A liquid level detection system based on a capacitive sensor array

Abstract

The present disclosure provides a liquid volume detection system based on a capacitive sensor array, and relates to the technical field of liquid volume detection. The system comprises: a capacitive sensor array arranged in the interior of a support shell; the support shell is used for supporting the capacitive sensor array, so that the capacitive sensor array is close to the outer surface of a tubular container; the tubular container contains a solution of a liquid volume to be detected; a control module is connected with the capacitive sensor array; the control module is used for controlling each excitation electrode in a plurality of excitation electrodes included in the capacitive sensor array to send an excitation signal to a plurality of detection electrodes included in the capacitive sensor array based on a mutual capacitance measurement method; the capacitive sensor array is used for outputting the capacitance value between the excitation electrode and the corresponding detection electrode under the action of the excitation signal, and obtaining a plurality of capacitance values; and a data calculation module is used for calculating the height of the liquid volume to be detected in the tubular container according to the plurality of capacitance values. The present disclosure improves the accuracy of liquid volume detection.

Description

Technical Field

[0001] This disclosure relates to the field of liquid volume detection technology, and more specifically, to a liquid volume detection system based on a capacitive sensing array. Background Technology

[0002] In the field of medical testing, to achieve the detection of multiple blood indicators, samples need to be centrifuged, and then the serum or plasma content in the centrifuged blood collection tubes needs to be measured. When an anticoagulant is added to the blood in the blood collection tube, the upper layer of the centrifuged blood is plasma, and the lower layer is red blood cells; if no anticoagulant is added to the blood in the blood collection tube, the upper layer of the centrifuged blood is serum, and the lower layer is blood clots.

[0003] With the automation of medical testing, routine blood tests are usually performed by machines. A key step is to measure the volume of serum or plasma in the blood collection tube. Traditional methods for measuring serum and plasma volumes mainly rely on optical imaging technology. While these methods offer advantages such as speed and efficiency, they are easily affected by multiple layers of label paper, leading to poor test results. Summary of the Invention

[0004] In view of this, the present disclosure provides a liquid volume detection system based on a capacitive sensing array.

[0005] One aspect of this disclosure provides a liquid volume detection system based on a capacitive sensor array. The system includes: a capacitive sensor array, a support housing, a control module, and a data calculation module. The capacitive sensor array is disposed inside the support housing. The support housing supports the capacitive sensor array, ensuring it is in close contact with the outer surface of a tubular container. The tubular container contains a solution of a volume to be detected. The control module is connected to the capacitive sensor array. The control module, based on a mutual capacitance measurement method, controls each of the plurality of excitation electrodes in the capacitive sensor array to send an excitation signal to the plurality of detection electrodes in the capacitive sensor array. Under the action of the excitation signal, the capacitive sensor array outputs the capacitance value between the excitation electrode and the corresponding detection electrode, obtaining multiple capacitance values. The data calculation module calculates the height of the liquid of the volume to be detected within the tubular container based on the multiple capacitance values.

[0006] According to an embodiment of this disclosure, the capacitive sensor array includes two sensor array units with identical structures; the two sensor array units are arranged opposite to each other; each of the sensor array units includes multiple electrode units; when the capacitive sensor array is in close contact with the outer surface of the tubular container, the multiple electrode units are uniformly distributed along the axial direction of the tubular container.

[0007] According to embodiments of this disclosure, each of the electrode units includes a capacitive sensing electrode and a lead electrode; a serpentine wire is arranged between the capacitive sensing electrode and the lead electrode; the capacitive sensing electrode is attached to the inner surface of the support housing under the support of the support housing; the lead electrode is connected to the control module and the data calculation module respectively; the lead electrode is used to connect to a DC excitation voltage source or the data calculation module under the control of the control module; wherein, when the lead electrode is connected to the DC excitation voltage source, the capacitive sensing electrode connected to the lead electrode is an excitation electrode; when the lead electrode is connected to the data calculation module, the capacitive sensing electrode connected to the lead electrode is a detection electrode.

[0008] According to an embodiment of this disclosure, the liquid volume detection system further includes a wire fixator; one end of the wire fixator is fixed to the outer surface of the support housing; the other end of the wire fixator is provided with a wire fixing groove; the connecting wires between the lead electrode and the control module and the data calculation module are fixed in the wire fixing groove.

[0009] According to an embodiment of this disclosure, when the lead electrode is not connected to the DC excitation voltage source or the data calculation module, the lead electrode is connected to ground under the control of the control module.

