A multi-modal modulatable flexible sensor and modulation method, preparation method thereof

Abstract

The application discloses a kind of multimodal modulatable flexible sensors and its modulation method, preparation method, it is related to sensor technical field, the flexible substrate layer of the sensor is by bottom to top sequentially deposited bottom electrode, intermediate composite functional layer and top sensitive layer;Bottom electrode and intermediate composite functional layer constitute intermediate layer;First filling layer is deposited on the side of intermediate layer;Second filling layer is deposited on the other side of intermediate layer;First electrode is deposited on first filling layer;Second electrode is deposited on second filling layer;First electrode and second electrode are in contact with top sensitive layer.The application not only can realize the independent perception of multimodal, but also can realize the online modulation of sensing performance, improve the adaptability and sensitivity of sensor while simplifying structure, facilitate integration.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a multimodal modulated flexible sensor and its modulation and fabrication methods. Background Technology

[0002] The continuous expansion of the IoT terminal device market has driven the rapid development of sensor technology. Compared to traditional rigid silicon-based sensors, the emergence of flexible sensors has greatly expanded the application of sensing technology in wearable IoT, healthcare, smart monitoring, and electronic skin. However, sensors currently face two major requirements: dynamically changing sensing scenarios and the need for multi-parameter sensing. For example, in the cold chain transportation of aquatic products, the products undergo different stages: live → dead → fresh → spoiled. The markers that need to be sensed differ in these four stages, including typical marker gases such as oxygen, carbon dioxide, and gases that may be produced during spoilage, such as ammonia and hydrogen sulfide. In addition to gases in the microenvironment, vibration can cause significant stress responses in living organisms or directly damage the product, all of which can cause significant and irreversible harm to the quality and safety of the product. Therefore, it can be seen that the development of flexible sensors currently faces two main problems:

[0003] 1) The sensing function of single-modal sensing is difficult to meet the needs of accurate analysis based on multi-source data fusion. For sensing information of a single parameter, it is difficult for terminal devices to perform multi-dimensional analysis, judgment and prediction based on a single type of sensing information, which is prone to a series of problems such as inaccurate analysis, judgment error and inaccurate prediction. It is difficult to meet the needs of IoT terminals or wearable devices to accurately judge and evaluate the complex environment in which they are located.

[0004] 2) Flexible sensors with fixed performance parameters struggle to simultaneously meet the dynamic changes of different sensing scenarios. Currently, a common solution for real-time dynamic applications is to deploy multiple sensors of various types (with different sensing ranges and sensitivity parameters) to meet the actual needs of the scenario and alleviate the applicability issues of flexible sensors. However, this solution obviously results in high area occupancy, high power consumption, high cost, and compatibility problems between different sensor models. This hinders the trend towards sensor integration and intelligence, as well as the numerous application requirements for sensor miniaturization, low power consumption, and high integration. Meanwhile, traditional impedance-based quality monitoring is susceptible to interference, has an unclear sensing mechanism, and exhibits significant individual monitoring differences, leading to poor coupling evaluation and decision-making effects based on the final sensing data.

[0005] Therefore, in view of the practical difficulties faced by the above-mentioned flexible sensors in practical applications, there is an urgent need to develop a multimodal flexible sensor device and integration method with modulated performance. Summary of the Invention

[0006] Based on this, embodiments of the present invention provide a multimodal modulated flexible sensor and its modulation and fabrication methods, which can not only realize independent sensing of multiple modes, but also realize online modulation of sensing performance. While improving the adaptability and sensitivity of the sensor, it simplifies the structure and facilitates integration.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A multimodal modulated flexible sensor includes: a flexible substrate layer, a bottom electrode, an intermediate composite functional layer, a top sensitive layer, a first filling layer, a second filling layer, a first electrode, and a second electrode;

[0009] The bottom electrode, the intermediate composite functional layer, and the top sensitive layer are deposited sequentially from bottom to top on the flexible substrate layer; the bottom electrode and the intermediate composite functional layer constitute an intermediate layer; a first filling layer is deposited on one side of the intermediate layer; a second filling layer is deposited on the other side of the intermediate layer; a first electrode is deposited on the first filling layer; a second electrode is deposited on the second filling layer; both the first electrode and the second electrode are in contact with the top sensitive layer.

[0010] The intermediate composite functional layer is used for:

[0011] In a pressure sensing scenario, the bottom electrode and the top electrode are connected to generate a pressure sensing signal; the top electrode is either the first electrode or the second electrode.

[0012] The top sensitive layer is used for:

[0013] In a gas sensing scenario, the first electrode and the second electrode are connected to generate a gas sensing signal;

[0014] The intermediate composite functional layer is also used for:

[0015] To meet different monitoring needs, different voltage pulses are applied to the bottom electrode and the top electrode to generate different modulation fields, thereby changing the type of the top sensitive layer and modulating the sensing performance of the top sensitive layer; the types include the initial zero bandgap state, the modulated N-type state, and the modulated P-type state.

[0016] Optionally, the multimodal modulated flexible sensor further includes a modulation module; the modulation module is connected to the bottom electrode and the top electrode respectively.

