A mixed gas component detection system based on electrochemical sensing

Abstract

The application relates to the technical field of mixed gas analysis, and discloses a mixed gas component detection system based on electrochemical sensing, which comprises an electrochemical sensing module, a time-domain excitation module, a data acquisition module and a multi-component decoupling module. The time-domain excitation module is used for applying an asymmetric time-domain electrode step excitation sequence to the electrochemical sensing module. The data acquisition module is used for pausing analog-digital conversion at the moment of potential transition and collecting a transient decay current sequence after the end of a sampling delay time constant. The multi-component decoupling module is used for calling a decoupling correction coefficient matrix, calculating the transient decay current sequence through first-order difference calculation, and outputting the concentration of each gas component. In the application, a non-equilibrium state mass transfer polarization layer is reconstructed on a time axis, potential interference conversion is overlapped into mass transfer decay slope difference, coexisting gas cross-sensitivity coupling and background noise are eliminated, and the detection accuracy and system zero-point anti-drift stability are improved.

Description

Technical Field

[0001] This invention belongs to the field of mixed gas analysis technology, and particularly relates to a mixed gas component detection system based on electrochemical sensing. Background Technology

[0002] Current conventional methods apply a constant bias voltage to the working electrode inside the gas sensor to control the catalytic interface of the sensitive electrode in a steady-state, limited diffusion state. The concentration of a specific gas is calculated by measuring the response current signal. However, when this method is applied to continuous online monitoring of high-humidity, high-sulfur industrial exhaust containing multiple active gas components, the discharge activation energy levels and intrinsic redox potentials of various associated harmful gas molecules on the surface of the catalytic layer of the sensitive electrode are highly similar. This leads to severe charge transfer crossover in the total output current signal. Traditional systems typically use a fixed correction polynomial matrix to perform algebraic compensation on the interference signals of each channel. However, such post-processing methods assume that the sensor is in an ideal steady-state environment, ignore the irregular random fluctuations of the polarization background current over time during continuous operation, and fail to detect the deposition of active sites in the catalytic layer caused by the competitive adsorption of associated components. This causes confusion in the physical causal relationship of the characteristic current response signal, resulting in the calibration parameters rapidly deviating from the true boundary under harsh operating conditions.

[0003] To mitigate multi-component aliasing interference, conventional improvement approaches tend to increase the catalyst loading on the working electrode or add an adsorption filter unit to the upstream sampling pipeline. Increasing the catalyst loading leads to an unexpected surge in the inherent double-layer capacitance at the sensitive electrode interface, generating a large polarization charging parasitic background current that severely overwhelms the characteristic transient weak current. Furthermore, the adsorption filter unit is prone to rapid saturation or even high-temperature desorption failure under severe continuous exhaust pressure, introducing significant flow resistance and component transport delay. Besides hardware limitations, the back-end data processing algorithm's decoupling control of the aliasing signal also suffers from fundamental deficiencies. For example, Chinese invention patent application CN120778833A discloses… This invention relates to a multi-channel electrochemical detection electrode, electrochemical sensor, and detection method. The method utilizes a multi-channel heterogeneous catalytic array to acquire signals from each component and combines a CNN-LSTM network to extract temporal and spatial features to correct cross-interference. However, this technology relies on the ideal steady-state or conventional low-frequency evolution of the response of each electrode channel. Under continuous online monitoring conditions in industry, it lacks a physical layer blocking mechanism for the background current of transient capacitor charging. Furthermore, continuous polarization induces irreversible adsorption poisoning and catalytic site collapse at sensitive interfaces, resulting in deep nonlinear aliasing across channels in the input data source. Simply relying on statistical fitting of the back-end neural network cannot reconstruct the distorted physical causal mapping and cannot cope with the long-term alternating drift caused by polarization sedimentation.

