CN111721710B - Method for calibrating silicon nanowire sensor by light - Google Patents
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Abstract
The invention provides a method for calibrating a silicon nanowire sensor by using light, which comprises the following steps: performing surface modification on the silicon nanowire sensor; obtaining photoresponse currents of the modified silicon nanowire sensor under different illumination intensities in a preset test environment; determining a photoresponse function analytic expression of a photoresponse function expression based on the photoresponse current; determining a target object response function analytic expression of the target object response function expression according to the light response function analytic expression and the environment variable offset value; and determining the concentration of the sample to be detected corresponding to the response current of the sample to be detected based on the analytical expression of the target object response function. The method utilizes the absorption efficiency of the silicon nanowire to light to evaluate the performance of the silicon nanowire sensor, and solves the problem of inconsistent response efficiency of a sensing device caused by sensing unit difference. The calibration method has the advantages of simplicity, high efficiency, low cost, no damage to the device and no interference to the use of subsequent devices.
Description
The technical field is as follows:
the invention relates to the technical field of sensors, in particular to a method for calibrating a silicon nanowire sensor by using light.
Background art:
the sensor using the silicon nanowire as the sensing unit has the advantages of high sensitivity, low cost, fast response and the like, so that the silicon nanowire sensor is concerned by a plurality of researchers. The silicon nanowire sensor takes silicon as a basic material, and the silicon nanowires can be obtained by a potassium hydroxide wet etching process due to different silicon etching rates of different crystal orientations. Compared with a processing method of chemical growth or electron beam pattern exposure, the traditional wet etching process has lower cost, so that the silicon nanowire sensor has incomparable advantages compared with other types of silicon nanowire sensors from the aspects of cost and rich raw materials.
By adopting the traditional wet etching process, due to slight differences of molecular diffusion rate, concentration of etching solution and the like, the phenomenon of different etching rates in different areas of the silicon wafer can occur, and finally, slight deviation of the sizes of the silicon nanowires in different areas of the silicon wafer can be caused, so that the overall consistency of the device is influenced. The silicon nanowire sensors in different batches or in different silicon chip regions are used for testing the same target object, and the obtained test results are different, so that accurate quantitative test cannot be carried out. Therefore, the sensor output needs to be modulated so that different silicon nanowire sensors respond the same to the same target.
The invention content is as follows:
in view of the above-mentioned drawbacks of the prior art, the present invention discloses a method for calibrating a silicon nanowire sensor using light.
The method comprises the following steps:
performing surface modification on the silicon nanowire sensor;
obtaining photoresponse currents of the modified silicon nanowire sensor under different illumination intensities in a preset test environment;
determining a photoresponse function analytic expression of a photoresponse function expression based on the photoresponse current;
determining a target object response function analytic expression of the target object response function expression according to the light response function analytic expression and the environment variable offset value;
and determining the concentration of the sample to be detected corresponding to the target response current of the sample to be detected based on the target object response function analytic expression.
Further, the acquiring photoresponse currents of the modified silicon nanowire sensor under different illumination intensities in a preset test environment comprises:
determining a predetermined test environment;
applying a preset voltage for a preset time to the silicon nanowire sensor under a preset test environment;
changing the illumination intensity irradiated on the silicon nanowire sensor according to a preset rule;
and recording the photoresponse current output by the silicon nanowire sensor after the illumination intensity is changed every time.
Further, the predetermined test environment includes any one or more of a test preset illumination intensity, a test preset temperature, and a test preset humidity.
Specifically, the duration of the preset time is at least longer than the signal output time used before the signal output by the silicon nanowire sensor is stable.
Further, the preset rule includes: the gradient of the illumination intensity irradiated on the silicon nanowire sensor is increased or decreased.
Further, before recording the photoresponse current output by the silicon nanowire sensor after each illumination intensity change, the method further comprises:
judging whether the output signal of the silicon nanowire sensor is saturated or not,
and if so, stopping illuminating the silicon nanowire sensor.
Further, the light response function expression is Rp ═ f (p), and the objective function expression is Rc ═ af (c) + B, where B is an environment variable offset value.