[0017] The modulation module is used for:

[0018] In the gas sensing scenario, when the monitoring requirement is an oxidizing gas scenario and modulation is required, the top electrode is controlled to be positively charged and the bottom electrode is grounded, thereby applying a positive voltage pulse to the intermediate composite functional layer, causing the intermediate composite functional layer to generate a modulation field with the polarization direction pointing downward, thereby causing the top sensitive layer to change from the zero bandgap state to the N-type state, so as to achieve modulation of the oxidizing gas sensing performance of the top sensitive layer;

[0019] In the gas sensing scenario, when the monitoring requirement is a reducing gas scenario and modulation is required, the top electrode is grounded and the bottom electrode is positively charged, thereby applying a negative voltage pulse to the intermediate composite functional layer. This causes the intermediate composite functional layer to generate a modulation field with the polarization direction pointing upward, thereby causing the top sensitive layer to change from a zero bandgap state or an N-type state to a P-type state, so as to achieve modulation of the reducing gas sensing performance of the top sensitive layer.

[0020] Optionally, the material of the intermediate composite functional layer is a ferroelectric material, which is one or more of lead titanate, barium titanate, strontium titanate, polyvinylidene fluoride, and hafnium-based ferroelectric materials.

[0021] Optionally, the material of the top sensitive layer is a zero-bandgap sensitive material, such as graphene.

[0022] Optionally, both the first electrode and the second electrode are made of one of titanium nitride, tungsten, silver and platinum.

[0023] The present invention also provides a modulation method for the above-described multimodal modulated flexible sensor, comprising:

[0024] For different monitoring needs, different voltage pulses are applied to the intermediate composite functional layer through the bottom electrode and the top electrode. The intermediate composite functional layer generates different modulation fields, thereby changing the type of the top sensitive layer to achieve modulation of the sensing performance of the top sensitive layer. The top electrode is either the first electrode or the second electrode. The type includes the initial zero bandgap state, the modulated N-type state, and the modulated P-type state.

[0025] Optionally, for different monitoring needs, different voltage pulses are applied to the intermediate composite functional layer through the bottom and top electrodes. The intermediate composite functional layer generates different polarization modulation fields, thereby changing the type of the top sensitive layer to modulate the sensing performance of the top sensitive layer. Specifically, this includes:

[0026] In a gas sensing scenario, when the monitoring requirement is an oxidizing gas scenario and modulation is required, the top electrode is connected to positive voltage and the bottom electrode is grounded, thereby applying a positive voltage pulse to the intermediate composite functional layer, causing the intermediate composite functional layer to generate a modulation field with the polarization direction pointing downward, thereby causing the top sensitive layer to change from a zero bandgap state to an N-type state, so as to achieve modulation of the oxidizing gas sensing performance of the top sensitive layer.

[0027] In the gas sensing scenario, when the monitoring requirement is a reducing gas scenario and modulation is required, the top electrode is grounded and the bottom electrode is positively charged, thereby applying a negative voltage pulse to the intermediate composite functional layer. This causes the intermediate composite functional layer to generate a modulation field with the polarization direction pointing upward, thereby causing the top sensitive layer to change from a zero-bandgap state or an N-type state to a P-type state, so as to achieve modulation of the reducing gas sensing performance of the top sensitive layer.

[0028] The present invention also provides a method for fabricating the above-described multimodal modulated flexible sensor, comprising:

[0029] A flexible substrate material is subjected to ozone plasma treatment for a set duration to obtain a flexible substrate layer.

[0030] A bottom electrode of a first predetermined thickness is deposited on the surface of the flexible substrate layer;

[0031] Under vacuum conditions, a second intermediate composite functional layer of a predetermined thickness is deposited on the surface of the bottom electrode and annealed to induce the piezoelectricity of the intermediate composite functional layer; the bottom electrode and the intermediate composite functional layer constitute an intermediate layer.

[0032] A first filler layer is deposited on one side of the intermediate layer, and a second filler layer is deposited on the other side of the intermediate layer;

[0033] A third top sensitive layer of a predetermined thickness is deposited on the surface of the intermediate composite functional layer, and then cured and dried.

[0034] A first electrode is deposited on the first filling layer, and a second electrode is deposited on the second filling layer; both the first electrode and the second electrode are in contact with the top sensitive layer, thereby obtaining a multimodal modulated flexible sensor.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] This invention proposes a multimodal modulated flexible sensor, its modulation method, and its fabrication method. An intermediate composite functional layer is configured, which connects the bottom and top electrodes (first or second electrode) in a pressure sensing scenario to generate a pressure sensing signal. A top sensitive layer is configured, which connects the first and second electrodes in a gas sensing scenario to generate a gas sensing signal. Independent sensing of the two modes is achieved through the independent sensing between the intermediate composite functional layer and the top sensitive layer. The intermediate composite functional layer can also generate different modulation fields under different voltage pulses applied through the bottom and top electrodes, thereby changing the type of the top sensitive layer. The coupling polarization effect between the intermediate composite functional layer and the top sensitive layer modulates the sensing performance of the top sensitive layer. Therefore, this invention not only achieves independent multimodal sensing but also modulates the sensing performance, improving the sensor's adaptability and sensitivity while simplifying the structure and facilitating integration. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a structural diagram of a multimodal modulated flexible sensor provided in an embodiment of the present invention;

[0039] Figure 2 A perspective view of a multimodal modulated flexible sensor provided in an embodiment of the present invention;

[0040] Figure 3 This is a flowchart illustrating the fabrication method of the multimodal modulated flexible sensor of this application;

[0041] Figure 4 This is a schematic diagram of the modulation method for the sensing performance of the multimodal modulated flexible sensor of this application;

[0042] Figure 5 This is a schematic diagram of the modulation and state discrimination output strategy of the multimodal modulated flexible sensor of this application;

[0043] Figure 6 This diagram illustrates the modulation principle of the multimodal modulated flexible sensor of this application and compares three different modulation states.

