A blood viscosity sensor and detection system based on dual-mode surface acoustic wave

Abstract

The application relates to the technical field of blood coagulation detection, and provides a blood viscosity sensor and a detection system based on a double-mode surface acoustic wave, the blood viscosity sensor at least comprising: a substrate base; a first interdigital transducer group arranged on the substrate base, the first interdigital transducer group comprising two first interdigital transducers arranged at intervals along a first direction; and a second interdigital transducer group arranged on the substrate base, the second interdigital transducer group at least comprising two second interdigital transducers arranged at intervals along a second direction. The blood viscosity sensor based on the double-mode surface acoustic wave can simultaneously excite Rayleigh waves and shear horizontal surface acoustic waves through the first interdigital transducer group and the second interdigital transducer group arranged in two different directions on the same substrate base, and the complementary characteristics of the two modes of surface acoustic waves are utilized to realize the unification of high sensitivity and wide detection range.

Description

Technical Field

[0001] This invention relates to the field of coagulation detection technology, specifically to a blood viscosity sensor and detection system based on dual-mode surface acoustic waves. Background Technology

[0002] Blood coagulation is a complex physiological process involving a series of biochemical reactions and cellular activities, including the liquid phase, gel phase, and clot formation phase. Timely detection of changes in blood viscosity is crucial for guiding clinicians in assessing patients' bleeding and thrombosis risks, and for the prevention and treatment of cardiovascular diseases. Currently, commercially available methods for blood viscosity detection include electrochemical methods, pressure sensor methods, optical turbidimetry, and magnetic bead methods, but these generally suffer from drawbacks such as small detection range, low accuracy, large size, complex operation, high cost, and slow detection speed. Therefore, there is an urgent need to develop a novel blood viscosity sensor that can perform whole blood testing with small blood sample volumes, a wide detection range, high accuracy, low cost, and portability. Surface acoustic wave (SAW) sensors offer advantages such as high sensitivity, fast response, and easy integration. Based on microelectromechanical systems (MEMS) technology, they can be miniaturized, and their application in blood viscosity detection is expected to overcome the shortcomings of traditional methods. Existing SAW sensors for blood viscosity detection are single-mode SAW sensors, which struggle to simultaneously achieve high sensitivity and a wide detection range. Summary of the Invention

[0003] Therefore, the present invention aims to solve the problem that existing surface acoustic wave (SAW) sensors used for detecting blood viscosity are single-mode SAWs, which make it difficult to achieve both high sensitivity and wide detection range. Thus, the present invention provides a blood viscosity sensor and detection system based on dual-mode SAWs.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0005] On one hand, the present invention provides a blood viscosity sensor based on dual-mode surface acoustic waves, comprising at least: a substrate; a first interdigital transducer group disposed on the substrate, the first interdigital transducer group comprising two first interdigital transducers spaced apart along a first direction; one of the first interdigital transducers being used to excite Rayleigh waves, and the other first interdigital transducer being used to receive Rayleigh waves; and a second interdigital transducer group disposed on the substrate, the second interdigital transducer group comprising at least two second interdigital transducers spaced apart along a second direction; one of the second interdigital transducers being used to excite shear horizontal surface acoustic waves, and the other second second interdigital transducer being used to receive shear horizontal surface acoustic waves; wherein the first direction and the second direction are two different directions.

[0006] Furthermore, the blood viscosity sensor based on dual-mode surface acoustic waves also includes a first sample reservoir disposed on the substrate and located between two adjacent first interdigital transducers.

[0007] Furthermore, a waveguide layer is deposited on the region of the substrate used for propagating shear horizontal surface acoustic waves. The shear wave velocity of the waveguide layer is lower than that of the substrate, so as to convert the shear horizontal surface acoustic waves into Leff waves.

[0008] Furthermore, the blood viscosity sensor based on dual-mode surface acoustic waves also includes a second sample reservoir disposed on the substrate and covering the area where the second interdigital transducer and the waveguide layer are located.

[0009] Furthermore, the waveguide layer is modified with a sensitive material, which achieves selective detection of specific components in the blood through specific binding; the waveguide layer is a waveguide layer formed of a corrosion-resistant material.

