Threshold voltage calibration and quantitative testing method of silicon nanowire sensor

Abstract

The application provides a threshold voltage calibration and quantitative test method of a silicon nanowire sensor, the threshold voltage response of a target object is normalized by using the change amount of the threshold voltage before and after the surface probe modification of the silicon nanowire sensor, the standard curve of the target object response is determined, and the concentration of the target object corresponding to the threshold voltage response of the target object is obtained; the consistency of the test results before and after the threshold voltage calibration is significantly improved, the repeatability is good, the calibration process does not need additional equipment, the calibration process and the test process can use the same equipment, the cost is effectively saved, the calibration process is lossless to the silicon nanowire sensor, and the subsequent test of the silicon nanowire sensor is not affected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a threshold voltage calibration and quantitative test method of a silicon nanowire sensor. BACKGROUND

[0002] The silicon nanowire sensor has the advantages of low cost, high sensitivity, excellent electrical and mechanical properties, and has been the focus of researchers since its inception. The silicon nanowire obtained by the self-limiting oxidation process from top to bottom has the advantages of low equipment precision requirement, high production efficiency and good uniformity. The silicon nanowire sensor prepared has significant advantages in cost and sensitivity. However, the response of the prepared silicon nanowire sensor to the same concentration of target solution is different. On the one hand, the in-die uniformity of different silicon nanowire sensors is poor during the manufacturing process, and the diameters of the silicon nanowires at different positions of the wafer are different. On the other hand, the modification effect of different silicon nanowire sensors is different when the groups and probes are modified on the silicon nanowire, which is specifically manifested as the difference in the areal density of the modified groups and probes. Therefore, the response of the silicon nanowire sensor to the target solution needs to be calibrated, so that the test results of different silicon nanowire sensors to the same concentration of target solution are the same after calibration.

[0003] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely describing the technical scheme of the present application and for the convenience of understanding by those skilled in the art. The above technical scheme cannot be considered as known to those skilled in the art only because it is described in the background section of the present application.

[0004] In view of the above, it is necessary to provide a threshold voltage calibration and quantitative test method of a silicon nanowire sensor to solve the difficulties and technical problems faced in the prior art. SUMMARY

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a threshold voltage calibration and quantitative test method of a silicon nanowire sensor to solve the difficulties and technical problems faced in the prior art.

[0006] To achieve the above-mentioned purpose and other related purposes, the present application provides a threshold voltage calibration and quantitative test method of a silicon nanowire sensor, which comprises:

[0007] S11: modifying probes on the surface of the silicon nanowire sensor, and obtaining the threshold voltage change amount before and after the probe modification on the surface of the silicon nanowire sensor;

[0008] S12: obtaining a threshold voltage response of the modified silicon nanowire sensor to the target object under different concentrations of standard solutions;

[0009] S13: based on the threshold voltage change amount of the silicon nanowire sensor surface probe before and after modification, normalizing the threshold voltage response of the target object, and determining the target object response standard curve;

[0010] S14: based on the target object response standard curve, determining the concentration of the target object corresponding to the threshold voltage response of the target object. Optionally, the method for obtaining the threshold voltage change amount of the silicon nanowire sensor surface probe before and after modification comprises:

[0011] S21: modifying a probe connecting group on the surface of the silicon nanowire sensor;

[0012] S22: obtaining the threshold voltage V th，1 of the silicon nanowire sensor surface probe before modification;

[0013] S23: modifying the probe corresponding to the target object on the surface of the silicon nanowire sensor;

[0014] S24: obtaining the threshold voltage V th，2 of the silicon nanowire sensor surface probe after modification;

[0015] S25: based on the threshold voltage of the silicon nanowire sensor surface probe before and after modification, obtaining the threshold voltage change amount ΔV th，probe = V th，2 -V th，1 of the silicon nanowire sensor surface probe before and after modification;

[0016] S26: using a blocking agent to block the remaining probe connecting group on the surface of the silicon nanowire sensor.