[0044] Figure 7 This is a schematic diagram of the multi-level polarization doped modulation states generated by the intermediate composite functional layer of the multimodal modulated flexible sensor of this application under different modulation voltages.

[0045] Symbol explanation: 1-Multimodal modulated flexible sensor; 11-Second electrode; 12-Second filling layer; 13-Flexible substrate layer; 14-First filling layer; 15-First electrode; 16-Bottom electrode; 17-Intermediate composite functional layer; 18-Top sensitive layer. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] To address the limitations of existing technologies in meeting multimodal sensing requirements and the applicability of traditional sensors, this invention provides a multimodal modulated flexible sensor and its modulation and fabrication method. Through the independent sensing and coupled polarization between the intermediate composite functional layer and the top sensitive layer, independent sensing of two parameters can be achieved. At the same time, by applying a corresponding voltage operation to the intermediate composite functional layer, the sensing performance of the top sensitive layer can be modulated online in real time.

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] See Figures 1-2 The multimodal modulated flexible sensor 1 of this embodiment includes: a flexible substrate layer 13, a bottom electrode 16, an intermediate composite functional layer 17, a top sensitive layer 18, a first filling layer 14, a second filling layer 12, a first electrode 15, and a second electrode 11.

[0050] The bottom electrode 16, the intermediate composite functional layer 17, and the top sensitive layer 18 are sequentially deposited from bottom to top on the flexible substrate layer 13; the bottom electrode 16 and the intermediate composite functional layer 17 constitute an intermediate layer; the first filling layer 14 is deposited on one side of the intermediate layer; the second filling layer 12 is deposited on the other side of the intermediate layer; the first electrode 15 is deposited on the first filling layer 14; the second electrode 11 is deposited on the second filling layer 12; both the first electrode 15 and the second electrode 11 are in contact with the top sensitive layer 18.

[0051] The intermediate composite functional layer 17 and the top sensitive layer 18 can sense different parameters, and the intermediate composite functional layer 17 can modulate the sensing response characteristics (sensing performance) of the top sensitive layer 18 online in real time according to monitoring requirements. Specifically:

[0052] The intermediate composite functional layer 17 is used for:

[0053] In a pressure sensing scenario, the bottom electrode 16 and the top electrode are connected to generate a pressure sensing signal; the top electrode is either the first electrode 15 or the second electrode 11. For example, when the multimodal modulated flexible sensor 1 is subjected to dynamic pressure, due to the piezoelectric effect of the intermediate composite functional layer 17, a circuit is formed by connecting the bottom electrode 16 and the top electrode, and a passive AC voltage signal is output. The output AC voltage signal is the pressure sensing signal, and the amplitude of the AC voltage signal is proportional to the magnitude of the dynamic pressure. Because the dynamic pressure signal is sensed by relying on the piezoelectric principle of the intermediate composite functional layer 17, the multimodal modulated flexible sensor 1 does not require any external power supply, which is particularly advantageous in scenarios with long-term monitoring and limited space.

[0054] The top sensitive layer 18 is used for:

[0055] In a gas sensing scenario, the first electrode 15 and the second electrode 11 are connected to generate a gas sensing signal. For example, when the top sensitive layer 18 of the multimodal modulated flexible sensor 1 comes into contact with corresponding gas (oxidizing or reducing gas) molecules, and it responds to both oxidizing gases (O2, Cl2, NO2, O3) and reducing gases (H2, H2S, CO), the gas molecules can reversibly act as temporary dopants, either increasing or decreasing the conductivity of the top sensitive layer 18. The amplitude of its response is proportional to the gas concentration. By connecting the first electrode 15 and the second electrode 11 through the top sensitive layer 18, the top sensitive layer 18 provides an active output. By measuring the resistance of the top sensitive layer 18 (gas sensing signal), the gas type and gas concentration are monitored.

[0056] The intermediate composite functional layer 17 is also used to modulate the top sensitive layer, such as... Figure 4 As shown, the process mainly includes three steps: connecting the modulation module to the bottom and top electrodes → applying a modulation pulse signal → obtaining a multimodal modulated flexible sensor. Specifically:

[0057] To meet different monitoring needs, different voltage pulses (voltage pulses of different polarities and amplitudes) applied to the bottom electrode 16 and the top electrode generate different modulation fields (modulation fields of different directions and magnitudes). The resulting non-volatile polarization charges dope the top sensitive layer 18 to varying degrees, thereby changing the type of the top sensitive layer 18 and modulating its sensing performance. This satisfies the requirements for online, real-time, and modification capabilities, altering the response characteristics of the top sensitive layer 18 to different types of gases. The types include several typical types, such as: the initial zero-bandgap state, the modulated N-type state, and the modulated P-type state. The initial zero-bandgap state is the pristine state. Modulating the pristine state yields either the modulated N-type or the modulated P-type state. In the N-type state, the electron concentration in the top sensitive layer 18 is greater than the hole concentration; in the P-type state, the hole concentration is greater than the electron concentration.

[0058] The multimodal modulated flexible sensor 1 of this embodiment includes a flexible substrate layer 13, a bottom electrode 16, a first electrode 15, and a second electrode 11 serving as a common electrical signal conduction path. An intermediate composite functional layer 17 is used to generate a first sensing signal (pressure sensing signal) without driver intervention, and a top sensitive layer 18 can generate a second sensing signal (gas sensing signal). The intermediate composite functional layer 17 can also be used to modulate the sensing performance of the top sensitive layer 18, enabling online performance modulation of the flexible sensor. This multimodal modulated flexible sensor 1 can sense multiple quantities with a single device and can perform real-time online modulation of the sensor's sensing characteristics. The device structure and fabrication process are simple, making it easy to integrate at high density in IoT terminals and wearable devices.

