A saturation current response calibration test method for silicon nanowire sensors

Abstract

This invention provides a calibration method for the saturation current response of a silicon nanowire sensor. The method normalizes the current response value of a standard solution using the saturation value of the silicon nanowire sensor, establishing a standard response curve for the silicon nanowire sensor to a solution containing the target analyte. The current response values ​​of the target sample and the calibration solution are obtained through testing. Based on the calibrated standard response curve, the concentration of the target sample is determined. The calibration results are stable, exhibit good repeatability, and the calibration process is convenient. Compared to other calibration methods, calibration using the current response saturation value does not rely on expensive equipment, and the calibration process is simple and cost-effective. Furthermore, the calibration process does not damage the silicon nanowire sensor itself and does not affect its performance.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a saturation current response calibration test method for silicon nanowire sensors. Background Technology

[0002] Silicon nanowires are fabricated using silicon as the basic material. Sensors using silicon nanowires as sensing elements have advantages such as low cost, high sensitivity, and excellent electrical and mechanical properties. Therefore, silicon nanowire sensors have attracted much attention from researchers since their inception. Currently, there are various techniques for fabricating silicon nanowires, such as metal-assisted chemical etching, chemical vapor deposition, thermal vapor deposition, and self-confined oxidation. Among these, silicon nanowires fabricated using the top-down self-confined oxidation process have advantages such as low equipment precision requirements, high production efficiency, and good uniformity. Silicon nanowire sensors based on this process have significant advantages in terms of both cost and sensitivity.

[0003] However, when silicon nanowires are prepared using the self-limiting oxidation process, on the one hand, the poor uniformity within the wafer during the manufacturing process causes differences in the size of silicon nanowires at different locations on the wafer; on the other hand, the modification effects of different silicon nanowire sensors vary when modifying silicon nanowires with groups and probes, resulting in differences in the response of silicon nanowire sensors to the same concentration of target solution. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a saturation current response calibration test method for silicon nanowire sensors, which solves the problem in the prior art of how to make different silicon nanowire sensors produce the same test results for the same concentration of target solution.

[0005] To achieve the above and other related objectives, the present invention provides a calibration test method for the saturation current response of a silicon nanowire sensor, the calibration test method comprising the following steps:

[0006] Surface modification of silicon nanowire sensors;

[0007] Obtain the current response value of the modified silicon nanowire sensor under predetermined test conditions in a standard solution containing a certain preset proportion of target material, and determine the current response saturation value based on the current response value;

[0008] The current response value of the silicon nanowire sensor is normalized based on the current response saturation value, and the normalization result is fitted to determine the target object response standard curve.

[0009] Based on the target analyte response standard curve, the concentration of the test sample corresponding to the current response value of the test sample is determined.

[0010] Optionally, the surface modification of the silicon nanowire sensor may include any one or more of hydroxyl, amino, aldehyde, carboxyl, nucleic acid, or protein groups.

[0011] Optionally, the predetermined test conditions include any one or more of the following: preset source-drain voltage for testing, preset light intensity for testing, preset ambient temperature for testing, and preset ambient humidity for testing.

[0012] Optionally, the preset source-drain voltage for the test is 0–5V, and the preset light intensity for the test is 0–100W / m. 2 The preset ambient temperature for the test is 0 to 30°C, and the preset ambient humidity for the test is 20% to 100%.

[0013] Optionally, the step of determining the current response saturation value includes:

[0014] Determine the pre-determined test conditions;

[0015] The current value I1 of the silicon nanowire sensor in a reference solution was obtained through testing.

[0016] The current value I2 of the silicon nanowire sensor in a standard solution containing a certain preset proportion of the target substance was obtained by testing.

[0017] Calculate the current response value of the silicon nanowire sensor in the standard solution, wherein the calculation formula is S(c)=I2-I1, and S(c) is the current response value of the silicon nanowire sensor in the standard solution;

[0018] When the current response value of the silicon nanowire sensor in the standard solution no longer changes with the increase of the target substance concentration in the standard solution, the current response value of the silicon nanowire sensor in the standard solution at this time is the current response saturation value S of the silicon nanowire sensor. max .