[0004] Therefore, the technical problem to be solved by this invention is how to reconstruct the transient concentration gradient field on the surface of the working electrode through the non-equilibrium multi-step polarization voltage excitation signal to strip the heterogeneous mass transfer current sequence in a time-division manner, and to coordinate the sampling time-domain gating suspension strategy and the in-situ desorption recovery mechanism to adaptively eliminate the interference of polarization capacitance background current and the adsorption poisoning of active sites. Summary of the Invention

[0005] To address the problems in the background art, the technical solution of the present invention is as follows: A mixed gas composition detection system based on electrochemical sensing, comprising: An electrochemical sensing module is used to contact the gas mixture to be measured and generate a mass transfer polarization current response. The time-domain excitation module is electrically connected to the electrochemical sensing module and is used to apply an asymmetric time-domain electrode step excitation sequence containing voltage transition actions to the electrochemical sensing module to change the electrochemical polarization state of the gas component at the catalytic interface. The data acquisition module, electrically connected to the electrochemical sensing module, is used to acquire the transient decay current sequence caused by voltage transition. The data acquisition module includes a low-noise transimpedance amplification module, a high-order analog-to-digital conversion module, a timing and counting module, and a high-frequency sampling channel module. It also has a built-in sampling delay time constant, which is used to forcibly suspend the conversion action of the high-order analog-to-digital conversion module at the moment the voltage transition occurs, keeping the data acquisition in a paused state until the holding time of the timing and counting module crosses the critical point of the sampling delay time constant. Then, the high-frequency sampling channel module is activated to digitally extract the transient decay current sequence that reflects the Faraday characteristics. Multiple decoupling modules are connected to the data acquisition module to receive transient decay current sequences. The multiple decoupling modules include a non-volatile storage module and a microprocessor module. The non-volatile storage module contains a decoupling correction coefficient matrix. The microprocessor module is used to retrieve the decoupling correction coefficient matrix, and the transient decay current sequence is stripped of nonlinear cross-sensitive overlapping components through first-order differential processing to output the concentration of each gas component. The flow rate adaptive compensation module, which is signal-connected to the time-domain excitation module, includes a micro-differential pressure measurement module located at the front end of the detection cavity module. This module is used to calculate the airflow velocity deflection in real time using the micro-differential pressure parameters collected by the micro-differential pressure measurement module. When the external fluid transport conditions deviate from the steady-state boundary, the module sends a timing fine-tuning command to the time-domain excitation module to dynamically adjust the pulse duration of the asymmetric time-domain electrode step excitation sequence in the next polarization cycle. The module uses the time-domain deformation feedforward of the unsteady diffusion layer thickness to offset the convective mass loss caused by airflow velocity disturbances and prevents the local fluid dissipation distortion from spreading to the transient decay current sequence.

[0006] Preferably, it further includes: a temperature feedforward compensation module, electrically connected to multiple decoupling modules, used to acquire the real-time temperature in the detection chamber module and retrieve the solidified activation energy constant. The activation energy constant is an algebraic weighted coefficient pre-calibrated based on the correspondence between the intrinsic activation energy and molecular diffusion coefficient of each gas component to be tested at the catalytic interface and the temperature change, used to characterize the linear intervention weight of temperature change on the decay slope of Faraday characteristic current; the temperature correction coefficient is calculated by multiplying the real-time temperature and the activation energy constant, and the temperature correction coefficient is embedded in the transient decay current sequence to offset the exponential intervention of temperature change on the multiphase catalytic rate constant of the interface and the intrinsic diffusion coefficient of gas molecules.

[0007] Preferably, in the data acquisition module, the low-noise transimpedance amplification module includes a microampere-level low-noise amplification unit, and the voltage output terminal of the low-noise transimpedance amplification module is electrically connected to the analog input terminal of the high-order analog-to-digital conversion module; the data acquisition module is signal-connected to the time-domain excitation module, which is used to forcibly suspend the conversion action of the high-order analog-to-digital conversion module at the instant when the voltage transition action is determined to occur, and maintain the data acquisition pause state until the maintenance time of the timing counting module crosses the critical point of the sampling delay time constant, then activates the high-frequency sampling channel module, digitally extracts the transient decay current sequence reflecting the Faraday characteristics, and blocks the double-layer capacitor charging background current generated by the inherent capacitance polarization of the electrochemical sensing module interface at the moment of transition.

