Carbon-based thin film transistor sensor array for multi-gas identification and preparation method thereof

Abstract

The present invention provides a carbon-based thin-film transistor sensor array for multiple gas identification and a preparation method thereof. The sensor array structure includes four independent gas detection channels, and each gas detection channel is composed of a silicon-based substrate, a dielectric layer, a source electrode, a drain electrode and a channel active layer to form a sensing component. The sensitive material layer in the area where the channel active layer is located is used to improve the selectivity of the CNT in the channel active layer. The CNT-TFT sensor component of each gas detection channel converts the changes in the gas into electrical signals before and after exposure to the target gas, collects information about the gas and outputs electrical signals. Gases are identified by analyzing the information based on the response output of the four gas detection channels in combination with a linear discriminant analysis algorithm. The carbon-based thin-film transistor sensor array for multiple gas identification proposed by the present invention can achieve highly sensitive detection and accurate identification of three gases: ammonia, hydrogen sulfide and formaldehyde, and promote real-time online monitoring of multiple harmful gases in the room.

Description

Technical Field

[0001] The present invention relates to the field of gas sensor technology, in particular to a TFT gas sensor array. The TFT sensor array uses multi-metal modified carbon nanotubes as a channel for multi-gas identification. A carbon-based thin film transistor gas sensor array using multi-metal modified carbon nanotubes as a channel for gas identification and a preparation method thereof are proposed. Background Art

[0002] Modern living and working environments force humans to spend 90% of their lives in enclosed indoor environments. Indoor toxic gases (such as NH3, HCHO, and H2S) can easily cause adverse health effects, such as pneumonia and leukemia. Therefore, identifying these harmful gases is crucial for medical research in tracing the root causes of diseases. However, using gas sensors to detect mixed gases in complex indoor environments remains a significant challenge. Besides considering the sensitivity, selectivity, and stability of the gas sensor, power consumption, cost, and portability must also be considered.

[0003] Currently, semiconductor-based resistive gas sensors are widely used commercially due to their low cost and ease of manufacturing. However, these sensors are bulky and sensitive to multiple gases, making them difficult to mass-produce and exhibiting poor stability. Therefore, it is necessary to develop a miniaturized, portable gas sensor compatible with integrated circuits that can simultaneously identify multiple gas types and concentrations.

[0004] Existing solutions typically rely on sensor arrays composed of several sensor elements to detect multiple hazardous gases in complex environments. Each sensor element interacts with gas molecules to varying degrees, and the combined response of all sensor elements produces a unique response pattern for each specific test gas. The mutually divergent response data generated by multiple elements requires pattern recognition techniques to intuitively distinguish gas species. Common pattern recognition methods include discriminant function analysis, partial least squares regression (PLS), and principal component analysis (PCA, LDA). Currently, arrays are often used in gas sensors modified with various metal nanoparticles. Viktor Bezugly et al. used gold nanoparticle-functionalized nanotube arrays to achieve a detection limit for H₂S as low as 3 ppb. Angjellari et al. found that nickel-modified SWCNT gas sensors achieved a sensitive response for NH₃, increasing from 1.58 to 5.87. These studies clearly demonstrate that metal nanoparticle-modified gas sensor arrays successfully enhance device selectivity. Therefore, by selecting characteristic metals for different gases to form sensor arrays, which provide varying degrees of specific interaction with gas molecules, it is ultimately possible to distinguish the specific hazardous gases in mixed gas environments. In recent years, field-effect transistors (FETs) have rapidly developed due to their small size, low cost, and ability to achieve high sensitivity and miniaturization in gas sensors. Semiconducting carbon nanotubes (s-CNTs), with their large surface area, high volume ratio, and high carrier mobility, are often used as transport layer materials in FET gas sensors. Therefore, utilizing s-CNT-based FFT gas sensors can achieve device miniaturization and strong signal transmission. Summary of the Invention

[0005] The present invention aims to provide a carbon-based thin-film transistor gas sensor array for gas identification and a method for preparing the same. The invention aims to detect and identify multiple gases through a TFT sensor array with multiple independent channels using nanotubes as the channel layer, thereby achieving highly sensitive detection and accurate identification of multiple gases simultaneously through a single TFT sensor array assembly, thereby promoting real-time online monitoring of multiple harmful gases in indoor environments.