[0010] Furthermore, the angle between the projections of the first direction and the second direction onto the same plane ranges from 15° to 90°.

[0011] Furthermore, the substrate material is selected from 36°-42°YX lithium tantalate, 41°YX lithium niobate, ST quartz, AT quartz, etc. Oriented zinc oxide or aluminum nitride thin films.

[0012] Furthermore, a first interdigital transducer group and a second interdigital transducer group form a sensor unit, and multiple sensor units are arrayed and integrated on the substrate.

[0013] Furthermore, the attenuation coefficient of the Rayleigh wave is:

[0014]

[0015] The frequency variation of the Lep wave is as follows:

[0016]

[0017] In the expression:

[0018] λ is the wavelength of the Rayleigh wave; ρ L ρ is the density of the liquid. S η is the density of the solid; ω is the angular frequency; η is the viscosity of the liquid; f0 is the natural frequency of the Leff wave without the influence of the liquid; μ S The shear modulus of the solid;

[0019] Therefore, the output of the blood viscosity sensor is:

[0020] C(t)=αΔαR (t)+βΔf SH (t)+γT(t);

[0021] Where α and β are weighting coefficients, γ is the temperature compensation coefficient, and T(t) is the temperature function.

[0022] On the other hand, the present invention provides a blood viscosity detection system, including a blood viscosity sensor based on dual-mode surface acoustic waves as described above, and further including a microfluidic unit, a signal processing circuit, and a packaging shell; the blood viscosity sensor, the microfluidic unit, and the signal processing circuit are integrated within the packaging shell.

[0023] The technical solution of this invention has the following advantages:

[0024] This invention provides a blood viscosity sensor based on dual-mode surface acoustic waves. On the same substrate, through a first interdigital transducer group and a second interdigital transducer group arranged in two different directions, Rayleigh waves and shear horizontal surface acoustic waves can be simultaneously excited. Utilizing the complementary characteristics of the two modes of surface acoustic waves, a balance between high sensitivity and a wide detection range is achieved. Rayleigh waves are vertically polarized surface acoustic waves with a large contact area with the liquid being tested. When blood viscosity changes slightly, the propagation characteristics of Rayleigh waves, such as velocity and attenuation, produce a significant response, resulting in high sensitivity to blood viscosity. This makes it particularly suitable for detecting low-viscosity blood samples or those with small viscosity changes, especially for real-time detection of the transition of fluid blood to the gel phase. Shear horizontal surface acoustic waves, on the other hand, are horizontally polarized guided wave modes. Their response to liquid viscosity is more linear than that of Rayleigh waves, making them suitable for detecting blood samples with a large viscosity range, especially for real-time monitoring of blood transitioning from the coagulation phase to clot formation. This setup utilizes the high sensitivity of the Rayleigh wave mode, which is suitable for detecting low-viscosity blood and providing rapid response, and the wide detection range and high resolution of the shear level surface acoustic wave mode, which is suitable for analyzing blood with different viscosity levels. Combining the two enables comprehensive, accurate, and real-time blood viscosity monitoring to meet the needs of clinical diagnosis and treatment monitoring. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a blood viscosity sensor based on dual-mode surface acoustic waves in one embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a blood viscosity sensor based on dual-mode surface acoustic waves in another embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the propagation characteristics of Rayleigh waves;

[0029] Figure 4 A schematic diagram illustrating the propagation characteristics of Rayleigh waves;

[0030] Figure 5 This is a schematic diagram of the propagation characteristics of the Lep wave;

[0031] Figure 6 This is a schematic diagram of the propagation characteristics of Lep waves.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Substrate; 2. Waveguide layer; 3. First interdigital transducer; 4. Second interdigital transducer; 5. First sample reservoir; 6. Rayleigh wave; 7. Leff wave. Detailed Implementation