[0019] Optionally, the reference solution is a solution that does not contain the target substance.

[0020] Optionally, the preset proportion of the target substance in the standard solution containing a certain preset proportion of the target substance varies in a gradient increasing manner.

[0021] Optionally, the process of normalizing the current response value of the silicon nanowire sensor includes: dividing the current response value S(c) of the silicon nanowire sensor in a standard solution containing a certain preset proportion of the target substance by the current response saturation value S. max ,Right now Wherein, S′(c) is the current response value of the silicon nanowire sensor after normalization.

[0022] Optionally, the step of determining the target object's response standard curve includes: fitting the normalized current response value S′(c) of the silicon nanowire sensor, wherein the function used for fitting includes at least: or One of them.

[0023] Optionally, the step of determining the concentration of the test sample corresponding to the current response value of the test sample includes: sequentially acquiring the current response value of the test sample and the current response value of the calibration solution, normalizing the current response value of the test sample based on the current response value of the calibration solution, and substituting the normalized current response value of the test sample into the target analyte response standard curve to obtain the concentration of the test sample corresponding to the current response value of the test sample.

[0024] As described above, the saturation current response calibration method for the silicon nanowire sensor of the present invention has the following advantages: The present invention utilizes the current response saturation value of the silicon nanowire sensor to normalize the current response value of the standard solution, establishing a response standard curve of the silicon nanowire sensor to a solution containing the target analyte. The current response values ​​of the required test sample and calibration solution are obtained through testing. Based on the calibrated response standard curve, the corresponding concentration of the test sample is determined. The calibration test results are stable, have good repeatability, and the calibration test process is convenient. Compared with other calibration methods, calibration using the current response saturation value does not rely on expensive equipment, the calibration process is simple, and the calibration cost is low. Furthermore, the calibration process does not damage the silicon nanowire sensor itself and does not affect its performance. Attached Figure Description

[0025] Figure 1 The diagram shows a flowchart of a saturated current response calibration test method for a silicon nanowire sensor according to the present invention.

[0026] Figure 2 The graph shows the current response curve of the silicon nanowire sensor in the standard solution in the calibration test method of this invention.

[0027] Figure 3 The figure shown is a current response curve after normalizing the current response value of the silicon nanowire sensor according to the present invention.

[0028] Figure 4 The diagram shown is a schematic representation of the target object's response standard curve according to the present invention. Detailed Implementation

[0029] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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. To solve the problems existing in the prior art, the present invention provides a saturation current response calibration test method for silicon nanowire sensors, such as... Figure 1 As shown, the method includes:

[0031] S1: Surface modification of silicon nanowire sensors;

[0032] Specifically, the present invention aims to calibrate the current response value of a target substance using the current response value of a silicon nanowire sensor, thereby obtaining a target substance response standard curve that can be used to test and obtain the concentration of the sample to be tested.

[0033] It is understood that the current response of the silicon nanowire sensor described in this specification is as follows: when the output signal of the silicon nanowire is stable, changing the concentration of the standard solution of the silicon nanowire sensor will also change the current response value. This change in the current response value caused by the change in concentration is called the current response of the silicon nanowire sensor.

[0034] Furthermore, in order to achieve highly specific detection of the target, the silicon nanowire sensor needs to be surface modified when performing current response testing. The surface modification targets include any one or more of hydroxyl, amino, aldehyde, carboxyl, nucleic acid or protein groups, and they must be modified one by one in a certain order.

[0035] In one feasible approach, the surface modification process for the silicon nanowire sensor is as follows:

[0036] The surface of the silicon nanowire sensor is treated with oxygen plasma for 5–15 minutes to modify the hydroxyl groups. The modified silicon nanowire sensor is then immersed in a 2% APTES ethanol solution for 8–24 hours to modify the amino groups. Finally, the probe modifier solution is dropped onto the surface of the silicon nanowire sensor and immersed for 1–5 hours to complete the modification of the probe.