[0006] According to a first aspect of the present invention, a carbon-based thin film transistor sensor array for multi-gas identification is provided. The carbon-based thin film transistor sensor array includes a plurality of independent gas detection channels, each of which includes a CNT-FET sensing unit composed of a silicon-based substrate, a dielectric layer, a source electrode, a drain electrode, and a channel layer.

[0007] The channel active layers of the CNT-FET type sensing units in the multiple gas detection channels are all different, and each CNT-FET type sensing unit is configured with an independent response signal output.

[0008] As an optional embodiment, each CNT-FET type sensing unit is configured to include the following components:

[0009] a silicon-based substrate defining a first surface and an opposing second surface;

[0010] a dielectric layer located on the first surface of the silicon-based substrate;

[0011] a channel layer overlying the dielectric layer; and

[0012] A source electrode and a drain electrode are located on both sides of the upper portion of the channel layer and are spaced apart from each other;

[0013] The channel layer of each CNT-FET type sensing unit is composed of a channel active layer, and the channel active layer is selected from one of an s-CNT channel and an s-CNT channel modified with different metals.

[0014] As an optional embodiment, the s-CNT modified with different metals includes:

[0015] s-CNT channels; and

[0016] A metal thin film layer is deposited on the surface of the s-CNT channel.

[0017] As an optional embodiment, the metal thin film layer is one of Au thin film, Cu thin film, Ti thin film, Ag thin film, Pt thin film or Pd thin film.

[0018] As an optional embodiment, the carbon-based thin film transistor sensor array is used to simultaneously detect formaldehyde, ammonia and hydrogen sulfide gases.

[0019] According to a second aspect of the present invention, a method for preparing a carbon-based thin film transistor sensor array for multi-gas identification is provided, the method comprising the following steps:

[0020] Step 1: depositing a certain thickness of SiO2 on a silicon-based substrate as a dielectric layer to form a Si / SiO2 structure;

[0021] Step 2: depositing an s-CNT film on the upper surface of the dielectric layer;

[0022] Step 3: Spread the Si / SiO2 structure surface with the s-CNT film by a spin coater, expose the corresponding source and drain area patterns by photolithography, and then use electron beam evaporation to deposit metal to form source and drain electrodes;

[0023] Step 4: Performing coating and exposure again, etching the s-CNT film between the source electrode and the drain electrode to obtain an s-CNT channel layer;

[0024] Step 5: Spreading and exposing the second s-CNT channel layer again, and depositing a certain thickness of the first sensitive material on the surface of the s-CNT channel layer by electron beam evaporation to serve as the first metal film layer;

[0025] Step 6: The third s-CNT channel layer is subjected to coating and exposure again, and a second sensitive material of a certain thickness is deposited on the surface of the s-CNT channel layer by electron beam evaporation as the second metal film layer.

[0026] Step 7: The fourth s-CNT channel layer is subjected to coating and exposure again, and a third sensitive material of a certain thickness is deposited on the surface of the s-CNT channel layer by electron beam evaporation to serve as a third metal thin film layer;

[0027] Thus, four independent CNT-FET type sensing units are obtained, each of which includes a silicon-based substrate, a dielectric layer, a source electrode, a drain electrode, and a channel layer. The channel layer is respectively composed of an s-CNT channel layer, a first metal film layer modified on the basis of the s-CNT channel layer, a second metal film layer modified on the basis of the s-CNT channel layer, and a third metal film layer modified on the basis of the s-CNT channel layer.

[0028] Wherein, the source electrode, the drain electrode and the channel layer of each CNT-FET type sensing unit are all led out through metal wires.

[0029] As an optional implementation, the first metal film layer, the second metal film layer and the third metal film layer are Au film, Cu film and Ti film respectively.

[0030] According to a third aspect of the present invention, a carbon-based thin film transistor sensor array assembly for multi-gas identification is provided, wherein the carbon-based thin film transistor sensor array assembly comprises the aforementioned carbon-based thin film transistor sensor array and a processing unit;

[0031] The response output of the CNT-FET type sensing unit of each gas detection channel of the carbon-based thin film transistor type sensor array is transmitted to the processing unit;

[0032] The processing unit is configured to have at least one processor and a memory, and the memory is configured to store response data from the CNT-FET type sensor unit and the LDA gas identification model; the at least one processor is configured to use the response data as input when executing the LDA gas identification model, and output the target gas identification result through the LDA gas identification model.