[0010] According to an embodiment of this disclosure, the support shell comprises, from the inside out, an elastic support body and a metal shielding shell; a first groove is provided inside the metal shielding shell; the first groove has a cylindrical structure; the elastic support body is disposed inside the first groove; the outer surface of the elastic support body is in close contact with the surface of the first groove; the capacitive sensor array is disposed inside the elastic support body; the capacitive sensor array is in close contact with the outer surface of the tubular container under the support of the elastic support body; the axial direction of the first groove is consistent with the axial direction of the tubular container.

[0011] According to an embodiment of this disclosure, a second groove is provided in the elastic support body; the second groove is a cylindrical structure; the curvature of the second groove is consistent with the curvature of the outer surface of the tubular container; when the tubular container is placed in the second groove, the axial direction of the tubular container is consistent with the axial direction of the second groove, and the length of the tubular container is less than the length of the second groove.

[0012] According to an embodiment of this disclosure, the data calculation module includes a data acquisition unit and a calculation unit; the data acquisition unit is used to acquire multiple capacitance values ​​output by the capacitance sensor array; the calculation unit is used to calculate the height of the liquid to be detected in the tubular container based on the multiple capacitance values.

[0013] According to an embodiment of this disclosure, the sensor array unit includes: a flexible substrate layer; a metal thin film layer including a plurality of electrode units formed on the flexible substrate layer; and an encapsulation layer covering the metal thin film layer on the flexible substrate layer.

[0014] According to embodiments of this disclosure, the control module includes a channel switching unit and a controller;

[0015] One end of the aforementioned channel switching unit is connected to the aforementioned lead electrode, and the other end is connected to the aforementioned DC excitation voltage source or the aforementioned data calculation module;

[0016] The controller is used to control the channel switching unit, so that the lead electrode is connected to the DC excitation voltage source or the data calculation module.

[0017] According to embodiments of this disclosure, during liquid volume detection, a capacitive sensor array is supported by a supporting housing, allowing the array to be in close contact with the outer surface of a tubular container, thus achieving non-contact measurement of the liquid to be detected within the tubular container. Based on a mutual capacitance measurement method, the liquid to be detected within the tubular container is used as a dielectric material, and multiple capacitance values ​​between the excitation electrode and the corresponding detection electrode at different locations within the tubular container are measured. The height of the liquid to be detected within the tubular container is calculated by analyzing these multiple capacitance values, thereby enabling the capacitive sensor array to measure the liquid volume within the tubular container. Because the electromagnetic characteristics of the capacitive sensor array are utilized and a mutual capacitance detection method is employed, the technical problem of low accuracy in liquid level height measurement under multi-layer label obstruction is at least partially overcome, thereby achieving the technical effect of improving the accuracy of liquid volume detection. Attached Figure Description

[0018] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0019] Figure 1 A schematic diagram of a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure is shown.

[0020] Figure 2 An external schematic diagram illustrating the positional relationship between a capacitive sensor array and a support housing according to an embodiment of the present disclosure is shown.

[0021] Figure 3 This schematically illustrates an internal view of the positional relationship between a capacitive sensor array and a support housing according to an embodiment of the present disclosure;

[0022] Figure 4 A schematic diagram of the structure of a capacitive sensing array according to an embodiment of the present disclosure is shown.

[0023] Figure 5 This illustration schematically shows a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure.

[0024] Figure 6 A schematic diagram illustrating the test flow of a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure is shown; and

[0025] Figure 7 The illustration shows a schematic diagram of the liquid level height prediction result of a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure. Detailed Implementation

[0026] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0030] In the embodiments disclosed herein, the collection, updating, analysis, processing, use, transmission, provision, disclosure, and storage of data (e.g., including but not limited to user personal information) comply with relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures have been taken to prevent unauthorized access to user personal information data and to safeguard user personal information security and network security.

[0031] In the embodiments disclosed herein, user authorization or consent is obtained before acquiring or collecting user personal information.

[0032] Capacitive sensors, due to their advantages such as low cost and high sensitivity, show promising application prospects in non-contact liquid level detection. The basic principle of a capacitive sensor for liquid level measurement is to detect the liquid level by measuring the change in capacitance caused by changes in the liquid level (as a dielectric material), and then converting this capacitance change into an electrical signal output. Currently, capacitive sensors used for liquid level measurement are mainly divided into two types: contact and non-contact. Contact capacitive sensors require immersion in the liquid for measurement, which can easily contaminate the sample, making them unsuitable, especially for medical applications. In contrast, non-contact capacitive sensors effectively avoid this problem, providing a safer and more reliable solution for liquid volume detection through a non-invasive measurement method.