[0059] In one example, the multimodal modulated flexible sensor 1 further includes a modulation module; the modulation module is connected to the bottom electrode 16 and the top electrode respectively.

[0060] The modulation module is also connected to the processor; the processor receives the gas sensing signal, analyzes whether the sensed gas is an oxidizing or reducing gas based on the signal, and decides whether to perform modulation processing based on the analyzed signal feedback to optimize the device's environment and monitoring requirements. When the signal feedback indicates that modulation processing is required, the modulation module is activated.

[0061] The multimodal modulated flexible sensor 1 can be used to specifically modulate the sensing characteristics of the top sensitive layer 18 by controlling the intermediate composite functional layer 17 to meet different sensing scenarios and monitoring needs. The specific modulation principle of the control module is as follows:

[0062] (1) In the initial state, the polarization direction of each ferroelectric domain in the intermediate composite functional layer 17 of the multimodal modulated flexible sensor 1 is inconsistent, resulting in a total macroscopic polarization of zero, such as Figure 6 As shown in part (a). At this point, there is no polarization effect on the top sensitive layer 18, which remains in its original state with zero band gap, and it maintains an equally low response to oxidizing and reducing gases.

[0063] (2) In oxidizing gas scenarios, a positive voltage pulse of a certain amplitude is applied to the intermediate composite functional layer 17 by connecting the bottom electrode 16 and the top electrode, thereby flipping the polarization direction of the intermediate composite functional layer 17 downwards, such as... Figure 6 As shown in section (b), due to the influence of the modulation field, the top sensitive layer 18 will change from the zero bandgap state to the N-type state, which is more suitable for sensing and responding to oxidizing gases.

[0064] (3) In a reducing gas scenario, a negative voltage pulse of a certain amplitude is applied to the intermediate composite functional layer 17 by connecting the bottom electrode 16 and the top electrode, thereby flipping the polarization direction of the intermediate composite functional layer 17 upwards, such as... Figure 6 As shown in (c), due to the influence of the modulation field, the top sensitive layer 18 will change from the zero bandgap state / N-type state to the P-type state, which is more suitable for sensing and responding to reducing gases.

[0065] Furthermore, by controlling the voltage polarity and magnitude of the intermediate composite functional layer 17, partial control of the remaining modulation field magnitude of the intermediate composite functional layer 17 can be achieved, thereby enabling precise control of the modulation degree of the top sensitive layer 18, such as... Figure 7 As shown.

[0066] Based on the above modulation principle, the modulation module is used for:

[0067] In the gas sensing scenario, when the monitoring requirement is an oxidizing gas scenario and modulation is required, the top electrode is controlled to be positively charged and the bottom electrode 16 is grounded, thereby applying a positive voltage pulse to the intermediate composite functional layer 17, causing the intermediate composite functional layer 17 to generate a modulation field with the polarization direction pointing downward, thereby causing the top sensitive layer 18 to change from a zero bandgap state to an N-type state, so as to achieve modulation of the oxidizing gas sensing performance of the top sensitive layer 18.

[0068] In the gas sensing scenario, when the monitoring requirement is a reducing gas scenario and modulation is required, the top electrode is grounded and the bottom electrode 16 is positively charged, thereby applying a negative voltage pulse to the intermediate composite functional layer 17, causing the intermediate composite functional layer 17 to generate a modulation field with the polarization direction pointing upward, thereby causing the top sensitive layer 18 to change from a zero bandgap state or an N-type state to a P-type state, so as to achieve modulation of the reducing gas sensing performance of the top sensitive layer 18.

[0069] Based on the above modulation principle, specifically for the application scenario of the multimodal modulated flexible sensor 1 in the cold chain transportation process of fresh aquatic products, the modulation strategy of the modulation module in this embodiment is as follows:

[0070] First, signal sensing is initialized in the eigenstate of the top sensitive layer 18. The sensed signal is then transmitted to the processor for analysis of threshold response characteristics to determine whether the environment is an oxidizing or reducing gas environment. Based on user settings and analysis results, a comprehensive decision is made regarding whether modulation should be performed. If the decision is to perform modulation, the modulation module sends a positive or negative voltage pulse of a certain amplitude to change the polarization direction of the intermediate composite functional layer 17, thereby modulating the top sensitive layer 18 accordingly.

[0071] like:

[0072] and ,

[0073] The threshold response characteristic is then a scenario involving oxidizing gas, corresponding to the "alive" state. Wherein: For the top sensitive layer 18 in t The response characteristic value at time 1, For the top sensitive layer 18 in t The response characteristic value at time 2, and The value can be positive or negative; a positive value corresponds to an oxidizing gas response, and a negative value corresponds to a reducing gas response. Indicates that the top sensitive layer 18 is in t The response eigenvalue at time 1 and the top sensitive layer 18 at t The difference in response eigenvalues ​​at time 2. The response threshold for oxidizing gases varies depending on the product category and quantity. It is a value greater than zero.

[0074] like: and

[0075] The threshold response characteristic is still for an oxidizing gas scenario, but its response characteristic value is greater than 0 and less than the response threshold for oxidizing gases. This corresponds to the "dead" state. T represents a set threshold time, which varies with the spoilage dynamics of different aquatic product types.

[0076] like: and

[0077] Then: the threshold response characteristics begin to change to a reducing gas scenario, and the system begins to send voltage pulses to the intermediate composite functional layer 17 for modulation, modulating the intermediate composite functional layer 17 to the corresponding state.