[0033] As an optional implementation, the LDA gas recognition model is a recognition model obtained by pre-training based on sample data of the target gas.

[0034] The technical solution of the present invention has the following significant beneficial effects:

[0035] The carbon-based thin-film transistor sensor array for multi-gas identification proposed in the present invention solves the problem that a single s-CNT gas sensor is difficult to accurately identify and detect multiple gases due to its own cross-sensitivity. By combining the sensor array of the present invention with a pre-trained LDA recognition model, simultaneous online identification of multiple gases can be achieved. For example, sensor arrays with four channel structures, s-CNT, Au / s-CNT, Cu / s-CNT, and Ti / s-CNT, can achieve real-time online selective gas detection and accurate identification of NH3, H2S, and HCHO.

[0036] The carbon-based thin-film transistor sensor array proposed in the present invention for simultaneous online identification of multiple gases converts gas signals into electrical response signal outputs through gas-sensitive materials, collects and integrates various gas information sources to generate a complete and effective comprehensive gas information library, and adopts a linear discriminant analysis (LDA) model with input data in matrix form as a learning algorithm. Through pattern recognition of sensor responses, classification and recognition of online detection response data are realized. Therefore, the sensor array of the present invention combined with the LDA recognition model can convert complex gas information into visual results, thereby promoting real-time online monitoring of multiple harmful gases in the room.

[0037] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below, as long as such concepts are not mutually inconsistent, can be considered part of the inventive subject matter of this disclosure. In addition, all combinations of the claimed subject matter are considered part of the inventive subject matter of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 FIG. 4 is a schematic diagram of a carbon-based thin film transistor sensor array for multi-gas recognition according to an exemplary embodiment of the present invention.

[0039] Figure 2 This invention Figure 1 Schematic diagram of a gas detection channel of a gas sensor array according to an embodiment.

[0040] Figure 3 1 is a transfer characteristic curve diagram of carbon-based thin film transistors prepared in batches according to an embodiment of the present invention.

[0041] Figure 4 FIG. 4 is a transfer characteristic curve diagram of the gas sensor array according to an embodiment of the present invention.

[0042] Figure 5 3 is a curve showing the relationship between the loading amount of Au / Cu / Ti nanoparticles and the CNT sensing performance in the gas sensor array according to an embodiment of the present invention.

[0043] Figure 6 6a-d and 6e-h are respectively graphs showing the response changes of the gas sensor array of an embodiment of the present invention to 10 ppm target gas at different test temperatures, and comparative bar graphs showing the response values ​​of the gas sensor array to seven 10 ppm reducing gases.

[0044] Figure 7 ac is a dynamic response diagram of the gas sensor array of an embodiment of the present invention to three major indoor pollutants: formaldehyde, ammonia and hydrogen sulfide at its optimal temperature.

[0045] Figure 8 ac are respectively the concentration-response curves, response value heat maps and classification maps of different gas types of the gas sensor array of an embodiment of the present invention to three VOC gases (ammonia, hydrogen sulfide and formaldehyde).

[0046] Figure 9 This is a repeatability test diagram of the gas sensor array according to an embodiment of the present invention.

[0047] Figure 10 Schematic diagram of training group data used for LDA model training according to an embodiment of the present invention.

[0048] Figure 11 This is a diagram illustrating test group data used for LDA model training according to an embodiment of the present invention.

[0049] Figure 12 It is a visualization diagram of the recognition result according to the LDA recognition model in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0051] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed herein are not limited to any embodiment. In addition, some aspects of the present disclosure may be used alone or in any appropriate combination with other aspects disclosed herein.

[0052] Carbon-based thin-film transistor sensor array for multi-gas identification

[0053] Combine Figure 1 、 2 The carbon-based thin film transistor sensor array 100 for multi-gas identification shown in the example includes multiple independent gas detection channels, each gas detection channel includes a CNT-FET type sensing unit 200 composed of a silicon-based substrate 1, a dielectric layer 2, a source electrode 3, a drain electrode 4 and a channel layer.

[0054] The channel active layers of the CNT-FET type sensing units in the multiple gas detection channels are all different, and each CNT-FET type sensing unit is configured with an independent response signal output.