[0033] However, non-contact capacitive sensors still face many challenges in practical applications. For example, measuring liquid level changes in liquid storage devices by measuring capacitance changes, combined with components such as capacitive drive sampling circuits and LC resonant circuits, has achieved accurate liquid level measurement. While this method is significant for liquid level detection in blood analyzers, such as sample diluents, it does not offer an effective solution for handling the coexistence of multiple liquids in serum or plasma volume detection.

[0034] In practical applications, serum and plasma volume detection requires not only high-precision level measurement but also the ability to accurately distinguish the interface between serum / plasma and other liquids, providing precise volume information and meeting the needs of automated acquisition and processing. However, existing non-contact capacitive sensors still have many shortcomings in serum and plasma volume detection. They often can only identify the height of a single liquid and cannot accurately identify the interface between serum / plasma and other liquids when they coexist, thus failing to obtain the volume height of serum or plasma. Furthermore, some non-contact capacitive sensors also have significant shortcomings in measurement accuracy and anti-interference capabilities, further limiting their application in serum and plasma volume detection.

[0035] Given the limitations of existing liquid level detection methods in detecting serum and plasma volumes, there is an urgent need for a liquid volume detection system that can perform high-precision, high-reliability, and non-contact detection of serum and plasma volumes in automated medical testing scenarios.

[0036] This disclosure provides a liquid volume detection system based on a capacitive sensor array, comprising: a capacitive sensor array, a support housing, a control module, and a data calculation module; the capacitive sensor array is disposed inside the support housing; the support housing supports the capacitive sensor array, causing the capacitive sensor array to be in close contact with the outer surface of a tubular container; the tubular container contains a solution of a volume to be detected; the control module is connected to the capacitive sensor array; the control module is used to control each of the multiple excitation electrodes included in the capacitive sensor array to send an excitation signal to the multiple detection electrodes included in the capacitive sensor array based on a mutual capacitance measurement method; the capacitive sensor array is used to output the capacitance value between the excitation electrode and the corresponding detection electrode under the action of the excitation signal, thereby obtaining multiple capacitance values; the data calculation module is used to calculate the height of the liquid of the volume to be detected within the tubular container based on the multiple capacitance values.

[0037] According to embodiments of this disclosure, during liquid volume detection, a capacitive sensor array is supported by a supporting housing, allowing the array to be in close contact with the outer surface of a tubular container, thus achieving non-contact measurement of the liquid to be detected within the tubular container. Based on a mutual capacitance measurement method, the liquid to be detected within the tubular container is used as a dielectric material, and multiple capacitance values ​​between the excitation electrode and the corresponding detection electrode at different locations within the tubular container are measured. The height of the liquid to be detected within the tubular container is calculated by analyzing these multiple capacitance values, thereby enabling the capacitive sensor array to measure the liquid volume within the tubular container. Because the electromagnetic characteristics of the capacitive sensor array are utilized and a mutual capacitance detection method is employed, the technical problem of low accuracy in liquid level height measurement under multi-layer label obstruction is at least partially overcome, thereby achieving the technical effect of improving the accuracy of liquid volume detection.

[0038] Figure 1 The schematic diagram illustrates a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure.

[0039] like Figure 1As shown, the liquid volume detection system based on a capacitive sensor array includes: a capacitive sensor array, a support housing 6, a control module 1, and a data calculation module 2. The capacitive sensor array is disposed inside the support housing 6; the support housing 6 supports the capacitive sensor array, ensuring it is in close contact with the outer surface of the tubular container 5; the tubular container 5 contains a solution of the volume to be detected; the control module 1 is connected to the capacitive sensor array; the control module 1, based on a mutual capacitance measurement method, controls each of the multiple excitation electrodes included in the capacitive sensor array to send an excitation signal to the multiple detection electrodes included in the capacitive sensor array; the capacitive sensor array, under the action of the excitation signal, outputs the capacitance value between the excitation electrode and the corresponding detection electrode, obtaining multiple capacitance values; the data calculation module 2 calculates the height of the liquid of the volume to be detected within the tubular container 5 based on the multiple capacitance values.

[0040] According to embodiments of this disclosure, the liquid volume detection system based on a capacitive sensing array further includes a mounting block 3. The mounting block 3 is fixed to the support housing 6. The mounting block 3 is used to assemble the support housing 6 into applications such as slide rails and robotic arms. A clamp 4 is provided at the top of the tubular container 5 to hold and move the tubular container 5. This arrangement facilitates the automatic measurement of the liquid height within the tubular container 5. The data calculation module analyzes multiple capacitance values ​​based on a preset algorithm model to obtain the height of the liquid within the tubular container 5.