[0017] Optionally, the method for obtaining the threshold voltage comprises: under a preset source-drain voltage, scanning the gate voltage of the silicon nanowire sensor to obtain the transfer characteristic curve of the silicon nanowire sensor, and the gate voltage corresponding to the preset current based on the transfer characteristic curve is the threshold voltage.

[0018] Optionally, the probe connecting group comprises any one or a combination of two or more of a hydroxyl group, an amino group, an aldehyde group and a carboxyl group.

[0019] Optionally, the blocking agent comprises any one or a combination of two or more of bovine serum albumin, casein, ethanolamine and Tween.

[0020] Optionally, the method for obtaining the threshold voltage response of the target object of the modified silicon nanowire sensor under different concentrations of standard solutions comprises the following steps:

[0021] S31: obtaining the threshold voltage V of the silicon nanowire sensor under a reference solution th，3 ;

[0022] S32: obtaining the threshold voltage V of the silicon nanowire sensor under standard solutions from low concentration to high concentration th，4 ;

[0023] S33: obtaining the threshold voltage response S(c) = V of the silicon nanowire sensor under standard solutions from low concentration to high concentration th，4 -V th，3 .

[0024] Optionally, the reference solution is a solution without the target object, and the standard solution is a solution containing a preset proportion of the target object.

[0025] Optionally, the normalization processing is that the threshold voltage response S(c) of the silicon nanowire sensor under standard solutions from low concentration to high concentration is divided by the threshold voltage change ΔV before and after the surface probe modification of the silicon nanowire sensor th，probe , that is

[0026] Optionally, the determination of the target object response standard curve comprises: fitting the threshold voltage response S'(c) of the target object after the normalization processing of the silicon nanowire sensor, so as to obtain the target object response standard curve f(c).

[0027] Optionally, the function for fitting the threshold voltage response S'(c) comprises: y = ax, y = ax b and

[0028] As described above, the threshold voltage calibration and quantitative test method of the silicon nanowire sensor has the following beneficial effects:

[0029] The present application utilizes the threshold voltage change before and after the surface probe modification of the silicon nanowire sensor to normalize the threshold voltage response of the target object, determines the target object response standard curve, and obtains the concentration of the target object corresponding to the threshold voltage response of the target object; the consistency of the test results before and after the threshold voltage calibration is significantly improved, the repeatability is good, the calibration process does not require additional equipment, the calibration process and the test process can use the same equipment, the cost is effectively saved, the calibration process is lossless to the silicon nanowire sensor, and the subsequent test of the silicon nanowire sensor is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A flow chart showing the threshold voltage calibration and quantitative test method of the silicon nanowire sensor of the present application.

[0031] Figure 2 A flow chart showing the method of obtaining the threshold voltage variation of the silicon nanowire sensor of the present application before and after surface probe modification.

[0032] Figure 3 A flow chart showing the method of obtaining the threshold voltage response of the modified silicon nanowire sensor of the present application to the target substance under different concentrations of standard solution.

[0033] Figure 4 A threshold voltage response graph of the standard solution of the present application.

[0034] Figure 5 A threshold voltage response graph of the normalized standard solution of the present application.

[0035] Figure 6 A target substance response standard curve graph of the present application.

[0036] Figure 7 A test data table of the present application.

[0037] Element number explanation

[0038] S11-S14, S21-S26, S31-S33 steps DETAILED DESCRIPTION

[0039] The present application will be described in detail below with specific reference being made to certain embodiments thereof. The advantages and effects of the present application can be easily understood by those skilled in the art from the contents disclosed in the present specification. The present application can also be implemented or applied in other different embodiments, and the details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.

[0040] As described in the detailed description of the embodiments of the present application, the cross-sectional view showing the device structure can be partially enlarged without the general scale for the convenience of explanation, and the schematic view is only an example, which should not limit the scope of protection of the present application herein.

[0041] For convenience in description, spatially relative terms such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a layer overlies another layer, it can be the case that the layer is the only layer between the two layers or that intervening layers exist. As used herein, "between" is intended to encompass both endpoints.

[0042] In the context of this application, a structure described as having a first feature "on" a second feature can include embodiments in which the first and second features are formed in direct contact, as well as embodiments in which additional features are formed between the first and second features, such that the first and second features can not be in direct contact.