[0055] As an optional embodiment, each CNT-FET type sensing unit is configured to include the following components:

[0056] A silicon-based substrate 1 defines a first surface and an opposite second surface;

[0057] A dielectric layer 2 located on the first surface of the silicon-based substrate;

[0058] a channel layer located above the dielectric layer 2; and

[0059] A source electrode 3 and a drain electrode 4 are located on both sides of the channel layer and are spaced apart from each other;

[0060] The channel layer of each CNT-FET type sensing unit is composed of a channel active layer, and the channel active layer is selected from one of an s-CNT channel and an s-CNT channel modified with different metals.

[0061] Combine Figure 1 As shown, the channel active layers are respectively an s-CNT channel layer 5, a first metal film layer 6 modified on the basis of the s-CNT channel layer, a second metal film layer 7 modified on the basis of the s-CNT channel layer, and a third metal film layer 8 modified on the basis of the s-CNT channel layer.

[0062] In an embodiment of the present invention, the first metal film layer, the second metal film layer, and the third metal film layer are Au film, Cu film, and Ti film, respectively.

[0063] That is, the material of the metal film layer is selected from sensitive materials used to improve the gas selectivity of the s-CNT channel: Au film, which is selective for NH3 gas and is used to detect ammonia NH3; Cu film, which is selective for H2S gas and is used to detect hydrogen sulfide H2S; Ti film, which is selective for HCHO gas and is used to detect formaldehyde gas HCHO.

[0064] It should be understood that in the aforementioned embodiment, the channel layer formed by the first metal thin film layer Au modified on the basis of the s-CNT channel layer is referred to as Au / CNT for short.

[0065] The channel layer formed by the second metal film layer Cu modified on the basis of the s-CNT channel layer is referred to as Cu / CNT.

[0066] The third metal thin film layer Ti modified on the basis of the s-CNT channel layer forms a channel layer, which is referred to as Ti / CNT for short.

[0067] Combine Figure 1 As shown, in an embodiment of the present invention, a plurality of CNT-FET type sensing units 200 share the same silicon-based substrate 1 and dielectric layer 2 .

[0068] A silicon dioxide dielectric layer of a certain thickness is grown on the surface of the silicon-based substrate 1 to form a Si / SiO2 structure, which constitutes a common base for the entire sensor arrangement.

[0069] It should be understood that each type of CNT-FET type sensing unit 200 corresponds to a channel active layer, that is, one selected from the aforementioned s-CNT channel and s-CNT channels modified with different metals. Figure 1 The sensor array design of the illustrated example includes the four CNT-FET type sensing units mentioned above, which respectively use s-CNT, Au / CNT, Cu / CNT and Ti / CNT as channels.

[0070] In the embodiment of the present invention, each type of CNT-FET type sensing unit 200 can be sequentially and periodically arranged on the common substrate composed of the aforementioned Si / SiO2 structure to improve the success rate of detection and effective response output. Figure 1 In the example sensor array design shown, each type of CNT-FET type sensor unit 200 is arranged and designed with 6 identical structures. The source electrode, drain electrode and channel layer of each CNT-FET type sensor unit 200 are led out through metal leads to achieve voltage bias and response signal output.

[0071] In the embodiment of the present invention, Figure 1 、 2 As shown, the silicon-based substrate 1 can be a P-type silicon substrate with a resistivity of 0.001 to 0.005 Ω·cm. The silicon-based substrate 1 defines a first surface and an opposite second surface. Figure 1 As shown, for the sake of convenience, the first surface is used as the growth surface to be prepared subsequently.

[0072] like Figure 1 、 2As shown, the dielectric layer 2 is grown on the first surface of the silicon-based substrate 1 .

[0073] As an optional example, the dielectric layer 2 is a silicon dioxide dielectric layer with a thickness of 100 to 300 nm.

[0074] Therefore, the silicon dioxide dielectric layer serves as a deposition base for the s-CNT film on the one hand, and realizes electrical insulation between the s-CNT film and the silicon-based substrate 1 on the other hand.

[0075] like Figure 1 、 2 As shown, the source electrode 3 and the drain electrode 4 are located on a surface of the channel layer away from the dielectric layer 2 .

[0076] Thus, a source electrode 3 and a drain electrode 4 are spaced apart on both sides above the channel layer. The source electrode 3 and the drain electrode 4 are arranged opposite each other and spaced apart, with an s-CNT thin film deposited between them, which is etched to form an s-CNT channel.

