A micro-material analysis method and a multi-frequency band surface acoustic wave sensor used therein

Abstract

The application discloses a kind of micro material analysis method and the multi-band surface acoustic wave sensor used therein.The micro material analysis method includes the following steps: one, the material to be measured is placed in the accommodating cavity.Two, a modulated signal is applied to one of the interdigital electrodes.The modulated signal is obtained by superimposing n sinusoidal signals with different frequencies;the receiving signal of the other interdigital electrode is collected.The phase difference between the modulated signal and the receiving signal is extracted respectively.Three, the n phase differences obtained in step two are substituted into the phase difference-Young's modulus relationship curve corresponding to different frequencies respectively, and n Young's modulus estimates are obtained.According to the n Young's modulus estimates, the deformation resistance of the material to be measured is determined.The application introduces a surface wave sensor into the measurement of Young's modulus of micro materials, and uses the phase difference corresponding to different frequencies between two interdigital electrodes to realize quantitative analysis of micro materials.

Description

Technical Field

[0001] This invention belongs to the field of surface acoustic wave sensor technology, specifically relating to a multi-band surface acoustic wave sensor and detection method. Background Technology

[0002] In biodiagnostics, researchers have made significant efforts to capture and enrich cells, employing methods ranging from immunomagnetic separation to density gradient centrifugation and microfluidic separation. However, studying the characteristics of tiny cells after capture remains a challenge. Traditionally, due to a lack of tools and methods to achieve even smaller dimensions, biological cell analysis has generally been performed in large cell populations. This has led researchers to primarily interpret results using averages, as changes at the cellular level remain unobservable. Therefore, characterizing the properties of micromaterials has become particularly important in recent years, and advances in biosensors in this area can help researchers understand behavior occurring at the micrometer level. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-band surface acoustic wave sensor and detection method.

[0004] A method for analyzing micromaterials employs a surface acoustic wave (SAW) sensor. The SAW sensor includes a substrate, a cavity, and two interdigitated electrodes serving as input and output electrodes, respectively. The cavity is disposed on the substrate. Both interdigitated electrodes are disposed on the substrate and arranged on opposite sides of the cavity. Each interdigitated electrode comprises n signal transceiver segments with varying interdigit widths, where n ≥ 2.

[0005] This method for analyzing tiny materials includes the following steps:

[0006] Step 1: Place the material to be tested into the receiving cavity.

[0007] Step 2: Apply a modulation signal to one of the interdigital electrodes. The modulation signal is obtained by superimposing n sinusoidal signals of different frequencies; the frequencies of the n sinusoidal signals are the same as the resonant frequencies of the n signal transceiver segments on the interdigital electrode. Acquire the received signal from the other interdigital electrode. Extract the phase difference between the n sinusoidal signals of different frequencies between the modulation signal and the received signal.

[0008] Step 3: Substitute the n phase differences obtained in Step 2 into the phase difference-Young's modulus relationship curves corresponding to different frequencies to obtain n estimated Young's modulus values. Based on the n estimated Young's modulus values, determine the deformation resistance of the tested material.

[0009] Preferably, in step three, the average of the n Young's modulus estimates is taken as the measured Young's modulus of the material being tested.

[0010] Preferably, the phase difference-Young's modulus relationship curves corresponding to different frequencies are obtained by calibrating the surface acoustic wave sensor using a variety of materials with known Young's modulus.

[0011] Preferably, the n signal transceiver pairs are arranged sequentially along the direction away from the receiving cavity.

[0012] Preferably, the length of the receiving cavity is 16μm to 24μm, the width is 16μm to 24μm, and the depth is 4μm to 12μm.