[0043] Referring to Figures 1 to 7 It is to be understood that the figures provided in the embodiments are only schematic and that the actual constitution of the application can deviate from the figures shown in the drawings. In the drawings, the size of the components, as well as their number and shapes, do not necessarily correspond to the size, number and shapes of the components in the actual implementation, and the layout of the components can be more complex.

[0044] Embodiment One

[0045] As shown in Figure 1 The threshold voltage calibration and quantitative test method of the silicon nanowire sensor provided by the embodiment includes:

[0046] S11: probe modification is performed on the surface of a silicon nanowire sensor, and the threshold voltage change amount before and after the probe modification on the surface of the silicon nanowire sensor is obtained;

[0047] S12: the threshold voltage response of the silicon nanowire sensor to a target object under different concentrations of standard solutions is obtained after the modification of the silicon nanowire sensor;

[0048] S13: based on the threshold voltage change amount before and after the probe modification on the surface of the silicon nanowire sensor, the threshold voltage response of the target object is normalized, and a standard curve of the target object response is determined;

[0049] S14: based on the standard curve of the target object response, the concentration of the target object corresponding to the threshold voltage response of the target object is determined.

[0050] In this embodiment, the consistency of test results before and after threshold voltage calibration is significantly improved, and the repeatability is good. The calibration process does not require additional equipment; the same equipment can be used for both calibration and testing, effectively saving costs. The calibration process is non-destructive to the silicon nanowire sensor and does not affect subsequent testing of the silicon nanowire sensor. The following detailed steps further describe this embodiment.

[0051] First, step S11 is performed to modify the surface of the silicon nanowire sensor with a probe, and the change in threshold voltage before and after probe modification of the silicon nanowire sensor surface is obtained.

[0052] like Figure 2 As shown, as an example, the method for obtaining the change in threshold voltage before and after surface probe modification of the silicon nanowire sensor includes:

[0053] S21: Modify the surface of the silicon nanowire sensor with probe linking groups;

[0054] S22: Obtain the threshold voltage V of the silicon nanowire sensor surface probe before modification. th，1 ;

[0055] S23: Modify the surface of the silicon nanowire sensor with a probe corresponding to the target object;

[0056] S24: Obtain the threshold voltage V after the probe on the surface of the silicon nanowire sensor is modified. th，2 ;

[0057] S25: Based on the threshold voltages before and after the modification of the silicon nanowire sensor surface probe, obtain the change ΔV of the threshold voltage before and after the modification of the silicon nanowire sensor surface probe. th，probe =V th，2 -V th，1 ;

[0058] S26: The remaining probe-connecting groups on the surface of the silicon nanowire sensor are sealed using a sealing agent.

[0059] As an example, the method for obtaining the threshold voltage includes: scanning the gate voltage of the silicon nanowire sensor at a preset source-drain voltage to obtain the transfer characteristic curve of the silicon nanowire sensor, and the gate voltage corresponding to the transfer characteristic curve at a preset current is the threshold voltage.

[0060] As an example, the probe linking group includes any one or a combination of two or more of hydroxyl, amino, aldehyde and carboxyl groups.

[0061] As an example, the blocking agent includes any one or a combination of two or more of bovine serum albumin, casein, ethanolamine, and Tween.

[0062] In the present embodiment, several silicon nanowire sensors with similar performance are selected, including device group 1, device group 2, device group 3, device group 4 and device group 5. The surface of the silicon nanowire sensor is modified by using an oxygen plasma device for 10 minutes to complete the modification of hydroxyl groups. The silicon nanowire sensor after modification of the hydroxyl groups is placed in a 2% APTES ethanol solution for immersion overnight to complete the modification of amino groups. The silicon nanowire sensor after modification of the amino groups is taken out, rinsed with ethanol, then dried with nitrogen, placed in a 120°C oven for baking for 15 minutes, 2.5% glutaraldehyde solution is added dropwise to the surface of the silicon nanowire sensor, and it is placed in the dark for 2 hours. Then it is rinsed with a phosphate buffer saline (PBS) solution and dried with nitrogen to complete the modification of aldehyde groups. At this point, the modification of the probe linking groups on the surface of the silicon nanowire sensor is completed.