Further, before determining the photoresponse function analytic expression of the photoresponse function expression based on the photoresponse current, the method further comprises:
determining an optical response model corresponding to the optical response current based on the optical response current;
determining the light response function expression based on the light response model.
Further, determining the target response function analytical expression of the target response function expression according to the light response function analytical expression and the environment variable offset value includes:
obtaining a reference response current of the modified silicon nanowire sensor under a reference object under a preset test environment;
obtaining a calibration response current of the modified silicon nanowire sensor under a target object under a preset test environment;
substituting the reference response current value and the calibration response current value into a target object function expression to obtain an unknown quantity A and an unknown quantity B;
and substituting the obtained A value and B value into the target object response function expression to obtain a target object response function analytical expression.
Further, the reference object is a solution of undissolved solutes, and the target object is a solution in which calibration solutes in a preset ratio are dissolved.
The invention utilizes the optical response of the silicon nanowire sensor to modulate and calibrate the response of the target object, the optical response measurement of the silicon nanowire sensor is very convenient, the test result is stable, the repeatability is good, the required concentration of the sample to be tested can be obtained based on the calibrated function analytic test, the test is convenient, and the result is accurate. Compared with other characterization means, the method has the advantages that the optical calibration does not need to depend on expensive equipment, the cost is low, the device is not damaged in the optical calibration process, and the subsequent use of the device is not influenced.
Description of the drawings:
FIG. 1 is a flow chart of a method for calibrating a silicon nanowire sensor using light according to the present invention;
FIG. 2 is a schematic diagram of the intrinsic absorption process described in an embodiment of the present invention;
fig. 3 is a response model diagram of a silicon nanowire sensor according to an embodiment of the present invention, wherein:
figure (a) is a schematic view of a distribution model of carriers in the silicon nanowire before photoresponse,
the graph (b) is a schematic view of a distribution model of carriers in the silicon nanowire after photoresponse,
FIG. (c) is a band diagram of silicon nanowire photoresponse;
FIG. (d) is a schematic diagram of the optical response of a silicon nanowire sensor;
FIG. 4 is a graph of the optical response of device a in an embodiment of the present invention;
FIG. 5 is a graph of the optical response of device b in an embodiment of the present invention;
FIG. 6 is a graph of the target response of device a in an embodiment of the present invention;
FIG. 7 is a graph of the target response of device b in an embodiment of the present invention;
FIG. 8 is a normal distribution fit graph as described in an embodiment of the present invention;
FIG. 9 is a graph comparing the theoretical target response current and the actual target response current.
The specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. In order to solve the problems in the prior art, the present invention provides a method for calibrating a silicon nanowire sensor by using light, as shown in fig. 1, the method comprising:
s100, performing surface modification on the silicon nanowire sensor;
specifically, the invention aims to modulate the response of a target object by utilizing the photoresponse of the silicon nanowire sensor, so as to obtain a function analytic expression which can be used for testing and obtaining the concentration of a sample to be tested.
It is understood that the optical response described in this specification is: under the condition that the output signal of the silicon nanowire is stable, the illumination intensity around the silicon nanowire is changed, the output signal changes, and the output signal change caused by the illumination intensity change is called the optical response of the silicon nanowire sensor.
Further, since surface modification is required when testing the response of the silicon nanowire sensor to the target object, in order to reduce the influence of the modification process on the test result of the response of the target object and the test result of the photoresponse, the surface modification is also performed on the silicon nanowire sensor when performing the photoresponse test on the silicon nanowire sensor.
It can be understood that the silicon nanowire sensor described in the present specification corresponds to the following objects: in the case that the output signal of the silicon nanowire sensor is stable, the output signal of the silicon nanowire sensor changes by changing the property of the target object to be tested, for example, changing the concentration of the target object, and the change of the output signal caused by the change of the property of the target object is called the response of the silicon nanowire sensor to the target object.