[0034] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] like Figure 1 As shown, this embodiment provides a blood viscosity sensor based on dual-mode surface acoustic waves, comprising at least: a substrate 1; a first interdigital transducer group disposed on the substrate 1, the first interdigital transducer group including two first interdigital transducers 3 spaced apart along a first direction; one of the first interdigital transducers 3 is used to excite Rayleigh waves, and the other first interdigital transducer 3 is used to receive Rayleigh waves; a second interdigital transducer group disposed on the substrate 1, the second interdigital transducer group including at least two second interdigital transducers 4 spaced apart along a second direction; one of the second interdigital transducers 4 is used to excite shear horizontal surface acoustic waves, and the other second interdigital transducer 4 is used to receive shear horizontal surface acoustic waves; wherein, the parameters of the first interdigital transducers 3 and the second interdigital transducers 4 can be optimized according to the detection requirements, such as wavelength, logarithm, bandwidth, etc., to obtain ideal transmission characteristics. The first direction and the second direction are two different directions. The first and second interdigital transducers can be coplanar, with the angle between the first and second directions ranging from 15° to 90°, for example, 38°. Alternatively, they can be non-coplanar, with the angle between their projections onto the same plane ranging from 15° to 90°, for example, 38°. This arrangement ensures that the first and second interdigital transducers 3 and 4 have a certain spatial angle, maximizing crosstalk suppression and enabling independent control. During operation, Rayleigh and Leff waves propagate at different frequencies in their respective directions, attenuating upon interaction with blood. The remaining energy is received by the output transducer, and the blood viscosity can be calculated based on the signal strength changes.

[0039] The blood viscosity sensor based on dual-mode surface acoustic waves provided in this embodiment, on the same substrate 1, can simultaneously excite Rayleigh waves and shear horizontal surface acoustic waves by using a first interdigital transducer group 3 and a second interdigital transducer group 4 arranged in two different directions. Utilizing the complementary characteristics of the two modes of surface acoustic waves, a combination of high sensitivity and a wide detection range is achieved. Rayleigh waves are vertically polarized surface acoustic waves with a large contact area with the liquid being tested. When blood viscosity changes slightly, the propagation characteristics of Rayleigh waves, such as velocity and attenuation, produce a significant response, thus exhibiting high sensitivity to blood viscosity. This makes it particularly suitable for detecting blood samples with low viscosity or small viscosity changes, especially for real-time detection of the transition of fluid blood to the gel phase. Shear horizontal surface acoustic waves, on the other hand, are horizontally polarized guided wave modes. Their response to liquid viscosity is more linear than that of Rayleigh waves, making them suitable for detecting blood samples with a large viscosity range, especially for real-time monitoring of blood transitioning from the coagulation phase to clot formation. This setup utilizes the high sensitivity of the Rayleigh wave mode, which is suitable for detecting low-viscosity blood and providing rapid response, and the wide detection range and high resolution of the shear level surface acoustic wave mode, which is suitable for analyzing blood with different viscosity levels. Combining the two enables comprehensive, accurate, and real-time blood viscosity monitoring to meet the needs of clinical diagnosis and treatment monitoring.

[0040] The blood viscosity sensor based on dual-mode surface acoustic waves also includes a first sample reservoir 5, which is disposed on the substrate 1. The first sample reservoir 5 is small in size and can be located between two adjacent first interdigital transducers 3. In use, the blood to be tested is dripped into the first sample reservoir 5. When a Rayleigh wave is excited by one of the first interdigital transducers 3 and passes through the first sample reservoir 5, the energy of the Rayleigh wave changes and is then received by the other first interdigital transducer 3. The viscosity information of the blood in the first sample reservoir 5 can be obtained based on the change in the energy of the Rayleigh wave before and after the change.

[0041] In this design, a waveguide layer 2 is deposited on the substrate 1 in the region used for propagating shear horizontal surface acoustic waves. For example, the waveguide layer 2 can be made of organic or inorganic media. The shear wave velocity of the waveguide layer 2 is lower than that of the substrate 1, thereby confining and propagating the shear horizontal surface acoustic waves, converting them into Leff waves, and improving sensitivity. The waveguide layer 2 can be made of corrosion-resistant materials. For example, the material of the waveguide layer 2 can be SiO2, ZnO, etc., with a thickness ranging from hundreds of nanometers to several micrometers. The optimized design of the waveguide layer 2 can significantly improve the sensitivity and signal-to-noise ratio of the Leff waves. Moreover, the presence of the waveguide layer 2 allows the energy of the Leff waves to be mainly confined at the interface between the substrate 1 and the waveguide layer 2, reducing dependence on the material of the substrate 1. The corrosion-resistant waveguide layer 2 material can withstand long-term immersion in blood samples without degradation, which helps extend the lifespan of the device.