[0008] Preferably, in the multiple decoupling modules, the decoupling correction coefficient matrix is ​​a constant-weighted algebraic mapping array pre-embedded in the specified sector address of the non-volatile storage module of the multiple decoupling modules; the decoupling correction coefficient matrix is ​​calculated based on the standard mass transfer decay current curves corresponding to each single pure working condition gas characteristic component collected in the standard gas calibration test before leaving the factory, after the nonlinear cross-sensitive overlapping components are stripped by first-order differential, and is used to directly convert the collected transient decay current sequence into the concentrations of each gas component that do not interfere with each other through matrix multiplication.

[0009] Preferably, the electrochemical sensing module includes a working electrode module, a counter electrode module, and a reference electrode module disposed inside the detection cavity module; the catalyst surface of the working electrode module is used to allow multiple gas components in the gas mixture to undergo redox reactions simultaneously; the time-domain excitation module is electrically connected to the working electrode module and is used to apply an asymmetric time-domain electrode step excitation sequence to the working electrode module, so that the molecules of different characteristic gas components in the early stage of catalytic reaction establishment produce heterogeneous mass transfer attenuation resistance characteristics on the time axis, which are determined by their intrinsic mass transfer rate and reaction activation energy level.

[0010] Preferably, the asymmetric time-domain electrode step excitation sequence delivered by the time-domain excitation module contains multiple pulse signals with different potential amplitudes, and a voltage transition action is provided between two adjacent pulse signals; the sampling delay time constant fixed in the data acquisition module is in the range of 10μs to 500μs, which is used to avoid the peak range of the background current of the double-layer capacitor charging, so that the transient current sequence extracted by the high-frequency sampling channel module is completely composed of Faraday characteristic currents that reflect the real electrochemical multiphase catalytic rate.

[0011] Preferably, the front end of the detection chamber module is provided with an air inlet pipe module with fixed flow resistance, and the air inlet pipe module is provided with a micro pressure difference measurement module. The micro pressure difference measurement module is used to monitor the local fluid pressure change caused by external airflow fluctuations in real time and convert the micro pressure difference parameters into the input basis of the flow velocity adaptive compensation module. In this way, by dynamically adjusting the pulse duration of the time domain excitation module in the next cycle, the unsteady diffusion layer thickness on the time axis can be dynamically offset.

[0012] Preferably, in the multiple decoupling modules, the non-volatile storage module is a flash memory storage unit, and the microprocessor module is a central processing unit; the decoupling correction coefficient matrix is ​​pre-programmed into a fixed sector of the flash memory storage unit as a constant weighted algebraic mapping array; the central processing unit is used to read the digitized discrete current data sequence from the data acquisition module, and to perform constant weighted matrix multiplication through the decoupling correction coefficient matrix to remove the cross-sensitive coupling components caused by high potential overlap, and output the concentration of each gas component after separation in an independent channel.

[0013] Compared with existing technologies, the mixed gas composition detection system based on electrochemical sensing of the present invention has the following advantages: 1. In the detection of mixed gas components by electrochemical sensing, the time-domain excitation module applies a periodic asymmetric multi-step voltage signal to the working electrode, changing the inherent steady-state diffusion limiting current measurement mode of molecules at the catalytic reaction interface, and promoting the transition of the polarization reaction process of the coexisting gas to a non-equilibrium mass transfer diffusion state; the differential acquisition module suspends the data sampling action at the moment of potential transition, and captures the transient decay current sequence within the delayed gating time window when the double-layer charging current decays to below the background noise level, converting the spatial dimension of polarization potential cross-overlap into the difference of Faraday characteristic current decay slope within the discrete time window of a single electrode, and establishing a pure data source that is not disturbed by dielectric constant fluctuations.