[0078] like:

[0079] The threshold response characteristic is a reducing gas scenario, but its response characteristic value is still within the lower limit range, corresponding to the "fresh" state. The response threshold for reducing gases varies depending on the product category and quantity.

[0080] like:

[0081] In the case of a reducing gas scenario with threshold response characteristics, the response characteristic value is already in a high range, corresponding to a "corrosion" state.

[0082] This example demonstrates that, through the aforementioned modulation, the sensing performance of a device for different types of gases can be improved using a single device without modifying the material of the top sensitive layer 18. This offers significant advantages compared to material modification or other methods. Furthermore, the modulation has virtually no impact on the sensing performance of the intermediate composite functional layer 17 itself, avoiding issues such as multimodal crosstalk and performance degradation. The modulation method in this embodiment achieves real-time, online, repeatable, and even precise modulation by applying corresponding positive and negative voltage pulses. It features convenient operation, high modulation speed (microsecond level), low power consumption (femtojoule level), and excellent modulation effect.

[0083] In one example, the material of the intermediate composite functional layer 17 can be a piezoelectric material. For example, the piezoelectric material can be a ferroelectric material; the ferroelectric material is one or more of the following: lead titanate (PZT), barium titanate (BaTiO3), strontium titanate (SrTiO3), polyvinylidene fluoride and its polymers (PVDF-TrFE), hafnium-based ferroelectric materials (HfO2) and various doped types of ferroelectric materials derived therefrom.

[0084] The top sensitive layer 18 is directly exposed to the air and can come into contact with external gases. The material of the top sensitive layer 18 can be a zero-bandgap sensitive material. For example, the sensitive material includes graphene.

[0085] The materials of the first electrode 15 and the second electrode 11 can both be one of the metals such as titanium nitride (TiN), tungsten (W), silver (Ag) and platinum (Pt).

[0086] The flexible substrate 13 can be made of high-temperature resistant flexible materials such as mica, PI, PEN, PET, and Ecoflex.

[0087] The size of the bottom electrode 16 is greater than or equal to the size of the intermediate composite functional layer 17, such as Figure 2 As shown, the bottom electrode 16 is larger than the intermediate composite functional layer 17 to facilitate lead wire connection.

[0088] The present invention also provides a modulation method for the above-described multimodal modulated flexible sensor, comprising:

[0089] For different monitoring needs, different voltage pulses are applied to the intermediate composite functional layer 17 through the bottom electrode 16 and the top electrode. The intermediate composite functional layer 17 generates different modulation fields, thereby changing the type of the top sensitive layer 18 to modulate the sensing performance of the top sensitive layer 18. The top electrode is either the first electrode 15 or the second electrode 11. The types include the initial zero-bandgap state, the modulated N-type state, and the modulated P-type state. Specifically:

[0090] In a gas sensing scenario, when the monitoring requirement is an oxidizing gas scenario and modulation is required, the top electrode is connected to positive voltage and the bottom electrode 16 is grounded, thereby applying a positive voltage pulse to the intermediate composite functional layer 17, causing the intermediate composite functional layer 17 to generate a modulation field with the polarization direction pointing downward, thereby causing the top sensitive layer 18 to change from a zero bandgap state to an N-type state, so as to achieve modulation of the oxidizing gas sensing performance of the top sensitive layer 18.

[0091] In the gas sensing scenario, when the monitoring requirement is a reducing gas scenario and modulation is required, the top electrode is grounded and the bottom electrode 16 is positively charged, thereby applying a negative voltage pulse to the intermediate composite functional layer 17, causing the intermediate composite functional layer 17 to generate a modulation field with the polarization direction pointing upward, thereby causing the top sensitive layer 18 to change from a zero bandgap state or an N-type state to a P-type state, so as to achieve modulation of the reducing gas sensing performance of the top sensitive layer 18.

[0092] The present invention also provides a method for fabricating the above-described multimodal modulated flexible sensor, comprising:

[0093] The flexible substrate material is subjected to ozone plasma treatment for a set duration to obtain the flexible substrate layer 13.

[0094] A bottom electrode 16 of a first predetermined thickness is deposited on the surface of the flexible substrate layer 13.

[0095] Under vacuum conditions, an intermediate composite functional layer 17 of a second predetermined thickness is deposited on the surface of the bottom electrode 16 and then annealed to induce the piezoelectricity and ferroelectricity of the intermediate composite functional layer 17; the bottom electrode 16 and the intermediate composite functional layer 17 constitute an intermediate layer. The second predetermined thickness can be selected between 10 nm and 10 μm depending on the material.

[0096] A first filler layer 14 is deposited on one side of the intermediate layer, and a second filler layer 12 is deposited on the other side of the intermediate layer. The functions of the first filler layer 14 and the second filler layer 12 are to achieve flushing and to prevent edge polarization problems.

[0097] A third top sensitive layer 18 of a predetermined thickness is deposited on the surface of the intermediate composite functional layer 17, and then cured and dried.

[0098] A first electrode 15 is deposited on the first filling layer 14, and a second electrode 11 is deposited on the second filling layer 12; both the first electrode 15 and the second electrode 11 are in contact with the top sensitive layer 18, thereby obtaining a multimodal modulated flexible sensor 1.