[0063] As shown in Figure 7 , the preset source-drain voltage is -0.4V, the gate voltage of each group of silicon nanowire sensors after surface probe linking group modification is scanned, the gate voltage range is -0.5V-0.5V, and the first transfer characteristic curve of the silicon nanowire sensor is obtained. According to the first transfer characteristic curve, the gate voltage corresponding to the preset 100nA current is the threshold voltage V th，1 before probe modification.

[0064] The surface of the silicon nanowire sensor is added with 1mg / mL CD63 probe, and it is placed in the dark for 2 hours. After taking it out, it is rinsed with a PBS solution and dried with nitrogen to complete the modification of the probe on the surface of the silicon nanowire sensor.

[0065] As shown in Figure 7 , the preset source-drain voltage is -0.4V, the gate voltage of each group of silicon nanowire sensors after surface probe modification is scanned, the gate voltage range is -0.5V-0.5V, and the second transfer characteristic curve of the silicon nanowire sensor is obtained. According to the second transfer characteristic curve, the gate voltage corresponding to the preset 100nA current is the threshold voltage V th，2 after probe modification.

[0066] Based on the threshold voltages before and after the modification of the probe on the surface of the silicon nanowire sensor, the change amount ΔV th，probe of the threshold voltage of each silicon nanowire sensor before and after the modification of the probe on the surface of the silicon nanowire sensor is obtained. V th，2 -V th，1 , and the results of the change amount of the threshold voltage of the specific device are shown in Figure 7 .

[0067] A 1% BSA solution is added dropwise to the surface of the silicon nanowire sensor to block the remaining probe linking groups on the surface of the silicon nanowire sensor.

[0068] As shown in Figure 1 , step S12 is then performed to obtain the threshold voltage response of the modified silicon nanowire sensor to the target substance under standard solutions of different concentrations.

[0069] As shown in Figure 3 , as an example, the method for obtaining the threshold voltage response of the modified silicon nanowire sensor to the target substance under standard solutions of different concentrations includes:

[0070] S31: Obtain the threshold voltage V th，3 of the silicon nanowire sensor under a reference solution.

[0071] S32: Obtain the threshold voltage V th，4 of the silicon nanowire sensor under standard solutions of different concentrations from low to high.

[0072] S33: Obtain the threshold voltage response S(c) = V th，4 -V th，3 of the silicon nanowire sensor under standard solutions of different concentrations from low to high.

[0073] As an example, the reference solution is a solution without the target substance, and the standard solution is a solution containing a preset proportion of the target substance.

[0074] As shown in Figure 7 , in this embodiment, the silicon nanowire sensor with the modified probe in each device group is used, 0.01×PBS reference solution is added dropwise to the surface of the silicon nanowire sensor, the preset source-drain voltage is -0.4V, the gate voltage of the silicon nanowire sensor is scanned, the gate voltage range is -0.5V~0.5V, the third transfer characteristic curve of the silicon nanowire sensor is obtained, and according to the third transfer characteristic curve, the gate voltage corresponding to the preset 100nA current is the threshold voltage V th，3 of the reference solution, wherein the reference solution is a blank buffer solution without the target substance.

[0075] As shown in Figure 7 , according to the concentration of the standard solution from low to high, 10ng / mL, 100ng / mL, 1μg / mL, 10μg / mL, and 100μg / mL of the standard solution are added dropwise to the device surface of the silicon nanowire sensor with the modified probe in different device groups, respectively, and the threshold voltage V th，4, the threshold voltage response S(c) of each of the silicon nanowire sensors in the standard solution is calculated th，4 -V th，3 , and the results are shown in Figure 7 , and the threshold voltage response curve of the standard solution is plotted Figure 4

[0076] Then, step S13 is performed, the threshold voltage response of the target substance is normalized based on the threshold voltage change amount before and after the surface probe modification of the silicon nanowire sensor, and a target substance response standard curve is determined.