[0042] The blood viscosity sensor based on dual-mode surface acoustic waves also includes a second sample reservoir disposed on the substrate 1. The second sample reservoir is relatively large, covering the area where the second interdigital transducer 4 and the waveguide layer 2 are located. In use, blood to be tested is dripped into the second sample reservoir. When a Leff wave is excited by one of the second interdigital transducers 4, its frequency changes due to the influence of the blood in the second sample reservoir during propagation. This change is then received by the other second interdigital transducer 4. The viscosity information of the blood in the second sample reservoir can be obtained based on the change in the Leff wave frequency. Since Leff waves cannot propagate in liquids, the second sample reservoir must be designed to be large enough to cover the area where the second interdigital transducer 4 and the waveguide layer 2 are located to measure the blood viscosity using the change in the Leff wave frequency. This configuration, taking into account the different characteristics of Rayleigh waves 6 and Leff waves 7, allows for a reasonable design of the position and size of the first and second sample reservoirs, which helps improve detection sensitivity and reduce sample consumption.

[0043] The waveguide layer 2 is modified with a sensitive material that achieves selective detection of specific components in the blood through specific binding. For example, the sensitive material can be biomolecules such as antibodies or aptamers, enabling selective detection of specific blood components, such as coagulation factors and fibrinogen, by specifically binding to them, thus expanding the dimensions of blood analysis. To facilitate rapid detection, a blood coagulation-promoting reagent is typically used; for example, the reagent can be added after the blood sample is added. Alternatively, the coagulation-promoting reagent can be incorporated into the sensitive material, requiring only the addition of a blood sample for use.

[0044] The substrate 1 can be made of a piezoelectric material compatible with Rayleigh wave 6 and Leff wave 7. For example, it can be lithium tantalate in the range of 36°YX to 42°YX, or lithium niobate in the range of 41°YX. It can also be ST quartz, AT quartz, or other similar materials. Oriented zinc oxide or aluminum nitride thin films. These materials, in specific crystal orientations, can both support the propagation of Rayleigh waves and excite surface acoustic waves as the basis for Leff waves.

[0045] It should be noted that the surface acoustic wave (SAW) mode on the piezoelectric substrate is related to the propagation direction. The crystal structure of the piezoelectric material determines the anisotropy of its elastic, piezoelectric, and dielectric properties. Substrates cut with different crystal orientations will exhibit different coupling coefficients and wave propagation characteristics. In practical applications, crystals have different symmetry types, and in some cases, special cases of wave decoupling may occur. In applications, it is necessary to distinguish and examine the crystal's symmetry type, the decoupling of the two displacement components, and the decoupling of the potential and horizontal displacement components. In this case, a piezoelectrically coupled Rayleigh wave may exist in the material. For example, a pure Rayleigh wave without piezoelectric coupling and a Loehr wave with piezoelectric coupling may exist in the crystal. Because SAW sensors utilize the piezoelectric effect, waves decoupled from the potential are meaningless. Therefore, both the Loehr wave and the Rayleigh wave used here must be modes coupled to the potential. Figures 3-6 As shown, both the Rayleigh and Leff wave modes calculated on the selected substrate 1 are coupled with the electric potential. To implement a dual-mode design on the substrate, the wave propagation characteristics must first be considered.

[0046] Rayleigh waves are surface waves whose energy is concentrated on the material surface and decays with depth. They propagate along the x-axis, but their displacement components U1, U2, and U3 simultaneously include vibrations in both the vertical direction (z-axis) and the propagation direction (x-axis).

[0047] like Figure 3 As shown, the U1, U2, and U3 components of the Rayleigh wave indicate that: U1 (blue curve) represents the displacement along the x-direction. U2 (red curve) represents a displacement along the y-direction that is almost zero.

