up tables (LUTs) 59. Each driver program 57 includes acoustic transducer excitation parameters adjusted for a specific fluid resistance. As described above, example excitation parameters for the acoustic transducer 32 include voltage / amplitude, electrical energy / frequency, and time / duration. Thus, each driver program can include one or more different numbers for each of these parameters. Each combination of these numbers is pre-determined based on tests performed on different test samples having different fluid resistances using the acoustic transducer 32. Each combination of these numbers has been shown to cause the acoustic transducer 32 to produce a large enough cell-free plasma region for optical testing.

[0059] Each driver program can include a voltage to be applied to the acoustic transducer to generate a sound wave having an amplitude, which can be specified in the driver program. Each driver program can include the frequency of the sound wave to be generated by the acoustic transducer, and the electrical energy for generating that frequency. Each driver program can include the duration for which the acoustic transducer is to apply the sound wave to produce a predefined separation width. The excitation parameters can be specific to the type of separation to be produced by the acoustic transducer. For example, the driver program for producing the Figure 2 erythrocyte / plasma separation type shown in Figure 5 may be different from the driver program for producing the erythrocyte / plasma separation type shown in

[0060] In one example, a fluid resistance greater than a value A (e.g., FD = 450 mV, which means the fluid detector reported a value of 450 mV) is associated with a first driver; a fluid resistance greater than a value B (e.g., FD = 400 mV) but less than or equal to value A is associated with a second driver; a fluid resistance greater than a value C (e.g., FD = 300 mV) but less than or equal to value B is associated with a third driver; a fluid resistance greater than a value D (e.g., FD = 200 mV) but less than or equal to value C is associated with a fourth driver; and so on. Thus, if the fluid resistance measured by the fluid detector 24 is greater than A, the control system can select the first driver and use it to drive the acoustic transducer 32 to generate acoustic waves. If the fluid resistance measured by the fluid detector 24 is greater than B but less than or equal to A, the control system can select the second driver and use it to drive the acoustic transducer 32 to generate acoustic waves; and so on.

[0061] In some embodiments, instead of drivers, the memory 51 may store a LUT 59. The LUT 59 may contain acoustic transducer excitation parameters for different fluid resistance values. For example, the LUT 59 may contain multiple voltages and, in some examples, amplitudes corresponding to the multiple voltages. Each voltage corresponds to the voltage to be applied to the acoustic transducer to generate an acoustic wave having an amplitude corresponding to that voltage for a specified fluid resistance. For example, the LUT 59 may contain multiple frequencies and, in some examples, the electrical energy to generate these frequencies. Each frequency may correspond to the frequency of the acoustic wave that the acoustic transducer is to generate for a specified fluid resistance. For example, the LUT 59 may contain multiple durations. Each duration may correspond to the length of time that the acoustic transducer is to apply an acoustic wave for a specified fluid resistance to achieve a predetermined separation width. Thus, in one example, if the fluid detector 24 determines the fluid resistance of a test sample, the control system can receive the determined fluid resistance and use the determined fluid resistance to access the LUT and retrieve one or more or all of the excitation parameters for that fluid resistance. The control system can use the excitation parameters to control the acoustic transducer 32 to generate acoustic waves. As described above, the excitation parameters may be specific to the type of separation generated by the acoustic transducer 32. For example, the excitation parameters for generating Figure 3 the separation type shown may be different from the excitation parameters for generating Figure 5 the separation type shown.

[0062] Figure 6illustrates operations including an example process 54 configured to (i) determine a value of a test sample, such as a fluid resistance corresponding to the hematocrit of the test sample, and (ii) generate an acoustic wave having a certain amplitude, frequency, and / or duration that is adjusted to be adapted to the value and thus to the hematocrit. Process 54 can be performed using Figure 2 , 3 and example systems of 5, but can also be performed using other systems, such as but not limited to those described in U.S. Patent Publication No. 2016 / 0202237, which is incorporated herein by reference, and those described in U.S. Patent Publication No. 2022 / 0113297 (Bosy) issued on April 14, 2022, which is incorporated herein by reference.

[0063] Process 54 includes monitoring (54a) a value based on the hematocrit in the test sample. As described above, in some embodiments, the hematocrit in the test sample is not determined but is inferred from the fluid resistance of the test sample. Thus, to implement the monitoring (54a), the fluid detector 24 determines the voltage difference in the test sample 17. This voltage difference is proportional to the fluid resistance of the test sample. The control system 49 receives the measured value of the fluid resistance from the fluid detector 24. For example, the control system 49 can monitor the readings of the fluid detector 24, or the fluid detector 24 can report its readings to the control system 49.