[0041] This disclosure utilizes the fusion of high-sensitivity measurement with a capacitive sensing array and an algorithm model to accurately identify the volume of serum and plasma, achieving a significant improvement in detection accuracy compared to traditional optical and ultrasonic methods. In particular, compared to traditional optical detection methods, this system leverages the electromagnetic properties of the capacitive sensing array to achieve high-precision, non-contact measurement of liquid level even under complex conditions where multiple layers of label paper obstruct the blood collection tube surface. This effectively overcomes the shortcomings of traditional optical imaging techniques, which suffer from poor detection results due to obstruction, thus demonstrating superior performance in various application scenarios.

[0042] Figure 2 An external schematic diagram illustrating the positional relationship between a capacitive sensor array and a support housing according to an embodiment of the present disclosure is shown.

[0043] like Figure 2As shown, the support housing includes an elastic support body and a metal shielding shell 10. The elastic support body is installed in the mounting groove of the metal shielding shell 10. Its inner surface has an arched structure with the same curvature as that of a tubular container, and the length of the mounting groove is less than the length of the metal shielding shell 10. The metal shielding shell 10 is used to shield electromagnetic interference outside the measurement domain. Its internal mounting groove is cylindrical, and its outer surface is provided with a wire holder 8 for fixing the connecting wire 7. The metal shielding shell 10 is made of aluminum alloy and can be machined by a CNC machine tool. The connecting wire 7 is connected to the capacitive sensing array and is used to transmit the data collected by the capacitive sensing array inside the support housing. Figure 2 The mounting block 3, clamp 4, and tubular container 5 are in conjunction with Figure 1 As described above, it will not be repeated here.

[0044] Figure 3 An internal schematic diagram illustrating the positional relationship between the capacitive sensor array and the support housing according to an embodiment of the present disclosure is shown.

[0045] like Figure 3 As shown, the support housing 6 comprises, from the inside out, an elastic support body 9 and a metal shielding shell 10. A first groove is provided inside the metal shielding shell 10; the first groove has a cylindrical structure. The elastic support body 9 is disposed within the first groove; the outer surface of the elastic support body 9 is tightly fitted to the surface of the first groove. A capacitive sensor array is disposed inside the elastic support body 9; supported by the elastic support body 9, the capacitive sensor array is tightly fitted to the outer surface of the tubular container. The axial direction of the first groove is consistent with the axial direction of the tubular container. The first groove is the mounting groove for the metal shielding shell 10.

[0046] The elastic support 9 has a second groove; the second groove is a cylindrical structure; the curvature of the second groove is consistent with the curvature of the outer surface of the tubular container; when the tubular container is placed in the second groove, the axial direction of the tubular container is consistent with the axial direction of the second groove, and the length of the tubular container is less than the length of the second groove.

[0047] According to embodiments of this disclosure, the metal shielding shell 10 can be divided into two parts, including a first metal shielding shell and a second metal shielding shell, which are arranged opposite to each other to form the metal shielding shell 10. The first metal shielding shell and the second metal shielding shell can have the same structure. The groove inside the first metal shielding shell and the groove inside the second metal shielding shell constitute a first groove, which serves as the mounting groove for the elastic support 9. The groove inside the first metal shielding shell and the groove inside the second metal shielding shell can have the same structure. The elastic support 9 can include two parts, one part being a first elastic support and a second elastic support, which are arranged opposite to each other to form the elastic support 9; the first elastic support and the second elastic support can have the same structure. The groove inside the first elastic support and the groove inside the second elastic support constitute a second groove; the groove inside the first elastic support and the groove inside the second elastic support can have the same structure. For example, the inner surfaces of the groove inside the first metal shielding shell, the groove inside the second metal shielding shell, the groove inside the first elastic support, and the groove inside the second elastic support are all arched structures, and the curvature is the same as the curvature of the tubular container.

[0048] According to embodiments of this disclosure, the wire retainer 8 may include a first wire retainer and a second wire retainer. The first wire retainer is fixed to the outer surface of the first metal shielding shell, and the second wire retainer is fixed to the outer surface of the second metal shielding shell.

[0049] The capacitive sensor array comprises two identical sensor array units arranged opposite each other. Each sensor array unit includes multiple electrode units. When the capacitive sensor array is in close contact with the outer surface of the tubular container, the multiple electrode units are uniformly distributed along the axial direction of the tubular container. Each electrode in one sensor array unit has a unique, directly opposite electrode unit in the other sensor array unit, ensuring uniform dielectric constant information intensity across the measured area of ​​the tubular container within the capacitive sensor array, thereby enabling the electrode units to obtain accurate capacitance data.