[0099] The aforementioned multimodal modulated flexible sensor 1 has the following advantages:

[0100] By achieving independent sensing and coupled polarization between the intermediate composite functional layer 17 and the top sensitive layer 18, independent sensing of two parameters can be achieved, as well as online real-time modulation of the sensing performance of the top sensitive layer 18. Traditional sensors can only monitor a single marker and cannot adjust in real time according to dynamic changes in the scene; bioimpedance-based sensing technology currently suffers from unclear sensing mechanisms, significant individual differences, and poor coupling effect of sensing data. Therefore, this embodiment has advantages such as a clear sensing mechanism, high device integration, wide applicability, and adjustable performance, which can meet the multi-parameter monitoring needs of the entire process of waterless live transportation of fresh aquatic products and the function of real-time rapid modulation according to dynamic changes in the application scenario. Table 1 analyzes the advantages of the three technologies.

[0101] Table 1 Comparative Analysis of Different Monitoring Technologies

[0102]

[0103] The following section addresses the four stages of fresh aquatic products during waterless, low-temperature transport: "live-dead-fresh-rotten," as well as the identification of markers at different stages and vibrations during transport. The multimodal modulated flexible sensor 1 described in the above embodiment is used to evaluate the quality of the aquatic products, as detailed below:

[0104] In this specific example, the multimodal modulated flexible sensor 1 uses a flexible substrate 13 made of flexible polyimide (PI) with a thickness of 125 micrometers. This substrate possesses high-temperature resistance exceeding 400°C and good flexibility, resulting in lower thermal budget requirements for subsequent fabrication processes. The specific fabrication method is as follows: Figure 3 As shown, see Figure 3 First, the flexible PI substrate was ultrasonically cleaned with isopropanol and deionized water, and then dried at 60°C. Next, its surface was treated with ozone plasma to increase its hydrophilicity and adhesion for subsequent electrode deposition.

[0105] Next, the bottom electrode 16 is deposited. The material used is nano-silver particle ink. The bottom electrode 16 with a thickness of 300 micrometers is deposited on the surface of the flexible substrate layer 13 by inkjet printing (preparing nano-silver bottom electrode), and then sintered at 150°C for 30 minutes to achieve conductivity.

[0106] Then, an intermediate composite functional layer 17 is deposited in a vacuum environment. In this specific example, PVDF-TrFE is used, which is a polymer material with excellent flexibility and piezoelectric coefficient, as well as high sensitivity and anti-interference performance. A PZT film of approximately 100-200 micrometers thick is deposited on the surface of the bottom electrode 16 using a coating / spin-coating method, and sintered for 15-30 minutes below the substrate's heat resistance threshold (e.g., sintering at 120°C). Additionally, insulating polymers are deposited and cured on both sides of the intermediate composite functional layer 17 to form a first filler layer 14 and a second filler layer 12, achieving flush alignment and preventing edge polarization. If a hafnium-based ferroelectric material is used, an additional capping layer needs to be deposited. Specifically, the capping layer is etched after rapid thermal annealing to induce ferroelectricity on top of the piezoelectric layer.

[0107] Next, a pre-prepared graphene solution is deposited on the surface of the PZT film (intermediate composite functional layer 17) using a wet coating method. The thickness of the solution can be controlled by parameters such as the coating parameters and ink viscosity. In this specific example, the thickness of the deposited graphene is about 50 micrometers. After curing and drying, the top sensitive layer 18 is formed.

[0108] Finally, using the same method, the first electrode 15 and the second electrode 11 were deposited on both sides of the top sensitive layer 18 using inkjet printing technology, and sintered at 150°C for 30 minutes in a vacuum environment to complete the fabrication and obtain the multimodal modulated flexible sensor 1.

[0109] In this specific example, inert nitrogen gas is used to apply dynamic pressure testing. When the multimodal modulated flexible sensor 1 is subjected to dynamic pressure, nitrogen gas is blown out from the compression bottle as the gas tube solenoid valve is opened and closed. The dynamic gas pressure is transmitted to the PZT film of the middle composite functional layer 17 through the top graphene film (top sensitive layer 18). Due to the piezoelectric effect of the middle composite functional layer 17, an AC voltage signal is output by connecting the bottom electrode 16 and the top electrode, and the amplitude of the AC voltage signal is proportional to the magnitude of the pressure. In a specific scenario, for waterless live aquatic products during long-distance transportation, the vibration generated by the transport vehicle will cause a large stress response to the live products, and the collision and friction of the fish packaging will interfere with the low-temperature dormancy state of the aquatic products, and may even accelerate the death of the live products and the quality deterioration. Therefore, the multimodal modulated flexible sensor 1 of this invention can be attached to the surface of aquatic products, and the vibration state of aquatic products during transportation can be monitored in real time without being noticed, while reducing the interference of the sensor itself on the aquatic products.

[0110] When the top sensitive layer 18 of the multimodal modulated flexible sensor 1 comes into contact with corresponding gas (oxidizing or reducing gas) molecules, the gas molecules can reversibly act as temporary dopants, either increasing or decreasing the conductivity of the top sensitive layer 18. The amplitude of the response is proportional to the gas concentration. By connecting the first electrode 15 and the second electrode 11 through the top sensitive layer 18, the gas type and concentration can be monitored by measuring their resistance.

[0111] (1) In the initial state, the polarization directions of the numerous ferroelectric domains in the intermediate composite functional layer 17 of the flexible sensor are inconsistent, resulting in a total macroscopic polarization of zero. At this time, the top sensitive layer 18 is unaffected by polarization doping and remains in its original state with zero bandgap, thus maintaining a relatively weak response to both oxidizing and reducing gases. The multimodal modulated flexible sensor 1 can be used to specifically modulate the response characteristics of the top sensitive layer 18 for different sensing scenarios and monitoring needs.