[0014] 2. The temperature feedforward compensation module acquires the temperature change rate and sign direction inside the detection chamber in real time. The temperature feedforward compensation module retrieves the corresponding activation energy and adjusts the constant to correct the one-dimensional discrete current vector, balancing the dynamic exponential interference of external temperature fluctuations on the multiphase catalytic rate constant of the interface and the intrinsic diffusion coefficient of high-humidity and high-sulfur exhaust gas molecules. This characteristic-level temperature feedforward mechanism is directly embedded in the algebraic product operation of the mass transfer current sequence, eliminating the semantic confusion of resistance and mass caused by sudden changes in airflow, avoiding coefficient distortion of the back-end static algebraic polynomial caused by multi-component competitive adsorption, and ensuring the intrinsic separation accuracy of the multi-component multi-group decoupling module under sudden operating conditions.

[0015] 3. The flow velocity adaptive compensation module calculates the airflow velocity deflection in real time based on the micro-pressure difference parameter at the front end of the detection cavity. When the external fluid transport conditions deviate from the steady-state boundary, it sends a timing fine-tuning command to the time-domain excitation module to dynamically shorten or extend the pulse duration of the electrode working detection voltage in the next polarization cycle. This process uses the time-domain deformation feedforward of the unsteady diffusion layer thickness to offset the unexpected convective mass loss caused by the airflow velocity disturbance, avoids the diffusion of local fluid dissipation distortion to the high-frequency characteristic current sequence, and prevents the geometric distortion of the topological dimension of the time-domain characteristic response matrix inside the multiple decoupling modules caused by the violent fluctuations of the external pipeline flow state. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the electrochemical sensing mixed gas composition detection system of the present invention; Figure 2 This is a diagram showing the module connection relationship of the electrochemical sensing mixed gas composition detection system of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0018] A mixed gas composition detection system based on electrochemical sensing, comprising: An electrochemical sensing module is used to contact the gas mixture to be measured and generate a mass transfer polarization current response. The time-domain excitation module is electrically connected to the electrochemical sensing module and is used to apply an asymmetric time-domain electrode step excitation sequence containing voltage transition actions to the electrochemical sensing module to change the electrochemical polarization state of the gas component at the catalytic interface. The data acquisition module, electrically connected to the electrochemical sensing module, is used to acquire the transient decay current sequence caused by voltage transition. The data acquisition module includes a low-noise transimpedance amplification module, a high-order analog-to-digital conversion module, a timing and counting module, and a high-frequency sampling channel module. It also has a built-in sampling delay time constant, which is used to forcibly suspend the conversion action of the high-order analog-to-digital conversion module at the moment the voltage transition occurs, keeping the data acquisition in a paused state until the holding time of the timing and counting module crosses the critical point of the sampling delay time constant. Then, the high-frequency sampling channel module is activated to digitally extract the transient decay current sequence that reflects the Faraday characteristics. Multiple decoupling modules are connected to the data acquisition module to receive transient decay current sequences. The multiple decoupling modules include a non-volatile storage module and a microprocessor module. The non-volatile storage module contains a decoupling correction coefficient matrix. The microprocessor module is used to retrieve the decoupling correction coefficient matrix, and the transient decay current sequence is stripped of nonlinear cross-sensitive overlapping components through first-order differential processing to output the concentration of each gas component. The flow rate adaptive compensation module, which is signal-connected to the time-domain excitation module, includes a micro-differential pressure measurement module located at the front end of the detection cavity module. This module is used to calculate the airflow velocity deflection in real time using the micro-differential pressure parameters collected by the micro-differential pressure measurement module. When the external fluid transport conditions deviate from the steady-state boundary, the module sends a timing fine-tuning command to the time-domain excitation module to dynamically adjust the pulse duration of the asymmetric time-domain electrode step excitation sequence in the next polarization cycle. The module uses the time-domain deformation feedforward of the unsteady diffusion layer thickness to offset the convective mass loss caused by airflow velocity disturbances and prevents the local fluid dissipation distortion from spreading to the transient decay current sequence.