[0050] According to embodiments of this disclosure, a first elastic support is installed in a groove inside the first support shell; a second elastic support is installed in a groove inside the second support shell; one sensor array unit is installed in a groove inside the first elastic support body, and another sensor array unit is installed in a groove inside the second elastic support body. The axes of the first groove, the second groove, and the tubular container coincide.

[0051] Each electrode unit includes a capacitive sensing electrode 11 and a lead electrode 13. A serpentine wire, referred to as a serpentine wire 12, connects the capacitive sensing electrode 11 and the lead electrode 13. The capacitive sensing electrode 11 is supported by the supporting housing and closely adheres to the inner surface of the supporting housing. The lead electrode 13 is connected to both the control module and the data calculation module. The lead electrode 13 is used to connect to either a DC excitation voltage source or the data calculation module under the control of the control module. Specifically, when the lead electrode 13 is connected to the DC excitation voltage source, the capacitive sensing electrode 11 connected to the lead electrode 13 is the excitation electrode; when the lead electrode 13 is connected to the data calculation module, the capacitive sensing electrode 11 connected to the lead electrode 13 is the detection electrode. When the lead electrode 13 is neither connected to the DC excitation voltage source nor to the data calculation module, it is connected to ground under the control of the control module.

[0052] According to embodiments of this disclosure, the edges of the grooves inside the first elastic support body and the grooves inside the second elastic support body can be rounded to increase the service life of the capacitive sensing electrode.

[0053] The connecting wire 7 includes a first connecting wire and a second connecting wire; the first connecting wire is connected to the lead electrode of one of the sensor array units and is fixed by a first wire retainer; the second connecting wire is connected to the lead electrode of another sensor array unit and is fixed by a second wire retainer.

[0054] One end of the wire holder of the liquid volume detection system based on capacitive sensing array is fixed to the outer surface of the support housing; the other end of the wire holder is provided with a wire fixing groove; the connecting wires between the lead electrode and the control module and the data calculation module are fixed in the wire fixing groove.

[0055] For example, when the tubular container is a blood collection tube, it includes a rubber stopper 51 and tubing. Inside the tubing, the blood volume to be tested is placed. When no anticoagulant is added, the blood volume to be tested is divided into two layers within the tubing: serum 52 and blood clot 53. A volume detection system based on a capacitive sensor array is used to detect the level of serum 52, so that the blood collection tube is surrounded by two sensor array units. Based on multiple capacitance values, the volume information of the blood volume to be tested inside the blood collection tube is calculated.

[0056] Figure 4 A schematic diagram of the structure of a capacitive sensing array according to an embodiment of the present disclosure is shown.

[0057] like Figure 4 As shown, each sensor array unit includes: a flexible substrate layer; a metal thin film layer including multiple electrode units formed on the flexible substrate layer; and an encapsulation layer covering the metal thin film layer on the flexible substrate layer.

[0058] Each sensor array unit comprises multiple electrode units fabricated in a single piece. For example, if a sensor array unit includes ten electrode units, all ten electrode units are fabricated simultaneously, and the surface of the sensor array unit is encapsulated using Parylene material.

[0059] According to embodiments of this disclosure, the fabrication process of the sensor array unit may include operations S11 to S15.

[0060] In operation S11, the pattern of the electrode unit is designed. Figure 4 In this design, the electrode unit consists of a capacitive sensing electrode 11 and a lead electrode 13. Since the capacitive sensing electrode 11 is used to enclose the tubular container, it can be designed as a relatively large-area cube structure or other shapes. To reduce the volume of the supporting shell, the lead electrode 13 can be designed as a relatively small-area cube structure or other shapes. The capacitive sensing electrode 11 and the lead electrode 13 are connected by a serpentine wire 12. The serpentine wire 12 structure effectively prevents the conductive layer from breaking during stretching, significantly improving the mechanical stability and durability of the device.

[0061] In operation S12, polyimide (PI) polymer film is selected as the material for the flexible substrate layer. This material has excellent high mechanical strength, thermal stability, and chemical stability. The thickness of the flexible substrate layer can be optimized according to the specific application scenario of the capacitive sensing unit to meet the flexibility requirements. For example, the thickness of the flexible substrate layer is less than 2 μm.

[0062] In operation S13, the PI film is cut to the required size. For example, if the capacitive sensing unit includes ten uniformly distributed electrode units, the required size is the size required when the ten uniformly distributed electrode units are integrated. It is then flattened onto the glass substrate using PI film-specific tape. Subsequently, the pre-prepared mask is precisely aligned using the PI film tape and fixed to the surface of the PI film. The pattern on the mask is the shape of the ten uniformly distributed electrode units, and the shape of each electrode unit is the pattern of the electrode units designed in (1). Precise alignment means that each pair of directly opposite electrode units must be aligned. Each pair of directly opposite electrode units means that each electrode unit in one sensor array unit has a directly opposite electrode unit in another sensor array unit.