[0077] As an example, the normalization processing is that the threshold voltage response S(c) of the silicon nanowire sensor in the standard solution from low concentration to high concentration is divided by the threshold voltage change amount ΔV th，probe , i.e.

[0078] As an example, the determination of the target substance response standard curve includes fitting the threshold voltage response S'(c) of the target substance after the normalization processing of the silicon nanowire sensor, thereby obtaining the target substance response standard curve f(c).

[0079] As shown in Figure 5 , in this embodiment, the threshold voltage response S(c) of the target substance is normalized based on the threshold voltage change amount ΔV th，probe , and the threshold voltage response of the standard solution after normalization processing is

[0080] As shown in Figure 6 , the results after the normalization processing of the silicon nanowire sensor are fitted, and the target substance response standard curve f(c) is obtained.

[0081] In a specific example, the silicon nanowire sensor with one modified probe in device group 5 is taken, as shown in Figure 7 , the threshold voltage V th，1 of the silicon nanowire sensor before probe modification is 0.019173V, the threshold voltage V th，2 of the silicon nanowire sensor after probe modification is 0.035494V, and the threshold voltage change amount ΔV Th，probe of the silicon nanowire sensor before and after probe modification is V th，2 -V th，1 ​=0.016321. A 0.01×PBS reference solution was dropped onto the surface of the silicon nanowire sensor. The preset source-drain voltage was -0.4V. The gate voltage of the silicon nanowire sensor was scanned, with a range of -0.5V to 0.5V, to obtain the fourth transfer characteristic curve of the silicon nanowire sensor. According to the fourth transfer characteristic curve, the gate voltage corresponding to a preset current of 100nA is the threshold voltage V of the reference solution. th，3 =0.076638V, wherein the reference solution is also a blank buffer solution, which is a solution that does not contain the target substance.

[0082] A test sample containing the target object is dropped onto the surface of the silicon nanowire sensor with a modified probe, and the threshold voltage V of the silicon nanowire sensor under the target object is measured. th，4 =0.05441V, calculate the threshold voltage response S(d) of the silicon nanowire sensor on the target object. test ) = V th，4 -V th，3 = -0.022228V.

[0083] The threshold voltage change ΔV before and after surface probe modification of the silicon nanowire sensor was utilized. th，probe The threshold voltage response S(c) of the target object test The threshold voltage response of the target object is then normalized.

[0084] All of the above steps are for calibrating the threshold voltage of the silicon nanowire sensor.

[0085] Finally, in step S14, based on the target object response standard curve, the concentration of the target object corresponding to the threshold voltage response of the target object is determined.

[0086] In this embodiment, the normalized threshold voltage response S′(c) of the target object is... test Substituting the target object's response standard curve f(c), we get S′(c) test )=f(c test The concentration c of the target analyte can then be obtained. test =11μg / ml.

[0087] As an example, the functions that fit the threshold voltage response S′(c) include: y = ax, y = ax b and The threshold voltage response S′(c) of the normalized standard solution of the silicon nanowire sensor can be fitted with an appropriate function according to actual needs to obtain the standard response curve f(c).

[0088] Step S14 is a quantitative test of the silicon nanowire sensor.