[0064] Process 54 includes the control system 49 selecting (54b) a value of an excitation parameter of the acoustic transducer 32 based on the fluid resistance value determined by the fluid detector 24. The value of the excitation parameter can be selected from the LUT as described above, or the value of the excitation parameter can be selected by selecting one of a plurality of drivers from the memory 51. In this example, process 54 selects (54b) a driver by comparing (54b1) the determined fluid resistance with a predetermined fluid resistance A. If the determined fluid resistance is greater than A, driver 1 is selected (54b2). If the determined fluid resistance is less than or equal to A, the determined resistance is compared with a predetermined fluid resistance B (54b3). If the determined fluid resistance is greater than B, driver 2 is selected (54b4). If the determined fluid resistance is less than or equal to B, the determined resistance is compared with a predetermined fluid resistance C (54b5). If the determined fluid resistance is greater than C, driver 3 is selected (54b6). If the determined fluid resistance is less than or equal to C, the determined resistance is compared with a predetermined fluid resistance D (54b7). If the determined fluid resistance is greater than D, driver 4 is selected (54b8). In this example, if the determined fluid resistance is less than or equal to D (54b9), driver 5 is selected (54b10). Although five comparisons and drivers are shown, process 54 can include more or less than five comparisons and alternative drivers, e.g., one, two, three, four, six, seven, eight, nine, etc. comparisons and drivers.

[0065] Process 54 includes the control system 49 using the selected value of the excitation parameter from the LUT or from the selected driver to control (54c) the acoustic transducer 32. For example, the control system 49 can apply a voltage from the selected driver to the acoustic transducer 32 to cause the acoustic transducer 32 to generate sound waves having a selected amplitude; process 54 can apply electrical energy to the acoustic transducer 32 to cause the acoustic transducer 32 to generate sound waves having a frequency from the selected driver; and process 54 can apply the voltage and electrical energy from the selected driver for a duration to cause the acoustic transducer 32 to generate sound waves having a frequency and amplitude from the selected driver for the duration.

[0066] The sound waves separate red blood cells and plasma as described herein, thereby creating a cell-free plasma region 36 in the center of the microchannel (as Figure 2 and 3 shown) or creating a particle region 44 in the center of the microchannel (as Figure 5 shown). This example uses the cell-free plasma region 36 in the center of the microchannel as described above. Thus, in this example, the separation width of the cell-free plasma region 36 is 70 μm or greater, and the area corresponds to 2000 pixels or more of the camera in the optical detector 34.

[0067] The optical detector 34 obtains measurements of the cell-free plasma region 36 by capturing an image of the cell-free plasma region. The control system 49 receives (54d) the measurements from the optical detector 34. The control system 49 determines (54e) the hemolysis of the test sample by processing the image. For example, the control system 49 can examine the image to estimate the plasma absorbance to detect and quantify cell-free hemoglobin (representing hemolysis). In an example, the system uses an LED light source such as the light source 28 etc. (e.g., at light wavelengths of 570 nanometers (nm) and 610 nm) to irradiate the microchannel and calculates the absorbance at each wavelength according to the Beer-Lambert law, where absorbance = Log 10 [I B / I S , where I B and I S are the transmitted light intensities in the process control solution B solution and the test sample S respectively. These absorbance values are converted to cell-free plasma hemoglobin (hemolysis) levels using stored hemolysis detection coefficients and labeled blood gas result coefficients. The determined presence of hemolysis and / or the amount of hemolysis can be output (54f) from the clinical analyzer in graphical or text form on the user interface, and / or used by the clinical analyzer for other diagnostic processes.

[0068] In some embodiments, while operations 54b to 54f are occurring, the fluid detector 24 can continuously, periodically, or intermittently monitor changes in the fluid resistance of the same test sample, thereby monitoring changes in the hematocrit. Optionally, process 54 can thus include operation 54g to determine whether the hematocrit has changed by comparing the current measurement of the fluid detector 24 with the immediately preceding measurement. Optionally, if a change has occurred, operations 54b to 54f can be repeated to determine a new value of the hemolysis of the same test sample. In some embodiments, operation 54g can be omitted.