[0037] It is understood that the above-described process for surface modification of silicon nanowire sensors is only one method. In other feasible solutions, other methods can also be used to modify the surface of the silicon nanowire sensors. In specific experiments, the specific method can be selected based on the laboratory materials, and no limitation is made here.

[0038] S2: Obtain the current response value of the modified silicon nanowire sensor under predetermined test conditions in a standard solution containing a certain preset proportion of target material, and determine the current response saturation value based on the current response value.

[0039] Specifically, obtaining the current response value of the modified silicon nanowire sensor in a standard solution containing a certain preset proportion of the target substance under a predetermined test environment and determining the current response saturation value based on the current response value includes:

[0040] S21: Determine the predetermined test conditions;

[0041] It is understood that the predetermined test conditions include any one or more of the following: preset source-drain voltage for testing, preset light intensity for testing, preset ambient temperature for testing, and preset ambient humidity for testing. The preset source-drain voltage for testing is 0–5V, for example, 0, 2V, 4V, or 5V; the preset light intensity for testing is 0–100W / m². 2 For example, 0.50W / m 2 Or 100W / m 2 The preset ambient temperature for the test is 0–30°C, for example, 0, 15°C, or 30°C; the preset ambient humidity for the test is 20%–100%, for example, 20%, 60%, or 100%. In specific experiments, these settings can be adjusted according to actual needs and the surrounding environment; no specific limitations are imposed here.

[0042] S22: Test and obtain the current value I1 of the silicon nanowire sensor in the reference solution;

[0043] It is understood that the reference solution is a solution that does not contain the target substance. The reference solution includes PBS buffer solution. The current value of the silicon nanowire sensor in the PBS buffer solution is obtained by testing. This current value is I1. In specific experiments, the reference solution can be set according to actual needs. Here, there is no limitation on this.

[0044] S23: Test and obtain the current value I2 of the silicon nanowire sensor in a standard solution containing a certain preset proportion of target material;

[0045] Understandably, in order to facilitate the determination of the current response variation of silicon nanowire sensors in standard solutions containing different preset proportions of target substances, certain variation rules can be set for the content of target substances in the standard solution. For example, in a standard solution containing a certain preset proportion of target substances, the preset proportion of target substances can be varied in a gradient-increasing manner, thereby forming a certain variation pattern.

[0046] In one feasible approach, the variation rule can be to gradually increase the preset proportion of the target substance in the standard solution. For example, the initial concentration of the target substance in the standard solution is 10 aM, the initial concentration of the target substance in the standard solution is 100 pM, and the gradient change is 10 times that of the previous concentration. The current I2 of the silicon nanowire sensor in the standard solution is then tested.

[0047] S24: Calculate the current response value of the silicon nanowire sensor in the standard solution, wherein the calculation formula is S(c)=I2-I1, and S(c) is the current response value of the silicon nanowire sensor in the standard solution;

[0048] Specifically, according to steps S22 and S23, the current response value of the silicon nanowire sensor in standard solutions with different target contents is calculated using the formula S(c)=I2-I1.

[0049] S25: When the current response value of the silicon nanowire sensor in the standard solution no longer changes with the increase of the target substance concentration in the standard solution, the current response value of the silicon nanowire sensor in the standard solution at this time is the current response saturation value S of the silicon nanowire sensor. max .

[0050] Understandably, when performing step S25, it is necessary to determine whether the current response value of the silicon nanowire sensor in the standard solution will still change with the increase of the target substance concentration in the standard solution. When the current response value of the silicon nanowire sensor in the standard solution no longer changes with the increase of the target substance concentration, the change of the target substance concentration in the standard solution is stopped, and the current response saturation value S of the silicon nanowire sensor is determined. max .

[0051] S3: Normalize the current response value of the silicon nanowire sensor based on the current response saturation value and fit the normalization result to determine the target object response standard curve.

[0052] Specifically, the process of normalizing the current response value of the silicon nanowire sensor in step S3 includes: based on the current response saturation value S of the silicon nanowire sensor determined in step S25... max In step S24, the current response value S(c) of the silicon nanowire sensor in standard solutions with different target analyte concentrations is obtained, and the current response value S(c) is divided by the current response saturation value S. max ,Right now S′(c) is the current response value of the silicon nanowire sensor after normalization.