[0048] U3 (green curve) represents the displacement along the z-direction. V (purple curve) represents the energy distribution or normalized parameter. Due to the characteristics of Rayleigh waves, the vertical displacement is greatest at the surface and decreases exponentially with depth. Figure 4 As shown, the surface undulations are large, and elliptical trajectories (red and blue areas) appear near the material surface. This indicates that the particle motion of Rayleigh waves follows an elliptical trajectory, meaning that Rayleigh waves have a combination of vertical and horizontal displacements.

[0049] For Röhler waves, they are surface waves of a pure shear mode, meaning their displacement primarily occurs in the horizontal direction, with no vertical vibrations. Their propagation direction is along the x-axis, but the displacement direction is entirely along the y-axis (perpendicular to the propagation direction). For example... Figure 5 As shown, U1 (blue) is close to 0 in the Röhler wave, indicating no displacement in the x-direction. U2 (red) exhibits significant shear displacement, indicating that the Röhler wave mainly vibrates along the y-direction. U3 (green) is essentially 0, indicating no vibration in the vertical direction. V (purple) represents the energy distribution or wave characteristics. Figure 6As shown, red and blue areas appear only near the material surface, indicating that the wave is confined to the surface. Because the Röhler wave vibrates only in the horizontal direction (y-axis), its energy is more easily coupled with the liquid through shear coupling, resulting in high sensitivity.

[0050] The working principle of dual-mode collaborative detection:

[0051] The core of the dual-mode detection strategy is to utilize the different mechanisms of Rayleigh waves and Röhler waves in their interaction with liquids to achieve a comprehensive characterization of liquid properties. Rayleigh waves have a displacement component perpendicular to the propagation direction; when they come into contact with a liquid, their energy is dissipated into the liquid through acoustic radiation. By measuring the attenuation characteristics of Rayleigh waves, the viscosity parameters of the sample liquid can be obtained. Röhler waves, on the other hand, have a displacement direction parallel to the substrate surface and perpendicular to the propagation direction; their interaction with the liquid is mainly achieved through shear coupling. When liquid is applied to the sensor surface, it causes a change in the frequency of the Röhler waves; this frequency change is closely related to the viscosity characteristics of the sample liquid.

[0052] Rayleigh wave interaction with liquid:

[0053] When a Rayleigh wave comes into contact with a liquid, its energy is radiated into the sample liquid due to its vertical displacement component, with an attenuation coefficient of:

[0054]

[0055] This formula describes the attenuation coefficient α of Rayleigh waves when in contact with a liquid. R This refers to the energy lost by a wave during propagation due to the influence of the liquid. In the expression: λ is the wavelength of the Rayleigh wave; ρ... L ρ is the density of the liquid. S η is the density of the solid; ω is the angular frequency; η is the viscosity of the liquid.

[0056] Physical meaning: Rayleigh waves have a vertical displacement component, meaning that during propagation, they not only move along the material surface but also vibrate in the vertical direction. When a liquid comes into contact with the solid surface from which Rayleigh waves propagate, some of the wave's energy is absorbed by the liquid through viscous shear, resulting in attenuation. The attenuation coefficient α R This reflects the extent of this energy loss. It increases with increasing liquid density and viscosity, indicating that the properties of the liquid have a significant impact on Rayleigh wave propagation.

[0057] Interaction of Röhler waves with liquids: Röhler waves mainly interact with the sample liquid through shear coupling. The relationship between frequency changes and liquid properties is as follows:

[0058]

[0059] This formula describes the frequency change Δf of the Leff wave under the influence of a liquid. SHThis refers to the frequency shift produced when a wave interacts with a liquid. In the expression: ρ L ρ is the density of the liquid. S η is the density of the solid; ω is the angular frequency; η is the viscosity of the liquid; f0 is the natural frequency of the Leff wave without the influence of the liquid; μ S This is the shear modulus of the solid.