[0063] In operation S14, a Ti / Cu bilayer metal film is sequentially deposited on the surface of the PI film using electron beam evaporation. The specific process parameters are as follows: first, a 10 nm thick Ti film is deposited as an adhesion layer, followed by a 500 nm thick Cu film deposited on top of it as a conductive layer.

[0064] After completing the metal layer deposition in operation S15, the mask is removed, and the PI film with the prepared capacitive sensing electrode, lead electrode and serpentine wire structure is peeled off from the glass substrate to obtain a complete flexible sensor array unit device.

[0065] According to embodiments of this disclosure, the preparation process of the elastic support may include operations S21 to S24.

[0066] In operation S21, based on the three-dimensional structural characteristics of the required elastic support, the inverted mold cavity of the elastic support is machined using a CNC machine tool.

[0067] In operation S22, accurately weigh the polydimethylsiloxane (PDMS) prepolymer and curing agent at a mass ratio of 10:1. Stir until the mixture is homogeneous. Then place the mixture in a vacuum drying oven and degas it at -0.1 MPa for 15-20 minutes to remove air bubbles from the mixture.

[0068] In step S23, the degassed PDMS mixture is slowly injected into the pre-prepared mold cavity. The filled mold is then transferred to a constant temperature oven and cured at 80°C for 2 hours to ensure complete cross-linking of the PDMS.

[0069] After operating S24 and allowing the mold to cool to room temperature, carefully remove the cured elastic support from the mold. Inspect the surface integrity of the product, remove any burrs or flash, and obtain the final usable elastic support.

[0070] Figure 5 The schematic diagram illustrates the detection principle of a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure.

[0071] like Figure 5 As shown, the data calculation module includes a data acquisition unit 503 and a calculation unit 504. The data acquisition unit 503 is used to acquire multiple capacitance values ​​output by the capacitive sensor array. The calculation unit 504 is used to calculate the height of the liquid to be detected in the tubular container based on the multiple capacitance values. The control module includes a channel switching unit 501 and a controller 502. One end of the channel switching unit 501 is connected to the lead electrode, and the other end is connected to a DC excitation voltage source or the data calculation module. The controller 502 is used to control the channel switching unit 501, so that the lead electrode is connected to the DC excitation voltage source or the data calculation module. The DC excitation voltage source is used to provide an excitation signal to the capacitive sensor array.

[0072] According to embodiments of this disclosure, the channel switching unit 501 can be a multiplexer. The data acquisition unit 503 can be a capacitance acquisition chip and a microcontroller, for example, the capacitance acquisition chip is a high-precision digital capacitance sensing chip MDC02 / MDC04. The multiplexer selects different electrode pairs of the capacitance sensing array and transmits the capacitance signal output by the selected electrode pair to the capacitance acquisition chip. The capacitance acquisition chip converts the acquired capacitance signal into a voltage signal. The microcontroller can process the voltage signal and convert it into a capacitance value. The calculation unit 504 can be a computer. The microcontroller transmits multiple capacitance values ​​to the calculation unit 504 via USB or serial port. The calculation unit 504 performs normalization processing on the capacitance matrix to eliminate errors and background noise, and obtains high-precision liquid level height information by analyzing the eigenvalue changes of the capacitance matrix and combining it with an algorithm model. The controller 502 can use a microcontroller to implement the function; that is, the controller can both control the channel switching unit 501 and process the voltage signal output by the capacitance acquisition chip and convert it into a capacitance value.

[0073] Based on mutual capacitance measurement technology, the channel switching unit 501 controls the connection of the lead electrodes of the capacitance sensing array to a DC excitation voltage source or to a data calculation module, enabling the capacitance sensing electrodes to function as excitation electrodes or detection electrodes. The channel switching unit 501 can control the connection of the lead electrodes to the DC excitation voltage source or to the data calculation module according to a preset sequence or rule. For example, when the capacitance sensing electrode of electrode unit N in sensor array unit M=1 is the excitation electrode, all other electrode units in sensor array unit M=1 are grounded, and all capacitance sensing electrodes in sensor array unit M=2 are detection electrodes, collecting data from the lead electrodes connected to the detection electrodes. By traversing all electrode units in sensor array unit M=1 as excitation electrodes, multiple capacitance values ​​are obtained, which can form a capacitance matrix. Taking a sensor array unit containing ten electrode units as an example, the following capacitance matrix C is obtained.

[0074] .