[0019] Preferably, it further includes: a temperature feedforward compensation module, electrically connected to multiple decoupling modules, used to acquire the real-time temperature in the detection chamber module and retrieve the solidified activation energy constant. The activation energy constant is an algebraic weighted coefficient pre-calibrated based on the correspondence between the intrinsic activation energy and molecular diffusion coefficient of each gas component to be tested at the catalytic interface and the temperature change, used to characterize the linear intervention weight of temperature change on the decay slope of Faraday characteristic current; the temperature correction coefficient is calculated by multiplying the real-time temperature and the activation energy constant, and the temperature correction coefficient is embedded in the transient decay current sequence to offset the exponential intervention of temperature change on the multiphase catalytic rate constant of the interface and the intrinsic diffusion coefficient of gas molecules.

[0020] Preferably, in the data acquisition module, the low-noise transimpedance amplification module includes a microampere-level low-noise amplification unit, and the voltage output terminal of the low-noise transimpedance amplification module is electrically connected to the analog input terminal of the high-order analog-to-digital conversion module; the data acquisition module is signal-connected to the time-domain excitation module, which is used to forcibly suspend the conversion action of the high-order analog-to-digital conversion module at the instant when the voltage transition action is determined to occur, and maintain the data acquisition pause state until the maintenance time of the timing counting module crosses the critical point of the sampling delay time constant, then activates the high-frequency sampling channel module, digitally extracts the transient decay current sequence reflecting the Faraday characteristics, and blocks the double-layer capacitor charging background current generated by the inherent capacitance polarization of the electrochemical sensing module interface at the moment of transition.

[0021] Preferably, in the multiple decoupling modules, the decoupling correction coefficient matrix is ​​a constant-weighted algebraic mapping array pre-embedded in the specified sector address of the non-volatile storage module of the multiple decoupling modules; the decoupling correction coefficient matrix is ​​calculated based on the standard mass transfer decay current curves corresponding to each single pure working condition gas characteristic component collected in the standard gas calibration test before leaving the factory, after the nonlinear cross-sensitive overlapping components are stripped by first-order differential, and is used to directly convert the collected transient decay current sequence into the concentrations of each gas component that do not interfere with each other through matrix multiplication.

[0022] Preferably, the electrochemical sensing module includes a working electrode module, a counter electrode module, and a reference electrode module disposed inside the detection cavity module; the catalyst surface of the working electrode module is used to allow multiple gas components in the gas mixture to undergo redox reactions simultaneously; the time-domain excitation module is electrically connected to the working electrode module and is used to apply an asymmetric time-domain electrode step excitation sequence to the working electrode module, so that the molecules of different characteristic gas components in the early stage of catalytic reaction establishment produce heterogeneous mass transfer attenuation resistance characteristics on the time axis, which are determined by their intrinsic mass transfer rate and reaction activation energy level.

[0023] Preferably, the asymmetric time-domain electrode step excitation sequence delivered by the time-domain excitation module contains multiple pulse signals with different potential amplitudes, and a voltage transition action is provided between two adjacent pulse signals; the sampling delay time constant fixed in the data acquisition module is in the range of 10μs to 500μs, which is used to avoid the peak range of the background current of the double-layer capacitor charging, so that the transient current sequence extracted by the high-frequency sampling channel module is completely composed of Faraday characteristic currents that reflect the real electrochemical multiphase catalytic rate.

[0024] Preferably, the front end of the detection chamber module is provided with an air inlet pipe module with fixed flow resistance, and the air inlet pipe module is provided with a micro pressure difference measurement module. The micro pressure difference measurement module is used to monitor the local fluid pressure change caused by external airflow fluctuations in real time and convert the micro pressure difference parameters into the input basis of the flow velocity adaptive compensation module. In this way, by dynamically adjusting the pulse duration of the time domain excitation module in the next cycle, the unsteady diffusion layer thickness on the time axis can be dynamically offset.

[0025] Preferably, in the multiple decoupling modules, the non-volatile storage module is a flash memory storage unit, and the microprocessor module is a central processing unit; the decoupling correction coefficient matrix is ​​pre-programmed into a fixed sector of the flash memory storage unit as a constant weighted algebraic mapping array; the central processing unit is used to read the digitized discrete current data sequence from the data acquisition module, and to perform constant weighted matrix multiplication through the decoupling correction coefficient matrix to remove the cross-sensitive coupling components caused by high potential overlap, and output the concentration of each gas component after separation in an independent channel.