[0053] It is understandable that the functions used to fit the normalized current response values ​​to determine the target object's response standard curve include at least the following: or One of them, in specific experiments, can be selected according to the actual fitting needs, and there is no limitation on it here.

[0054] S4: Based on the target analyte response standard curve, determine the concentration of the test sample corresponding to the current response value of the test sample.

[0055] Specifically, after determining the target analyte response standard curve, the current response values ​​of the test sample and the calibration solution are obtained sequentially. The current response value of the test sample is then normalized based on the current response value of the calibration solution. The calibration solution is defined as a solution containing a target analyte concentration sufficient to saturate the current response. The normalization steps have been described above and will not be repeated here. The normalized current response value of the test sample is then substituted into the target analyte response standard curve to obtain the concentration of the test sample corresponding to the current response value of the test sample.

[0056] In one embodiment, to calibrate the saturation current response of a silicon nanowire sensor targeting nucleic acid, the following experiment is designed:

[0057] Four silicon nanowire sensors (named First Silicon Nanowire Sensor, Second Silicon Nanowire Sensor, Third Silicon Nanowire Sensor, and Fourth Silicon Nanowire Sensor, respectively) were selected, and their surfaces were modified. The specific surface modification methods have been described above and will not be repeated here.

[0058] Modified first, second, and third silicon nanowire sensors were used. A source-drain voltage of 0.4V was applied in a dark environment at room temperature. 0.01 times the volume of PBS buffer solution was added to the sensor surface. The current values ​​I1 of the first, second, and third silicon nanowire sensors in the standard solution were measured. Standard solutions of 10aM, 100aM, 1fM, 10fM, 100fM, 1pM, 10pM, and 100pM were added to the surfaces of the first, second, and third silicon nanowire sensors in ascending order of nucleic acid concentration. The current values ​​I2 of the first, second, and third silicon nanowire sensors in standard solutions of different nucleic acid concentrations were measured. The current response values ​​S(c) of the first, second, and third silicon nanowire sensors in standard solutions of different nucleic acid concentrations were calculated, and the results are as follows: Figure 1 As shown.

[0059] like Figure 1 As shown, in a nucleic acid standard solution with a nucleic acid concentration of 100 pM, the current response values ​​S(c) of the first, second, and third silicon nanowire sensors no longer change with the nucleic acid concentration in the standard solution. Therefore, the saturation current response values ​​S of the first, second, and third silicon nanowire sensors can be determined. max1 S max2 S max3 .

[0060] The current response values ​​of the first, second, and third silicon nanowire sensors in standard solutions with different nucleic acid concentrations were normalized. The normalized current response values ​​of the first, second, and third silicon nanowire sensors in standard solutions are: the current response value S(c) of the first silicon nanowire sensor in standard solutions with different nucleic acid concentrations divided by the saturation current response value S of the first silicon nanowire sensor. max1 The current response value S(c) of the second silicon nanowire sensor under standard solutions of different nucleic acid concentrations is divided by the saturation current response value S of the second silicon nanowire sensor. max2 The current response value S(c) of the third silicon nanowire sensor under standard solutions of different nucleic acid concentrations is divided by the saturation current response value S of the third silicon nanowire sensor. max3 The result is as follows Figure 2 As shown.

[0061] The normalized results of the first, second, and third silicon nanowire sensors were fitted using the following function: Thus, we can obtain the following: Figure 3 The standard curve of nucleic acid response is shown.

[0062] A fourth silicon nanowire sensor was also tested. First, 0.01 times the volume of PBS buffer solution was added to the surface of the fourth silicon nanowire sensor. The current I1 of the fourth silicon nanowire sensor in the reference solution was measured to be 3.027 × 10⁻⁶. -10 A. Secondly, the solution containing the sample to be tested is dropped onto the surface of the fourth silicon nanowire sensor to measure I. 1，test =4.171×10 -10 A, then, a standard solution containing 100 pM nucleic acid was added dropwise to the surface of the fourth silicon nanowire sensor to measure I. 1，100pM =4.41910 -10 A, the current response S(c) of the sample under test is obtained by calculation. test ) = I 1，test -I1=1.144×10 -10 A, its saturation current response S max =I 1，100pM -I1=1.392×10 -10 A.