[0089] In summary, the present application provides a threshold voltage calibration and quantitative test method of the silicon nanowire sensor, comprising: S11: probe modification is performed on the surface of the silicon nanowire sensor, and the threshold voltage variation before and after the probe modification on the surface of the silicon nanowire sensor is obtained; S12: the threshold voltage response of the modified silicon nanowire sensor to the target object under different concentrations of standard solution is obtained; S13: based on the threshold voltage variation before and after the probe modification on the surface of the silicon nanowire sensor, the threshold voltage response of the target object is normalized, and a target object response standard curve is determined; S14: based on the target object response standard curve, the concentration of the target object corresponding to the threshold voltage response of the target object is determined. The present application uses the threshold voltage variation before and after the probe modification on the surface of the silicon nanowire sensor to normalize the threshold voltage response of the target object, determine the target object response standard curve, and obtain the concentration of the target object corresponding to the threshold voltage response of the target object; the consistency of the test results before and after the threshold voltage calibration is significantly improved, the repeatability is good, the calibration process does not require additional equipment, the calibration process and the test process can use the same equipment, the cost is effectively saved, the calibration process is lossless to the silicon nanowire sensor, and does not affect the subsequent test of the silicon nanowire sensor. Therefore, the present application effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0090] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for threshold voltage calibration and quantitative testing of a silicon nanowire sensor, characterized in that, The threshold voltage calibration and quantitative test method of the silicon nanowire sensor comprises: S11: modifying a probe on the surface of the silicon nanowire sensor, and obtaining the threshold voltage change amount before and after the probe modification on the surface of the silicon nanowire sensor; S12: obtaining the threshold voltage response of the target object under different concentrations of standard solution of the modified silicon nanowire sensor; S13: based on the threshold voltage change amount before and after the probe modification on the surface of the silicon nanowire sensor, normalizing the threshold voltage response of the target object, and determining the target object response standard curve; S14: based on the target object response standard curve, determining the concentration of the target object corresponding to the threshold voltage response of the target object. 2.The method of claim 1, wherein, The method for obtaining the threshold voltage change amount before and after the probe modification on the surface of the silicon nanowire sensor comprises: S21: modifying a probe linker group on the surface of the silicon nanowire sensor; S22: Obtain the threshold voltage V of the silicon nanowire sensor surface probe before modification th,1 ; S23: modifying the probe corresponding to the target object on the surface of the silicon nanowire sensor; S24: Obtain the threshold voltage V of the silicon nanowire sensor surface probe after modification th,2 ; S25: obtaining a variation amount AV of the threshold voltage of the silicon nanowire sensor before and after the surface probe modification of the silicon nanowire sensor based on the threshold voltage before and after the surface probe modification of the silicon nanowire sensor th,probe = V th,2 -V th,1 ; S26: closing the remaining probe linker group on the surface of the silicon nanowire sensor by using a blocking agent. 3.The method of claim 2, wherein, The method for obtaining the threshold voltage comprises: under a preset source-drain voltage, scanning the gate voltage of the silicon nanowire sensor to obtain the transfer characteristic curve of the silicon nanowire sensor, and the gate voltage corresponding to the preset current based on the transfer characteristic curve is the threshold voltage. 4.The method of claim 2, wherein: The probe linker group comprises any one or a combination of two or more of a hydroxyl group, an amino group, an aldehyde group and a carboxyl group.

5. The method of claim 2, wherein the threshold voltage of the silicon nanowire sensor is calibrated and quantitatively tested by: The blocking agent comprises any one or a combination of two or more of bovine serum albumin, casein, ethanolamine and Tween. 6.The method of claim 1, wherein The method for obtaining the threshold voltage response of the target object under different concentrations of standard solution of the modified silicon nanowire sensor comprises: S31: Obtain the threshold voltage V of the silicon nanowire sensor under the reference solution th,3 ; S32: Obtain the threshold voltage V of the silicon nanowire sensor under the standard solution from low concentration to high concentration th,4 ; S33: find the threshold voltage response S(c) = V of the silicon nanowire sensor under standard solution from low concentration to high concentration th,4 -V th,3 .

7. The method of claim 6, wherein the threshold voltage of the silicon nanowire sensor is calibrated and quantitatively tested by: The reference solution is a solution without the target object, and the standard solution is a solution containing a preset proportion of the target object. 8.The method of claim 1, wherein The normalization processing is: dividing the threshold voltage response S(c) of the silicon nanowire sensor under the standard solution from low concentration to high concentration by the threshold voltage change amount AV before and after the surface probe modification of the silicon nanowire sensor th,probe i.e. 9.The method of claim 1, wherein The determination of the target response standard curve comprises: determining the threshold voltage response S of the target after the normalization of the silicon nanowire sensor ′ (c) performing fitting, thereby obtaining the target response standard curve f(c). 10.The method of claim 9, wherein the threshold voltage of the silicon nanowire sensor is calibrated and quantitatively tested. The function to which the threshold voltage response S'(c) is fitted comprises: y = ax, y = ax b and

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