[0060] Physical meaning:

[0061] Leff waves primarily rely on shear coupling and fluid interaction, meaning they are more sensitive to changes in the viscosity and density of the fluid. Frequency variation Δf SH The frequency shift is determined by both the density and viscosity of the liquid. When the liquid comes into contact with the sensor surface, shearing alters the wave propagation characteristics, causing a decrease in its resonant frequency. The frequency shift Δf SH With liquid density ρ L The Rough wave increases with increasing viscosity η, which allows it to be used as a sensor for detecting liquid properties. Since shear waves cannot propagate in liquids, the signal changes of the Rough wave are mainly related to the adhesion properties of the liquid surface, rather than directly attenuating like Rayleigh waves.

[0062] Therefore, the output of the blood viscosity sensor is:

[0063] C(t)=αΔα R (t)+βΔf SH (t)+γT(t);

[0064] Where α and β are weighting coefficients, γ is the temperature compensation coefficient, and T(t) is the temperature function. For signal processing, an innovative data fusion algorithm is used to detect the output. Specifically, based on the input quantities of the Leff wave, Rayleigh wave, and temperature, a single output quantity is generated. This algorithm fully utilizes the complementary characteristics of the two wave modes, significantly improving the accuracy and reliability of the measurement.

[0065] The first interdigital transducer 3 operates at a lower frequency, ranging from 100MHz to 150MHz, primarily due to its tendency to attenuate. The second interdigital transducer 4 operates at a higher frequency, ranging from 200MHz to 250MHz, to achieve higher quality sensitivity. This separation of the two frequency bands ensures effective signal separation and processing. For example, the first interdigital transducer 3 can operate at 155MHz with a 25μm periodic structure and 50 pairs of fingers; the second interdigital transducer 4 can operate at 245MHz with a 20μm period and 60 pairs of fingers. Through a reasonable spatial layout and isolation design, minimal mutual interference is achieved.

[0066] Furthermore, device performance can be further optimized by introducing reflective gratings and sound-absorbing structures. For example, the device size can be 10mm*5mm, the channel spacing can be 1mm, the effective detection area can be 2mm*2mm, and the microfluidic channel height can be 100μm.

[0067] like Figure 2 As shown, a first interdigital transducer group 3 and a second interdigital transducer group 4 form a sensor unit, and multiple sensor units are arrayed and integrated on the substrate 1.

[0068] Another embodiment provides a blood viscosity detection system, including the blood viscosity sensor based on dual-mode surface acoustic waves as described above, and further including a microfluidic unit, a signal processing circuit, and a packaging shell; the blood viscosity sensor, microfluidic unit, and signal processing circuit are integrated within the packaging shell. This configuration integrates the blood viscosity sensor, microfluidic unit, and signal processing circuit into a single miniature packaging shell, forming a complete blood viscosity detection system. This integrated design reduces size and power consumption, improves system reliability and ease of use, and facilitates rapid, portable detection of blood viscosity.

[0069] The blood viscosity sensor based on dual-mode surface acoustic waves in this application is low in cost, mainly due to the following aspects:

[0070] Simple manufacturing process: The manufacturing of surface acoustic wave (SAW) sensors mainly relies on standard microelectronics and microelectromechanical systems (MEMS) processes, such as photolithography, thin film deposition, and etching. These processes are highly mature and can be mass-produced, thereby reducing the manufacturing cost of individual devices.

[0071] Low material cost: The substrates of surface acoustic wave (SAW) sensors are mostly made of common piezoelectric materials such as quartz, zinc oxide, and aluminum nitride, which are relatively inexpensive. Metal interdigital transducers are typically made of materials with good conductivity and moderate cost, such as aluminum and gold. Therefore, the material cost is also low.

[0072] High integration: Surface acoustic wave (SAW) sensors are small and lightweight, allowing for easy integration with other electronic components onto the same chip to form a unified sensing system. This high level of integration not only reduces device size and material usage but also simplifies packaging and assembly processes, further reducing costs.

[0073] No complex signal processing circuits are required: The working principle of surface acoustic wave (SAW) sensors is simple, and the output signal is directly related to the measured quantity. Compared with other types of sensors, SAW sensors do not require complex signal conversion and amplification circuits, reducing the use of supporting electronic components and thus lowering the overall cost.