In one implementation, the surface modification process for the silicon nanowire sensor is as follows:
and (3) treating the surface of the silicon nanowire for 30min by using oxygen plasma equipment, and soaking the treated silicon nanowire sensor in 2% APTES ethanol solution for 12-24 h. And taking out the soaked silicon nanowire sensor, washing the silicon nanowire sensor for 3 times by using an ethanol solution, drying the sensor by using nitrogen, and putting the sensor into a 120-DEG C oven for 15 minutes. And (3) dropwise adding a 2.5% glutaraldehyde solution to the surface of the silicon nanowire sensor, putting the silicon nanowire sensor into a light-proof box for 2 hours, taking out the silicon nanowire sensor, washing the silicon nanowire sensor with a PBS solution, and drying the silicon nanowire sensor with nitrogen. And then 0.5 mu M PNA probe solution is dripped on the surface of the silicon nanowire sensor, the silicon nanowire sensor is placed in a lightproof box for 2 hours, and the silicon nanowire sensor is taken out, washed for 3 times by PBS and dried by nitrogen for standby.
It is to be understood that the above-described process of surface modification of the silicon nanowire sensor is only one solution, and in other implementable solutions, the surface modification of the silicon nanowire sensor may be performed by the following steps:
firstly, acetone is used for ultrasonic treatment for 10 minutes, ethanol is used for washing for 30 seconds, deionized water is used for washing for 1 minute, nitrogen is used for blow-drying, and the surface of the silicon nanowire is cleaned. And heating 30ml of mixed solution of concentrated sulfuric acid and hydrogen peroxide (H2SO4: H2O 2: 7:3) to 90 ℃, and continuously dripping the mixed solution on the surface of the silicon nanowire for about 30min for multiple times to ensure that more hydroxyl groups are generated on the surface and the surface is more hydrophilic. Washing with deionized water for 1 minute, blowing dry with nitrogen, and soaking in 2% ethanol solution of silanization reagent APTES for 12-24 hr. The unreacted APTES was rinsed with ethanol for 30s, then blown dry with nitrogen, and dried in an oven at 120 ℃ for 5 minutes. And dropwise adding an antibody solution with the concentration of 50 mu g/ml onto the surface of the silicon nanowire FET sensor, putting the silicon nanowire FET sensor into a lightproof box for 2 hours, taking out the silicon nanowire FET sensor, washing the silicon nanowire FET sensor for 3 times by using PBS, and drying the silicon nanowire FET sensor by using nitrogen. And then, adding ethanolamine with the concentration of 1mM dropwise onto the surface of the silicon nanowire FET sensor, putting the silicon nanowire FET sensor into a light-proof box for 30 minutes, taking out the silicon nanowire FET sensor, washing the silicon nanowire FET sensor for 3 times by PBS, and blow-drying the silicon nanowire FET sensor for later use by nitrogen.
It is understood that the surface modification of the silicon nanowire sensor is not limited to the above-mentioned scheme, but may be other schemes besides the above-mentioned scheme, and during the specific test process, the specific selection may be performed according to laboratory materials, and is not limited herein.
S102, acquiring photoresponse currents of the modified silicon nanowire sensor under different illumination intensities in a preset test environment;
specifically, the acquiring photoresponse currents of the modified silicon nanowire sensor under different illumination intensities in a predetermined test environment includes:
s1020, determining a preset test environment;
it is to be understood that the predetermined test environment may include any one or more of a test preset illumination intensity, a test preset temperature, and a test preset humidity. In a specific test, the setting may be performed according to actual needs and the surrounding environment, and this is not limited herein.
S1022, applying a preset voltage for a preset time to the silicon nanowire sensor under a preset test environment;
it is understood that, in order to obtain a stable output signal of the silicon nanowire sensor, the preset time should be at least greater than a signal output time used before the signal output by the silicon nanowire sensor is stable.
S1024, changing the illumination intensity irradiated on the silicon nanowire sensor according to a preset rule;
it can be understood that, in order to clearly observe the change rule of the photoresponse of the silicon nanowire sensor under different illumination intensities, a certain change rule may be set for the illumination intensity irradiated on the silicon nanowire sensor, and preferably, the preset rule may be to increase or decrease the gradient of the illumination intensity irradiated on the silicon nanowire sensor to form a certain change rule.
In an implementation, the preset rule may be to increase the gradient of the illumination intensity on the silicon nanowire sensor, for example, the initial illumination intensity corresponds to an optical power of 0W/m2Terminating the light power corresponding to the light intensityIs 120W/m2Gradient variation of 20W/m2。
And S1026, recording the photoresponse current output by the silicon nanowire sensor after the illumination intensity is changed every time.