[0026] Example 1: In the application scenario of online monitoring of mixed gases in high-humidity and high-sulfur environments in petrochemical industrial parks, to solve the problem of cross-sensitivity coupling and zero-point drift caused by the high overlap of redox potentials of multiple components in the electrochemical sensor array under continuous operation, this embodiment of the invention provides a mixed gas component detection system based on electrochemical sensing. The overall system structure of this detection system is described in [reference needed]. Figure 1 As shown, the specific connections and cascading relationships between its internal functional modules are detailed in [reference needed]. Figure 2As shown, the detection system relies on a standard three-electrode electrochemical measurement chamber architecture, including a working electrode, a reference electrode, and a counter electrode. The time-domain excitation module is electrically connected to the working electrode. Its integrated digital programmable waveform generation circuit applies an asymmetric time-domain electrode step excitation sequence containing voltage transitions to the working electrode according to a preset time period. Within one working detection cycle, this excitation sequence sequentially includes an oxidation detoxification phase lasting 1.5 s, a zero-current relaxation phase lasting 2 s, and a first voltage polarization phase and a second voltage polarization phase executed sequentially. The potential amplitude applied during the oxidation detoxification phase is set to 1.2 V, which is higher than the 0.4 V of the first voltage polarization phase, forcibly desorbing and removing sulfide adsorbates from the catalyst surface. During the entire monitoring cycle, a micro-differential pressure measurement module located inside the inlet pipe at the front end of the detection chamber collects local flow data in real time at a frequency of 50 Hz. When the airflow velocity deviates from the steady-state boundary of 2 liters per second due to valve action or pump speed fluctuations in the external pipeline, the micro-pressure difference measurement module generates a micro-pressure difference signal that deviates from the calibration value. The flow rate adaptive compensation module receives this signal and retrieves the fluid resistance mass transfer mapping table pre-stored in its non-volatile memory. This mapping table is a set of calibration data obtained from convective mass transfer loss tests conducted under different flow rate gradients before leaving the factory. Based on the current pressure change, the flow rate adaptive compensation module calculates the pulse time fine-tuning amount of the electrode working detection voltage in the next polarization cycle according to the linear conversion rule that shortens the pulse duration by 15 milliseconds for every 10 Pascals increase in pressure difference. This is then sent to the time domain excitation module in the form of a timing fine-tuning instruction. By directly modifying the initial value of the period register of the digital programmable waveform generator circuit, the effect of thinning of the unsteady diffusion layer caused by the increased gas flow rate is dynamically offset on the time axis.

[0027] In the hardware physical topology and signal conditioning link, the low-noise transimpedance amplifier module and the high-bit analog-to-digital converter module inside the data acquisition module present a clear parallel and cascaded architecture, which is consistent with... Figure 1 Corresponding to the module layout, the low-noise transimpedance amplifier module integrates a microampere-level low-noise amplifier unit. When the front-end electrochemical sensing module generates a weak mass transfer polarization current response due to the redox reaction, this microampere-level low-noise amplifier unit, as the pre-conditioning core of the data acquisition module, captures the weak microampere-level current signal in situ and uses a high-resistance feedback network to accurately and linearly convert it into the corresponding analog voltage signal. After conversion, the analog voltage signal is directly and seamlessly transmitted to the analog input of the high-level analog-to-digital converter module cascaded in parallel through the voltage output terminal of the low-noise transimpedance amplifier module. This front-to-back electrical connection architecture ensures that the current-to-voltage conditioning process is carried out independently and with high fidelity within the low-noise transimpedance amplifier module, and also ensures that the high-level analog-to-digital converter module can perform subsequent forced suspension or high-frequency extraction actions on the clean analog voltage source at any time.