[0074] The miniaturization of surface acoustic wave (SAW) sensors stems from their unique working principle and advanced manufacturing processes. Micrometer-level device structures, chip-based packaging, array integration, and integration with microfluidic units and wireless electronic circuitry collectively create a miniaturized, integrated, and intelligent sensor platform. This miniaturization enables SAW sensors to be widely used in environmental monitoring, medical diagnostics, food safety, and other fields.

[0075] The blood viscosity sensor based on dual-mode surface acoustic waves in this application is small in size and light in weight, exhibiting a high degree of miniaturization, mainly reflected in the following aspects:

[0076] Micrometer-scale device structure: The core structure of a surface acoustic wave (SAW) sensor is an interdigital transducer fabricated on a piezoelectric substrate. Thanks to advancements in microelectronics and microelectromechanical systems (MEMS) fabrication techniques, the feature size of interdigital transducers can be achieved at the micrometer or even sub-micrometer level. For example, for SAW sensors operating at frequencies of hundreds of megahertz, the period of the interdigital transducer is typically on the order of micrometers. This tiny device structure makes the overall size of SAW sensors extremely compact.

[0077] Chip-based packaging: Surface acoustic wave (SAW) sensors are typically packaged on a chip-based basis. A tiny sensor chip is integrated with electronic circuitry and a housing to form a complete sensor element. Chip-based packaging not only protects the sensor from external environmental interference but also significantly reduces its size and weight. Currently, SAW sensor package sizes range from millimeters to centimeters, and weights are in the sub-gram range.

[0078] Array-based integration: Thanks to the tiny size of surface acoustic wave (SAW) sensors, multiple sensor units can be easily integrated onto the same substrate 1 to form a sensor array. Array-based design enables parallel detection of multiple parameters and channels without significantly increasing device size, thus improving the functional density of the sensor.

[0079] Integration with microfluidic units: The miniaturization of surface acoustic wave (SAW) sensors makes them easy to integrate with microfluidic units to build micro total analysis systems or laboratory chips. By integrating miniaturized fluid channels, sample processing chambers, and other components onto the same chip, automated sample delivery, reaction, and detection functions can be achieved, greatly simplifying the sensor's operation and realizing its miniaturization and intelligence.

[0080] The blood viscosity sensor based on dual-mode surface acoustic waves in this application differs from traditional analytical methods. Surface acoustic wave sensors typically require only a small sample volume when detecting sample solutions, mainly in the following aspects:

[0081] The sensing area is tiny: the sensitive area of ​​a surface acoustic wave (SAW) sensor, i.e., the region where the SAW interacts with the sample, is typically only a few square millimeters to tens of square millimeters in size. This tiny sensitive area dictates that the required sample volume is extremely small. For example, for a typical delay-line SAW sensor, the area of ​​its sensitive region is approximately 1 mm². 2 The corresponding sample volume can be as low as microliters.

[0082] High sensitivity: Surface acoustic wave (SAW) sensors exhibit high sensitivity to minute changes in sample properties. When a SAW wave comes into contact with the sample, even slight changes in the sample's mass, viscoelasticity, and conductivity will cause significant changes in the SAW propagation characteristics, such as phase velocity, amplitude, and phase. Thanks to this high sensitivity, even with very small sample quantities, SAW sensors can generate detectable signal responses, enabling accurate measurement of sample properties.

[0083] Microfluidics: Integrating surface acoustic wave (SAW) sensors with microfluidic units allows for precise control of sample delivery and reaction, minimizing sample consumption. The fluid channels on microfluidic chips are typically on the micrometer scale, and the volume of a single reaction chamber can be as low as the nanoliter level. By injecting the sample into the microfluidic chip and guiding it to the surface of the SAW sensor, automated sample analysis can be achieved, with sample volume controllable at the microliter level.