[0069] Figure 7 is a graph showing how the separation width (plasma width) of the cell-free plasma region expands over time for the same test sample and sound waves with different amplitudes, frequencies, and / or durations. In 59, a fixed driver is used to drive the acoustic transducer to generate sound waves to apply to the test sample. In the fixed driver, the excitation parameters have not been adjusted for the hematocrit level. In 60, the sound waves generated using process 54 are applied to the same test sample by the same acoustic transducer, where the excitation parameters are adjusted for the sample hematocrit level (inferred from the sample fluid resistance). As shown, in 60 compared to 59, the amplitude of the final separation width is greater 61, and the separation starts earlier 62.

[0070] Figure 8A graph showing the relationship between a histogram (y-axis frequency = sample count) of a patient blood sample showing acoustic wave excitation applied by an acoustic transducer and the separation width of the cell-free plasma region in the test sample. Figure 8 Shows the performance 64 of a fixed driver for driving the acoustic transducer. Figure 8 Also shows the performance 65 of the acoustic waves generated using process 54. As shown, when using the acoustic waves generated by process 54, the separation width (plasma width) 67 of the test sample is mostly greater than the separation width (plasma width) (69) when using the acoustic waves generated by the fixed driver.

[0071] Figure 9 Is a scatter plot showing the separation width of an example test sample with a hematocrit (Hct) of 75%, which is generated by applying the excitation parameters of the fixed driver to the acoustic transducer and using the acoustic waves generated according to process 54. In examples 70 and 71, the separation width of the acoustic waves generated using the fixed driver is mostly less than 70 μm, which may be unacceptable in some embodiments. In examples 72, 74, 75, and 76, the separation width generated by the acoustic waves generated according to process 54 is mostly greater than 70 μm, which may be desirable in some embodiments.

[0072] Figure 10 Shows the operation including example process 55, which is configured to (i) determine a value of the test sample, such as the fluid resistance corresponding to the hematocrit of the test sample, and (ii) generate acoustic waves that scan over a certain frequency range. Process 55 can be performed using Figure 2 、 3 and the example system of 5, but can also be performed using other systems, such as but not limited to those described in U.S. Patent Publication No. 2016 / 0202237 and U.S. Patent Publication No. 2022 / 0113297 (Bosy), which are incorporated herein by reference.

[0073] Process 55 includes monitoring (55a) a value based on the hematocrit in the test sample. Operation 55a can be performed in the same manner as operation 54a of process 54. And, like operation 54a, the value can be the fluid resistance.

[0074] Process 55 includes the control system selecting (55b) a frequency range based on the value obtained in operation 55a. This operation can be the same as operation 54b of process 54, except that in this example each driver can include a different frequency range (instead of a single frequency) to be generated by acoustic transducer 32, and the electrical energy supplied to the acoustic transducer to process these frequencies. These ranges were previously determined based on tests performed using acoustic transducer 32 on different test samples having different fluid resistances. These ranges have been shown to cause acoustic transducer 32 to generate a large enough cell-free plasma region for optical testing. In some embodiments, each frequency range includes frequencies greater than 1.85 megahertz (MHz). Different ranges that can be used include, but are not limited to, 1.85 MHz to 1.9 MHz, 1.85 MHz to 1.95 MHz, 1.85 MHz to 2.0 MHz, 1.85 MHz to 2.05 MHz, and so on. In some embodiments, the driver can include voltage / amplitude and / or time / duration values specific to the fluid resistance, which can remain constant during the frequency sweep, as described below. In some embodiments, the voltage / amplitude and / or time / duration values can be independent of the fluid resistance of the test sample.

[0075] Process 55 includes the control system 49 exciting the acoustic transducer with electrical energy so that the acoustic transducer outputs sound waves that sweep over the selected drive frequency range (55c). The sound waves generated can create a cell-free plasma region, such as region 36 ( Figure 2 ).

[0076] The optical detector 34, for example, obtains measurements of the cell-free plasma region by capturing an image of the cell-free plasma region. The control system 49 receives (55d) the measurements from the optical detector 34. The control system 49 determines (55e) the hemolysis of the test sample by processing the image, as described above with respect to operation 54e of process 54. The presence and / or amount of hemolysis can be output (55f) in graphical or text form from the clinical analyzer on the user interface, and / or used for other processes.