[0112] (2) In scenarios emphasizing oxidizing gases, such as when aquatic products are fresh, the amount of oxygen consumed (O2 gas) can reflect their health and vitality to a certain extent. In this case, the monitoring requirement is to monitor oxidizing gases. When the top sensitive layer 18 is not modulated (zero bandgap state) or is in the P-type state, its response value to oxygen gas is low, which makes its sensitivity and anti-interference performance in actual measurement poor. By connecting the bottom electrode 16 and the top electrode, and applying a +5V positive voltage pulse (the top electrode is connected to a positive voltage, and the bottom electrode 16 is grounded) to the middle composite functional layer 17 with the original top sensitive layer 18, the polarization direction of the middle composite functional layer 17 is flipped downward. Due to the influence of the modulation field, the top sensitive layer 18 will change from the zero bandgap state or the P-type state to the N-type state, which makes the response value of the top sensitive layer 18 when in contact with O2 gas larger, which can improve the sensitivity of the sensor to a certain extent, so that the flexible sensor has better sensing performance for oxidizing gas scenarios.

[0113] (3) For scenarios emphasizing reducing gases, such as when aquatic products deteriorate and rot, a certain amount of NH3 gas will be generated in the microenvironment, which can serve as a marker for assessing the spoilage of aquatic products. At this time, the sensing requirement of the scenario changes from the oxidizing gas in the early stage to the monitoring of reducing gases in the later stage. When the top sensitive layer 18 is not modulated or is in the N-type state, its response value to a certain concentration of NH3 gas is low, which makes its sensitivity and anti-interference in actual measurement poor. By connecting the bottom electrode 16 and the top electrode, and applying a -5V negative pulse signal to the middle composite functional layer 17 (the top electrode is grounded and the bottom electrode 16 is connected to a positive voltage) with the original top sensitive layer 18, the polarization direction of the middle composite functional layer 17 is flipped upward. Due to the influence of electrostatic doping of the modulation field, the top sensitive layer 18 will change from the zero bandgap state or the N-type state to the P-type state, which makes the response value of the top sensitive layer 18 when in contact with NH3 gas larger, improves the sensitivity of the sensor, and makes the flexible sensor have better sensing performance for reducing gas scenarios.

[0114] Therefore, this specific example, through the aforementioned adjustment mechanism, can achieve the required sensing performance for different types of gases using a single device without altering the material of the top sensitive layer 18. This offers significant advantages compared to material modification or the arrangement of multiple types of sensors. Furthermore, the corresponding modulation has almost no impact on the sensing performance of the intermediate composite functional layer 17 itself, avoiding issues such as crosstalk and performance degradation in multimodal sensing. The modulation method in this specific example allows for real-time, online, repeatable, and even precise modulation by applying appropriate positive and negative pulse voltages. It features convenient operation, fast modulation speed (microsecond level), low power consumption (femtojoule level), and excellent modulation effect.

[0115] Furthermore, based on the above modulation principle, this embodiment also has a corresponding modulation strategy, such as... Figure 5 As shown:

[0116] First, the system performs an initialization operation to determine whether the system is working properly; then, an initial saturation modulation voltage is applied to the bottom electrode 16 and the first electrode 15 to initialize the polarization state. The specific purpose is to: (1) unify the disordered polarization direction in the intermediate composite functional layer 17 so that it has the ability to modulate the polarization of the top sensitive layer 18; (2) modulate the initial polarization direction of the intermediate composite functional layer 17 downward so as to modulate the top sensitive layer 18 into an N-type state to meet the sensing requirements of oxidizing gas in the scene.

[0117] For aquatic products that are still alive in the initial stage, they need to consume a certain amount of oxygen to maintain normal physiological activities. If the difference Δρ between the response characteristic values ​​of the top sensitive layer 18 to the gas at two different times in this stage is greater than 0, then the response characteristic value is greater than the response threshold of the oxidizing gas. If the response characteristic value of the top sensitive layer 18 to oxidizing gas is less than the response threshold of oxidizing gas but greater than zero during this stage, it indicates that the oxygen content in the microenvironment remains basically unchanged. This indicates that the fresh aquatic products have died during cold chain transportation and are no longer consuming oxygen in the microenvironment. At this time, the system outputs the "dead" status information and informs the relevant decision-makers.

[0118] When the response characteristic value of the top sensitive layer 18 to the gas is less than zero, the system determines that the scenario is dominated by non-oxidizing gas and starts sending a modulation signal to the modulation module. The modulation module modulates the voltage pulse sent to the intermediate composite functional layer 17, modulating the top sensitive layer 18 into a P-type mode to adapt to the response of reducing gas.

[0119] If the absolute value of the response characteristic value of the top sensitive layer 18 to a reducing gas (e.g., NH3) is greater than 0 and less than the absolute value of the reducing gas's response threshold, it indicates that the content of the reducing gas in the microenvironment is low or the generation rate is slow. In this case, the system outputs "fresh" status information and informs relevant decision-makers. Otherwise, it indicates that the absolute value of the response characteristic value of the top sensitive layer 18 to the reducing gas is greater than the absolute value of the reducing gas's response threshold. This means that there is a large amount of NH3 gas in the aquatic product's microenvironment, indicating that the aquatic product has undergone a certain degree of spoilage. In this case, the system outputs "rotten" status information and informs relevant decision-makers. This completes the full-stage judgment and automatic sensing performance modulation of the entire cold chain process.