[0084] In summary, the blood viscosity sensor based on dual-mode surface acoustic waves presented in this application ingeniously combines Rayleigh waves and Leff waves in a monolithic dual-mode sensor design. This retains the high sensitivity of Rayleigh waves while inheriting the wide detection range of Leff waves, simultaneously simplifying the device structure and reducing manufacturing costs. This novel design is expected to advance blood viscosity sensing technology, providing a more optimized solution for clinical diagnosis and disease monitoring. With further research and process refinement, the monolithic dual-mode sensor is expected to find widespread application in the field of blood analysis.

[0085] The blood viscosity sensor based on dual-mode surface acoustic waves in this application features interdigital transducers arranged according to the maximum energy flux angle, offering high flexibility. The two modes operate at different frequencies, preventing interference. An optional waveguide layer 2 can be added to further improve sensitivity. A multi-parameter fusion algorithm is used to process the two modes of signals, resulting in high accuracy. Therefore, this application realizes a novel blood viscosity sensor that is portable, requires small blood samples, has a wide detection range, high accuracy, low cost, short processing time, and is suitable for whole blood testing. It is expected to be applied in clinical coagulation function assessment and home health monitoring.

[0086] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A dual-mode surface acoustic wave-based blood viscosity sensor, characterized by, At least comprising: a substrate base (1); a first interdigital transducer group disposed on the substrate base (1), the first interdigital transducer group comprising two first interdigital transducers (3) disposed at intervals along a first direction; one of the first interdigital transducers (3) is used to excite Rayleigh waves, and the other first interdigital transducer (3) is used to receive Rayleigh waves; a second interdigital transducer group disposed on the substrate base (1), the second interdigital transducer group comprising at least two second interdigital transducers (4) disposed at intervals along a second direction; one of the second interdigital transducers (4) is used to excite shear horizontal surface acoustic waves, and the other second interdigital transducer (4) is used to receive shear horizontal surface acoustic waves; wherein the first direction and the second direction are two different directions; further comprising a first sample reservoir (5) disposed on the substrate base (1) and located between two adjacent first interdigital transducers (3); a region on the substrate base (1) for propagating shear horizontal surface acoustic waves is deposited with a waveguide layer (2), the shear wave velocity of the waveguide layer (2) is less than the shear wave velocity of the substrate base (1), so as to convert the shear horizontal surface acoustic waves into Love waves; further comprising a second sample reservoir disposed on the substrate base (1) and covering the region where the second interdigital transducer (4) and the waveguide layer (2) are located; wherein the attenuation coefficient of Rayleigh waves is: wherein the frequency change of Love waves is: in the expression: λ is the wavelength of the Rayleigh wave; p L is the density of the liquid; p S is the density of the solid; ω is the angular frequency; η is the viscosity of the liquid; f0is the natural frequency of the Love wave without the influence of the liquid; μ S is the shear modulus of the solid; then the output of the blood viscosity sensor is: wherein α, β are weight coefficients, γ is a temperature compensation coefficient, and T(t) is a temperature function.

2. The dual-mode surface acoustic wave-based blood viscosity sensor according to claim 1, wherein the waveguide layer (2) is modified with a sensitive material, and the sensitive material realizes selective detection of specific components in blood through specific binding; the waveguide layer (2) is a waveguide layer (2) formed of a corrosion-resistant material.

3. The dual-mode surface acoustic wave-based blood viscosity sensor according to claim 1, wherein the angle between the projections of the first direction and the second direction in the same plane is in the range of 15°-90°.

4. The dual-mode surface acoustic wave-based blood viscosity sensor according to claim 1, wherein The material of the substrate base (1) is selected from 36°-42° YX lithium tantalate, 41° YX lithium niobate, ST quartz, AT quartz, [11 0] oriented zinc oxide or aluminum nitride film.

5. The dual-mode surface acoustic wave-based blood viscosity sensor according to claim 1, wherein one of the first interdigital transducer groups and one of the second interdigital transducer groups form a sensor unit, and a plurality of the sensor units are arrayed and integrated on the substrate base (1).

6. A blood viscosity detection system comprising the dual-mode surface acoustic wave-based blood viscosity sensor according to any one of claims 1-5, characterized in that, further comprising a microfluidic unit, a signal processing circuit, and a packaging shell; the blood viscosity sensor, the microfluidic unit, and the signal processing circuit are integrated in the packaging shell.

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