[0077] In some embodiments, while operations 55b through 55f are occurring, the fluid detector 24 can continuously, periodically, or intermittently monitor changes in the fluid resistance of the same test sample, and thus monitor changes in the hematocrit. Optionally, process 55 can thus include operation 55g to determine whether the hematocrit has changed by comparing the current measurement from the fluid detector 24 with the immediately preceding measurement. Optionally, if a change has occurred, operations 55b through 55f can be repeated to determine a new value of hemolysis in the same test sample. In some embodiments, operation 55g can be omitted.

[0078] In some embodiments, the driver may include a range of voltage / magnitude and / or time / duration values and may change one or more of these parameters while keeping the scan frequency or hold frequency constant.

[0079] Figure 11 Shown are example microchannels, each containing a test sample with a hematocrit of 70%. In this example, different AFDs (AFD1, AFD2, and AFD3) control the acoustic transducer to scan the test sample over different frequency ranges 77 and 79 while keeping the amplitude and duration of the acoustic wave constant. In this example, the frequency ranges are characterized by a wide scan (77) from 1.85 MHz to 2.15 MHz (79) and a narrow scan (79) from 1.85 MHz to 1.95 MHz. The frequency scans result in different separation widths 80 to 85 in the different AFDs. In this particular example, the narrow scan (79) from 1.85 MHz to 1.95 MHz produces a separation region that is wider and has a larger area than the wide scan (77) from 1.85 MHz to 2.15 MHz.

[0080] All or part of the systems and processes described herein (including but not limited to processes 54 and 55) and modifications thereof can be configured and / or controlled, at least in part, by one or more computers using one or more computer programs tangibly embodied in one or more information carriers (e.g., one or more non-transitory machine-readable storage media). The computer programs can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as modules, parts, subroutines, or other units suitable for use in a computing environment. The computer programs can be deployed on one computer or multiple computers at one site or distributed across multiple sites and executed interconnectedly.

[0081] Actions associated with configuring or controlling the test systems and processes described herein can be performed by one or more programmable processors that execute one or more computer programs to control or perform all or part of the operations described herein. All or part of the test systems and processes can be configured or controlled by dedicated logic circuitry, such as FPGAs (field-programmable gate arrays) and / or ASICs (application-specific integrated circuits) or embedded microprocessors located in the instrument hardware.

[0082] Processors suitable for executing computer programs include, for example, general and special purpose microprocessors, as well as any one or more processors of any type of digital computer. Generally, a processor will receive instructions and data from a read-only storage area or a random access storage area or both. Elements of a computer include one or more processors for executing instructions and one or more storage area devices for storing instructions and data. Generally, a computer will also include or be operatively coupled to receive data from, or transfer data to, or both, one or more machine-readable storage media, such as mass storage devices for storing data, such as magnetic disks, magneto-optical disks, or optical disks. Non-transitory machine-readable storage media suitable for embodying computer program instructions and data include all forms of non-volatile storage areas, including, for example, semiconductor storage area devices, such as EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), and flash memory storage area devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD-ROM (compact disc read-only memory) and DVD-ROM (digital versatile disc read-only memory).

[0083] In the specification and claims provided herein, unless the context otherwise indicates, adjectives such as "first", "second", "third", etc. do not denote a priority order or sequence. Instead, these adjectives may be used solely to distinguish the nouns they modify.

[0084] Elements of the different embodiments may be combined to form other embodiments not specifically set forth previously. An element may be excluded from a previously described system without adversely affecting its operation or the operation of the overall system. Additionally, various different elements may be combined into one or more separate elements to perform the functions described in this specification.

[0085] Other embodiments not specifically described in this specification also fall within the scope of the following claims.

Claims

1. A system comprising: a detector configured to detect a hematocrit value based on a test sample comprising plasma and red blood cells; a fluid channel configured to receive the test sample; as well as An acoustic transducer is configured to apply an acoustic wave to the fluid channel to separate the plasma from the red blood cells in the fluid channel, the acoustic wave having at least one of an amplitude, a frequency, or a duration based on the value.

2. The system according to claim 1, further comprising: an optical detector configured to optically detect the plasma separated in the fluid channel; as well as A control system is configured to determine hemolysis in the test sample based on the results of the optical detection.

3. The system of claim 1 , wherein the value comprises a fluid resistance; and The amplitude, frequency and duration of the sound waves are based on the fluid resistance.

4. The system of claim 1, further comprising: a control system configured to control the acoustic transducer based on the value to apply the acoustic wave to the fluid channel; Wherein, the control system is configured to apply a voltage to the sound transducer to generate a sound wave having the amplitude.