[0028] During the first voltage polarization phase, at the instant the control unit trigger voltage transitions from the zero-current relaxation phase to 0.4V, the timing and counting module in the data acquisition module starts timing. The analog-to-digital conversion operation of the data acquisition module has a sampling delay time constant of 0ms to 15ms. The window is forcibly suspended to shield the background current caused by the charging of the double-layer capacitor. In actual operation, the above-mentioned forced suspension action is implemented through a hardware-level timer-triggered interrupt masking mechanism. When the control unit sends a voltage transition command to the electrochemical sensing module, the command is simultaneously sent as a hardware trigger signal to the timing and counting module inside the data acquisition module. The timing and counting module uses a 24-bit incrementing counter, which immediately clears to zero and starts counting when it receives the rising edge of the trigger signal. At the same time, its hardware output generates a high-level control blocking signal, which is directly connected to the external conversion enable pin of the high-order analog-to-digital conversion module, forcibly pulling up the conversion enable pin. The clock signal is lowered, blocking the clock drive of the internal successive approximation register, thus causing the analog-to-digital conversion to momentarily enter a suspended sleep state, cutting off the digital sampling of the background current charging the double-layer capacitor at the input. When the counter value reaches the corresponding preset threshold of 15 milliseconds, the control blocking signal at the hardware output automatically flips to a low level, releasing the conversion enable pin of the high-order analog-to-digital conversion module, self-activating and opening the high-frequency sampling channel module. After the count crosses the 15ms threshold, the data acquisition module activates the high-frequency sampling channel, acquiring 50 data points within a time window of 15ms to 20ms at a sampling rate of 10kHz, forming the first characteristic transient current sequence. After the second voltage polarization phase is completed, the system acquires the second characteristic quasi-steady-state current sequence within an 80ms to 100ms window. .

[0029] Microprocessor module reading from multiple decoupled modules and The characteristic values ​​of each component are obtained through first-order difference calculation, and the transient temperature change rate signal is obtained based on the temperature feedforward compensation module. Arrhenius correction is performed because, in the actual operating conditions of continuous industrial exhaust monitoring, ambient temperature not only exhibits steady-state deviations but also experiences sudden transient pulse fluctuations due to gas flow. Although the multiphase catalytic rate constant is intrinsically determined by the exponential relationship of absolute temperature according to the Arrhenius equation, within extremely small microsecond and millisecond transient sampling windows, minute perturbations in absolute temperature cannot be captured in time by static thermistors. This invention introduces the dynamic temperature change rate measured by a high-speed, highly sensitive temperature sensor as a predictor of the deviation of the absolute temperature in local micro-regions of the sensor's catalytic interface from the true calibration. The specific steps of the point-based forward prediction factor are as follows: The microprocessor module reads the real-time absolute temperature of the current cycle and calculates a temperature reference correction term based on the pre-stored exponential function mapping relationship under the standard state; the captured temperature change rate of 0.2 degrees Celsius per second is multiplied by the activation energy constant, which is used to perform a first-order Taylor series approximate linear expansion compensation on the temperature reference correction term. This transforms the complex nonlinear intervention, which is difficult to perform exponential calculations in real time on a single chip, into a fast linear scaling adjustment of the current discrete current sequence. The temperature feedforward compensation module retrieves the corresponding activation energy constant. In this embodiment, the activation energy is set to an average. It has a clear electrochemical kinetic physical meaning and intrinsic acquisition method; from the perspective of microscopic kinetics, the rate constant of the heterogeneous catalytic reaction on the electrode surface Strictly follow Arrhenius's law, that is: In the formula, This represents the intrinsic activation energy of a specific gas component at the catalytic interface of the sensitive electrode. Let be the ideal gas constant. Absolute temperature It is a pre-exponential factor; due to temperature Fluctuations will affect the catalytic rate constant Furthermore, the intrinsic diffusion coefficient of gas molecules generates nonlinear exponential interference, causing unexpected deflection of the extracted transient decay current sequence. To achieve low computational cost and high real-time dynamic compensation within a microprocessor, this invention introduces an activation energy constant. As the equilibrium intrinsic activation energy The algebraic weighting coefficients equate complex exponential interventions to linear intervention weights proportional to real-time temperature within the operating temperature window; this activation energy is balanced by a constant. The following standard factory calibration test was used for in-situ data acquisition: During the offline calibration phase, the detection system was placed in a controlled high and low temperature alternating test chamber, and characteristic components of each single pure operating condition gas of known concentration were introduced at a constant flow rate; the test chamber was controlled to establish multiple steady-state temperature environments in 5℃ increments within the full operating temperature window from 10℃ to 45℃; at each steady-state temperature node, the transient decay current sequence caused by voltage transition was acquired using the data acquisition module. And record the corresponding real-time temperature of the cavity. Using the current curve at a standard temperature range, such as 25°C, as a benchmark, the deflection of the Faraday characteristic current decay slope at other temperature nodes is extracted. The least squares method is used to perform linear regression fitting on multiple sets of real-time temperature-current slope deflection data. The fitted slope, or normalized value, is confirmed as the activation energy constant corresponding to the characteristic gas component. After calibration, the activation energies specific to each gas component in each channel are set to constants. As a constant matrix, it is pre-programmed and solidified in the designated sector addresses of the flash memory storage units (i.e., non-volatile storage modules) of multiple decoupled modules, for real-time retrieval during runtime; through The target feature vector is calculated. , After the sampling delay time constant has elapsed, the data acquisition module digitizes the discrete transient decaying current sequence vector through the high-frequency sampling channel module. Finally, multiple decoupling modules call a preset time-domain discrete operator matrix stored in the non-volatile memory module. By using time-domain discrete operator matrices With target feature vector Perform constant-weighted matrix multiplication to construct an explicit linear decoupling algebraic mapping relationship: Make the target feature vector As a multidimensional input column vector, and the time-domain discrete operator matrix The row constant weighting coefficients corresponding to specified addresses in each specified sector are summed by inner product calculation. Then, using the algebraic interference cancellation mechanism of matrix reconstruction, the target feature vector is... The non-Radidatic interference components and cross-channel overlapping components are stripped in situ to calculate the final component concentration result vector. each discrete term in the vector Representing the absolute volume percentage concentration of each component in the mixed gas, the measured data from 1440 hours of continuous operation in the field show that, under closed conditions with a hydrogen sulfide concentration of 50 ppm and an ambient humidity greater than 85%, the measurement accuracy error of this system is maintained within ±3.1%, and the zero-point drift value is strictly limited to within 0.5% of the initial set value. This achieves accurate discrete separation of the intrinsic electrochemical response signal of multi-component gases and long-term stable anti-drift output.