[0075] In the capacitance matrix C, C ij The value can be expressed as the capacitance value of the capacitor formed by the excitation electrode i and the detection electrode j. Where i takes the value 1, 2, ... 10; j takes the value 1, 2, ... 10; F = 10.

[0076] Based on mutual capacitance measurement technology, each electrode unit in the capacitive sensing array can serve as either an excitation electrode or a detection electrode. The controller manages the channel switching unit to switch the electrode unit between these two functions. High-precision measurement is achieved by alternating the excitation and detection electrodes within the capacitive sensing array.

[0077] For example, firstly, a pair of electrode units from one of the sensor array units is randomly selected. The first electrode is used as the excitation electrode, and a DC excitation voltage with an amplitude of U is applied. The second electrode is used as the detection electrode to receive signals. The remaining electrodes are grounded to eliminate external interference. The mutual capacitance value Cmn between the electrode pair is obtained through the data acquisition unit, where m represents the excitation electrode number and n represents the detection electrode number. Each electrode is used as the excitation electrode in a preset order, and the remaining 9 electrodes are used as detection electrodes for capacitance measurement. Specifically, when the m-th electrode is used as the excitation electrode, the mutual capacitance value Cmn between it and the 1st to 10th (m≠n) electrodes is measured respectively, resulting in 10×9=90 independent capacitance measurements. The capacitance values ​​of each pair of opposite electrodes are distributed along the diagonal of the data matrix. After the measurement data is structured, the capacitance values ​​of two opposite capacitance sensing electrode pairs are placed on the diagonal of the capacitance matrix, that is, at the position where m=n, thus forming a 10×10 capacitance matrix C=[Cmn]. In this symmetrical matrix, the diagonal elements represent self-capacitance characteristics, and the off-diagonal elements Cmn (m≠n) reflect mutual capacitance parameters. Its mathematical symmetry Cmn=Cnm significantly improves the reliability of the data.

[0078] The computer acquires capacitance data from the data acquisition unit via serial communication. Different programming languages ​​and software platforms can be used to implement data processing functions to meet the needs of different users and development environments. For example, Support Vector Machine Regression (SVR) can be used for data processing. The normalized capacitance matrix is ​​input into a trained model, which can accurately identify the capacitance characteristics of different media (such as serum, plasma, and blood cells). Based on the input capacitance matrix data, the model can accurately calculate the volume of serum or plasma in the blood collection tube using its built-in algorithm and trained parameters.

[0079] Figure 6 The schematic diagram illustrates a test flow diagram of a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure.

[0080] like Figure 6 As shown, taking a tubular container as a blood collection tube and blood as the solution to be tested as an example, the test procedure includes operations S601~S604.

[0081] When operating S601, place a standard blood collection tube in the detection area of ​​the capacitive sensing array.

[0082] The standard blood collection tube is precisely placed within the detection area enclosed by the capacitive sensing array, ensuring that the axis of the blood collection tube coincides with the central axis of the array, with the deviation controlled within ±0.5mm.

[0083] When operating the S602, the parallel acquisition function of the capacitance sensing array is used to simultaneously acquire the capacitance value of the mutual capacitance formed by the excitation and detection electrodes.

[0084] Capacitive sensing arrays can achieve synchronous data acquisition from multiple signal acquisition channels.

[0085] When operating the S603, signal amplification, filtering, and conditioning are performed, and the conditioned digital signal is transmitted to the computer.

[0086] The data processing module converts the capacitance value measured between the excitation electrode and the detection electrode into a voltage signal on the detection electrode. At the same time, the acquired voltage signal is amplified, filtered, and conditioned, and then transmitted to a computer via a USB interface for functional testing and performance verification.

[0087] When operating the S604, the SVR or deep learning algorithm is run to process the conditioned digital signal and output the height value of the plasma or serum liquid level.

[0088] Data is acquired from the data transmission processing module via serial communication. The computer can use different programming languages ​​and software platforms to implement this. For example, support vector machine regression (SVR) algorithms or deep learning algorithms can be used to calculate the serum and plasma volume levels within the blood collection tube.

[0089] Figure 7 The illustration shows a schematic diagram of the liquid level height prediction result of a liquid volume detection system based on a capacitive sensing array according to an embodiment of the present disclosure.

[0090] like Figure 7 As shown, taking the detection of serum in a blood collection tube as an example, an experimental verification of the liquid volume detection system based on a capacitive sensor array was conducted. The experiment revealed that the actual value of the serum in the blood collection tube essentially coincided with the height prediction value of the liquid volume detection system based on the capacitive sensor array, effectively demonstrating the measurement accuracy and reliability of the system. The capacitance data collected by the capacitive sensing module, after processing by a preset algorithm, can accurately predict the liquid volume information in the blood collection tube. The system's measurement error for liquid volume height is stably and precisely controlled within ±1 mm, and the fitting degree between the actual liquid volume height and the predicted height is extremely excellent, further verifying the effectiveness and practicality of the liquid volume detection system based on the capacitive sensor array.