[0077] In the embodiment of the present invention, the s-CNT channel adopts a network-structured semiconducting carbon nanotube with a thickness of 1 to 2 nm.

[0078] As an optional example, the channel width is 10 to 30 μm, and the channel length is 5 to 100 μm.

[0079] exist Figure 1 、 2 In the example shown, the s-CNT channel has a channel width of 20 μm and a channel length of 5 μm.

[0080] As an optional embodiment, the source electrode 3 and the drain electrode 4 have the same thickness.

[0081] As an optional embodiment, the source electrode and the drain electrode are both Au / Pd electrode layers, and the thickness thereof are both 20 to 60 nm.

[0082] In an embodiment of the present invention, the sensitive material layer is a metal film layer deposited on the surface of the s-CNT channel using electron beam evaporation technology. For example, the sensor array proposed in the aforementioned embodiment for simultaneously detecting formaldehyde, ammonia and hydrogen sulfide gases, the corresponding design uses a Ti film for detecting formaldehyde gas HCHO, an Au film for detecting ammonia gas NH3, and a Cu film for detecting hydrogen sulfide H2S.

[0083] In another embodiment, the metal film layer may also be made of a sensitive material with gas selectivity in gas pressure, such as Pd, Pt, or Ag.

[0084] As an optional embodiment, in the carbon-based thin-film transistor sensor array for multi-gas identification of the present invention, during a specific detection process, the gate voltage applied is -60 to +40V, and the gate voltage is scanned from a starting point to an end point. The readout voltage applied to the source and drain electrodes is -0.1V.

[0085] Combine Figure 1 、 2 As shown, the CNT-FET sensor unit 200 in each gas detection channel, upon exposure to the target gas, converts gas changes into electrical signals, collecting gas information. Based on the response outputs of the CNT-FET sensor units 200 in the four gas detection channels, the processing unit classifies and identifies the gases, outputting the target gas identification results.

[0086] In an optional embodiment, the target gas identification result is output and represented in a visual manner.

[0087] Carbon-based thin-film transistor sensor array assembly for multi-gas identification

[0088] In combination with an embodiment of the present invention, a carbon-based thin-film transistor sensor array assembly for identifying multiple gases is proposed, which includes the carbon-based thin-film transistor sensor array 100 of an embodiment of the present invention, and a processing unit that is signal-connected to the carbon-based thin-film transistor sensor array 100 and is used to classify and identify response signals output by the carbon-based thin-film transistor sensor array 100.

[0089] The response output of the CNT-FET type sensing unit of each gas detection channel of the carbon-based thin film transistor type sensor array 100 is transmitted to the processing unit.

[0090] In an optional embodiment, the processing unit can be configured to be integrated with the carbon-based thin film transistor type sensor array 100 in a favorable manner, for example, integrated with the carbon-based thin film transistor type sensor array 100 in the form of a processing chip (IC) to achieve real-time online processing of the response data output by the carbon-based thin film transistor type sensor array 100.

[0091] As an optional embodiment, the processing unit is configured to include at least one processor and a memory, wherein the memory is configured to store response data from the CNT-FET sensor unit and the LDA gas identification model. The at least one processor is configured to receive the response data as input when executing the LDA gas identification model and output a target gas identification result based on the LDA gas identification model.

[0092] Among them, the LDA gas recognition model is a recognition model obtained by pre-training based on sample data of the target gas.

[0093] Below we will use some examples to describe the training of the LDA gas recognition model and its operation process in the embodiments of the present invention. In the following embodiments, we take the sensor array prepared in the above embodiment for the simultaneous detection of formaldehyde HCHO, ammonia NH3 and hydrogen sulfide H2S gases as an example.

[0094] The training process of the LDA gas recognition model includes the following steps:

[0095] Step 1: The sensor array collects the response current data of three gases, H2S, NH3 and HCHO, and the response output of the sensor array to each gas at a predetermined gas concentration can be obtained. The response output of each gas includes the response output of four different gas detection channels corresponding to s-CNT, Au / CNT, Cu / CNT and Ti / CNT channel structures. In the embodiment of the present invention, 1ppm, 3ppm, 5ppm, 8ppm and 10ppm are used as examples for explanation. The specific response output can be expressed as follows: Figure 7 Take ac as an example;

[0096] Step 2: Processing the response output of the gas collected by the sensor array into a response value S;

[0097] The conversion formula as an example is:

[0098] S=(I gas -I air ) / I air *100%

[0099] Among them I gas , I ai are the current values ​​of the sensing array in the target gas and background gas respectively;

[0100] Step 3: Classify the response data according to the channel structures of s-CNT, Au / CNT, Cu / CNT and Ti / CNT, and divide them into training group and test group, as shown in Figure 3. Figure 10 and Figure 11 In the example shown, the training group is used to train the LDA model, and the test group is used to test the accuracy of the LDA model.