5. The system of claim 1, wherein the value comprises a fluid resistance corresponding to a voltage difference between two locations in the test sample, the fluid resistance varying as the hematocrit varies.

6. The system of claim 1, wherein separating the plasma from the red blood cells in the fluid channel comprises forming a plasma region in a center of the fluid channel.

7. The system of claim 1, wherein separating the plasma from the red blood cells in the fluid channel comprises forming a red blood cell region in the center of the fluid channel.

8. The system of claim 1, further comprising: a control system configured to control the acoustic transducer based on the value to apply the acoustic wave to the fluid channel; wherein the detector is configured to detect a change in the value over time; and Wherein the control system is configured to control the acoustic transducer to adjust at least one of an amplitude, a frequency or a duration of the acoustic wave applied to the fluid channel based on a range of changes in the detected value over time.

9. The system of claim 1, further comprising: A control system configured to control the acoustic transducer based on the value, wherein controlling the acoustic transducer based on the value comprises: selecting a driver from a plurality of drivers stored in a memory, each driver specifying a voltage for a corresponding value based on the hematocrit, the voltage corresponding to an amplitude of an acoustic wave generated by the acoustic transducer, a frequency of the acoustic wave generated by the acoustic transducer, and a duration of an acoustic wave applied by the acoustic transducer; and The acoustic transducer is controlled according to the selected driver program.

10. The system of claim 1, further comprising: A memory storing a lookup table (LUT), wherein the LUT stores: a plurality of voltages, each voltage corresponding to an amplitude of the sound wave for a specified value; a plurality of frequencies, each frequency corresponding to a frequency of a sound wave for a specified value; and a plurality of durations, each duration corresponding to a duration of the sound wave to be applied for a specified value; A control system configured to control the acoustic transducer based on the value, wherein controlling the acoustic transducer based on the value comprises: selecting a voltage from the LUT based on the value; selecting a frequency from the LUT based on the value; selecting a duration from the LUT based on the value; and The acoustic transducer is controlled based on the selected voltage, the selected frequency, and the selected duration.

11. A method comprising: Determining a value based on the hematocrit of a test sample containing plasma and red blood cells; applying acoustic waves to a fluid channel containing the test sample to separate the plasma from the red blood cells, at least one of an amplitude, a frequency, or a duration of the acoustic waves applied to the fluid channel being based on the value; performing optical detection on the plasma; as well as Hemolysis of the test sample is determined based on the results of the optical detection.

12. The method of claim 11, wherein the amplitude, frequency, and duration of the acoustic wave applied to the fluid channel are based on the values.

13. The method of claim 11, wherein the sound waves are applied by the sound transducer; and in, Controlling the amplitude includes applying a voltage to the acoustic transducer.

14. The method of claim 11, wherein determining the value comprises: A voltage difference is measured between two locations in the test sample, the voltage difference corresponding to a fluid resistance of the test sample, the fluid resistance changing as the hematocrit changes.

15. The method of claim 1, wherein separating the plasma from the red blood cells in the fluid channel comprises forming a plasma region in the center of the fluid channel; or in, Separating the plasma from the red blood cells in the fluid channel includes forming a red blood cell region in the center of the fluid channel.

16. The method of claim 11, wherein detecting the value of the test sample is performed over time; and The method includes varying at least one of an amplitude, a frequency, or a duration of an acoustic wave applied to the fluid channel based on the detected change in the value over time.

17. A system comprising: a detector configured to detect a hematocrit value based on a test sample comprising plasma and red blood cells; a fluid channel configured to receive the test sample; an acoustic transducer configured to apply acoustic waves to the fluid channel to separate the plasma from the red blood cells in the fluid channel; as well as A control system is configured to control the acoustic transducer to generate an acoustic wave that sweeps over a frequency range based on the hematocrit.

18. The system of claim 17, further comprising: an optical detector configured to optically detect the plasma separated in the fluid channel; as well as A control system is configured to determine hemolysis in the test sample based on the results of the optical detection.

19. The system of claim 17, wherein the frequency range is a first frequency range; in, The detector is configured to detect a change in the value over time; and Wherein the control system is configured to control the acoustic transducer to generate an acoustic wave that sweeps over a second frequency range different from the first frequency range, the second frequency range being based on a change in the detected value over time.

20. The system of claim 19, wherein the frequency range includes frequencies greater than 1.85 megahertz (MHz).

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