[0063] Current response S(c) of the sample under test test The current response of the sample after normalization is then normalized. Substituting the normalized current response of the sample to be tested, 0.822, into the standard curve f(c) of the nucleic acid response, we can obtain the nucleic acid concentration in the sample to be tested as 31.8fM.

[0064] In summary, the saturation current response calibration method for a silicon nanowire sensor of the present invention normalizes the current response value of a standard solution using the current response saturation value of the silicon nanowire sensor, establishing a response standard curve of the silicon nanowire sensor to a solution containing the target analyte. The current response value of the desired test sample is obtained through testing, and the corresponding concentration of the test sample is determined based on the calibrated response standard curve. The calibration test results are stable, exhibit good repeatability, and the calibration process is convenient. Compared to other calibration methods, calibration using the current response saturation value does not rely on expensive equipment, the calibration process is simple, and the calibration cost is low. Furthermore, the calibration process does not damage the silicon nanowire sensor itself and does not affect its performance. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for calibrating the saturated current response of a silicon nanowire sensor, comprising: The calibration test method comprises the following steps: surface modification of the silicon nanowire sensor; determining predetermined test conditions, the predetermined test conditions comprising any one or more of a preset source-drain voltage for testing, a preset light intensity for testing, a preset ambient temperature for testing, and a preset ambient humidity for testing; testing to obtain a current value I1 of the silicon nanowire sensor in a reference solution, the reference solution being a solution containing no target object; testing to obtain a current value I2 of the silicon nanowire sensor in a standard solution containing a preset proportion of target object; calculating the current response value of the silicon nanowire sensor in the standard solution, wherein the calculation formula is S(c) = I2-I1, S(c) being the current response value of the silicon nanowire sensor in the standard solution; When the current response value of the silicon nanowire sensor in the standard solution no longer changes with the increase of the target object concentration in the standard solution, the current response value of the silicon nanowire sensor in the standard solution at this time is the current response saturation value S of the silicon nanowire sensor max ; normalizing the current response value of the silicon nanowire sensor based on the current response saturation value and fitting the normalized result to determine a target object response standard curve; sequentially obtaining the current response value of the sample to be tested and the current response value of the calibration solution, and normalizing the current response value of the sample to be tested based on the current response value of the calibration solution, the calibration solution being defined as a solution containing a target object concentration capable of saturating the current response, and the normalized current response value of the sample to be tested being substituted into the target object response standard curve to obtain the concentration of the sample to be tested corresponding to the current response value of the sample to be tested.

2. The calibration test method of claim 1, wherein, The surface modification of the silicon nanowire sensor comprises any one or more of hydroxyl, amino, aldehyde, carboxyl, nucleic acid or protein.

3. The calibration test method of claim 1, wherein, The preset source-drain voltage for the test is 0-5V, the preset light intensity for the test is 0-100W / m 2 , the preset environment temperature for the test is 0-30℃, and the preset environment humidity for the test is 20%-100%.

4. The calibration test method of claim 1, wherein: The reference solution is a solution containing no target object.

5. The calibration test method of claim 1, wherein: The preset proportion of target object in the standard solution containing a preset proportion of target object varies in a gradient increasing manner.

6. The calibration test method of claim 1, wherein: The process of normalizing the current response value of the silicon nanowire sensor includes: dividing the current response value S(c) of the silicon nanowire sensor in a standard solution containing a preset proportion of target objects by the current response saturation value S max That is Wherein, S'(c) is the current response value of the silicon nanowire sensor after normalization processing.

7. The calibration test method of claim 1, wherein, The step of determining the target response standard curve comprises fitting the normalized current response value S'(c) of the current response value of the silicon nanowire sensor, wherein the function used in the fitting at least includes: or one of

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