[0101] Therefore, the LDA model is trained using the training set data, and an LDA recognition model that meets the prediction progress is obtained through training.

[0102] It should be understood that the training group data and test group data listed in the figure are illustrated using 5 groups as an example. In other embodiments, the model can be trained based on more sampling data, such as response data under more concentration conditions.

[0103] The training process may adopt the training process of the existing LDA recognition model.

[0104] For example, Figure 10 、 11 For sample data, the training process of the LDA recognition model includes: calculating the between-group covariance matrix B; calculating the within-group variance matrix W4x4; calculating the matrix W-1B and the eigenvectors of the matrix; sorting the eigenvalues ​​of the matrix W-1B and projecting the dimension. Through projecting the dimension, we can obtain the visual classification results, such as Figure 12 shown.

[0105] Preparation of sensor arrays

[0106] A method for preparing a carbon-based thin film transistor sensor array for multi-gas identification according to an embodiment of the present invention includes the following steps:

[0107] Step 1: depositing SiO2 of a certain thickness on a silicon-based substrate 1 as a dielectric layer 2 to form a Si / SiO2 structure;

[0108] Step 2: depositing an s-CNT film on the upper surface of the dielectric layer;

[0109] Step 3: Spread the Si / SiO2 structure surface with the s-CNT film by a spin coater, expose the corresponding source and drain region patterns by photolithography, and then use electron beam evaporation to deposit metal to form the source electrode 3 and the drain electrode 4;

[0110] Step 4: Performing coating and exposure again, etching the s-CNT film between the source electrode and the drain electrode to obtain the s-CNT channel layer 5;

[0111] Step 5: Spreading and exposing the second s-CNT channel layer again, and depositing a first sensitive material of a certain thickness on the surface of the s-CNT channel layer by electron beam evaporation to form the first metal film layer 6;

[0112] Step 6: Spreading and exposing the third s-CNT channel layer again, and depositing a second sensitive material of a certain thickness on the surface of the s-CNT channel layer by electron beam evaporation to form a second metal film layer 7;

[0113] Step 7: The fourth s-CNT channel layer is subjected to coating and exposure again, and a third sensitive material having a certain thickness is deposited on the surface of the s-CNT channel layer by electron beam evaporation to serve as a third metal film layer 8;

[0114] Thus, four independent CNT-FET type sensing units are obtained, each of which includes a CNT-FET type sensing unit composed of a silicon substrate, a dielectric layer, a source electrode, a drain electrode, and a channel layer, wherein the channel layer is respectively an s-CNT channel layer 5, a first metal film layer 6 modified on the basis of the s-CNT channel layer, a second metal film layer 7 modified on the basis of the s-CNT channel layer, and a third metal film layer 8 modified on the basis of the s-CNT channel layer;

[0115] The source electrode, drain electrode and channel layer of each CNT-FET type sensing unit are all led out through metal wires.

[0116] The first metal film layer 6 , the second metal film layer 7 , and the third metal film layer 8 are Au film, Cu film, and Ti film, respectively.

[0117] The deposition of the SiO2 dielectric layer and the deposition of s-CNT can be prepared using existing semiconductor micro-nano processes.

[0118] Preferably, the s-CNT film has a network-structured semiconducting carbon nanotube with a purity of 99.99% or more.

[0119] In an optional embodiment, the source electrode and the drain electrode are Pd / Au metal electrodes with a thickness of 20 to 60 nm.

[0120] Sensor array electrical performance test

[0121] Electrical testing and analysis were performed on the carbon-based thin film transistor sensor array for multi-gas identification prepared in the aforementioned embodiment.

[0122] Figure 3 The transfer characteristic curves of 70 sensors fabricated on the same substrate are shown. ds =-0.1V, V gs Increase the voltage from -60V to +40V in steps of 0.5V and measure the corresponding I ds .