It is understood that before step S1026 is performed, whether the output signal of the silicon nanowire sensor is saturated or not may be determined,
and if the output signal of the silicon nanowire sensor is saturated, stopping illuminating the silicon nanowire sensor.
S104, determining a photoresponse function analytic expression of the photoresponse function expression based on the photoresponse current;
specifically, the step S104 of determining the photoresponse function analytical expression of the photoresponse function expression based on the photoresponse current specifically includes the following steps:
s1040, determining an optical response model corresponding to the optical response current based on the optical response current;
specifically, before determining the photoresponse function analytic expression, a photoresponse model may be established, and the photoresponse function expression R may be determined based on the photoresponse modelPF (P), preferably, P-type silicon nanowires are selected in this embodiment.
In particular, absorption of radiation energy by the semiconductor material causes an electron to transition from a lower energy level to a higher energy level, and thus a photon of sufficient energy causes the electron in the valence band to be excited and to transition across the forbidden band into the conduction band, leaving a hole in the valence band, i.e., forming an electron-hole pair. This absorption process, in which an electron inside the conduction band is excited to transition into the conduction band due to the absorption of a photon by the semiconductor, and an electron-hole pair is generated, is called intrinsic absorption. The principle diagram of the intrinsic absorption process is shown in fig. 2.
The forbidden band width Eg of silicon is 1.12Ev, and for intrinsic absorption to occur, the energy of the photon must be greater than or equal to the forbidden band width of silicon, i.e., the energy of the photon must be greater than or equal to the forbidden band width of silicon
hv≥Eg
Therefore, the silicon nanowire has intrinsic absorption, the wavelength of incident light is less than 1.1 mu m, and the intrinsic absorption of silicon can be caused by partial infrared light, visible light and ultraviolet light.
The optical response mechanism of the silicon nanowire is greatly different from that of bulk silicon, and the response model is shown as (a), (b), (c) and (d) in FIG. 3,
photons are incident to the surface of the silicon nanowire, energy is absorbed by valence electrons to generate electron-hole pairs, and the electron-hole pairs are separated under the influence of an interface state of the surface of the silicon nanowire to form a shell-core structure. The 'core-shell' structure greatly prolongs the service life of the generated nonequilibrium current carrier and greatly increases the gain current.
It can therefore be seen that the non-equilibrium carrier concentration within the silicon nanowire after light incidence
Wherein: beta is the quantum yield, i.e. the number of electron-hole pairs that can be excited to generate per photon;
alpha is the absorption coefficient of the material;
a is the sectional area of the silicon nanowire;
v is the length of the silicon nanowire;
p is incident light power in W/m 2;
P0the incident optical power when the interface trap is just full;
τ is carrier lifetime;
τ0the lifetime of the carriers when the interface traps are just fully occupied;
k is the decay factor of the carrier lifetime.
Photocurrent thus generated
Namely, the light response function expression is finally obtained:
RP＝KP·Pαα∈(0,1)
S1042、determining a photoresponse function expression R based on the photoresponse modelP＝f(P)；
Specifically, to obtain the unknown quantity in the photoresponse function expression and obtain the final photoresponse function analytic expression, the following experiment is designed:
taking 2 silicon nanowire sensors (briefly described as a device a and a device b below), and performing surface modification on the device a and the device b. The specific surface modification method has been described above and will not be described herein.
Furthermore, 450nm blue light can be selected as a light source to provide illumination for the device a and the device b, and the light power corresponding to the initial illumination intensity is determined to be 0W/m2The light power corresponding to the termination light intensity is 120W/m2The gradient variation of the illumination intensity is 20W/m2The photoresponse currents of the device a and the device b under different illumination intensities are respectively tested, gradient photoresponse current change quantities of the device a and the device b are respectively calculated, the photoresponse curve of the device a shown in figure 4 and the photoresponse curve of the device b shown in figure 5 are respectively drawn based on the test results, and respective fitting results are given. It is understood that the gradient photoresponse current change amount Δ ═ I1-I0Wherein, I0Output current of silicon nanowire sensor tested in the absence of illumination, I1The preset illumination may vary according to the above-described gradient in order to test the output current of the silicon nanowire sensor after applying the preset illumination intensity.