[0091] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A liquid volume detection system based on a capacitive sensing array, characterized in that, The liquid volume detection system includes: a capacitive sensor array, a support housing, a control module, and a data calculation module; The capacitive sensor array is disposed inside the support housing; The supporting housing is used to support the capacitive sensor array, so that the capacitive sensor array is in close contact with the outer surface of the tubular container; the tubular container contains a solution whose volume to be detected. The control module is connected to the capacitance sensor array; the control module is used to control each of the multiple excitation electrodes included in the capacitance sensor array to send excitation signals to the multiple detection electrodes included in the capacitance sensor array based on the mutual capacitance measurement method. The capacitance sensor array is used to output the capacitance value between the excitation electrode and the corresponding detection electrode under the action of the excitation signal, thereby obtaining multiple capacitance values. The data calculation module is used to calculate the height of the liquid to be detected in the tubular container based on the multiple capacitance values. The capacitive sensor array comprises two sensor array units with identical structures. The two sensor array units are arranged opposite to each other; Each of the sensor array units includes multiple electrode units; When the capacitive sensor array is in close contact with the outer surface of the tubular container, the plurality of electrode units are uniformly distributed along the axial direction of the tubular container; Each of the electrode units includes a capacitive sensing electrode and a lead electrode; The capacitive sensing electrode and the lead electrode include a serpentine wire; The capacitive sensing electrode is attached to the inner surface of the supporting housing under the support of the supporting housing. The lead electrodes are respectively connected to the control module and the data calculation module; The lead electrode is used to connect to the DC excitation voltage source or the data calculation module under the control of the control module; Wherein, when the lead electrode is connected to the DC excitation voltage source, the capacitive sensing electrode connected to the lead electrode is the excitation electrode; when the lead electrode is connected to the data calculation module, the capacitive sensing electrode connected to the lead electrode is the detection electrode.

2. The liquid volume detection system based on a capacitive sensing array according to claim 1, characterized in that, The liquid volume detection system also includes a wire retainer; One end of the wire fixator is fixed to the outer surface of the support housing; The other end of the wire holder is provided with a wire fixing groove; the connecting wires between the lead electrode and the control module and the data calculation module are fixed in the wire fixing groove.

3. The liquid volume detection system based on a capacitive sensing array according to claim 1, characterized in that, When the lead electrode is not connected to the DC excitation voltage source or the data calculation module, the lead electrode is connected to ground under the control of the control module.

4. The liquid volume detection system based on a capacitive sensing array according to claim 1, characterized in that, The supporting shell comprises, from the inside out, an elastic support body and a metal shielding shell; The metal shielding shell has a first groove inside; the first groove has a cylindrical structure. The elastic support is disposed within the first groove; the outer surface of the elastic support is in close contact with the surface of the first groove; The capacitive sensor array is disposed inside the elastic support; the capacitive sensor array is attached to the outer surface of the tubular container under the support of the elastic support.

5. The liquid volume detection system based on a capacitive sensing array according to claim 4, characterized in that, The elastic support body is provided with a second groove; the second groove has a cylindrical structure; The curvature of the second groove is consistent with the curvature of the outer surface of the tubular container; When the tubular container is placed in the second groove, the axial direction of the tubular container is consistent with the axial direction of the second groove, and the length of the tubular container is less than the length of the second groove.

6. The liquid volume detection system based on a capacitive sensing array according to claim 1, characterized in that, The data calculation module includes a data acquisition unit and a calculation unit; The data acquisition unit is used to receive multiple capacitance values ​​output by the capacitance sensor array; The calculation unit is used to calculate the height of the liquid to be detected within the tubular container based on the plurality of capacitance values.

7. The liquid volume detection system based on a capacitive sensing array according to claim 1, characterized in that, The sensor array unit includes: Flexible substrate; A metal thin film layer, comprising a plurality of electrode units formed on the flexible substrate layer; An encapsulation layer, which covers the metal thin film layer on the flexible substrate layer.

8. The liquid volume detection system based on a capacitive sensing array according to claim 1, characterized in that, The control module includes a channel switching unit and a controller; One end of the channel switching unit is connected to the lead electrode, and the other end is connected to the DC excitation voltage source or the data calculation module; The controller is used to control the channel switching unit, so that the lead electrode is connected to the DC excitation voltage source or the data calculation module.

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