[0013] This invention discloses a multi-band surface acoustic wave (SAW) sensor, comprising a substrate, a receiving cavity, and two interdigitated electrodes serving as input and output electrodes, respectively. The receiving cavity is disposed on the substrate. The length of the receiving cavity is 16 μm to 24 μm, the width is 16 μm to 24 μm, and the depth is 4 μm to 12 μm. Both interdigitated electrodes are disposed on the substrate and are arranged on opposite sides of the receiving cavity. The interdigitated electrodes comprise n signal transceiver segments connected together, where n ≥ 2. The n signal transceiver segments are arranged sequentially along a direction away from the receiving cavity. The interdigitated widths of the n signal transceiver segments are not equal.

[0014] Preferably, the cavity is formed by etching the substrate.

[0015] Preferably, along the direction away from the receiving cavity, the interdigital width of the n signal transceiver segments on the same interdigital electrode increases sequentially.

[0016] Preferably, the number of signal transceiver segments, n, is equal to 4; the number of electrode pairs in the four signal transceiver segments is 10, 10, 16, and 16 respectively. The interdigitation widths of the four signal transceiver segments are 4μm, 4.44μm, 5μm, and 5.7μm respectively.

[0017] The beneficial effects of this invention are:

[0018] 1. This invention introduces a surface wave sensor into the measurement of Young's modulus of micromaterials. By utilizing the phase difference corresponding to different frequencies between two interdigitated electrodes, the Young's modulus of micromaterials is accurately obtained, thereby realizing quantitative analysis of micromaterials.

[0019] 2. The present invention sets multiple signal transceiver segments with different resonant frequencies on the interdigitated electrodes of the surface wave sensor, thereby efficiently converting electrical signals of different frequencies into surface acoustic wave signals, and thus obtaining phase difference parameters of multiple frequency bands, improving the accuracy of the Young's modulus of the obtained micromaterials. Attached Figure Description

[0020] Figure 1a A schematic diagram of the overall structure of the surface acoustic wave sensor provided by the present invention;

[0021] Figure 1bThis is a schematic diagram of the partial structure of the cavity containing the surface acoustic wave sensor provided by the present invention;

[0022] Figure 2a This is a diagram of the time-domain excitation signal applied to the interdigital electrodes, which serve as input electrodes, in this invention.

[0023] Figure 2b This is a time-domain received signal diagram of the interdigitated electrode output terminal, which serves as the output electrode in this invention.

[0024] Figure 3a for Figure 2a The real-time phase shift diagram of the corresponding time-domain excitation signal;

[0025] Figure 3b for Figure 2b The real-time phase shift diagram of the corresponding time-domain received signal;

[0026] Figure 4 Real-time phase difference diagram of time-domain excitation signals and time-domain received signals at different frequencies;

[0027] Figure 5 The S21 parameter curve of the surface acoustic wave sensor provided by the present invention;

[0028] Figure 6 The graph showing the relationship between the absolute phase and Young's modulus extracted at multiple frequencies for the surface acoustic wave sensor provided by this invention. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings.

[0030] Example 1

[0031] like Figure 1a and 1b As shown, a multi-band surface acoustic wave (SAW) sensor includes a substrate 1, a receiving cavity 2, and two interdigitated electrodes serving as input and output electrodes, respectively. The receiving cavity 2 is located in the middle of the substrate 1. The receiving cavity 2 is formed by etching the substrate 1. The length of the receiving cavity 2 is 16 μm to 24 μm, the width is 16 μm to 24 μm, and the depth is 4 μm to 12 μm. The small size of the receiving cavity 2 allows it to capture minute materials, such as cells and solutions. When a SAW wave passes through the receiving cavity 2, the difference in material between the receiving cavity 2 and the substrate 1 causes changes in the speed and propagation angle of the sound wave, resulting in changes in the phase characteristics of the electrical signal received by the interdigitated electrodes 3 at the receiving end.

[0032] Two interdigitated electrodes 3 are disposed on the substrate 1 and symmetrically arranged on both sides of the receiving cavity 2. The interdigitated electrodes 3 are divided into four signal transceiver segments connected together. The four signal transceiver segments are arranged sequentially along the direction away from the receiving cavity 2, and the interdigitation width increases sequentially. The number of electrode pairs in the four signal transceiver segments are 10, 10, 16, and 16, respectively. The interdigitation widths of the four signal transceiver segments are 4μm, 4.44μm, 5μm, and 5.7μm, respectively. Under these dimensions, the resonant frequencies of the four signal transceiver segments are 200MHz, 180MHz, 160MHz, and 140MHz, respectively.