[0120] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0121] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A multimodal modulated flexible sensor, characterized in that, include: Flexible substrate layer, bottom electrode, intermediate composite functional layer, top sensitive layer, first filling layer, second filling layer, first electrode and second electrode; The bottom electrode, the intermediate composite functional layer, and the top sensitive layer are deposited sequentially from bottom to top on the flexible substrate; the bottom electrode and the intermediate composite functional layer constitute the intermediate layer; the first filler layer is deposited on one side of the intermediate layer; A second filler layer is deposited on the other side of the intermediate layer; a first electrode is deposited on the first filler layer; a second electrode is deposited on the second filler layer; both the first electrode and the second electrode are in contact with the top sensitive layer. The intermediate composite functional layer is used for: In a pressure sensing scenario, the bottom electrode and the top electrode are connected to generate a pressure sensing signal; the top electrode is either the first electrode or the second electrode. The top sensitive layer is used for: In a gas sensing scenario, the first electrode and the second electrode are connected to generate a gas sensing signal; The intermediate composite functional layer is also used for: To meet different monitoring needs, different voltage pulses are applied to the bottom electrode and the top electrode to generate different modulation fields, thereby changing the type of the top sensitive layer and modulating its sensing performance; the types include the initial zero-bandgap state, the modulated N-type state, and the modulated P-type state; The multimodal modulated flexible sensor further includes a modulation module; the modulation module is connected to the bottom electrode and the top electrode respectively; The modulation module is used for: In the gas sensing scenario, when the monitoring requirement is an oxidizing gas scenario and modulation is required, the top electrode is controlled to be positively charged and the bottom electrode is grounded, thereby applying a positive voltage pulse to the intermediate composite functional layer, causing the intermediate composite functional layer to generate a modulation field with the polarization direction pointing downward, thereby causing the top sensitive layer to change from the zero bandgap state to the N-type state, so as to achieve modulation of the oxidizing gas sensing performance of the top sensitive layer; In the gas sensing scenario, when the monitoring requirement is a reducing gas scenario and modulation is required, the top electrode is grounded and the bottom electrode is positively charged, thereby applying a negative voltage pulse to the intermediate composite functional layer, causing the intermediate composite functional layer to generate a modulation field with the polarization direction pointing upward, thereby causing the top sensitive layer to change from a zero bandgap state or an N-type state to a P-type state, so as to achieve modulation of the reducing gas sensing performance of the top sensitive layer; The intermediate composite functional layer is made of a ferroelectric material; the ferroelectric material is one or more of lead titanate, barium titanate, strontium titanate, polyvinylidene fluoride, and hafnium-based ferroelectric materials. The material of the top sensitive layer is a zero-bandgap sensitive material; the sensitive material is graphene.

2. The multimodal modulated flexible sensor according to claim 1, characterized in that, The materials of the first electrode and the second electrode are both titanium nitride, tungsten, silver and platinum.

3. A modulation method for a multimodal modulated flexible sensor as described in any one of claims 1-2, characterized in that, include: For different monitoring needs, different voltage pulses are applied to the intermediate composite functional layer through the bottom electrode and the top electrode. The intermediate composite functional layer generates different modulation fields, thereby changing the type of the top sensitive layer to achieve modulation of the sensing performance of the top sensitive layer. The top electrode is either the first electrode or the second electrode. The type includes the initial zero bandgap state, the modulated N-type state, and the modulated P-type state.

4. The modulation method according to claim 3, characterized in that, To meet different monitoring needs, different voltage pulses are applied to the intermediate composite functional layer through the bottom and top electrodes. This generates different modulation fields in the intermediate composite functional layer, thereby changing the type of the top sensitive layer and modulating its sensing performance. Specifically, this includes: In a gas sensing scenario, when the monitoring requirement is an oxidizing gas scenario and modulation is required, the top electrode is connected to positive voltage and the bottom electrode is grounded, thereby applying a positive voltage pulse to the intermediate composite functional layer, causing the intermediate composite functional layer to generate a modulation field with the polarization direction pointing downward, thereby causing the top sensitive layer to change from a zero bandgap state to an N-type state, so as to achieve modulation of the oxidizing gas sensing performance of the top sensitive layer. In the gas sensing scenario, when the monitoring requirement is a reducing gas scenario and modulation is required, the top electrode is grounded and the bottom electrode is positively charged, thereby applying a negative voltage pulse to the intermediate composite functional layer. This causes the intermediate composite functional layer to generate a modulation field with the polarization direction pointing upward, thereby causing the top sensitive layer to change from a zero-bandgap state or an N-type state to a P-type state, so as to achieve modulation of the reducing gas sensing performance of the top sensitive layer.

5. A method for fabricating a multimodal modulated flexible sensor as described in any one of claims 1-2, characterized in that, include: A flexible substrate material is subjected to ozone plasma treatment for a set duration to obtain a flexible substrate layer. A bottom electrode of a first predetermined thickness is deposited on the surface of the flexible substrate layer; Under vacuum conditions, a second intermediate composite functional layer of a predetermined thickness is deposited on the surface of the bottom electrode and annealed to induce the piezoelectricity of the intermediate composite functional layer; the bottom electrode and the intermediate composite functional layer constitute an intermediate layer. A first filler layer is deposited on one side of the intermediate layer, and a second filler layer is deposited on the other side of the intermediate layer; A third top sensitive layer of a predetermined thickness is deposited on the surface of the intermediate composite functional layer, and then cured and dried. A first electrode is deposited on the first filling layer, and a second electrode is deposited on the second filling layer; both the first electrode and the second electrode are in contact with the top sensitive layer, thereby obtaining a multimodal modulated flexible sensor.

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