[0123] Figure 4 The transfer characteristic curve of the sensor array is shown. ds =-0.1V, V gs Increase the voltage from -80V to +60V in steps of 0.5V and measure the corresponding I ds .

[0124] Combine Figure 3 As shown, Figure 3The high overlap of the transfer characteristic curves shown in shows that the electrical parameters of the devices prepared in batches are consistent, which can provide reliable support for obtaining stable gas sensing performance. Figure 4 As can be seen in the figure, after the deposition of Au / Cu / Ti metal nanoparticles, the device transfer characteristic curve changes to a certain extent, proving the successful modification of the metal particles.

[0125] Gas sensing performance test of sensor array

[0126] Gas sensing testing and analysis were performed based on the carbon-based thin film transistor sensor array for multi-gas identification prepared in the above embodiment.

[0127] Figure 5 The relationship curve between the loading amount of Au / Cu / Ti nanoparticles and CNT sensing performance in the gas sensor array is shown in Figure 2. Figure 5 The results show that the response of the gas sensors corresponding to Au / CNT, Cu / CNT and Ti / CNT shows a gradually decreasing trend with the increase of the thickness of the metal Au / Cu / Ti deposition), while the CNT gas sensor modified with 1nm Au / Cu / Ti shows the highest response value, which indicates that the CNT modified with 1nm metal particles is the optimal doping amount and can obtain the expected maximum response output.

[0128] In an embodiment of the present invention, in addition to the 1nm thickness of the metal deposited on the surface of the s-CNT channel, the effects of the deposition thickness of 3nm, 5nm, and 7nm on the gas-sensing performance of the s-CNT are also explored. Among them, when the metal deposition thickness is 1nm, the gas-sensing performance is the best. Among them, when the sensitive material is deposited with a thickness of 1nm and 3nm, it appears as a metal particle layer, which we usually call a discontinuous metal film, and when the deposition thickness is 5nm and 7nm, it is a metal film, which we usually call a continuous metal film. For the sake of convenience and unification, we collectively refer to the 1nm, 3nm, 5nm, and 7nm metal layers deposited on the surface of the s-CNT channel as metal film layers.

[0129] like Figure 6 As shown in Figures ad, the sensor array's response to a 10ppm target gas at different test temperatures shows that the optimal response temperature for the CNT gas sensor in the sensor array is 175°C, while the optimal operating temperature for the Au / CNT, Cu / CNT, and Ti / CNT gas sensors is 150°C. Therefore, the gas sensor fabricated in this invention can be used for online testing at a temperature of 150°C. For example, the sensor assembly can be packaged in a detection device, where ambient gas detection can be achieved by heating the device and allowing ambient gas to flow across the sensor array surface.

[0130] like Figure 6 eh shows a comparative histogram of the response values ​​of the gas sensor array prepared by the present invention to seven 10ppm reducing gases. Through comparison, it is found that modifying different types of metal particles on CNT will lead to different changes in the selectivity of the CNT gas sensor. Figure 7 ac represents the dynamic response diagram of the gas sensor array to three major indoor pollutants: formaldehyde, ammonia and hydrogen sulfide at its optimal temperature.

[0131] Figure 8 ac are the concentration-response curves of the gas sensor array to three VOC gases (ammonia, hydrogen sulfide and formaldehyde), the response value heat map and the classification map of different gas types.

[0132] Figure 9 This is a repeatability test diagram of the gas sensor array. It can be seen that the sensor array has good selectivity.

[0133] It can be seen that the carbon-based thin-film transistor sensor array for multi-gas identification based on the exemplary embodiment of the present invention utilizes carbon nanotubes modified with different metal nanoparticles (Au, Cu and Ti) to construct a TFT gas sensor array, and the LDA algorithm is used to perform data analysis on the gas-sensitive signals with different responses to achieve selective identification of three target gases (NH3, H2S and HCHO), providing an effective way to achieve online rapid detection of target gases in complex indoor gas environments.