[0033] The four signal transceiver segments are designated as first signal transceiver segment 3-1, second signal transceiver segment 3-2, third signal transceiver segment 3-3, and fourth signal transceiver segment 3-4; the S21 parameters of the surface acoustic wave sensor provided in this embodiment are as follows: Figure 5 As shown.

[0034] During detection, the micromaterial or cell to be detected is placed in the receiving cavity 2. A time-domain electrical signal, obtained by superimposing sinusoidal signals with input frequencies of 200MHz, 180MHz, 160MHz, and 140MHz, is applied to the interdigitated electrodes 3, which serve as input electrodes. This time-domain electrical signal is as follows: Figure 2a As shown, the actual phase shift is as follows: Figure 3a As shown, the time-domain electrical signal, under the influence of the inverse piezoelectric effect, is converted into the deformation of the substrate 1 material, specifically manifested as the propagation of surface acoustic waves (SAWs) and bulk acoustic waves within the substrate 1 material. The bulk acoustic waves dissipate within the substrate 1 material. The SAWs propagate on the surface of the substrate 1 and are transmitted to the interdigital electrode 3, which serves as the output electrode. The piezoelectric effect converts the deformation into an electrical signal, which is received and output by the interdigital electrode 3. After the time-domain electrical signal obtained by superimposing sinusoidal signals of 200MHz, 180MHz, 160MHz, and 140MHz is applied, the interdigital electrode 3 receives modulation signals of four frequencies. The modulation signals received by the output electrode are as follows: Figure 2b As shown, the actual phase shift is as follows: Figure 3b As shown.

[0035] The time at which the maximum signal first appears is different for each frequency signal; the arrival time T of each frequency signal is calculated as follows:

[0036] T=cavW / V0+(2·L1+L2+gap-cavW) / V1

[0037] Where gap is the distance between the delay lines at the midpoint of the two interdigitated electrodes 3; L1 is the sum of the interdigitated widths of the interdigitated electrodes at frequencies other than the calculated frequency in the direction of surface acoustic wave propagation; L2 is the interdigitated width of the signal transceiver segment corresponding to the measured frequency signal; V0 is the propagation speed of the surface acoustic wave in the cavity 2, and V1 is the propagation speed of the surface acoustic wave in the substrate 1. Therefore, it can be seen that the material of the cavity 2 affects the signal propagation time, thereby changing the phase of the electrical signal received at the output end.

[0038] In this embodiment, the phase differences between the input and output signals at the four frequencies are as follows: Figure 4 As shown, four sinusoidal signals with frequencies of 200MHz, 180MHz, 160MHz, and 140MHz have sinusoidal phase differences of 101.7°, 68.07°, 139.89°, and -191.544° between the input and output electrodes, respectively. It can be seen that the phase difference increases with increasing frequency.

[0039] Example 2

[0040] A multi-band surface acoustic wave sensor is disclosed in this embodiment, which differs from Embodiment 1 in that the interdigitated electrode 3 is divided into five interconnected signal transceiver segments. The resonant frequencies of the five signal transceiver segments are adjusted to be 200MHz, 190MHz, 180MHz, 160MHz, and 140MHz, respectively, by adjusting the width of the interdigitated electrodes.

[0041] Materials with different Young's moduli were placed in the receiving cavity, and the phase difference between the two interdigitated electrodes 3 was measured when sinusoidal signals of 200MHz, 190MHz, 180MHz, 160MHz, and 140MHz were input. For the relationship between the phase difference and Young's modulus corresponding to the sinusoidal signal at each frequency, a relationship curve was fitted, and the results are shown below. Figure 6 As shown.