It is understood that the light source selected may be other than the above-mentioned 450nm blue light, and is not limited thereto. The gradient change amount may also be set according to experimental needs, and is not limited herein.
Specifically, the analytical formula of the photoresponse function of the device a is R obtained from the fitting resultP＝0.806586·P0.31661The optical response function of the device b has an analytical formula of RP＝1.34952·P0.3359504。
It can be understood that the optical response of the silicon nanowire is mainly caused by the trapping effect of the interface trap and the coulomb force action of the surface charge to the carrier. These two factors still play a major role in the target response of silicon nanowires, and therefore the target response of silicon nanowires can be considered to have a similar expression to its optical response, namely:
RC＝KC·Cββ∈(0,1)
to verify the above reasoning, the following experiment was designed, and the test of the target response was continued for the modified device a and the modified device b. Specifically, the target is a serum solution with a solvent of 1%, the initial concentration of the target is determined to be 0mol/L, the final concentration is determined to be 6mol/L, the variation of the concentration gradient is 1mol/L, the target response currents of the device a and the device b at different concentrations are respectively tested, the gradient target response current variation of the device a and the gradient target response current variation of the device b are respectively calculated, the target response curve of the device a shown in fig. 6 and the target response curve of the device b shown in fig. 7 are respectively drawn based on the test results, and the respective fitting results are given. It is understood that the gradient photoresponse current change amount Δ' ═ I1'-I0', wherein, I0' output Current, I, of the silicon nanowire sensor measured when the concentration of the target is zero1' the output current of the silicon nanowire sensor tested for applying a target of a preset concentration, which may vary according to the above-described gradient.
Specifically, the analytic formula of the target object response function of the device a obtained from the fitting result is RC＝0.793324·C0.301365The analytic formula of the target object response function of the device b is RC＝0.7787265·C0.350318。
From the test results, the optical response of the silicon nanowire sensor and the target response of the silicon nanowire sensor have similar response function expressions.
And S106, determining a target object response function analytic expression of the target object response function expression according to the light response function analytic expression and the environment variable offset value.
It can be understood that, since the optical response function expression of the silicon nanowire sensor is similar to the target object response function expression of the silicon nanowire sensor, if some quantitative relationship between the two function expressions can be determined, the target object response function expression of the silicon nanowire sensor can be obtained through the optical response function expression of the silicon nanowire sensor, and specifically, the theoretical analysis is as follows:
for silicon nanowires, the conductivity in the absence of light is
σ01＝q(n01μn+p01μp)
Assuming that the non-equilibrium carrier concentrations of light injection are Δ n1 and Δ p1, respectively, the additional conductivity Δ σ 1 is
Δσ1＝qΔn1μn+qΔp1μp
So that the relative change amount of the photocurrent
With additional carrier concentration for intrinsic absorption
Wherein: i is the number of photons passing through a unit area per unit time;
t is the photon incidence time;
from the formula, it can be seen that the number of the photon-generated carriers does not increase all the time because the number of the electron-hole pairs generated by light excitation increases linearly with the increase of the incident time t of the photons, but the recombination process also exists while the electron-hole pairs are generated by light excitation. When the generation rate of carriers is equal to the recombination rate, generation and recombination form a dynamic balance inside the semiconductor, and the number of photogenerated carriers does not increase any more.
Assuming that the lifetime of electrons generated by photoexcitation is τ n, the electron concentration at dynamic equilibrium is
So the relative change of current in dynamic balance
The response of the silicon nanowire to the target is mainly due to the fact that target molecules are accumulated on the outer surface of the nanowire, so that the surface potential of the silicon nanowire is changed, the internal carrier concentration is changed, the conductivity of the silicon nanowire is changed, and finally the macro-scale effect is achieved, namely the resistance of the silicon nanowire is changed along with the change of the concentration of an external target.