[0134] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A carbon-based thin film transistor sensor array for multi-gas identification, characterized in that: The carbon-based thin film transistor sensor array includes multiple independent gas detection channels for simultaneously detecting formaldehyde, ammonia and hydrogen sulfide gases. Each gas detection channel includes a CNT-FET type sensing unit composed of a silicon-based substrate, a dielectric layer, a source electrode, a drain electrode and a channel layer. The channel active layers of the CNT-FET type sensing units in the multiple gas detection channels are all different, and each CNT-FET type sensing unit is configured with an independent response signal output; Each CNT-FET type sensing unit is configured to include the following components: a silicon-based substrate defining a first surface and an opposing second surface; a dielectric layer located on the first surface of the silicon-based substrate; a channel layer overlying the dielectric layer; and A source electrode and a drain electrode are located on both sides of the upper portion of the channel layer and are spaced apart from each other; Wherein, the channel layer of each CNT-FET type sensing unit is composed of a channel active layer, and the channel active layer is selected from one of an s-CNT channel and an s-CNT channel modified with different metals; The different metal modified s-CNTs include: s-CNT channels; and A metal film layer deposited on the surface of the s-CNT channel, wherein the metal film layer is a Ti film, an Au film, and a Cu film; The s-CNT channel is a network-shaped s-CNT channel structure with a thickness of 1 to 2 nm.

2. The carbon-based thin film transistor sensor array for multi-gas identification according to claim 1, characterized in that: The thickness of the metal thin film layer is greater than or equal to 1 nm.

3. The carbon-based thin film transistor sensor array for multi-gas identification according to claim 1, characterized in that: The source electrode and the drain electrode are both Au / Pd electrode layers, and the thickness thereof is 20-60 nm.

4. A method for preparing a carbon-based thin film transistor sensor array for multi-gas identification according to claim 3, characterized in that: The preparation method comprises the following steps: Step 1: depositing a certain thickness of SiO2 on a silicon-based substrate as a dielectric layer to form a Si / SiO2 structure; Step 2: depositing an s-CNT film on the upper surface of the dielectric layer; Step 3: Spread the Si / SiO2 structure surface with the s-CNT film by a spin coater, expose the corresponding source and drain area patterns by photolithography, and then use electron beam evaporation to deposit metal to form source and drain electrodes; Step 4: Performing coating and exposure again, etching the s-CNT film between the source electrode and the drain electrode to obtain an s-CNT channel layer; Step 5: Spreading and exposing the second s-CNT channel layer again, and depositing a certain thickness of the first sensitive material on the surface of the s-CNT channel layer by electron beam evaporation to serve as the first metal film layer; Step 6: The third s-CNT channel layer is subjected to coating and exposure again, and a second sensitive material of a certain thickness is deposited on the surface of the s-CNT channel layer by electron beam evaporation as the second metal film layer. Step 7: The fourth s-CNT channel layer is subjected to coating and exposure again, and a third sensitive material of a certain thickness is deposited on the surface of the s-CNT channel layer by electron beam evaporation to serve as a third metal thin film layer; Thus, four independent CNT-FET type sensing units are obtained, each of which includes a silicon-based substrate, a dielectric layer, a source electrode, a drain electrode, and a channel layer. The channel layer is respectively composed of an s-CNT channel layer, a first metal film layer modified on the basis of the s-CNT channel layer, a second metal film layer modified on the basis of the s-CNT channel layer, and a third metal film layer modified on the basis of the s-CNT channel layer. Wherein, the source electrode, the drain electrode and the channel layer of each CNT-FET type sensing unit are all led out through metal wires.

5. The method for preparing a carbon-based thin film transistor sensor array for multi-gas identification according to claim 4, characterized in that: The first metal thin film layer, the second metal thin film layer and the third metal thin film layer are Au thin film, Cu thin film and Ti thin film respectively.

6. A carbon-based thin film transistor sensor array assembly for multi-gas identification, characterized in that: The carbon-based thin film transistor sensor array assembly comprises the carbon-based thin film transistor sensor array according to any one of claims 1 to 3 and a processing unit; The response output of the CNT-FET type sensing unit of each gas detection channel of the carbon-based thin film transistor type sensor array is transmitted to the processing unit; The processing unit is configured to have at least one processor and a memory, and the memory is configured to store response data from the CNT-FET type sensor unit and the LDA gas identification model; the at least one processor is configured to use the response data as input when executing the LDA gas identification model, and output the target gas identification result through the LDA gas identification model.

7. The carbon-based thin film transistor sensor array assembly for multi-gas identification according to claim 6, characterized in that: The LDA gas recognition model is a recognition model obtained by pre-training based on sample data of the target gas.

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