[0042] When measuring the Young's modulus of a small material, the material to be measured is placed in a receiving cavity. A modulated signal, consisting of superimposed sinusoidal signals of 200MHz, 190MHz, 180MHz, 160MHz, and 140MHz, is input to one of the interdigital electrodes 3; the received signal is acquired from the other interdigital electrode 3. The phase differences between the input modulated signal and the received signal corresponding to the 200MHz, 190MHz, 180MHz, 160MHz, and 140MHz sinusoidal signals are extracted. The five phase differences are then substituted into the corresponding frequency relationship curves to obtain the Young's modulus.

[0043] The average of the five Young's moduli is taken as the Young's modulus of the material being tested. Alternatively, the final Young's modulus of the material can be selected or calculated from the five Young's moduli using other methods. Therefore, this invention can accurately obtain the Young's modulus of minute materials using surface acoustic waves.

Claims

1. A method for analyzing micromaterials, characterized by: The surface acoustic wave (SAW) sensor is used for analysis. The SAW sensor includes a substrate (1), a cavity (2), and two interdigitated electrodes (3) that serve as input and output electrodes, respectively. The cavity (2) is disposed on the substrate (1). The two interdigitated electrodes (3) are disposed on the substrate (1) and are arranged on both sides of the cavity (2). The interdigitated electrodes (3) include n signal transceiver segments with different interdigit widths, where n≥2. This method for analyzing tiny materials includes the following steps: Step 1: Place the material to be tested in the receiving cavity (2); Step 2: Apply a modulation signal to one of the interdigital electrodes (3); the modulation signal is obtained by superimposing n sinusoidal signals of different frequencies; the frequencies of the n sinusoidal signals are the same as the resonant frequencies of the n signal transceiver segments on the interdigital electrode (3); collect the received signal of the other interdigital electrode (3); extract the phase difference between the n sinusoidal signals of different frequencies between the modulation signal and the received signal. Step 3: Substitute the n phase differences obtained in Step 2 into the phase difference-Young's modulus relationship curves corresponding to different frequencies to obtain n Young's modulus estimates; determine the deformation resistance of the tested material based on the n Young's modulus estimates.

2. The method for analyzing micromaterials according to claim 1, characterized in that: In step three, the average of the n Young's modulus estimates is taken as the measured Young's modulus of the material being tested.

3. The method for analyzing micromaterials according to claim 1, characterized in that: The phase difference-Young's modulus relationship curves corresponding to different frequencies were obtained by calibrating the surface acoustic wave sensor using a variety of materials with known Young's modulus.

4. The method for analyzing micromaterials according to claim 1, characterized in that: The n signal transceiver pairs are arranged sequentially along the direction away from the receiving cavity (2).

5. The method for analyzing micromaterials according to claim 1, characterized in that: The length of the receiving cavity (2) is 16μm to 24μm, the width is 16μm to 24μm, and the depth is 4μm to 12μm.

6. A multi-band surface acoustic wave sensor, characterized in that: The method for performing a micromaterial analysis according to claim 1 is used; the length of the cavity (2) is 16μm to 24μm, the width is 16μm to 24μm, and the depth is 4μm to 12μm; the interdigitated electrode (3) includes n signal transceiver segments connected together, n≥2; the n signal transceiver segments are arranged sequentially along the direction away from the cavity (2).

7. A multi-band surface acoustic wave sensor according to claim 1, characterized in that: The cavity (2) is formed by etching the substrate (1).

8. A multi-band surface acoustic wave sensor according to claim 1, characterized in that: Along the direction away from the receiving cavity (2), the interdigital width of the n signal transceiver segments on the same interdigital electrode (3) increases sequentially.

9. A multi-band surface acoustic wave sensor according to claim 1, characterized in that: The number of signal transceiver segments, n, is equal to 4; the number of electrode pairs in the four signal transceiver segments is 10, 10, 16, and 16 respectively; and the interdigitation widths of the four signal transceiver segments are 4μm, 4.44μm, 5μm, and 5.7μm respectively.

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