Silicon nanowire current
With the increase of the concentration of the calibration object, the concentration of the charges accumulated on the surface of the silicon nanowire is larger and larger. When the surface charge areal density reaches a maximum, denoted as Qs, the silicon nanowire's calibrant response current reaches a maximum. Change in carrier concentration at this time
So the relative change of the current of the silicon nanowire
The ratio of the relative change of the light response current to the relative change of the calibration object response current can be calculated as
Mu in the formula,Beta, alpha, tau, Ceq and Qs can be considered as constants for silicon nanowires, I is determined by the light source, n0、p0Determined by the initial conditions of the test. Therefore, when the process conditions and the experimental conditions are kept unchanged, the optical response of the silicon nanowire sensor and the response of the target object really meet a certain quantitative relation.
To verify the correctness of the theoretical derivation and the quantitative relationship between the optical response of the silicon nanowire sensor and the response of the target, experiments were designed as follows:
firstly, surface modification is carried out on the silicon nanowire sensors, in the experiment, after the surface modification of 14 silicon nanowire sensors, a target object response test and a light response test are carried out, the saturation response of the silicon nanowire sensors to the target object and light is respectively recorded, and the test results are shown in table 1.
TABLE 1
As can be seen from the table, there is a certain proportional relationship between the response of the silicon nanowire sensor in the target and the response to light. The target in the experiment is 0.01% serum solution, and the detection result shows that the proportionality coefficient of the response of 14 devices to light and the target is between 24 and 30. It can be concluded from this that under the same test conditions, the saturation light response and the saturation calibrant response of the silicon nanowire sensor are proportional, i.e.:
in order to obtain a more reliable scaling factor K, the scaling factors of the upper 14 sets of data were averaged and standard-deviation-calculated, and a normal distribution fitting was performed as shown in fig. 8, so that the final scaling factor K was 27.80.
By combining the theoretical derivation and the experimental results, the target response and the light response of the silicon nanowire sensor are considered to have similar response functions and to meet a certain quantitative relationship. Considering the interference of common-mode signals in the actual test process, such as temperature and the like, introducing an environment variable bias value B, thereby obtaining a silicon nanowire sensor target object response function expression related to the silicon nanowire sensor optical response function expression:
Rc＝Af(c)+B
wherein the function f (c) is an expression of a target response function of the silicon nanowire sensor.
Furthermore, it should be noted that the binding of the probe modified on the surface of the silicon nanowire and the target during the detection may cause the probe on the surface to be consumed out if the target used is too high, and in this step, a solution with a relatively low concentration of the target may be selected, for example, a target solution with a concentration ranging from 1mol/L to 10mol/L may be selected.
Further, the determining an objective response function analytic expression of the objective response function expression according to the optical response function analytic expression and the environment variable offset value includes:
s1060, obtaining a reference response current of the modified silicon nanowire sensor under a reference solution in a preset test environment;
s1062, obtaining a calibration response current of the modified silicon nanowire sensor under a target object under a preset test environment;
s1064, substituting the reference response current value and the calibration response current value into the target object function expression to obtain an unknown quantity A and an unknown quantity B;
and S1066, substituting the obtained A value and B value into the target response function expression to obtain a target response function analytical expression.
Specifically, in order to obtain the unknown quantity a and the unknown quantity B, this embodiment selects the above calculated photoresponse function analytical formula R of the device B according to the data in the verification testP＝1.34952·P0.3359504Coordinate transformation of each concentration C in the object used for the test device bThe converted quantity c, the corresponding reference response current and the calibration response current are substituted into a target response function expression, parameters a 1.73295 and B0.0002 in the target response function expression are obtained, and the obtained a value and the obtained B value are substituted into the target response function expression to obtain a target response function analytical expression.
Further, after a target object response function analytic expression is determined, the verification test also calculates a theoretical target response current based on the target object response function analytic expression; and a comparison of the theoretical target response current and the actual target response current is plotted as described in fig. 9.
Specifically, based on the target response function analytical expression obtained above, the target response current at each concentration is calculated and compared with the current actually tested, and the comparison result is shown in fig. 9 below.
As can be seen from fig. 9, the theoretical value obtained by the method is well matched with the actual value, and the effectiveness of calibrating the target response by using the optical response of the silicon nanowire sensor is proved.
And S108, determining the concentration of the sample to be detected corresponding to the response current of the sample to be detected based on the target object response function analytic expression.
It is understood that, based on the above calibration process, a functional analytical expression of the response current after calibration with respect to the concentration C, Rc ═ af (C) + B, is obtained, and in the subsequent application, the concentration of the sample to be measured corresponding to the response current of the sample to be measured, which may be a sample whose concentration needs to be measured, such as blood, can be determined based on the functional analytical expression.
The invention utilizes the optical response of the silicon nanowire sensor to modulate the response of the sample to be tested, the measurement of the optical response of the silicon nanowire sensor is very convenient, the test result is stable, the repeatability is good, the required concentration of the sample to be tested can be obtained based on the calibrated function analytic test, the test is convenient, and the result is accurate. Compared with other characterization means, the method has the advantages that the optical calibration does not need to depend on expensive equipment, the cost is low, the device is not damaged in the optical calibration process, and the subsequent use of the device is not influenced.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A method of calibrating a silicon nanowire sensor with light, the method comprising:
performing surface modification on the silicon nanowire sensor;
obtaining photoresponse currents of the modified silicon nanowire sensor under different illumination intensities in a preset test environment;
determining a photoresponse function analytic expression of a photoresponse function expression based on the photoresponse current;
determining a target object response function analytic expression of the target object response function expression according to the light response function analytic expression and the environment variable offset value;
and determining the concentration of the sample to be detected corresponding to the response current of the sample to be detected based on the analytical expression of the target object response function.
2. The method for calibrating a silicon nanowire sensor by using light according to claim 1, wherein the obtaining the photoresponse current of the modified silicon nanowire sensor under different illumination intensities in a predetermined test environment comprises:
determining a predetermined test environment;
applying a preset voltage for a preset time to the silicon nanowire sensor under a preset test environment;
changing the illumination intensity irradiated on the silicon nanowire sensor according to a preset rule;
and recording the photoresponse current output by the silicon nanowire sensor after the illumination intensity is changed every time.
3. The method of calibrating a silicon nanowire sensor using light according to claim 1 or 2, wherein the predetermined test environment comprises any one or more of a test preset light intensity, a test preset temperature, and a test preset humidity.
4. The method of calibrating a silicon nanowire sensor using light according to claim 2, wherein the duration of the preset time is at least longer than a signal output time used before a signal output from the silicon nanowire sensor is stabilized.
5. The method of calibrating a silicon nanowire sensor using light according to claim 2, wherein the preset rule comprises: the gradient of the illumination intensity irradiated on the silicon nanowire sensor is increased or decreased.
6. The method of calibrating a silicon nanowire sensor with light according to claim 2, wherein before recording the photoresponse current outputted from the silicon nanowire sensor after each change of the illumination intensity, the method further comprises:
judging whether the output signal of the silicon nanowire sensor is saturated or not,
and if so, stopping illuminating the silicon nanowire sensor.
7. The method of calibrating a silicon nanowire sensor with light of claim 1, wherein the photoresponse function expression is Rp(P), the target response function expression is Rc ═ af (c) + B, where P is incident light power, R is incident light powerpAnd the value of the optical response is A, the value of the unknown variable in the target response function expression is B, the bias value of the environment variable is C, the concentration of the target is C, and the value of Rc is the response value of the target.
8. The method of calibrating a silicon nanowire sensor with light according to claim 7, wherein prior to determining the photoresponse function analytic expression of the photoresponse function expression based on the photoresponse current, the method further comprises:
determining an optical response model corresponding to the optical response current based on the optical response current;
determining the light response function expression based on the light response model.
9. The method of calibrating a silicon nanowire sensor with light of claim 7, wherein determining a target response function analytic expression of a target response function expression from the photoresponse function analytic expression and the environmental variable bias value comprises:
obtaining a reference response current of the modified silicon nanowire sensor under a reference object under a preset test environment;
obtaining a calibration response current of the modified silicon nanowire sensor under a target object under a preset test environment;
substituting the reference response current value and the calibration response current value into a target object response function expression to obtain an unknown quantity A and an unknown quantity B;
and substituting the obtained A value and B value into the target object response function expression to obtain a target object response function analytical expression.
10. The method of calibrating a silicon nanowire sensor using light according to claim 9, wherein the reference substance is a solution in which a solute is not dissolved, and the target substance is a solution in which a predetermined ratio of a calibration solute is dissolved.
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