[0030] Example 2: This experiment aims to verify the electrochemical sensing data processing method proposed in this invention by constructing a multi-dimensional experimental system covering typical operating conditions and extreme interference scenarios. The experimental platform adopts a standard three-electrode sensing module controlled by an electrochemical workstation. The surface of the sensor working electrode is modified with gold nanoparticles to enhance electrocatalytic activity. The gas mixture to be tested is mixed by a mass flow controller and precisely stabilized at 25.0℃ by a temperature control system. The experimental design includes three sample groups to evaluate the performance under different concentrations of hydrogen sulfide background interference and environmental humidity fluctuations. Sample group one is the experimental group, which uses the dynamic time-domain excitation sequence and sampling delay gating processing proposed in this invention. The hydrogen sulfide concentration was set to 10.0 ppm, and the relative humidity was set to 85.0%. Test group two served as the control group, using a constant potential continuous polarization method for measurement; all other operating conditions were identical to test group one. Test group three was the edge group, employing the technical solution of this invention, but with the hydrogen sulfide concentration increased to an extreme high concentration limit of 50.0 ppm and the relative humidity increased to 95.0% to verify the stability of the solution under boundary states. During the experiment, the data acquisition module synchronously recorded the original sensor current response. The experimental system executed preset processing steps: at the instant the potential transition occurred, the control unit instructed the data acquisition module to suspend sampling, waiting... After the critical point is exceeded, high-frequency acquisition is initiated. Taking test group one as an example, in the initial input stage, the sensor is affected by intrinsic background current interference caused by sulfide adsorption. The original signal exhibits significant nonlinear fluctuations within 10.0 ms. By implementing the sampling delay gating strategy of this embodiment, in After the delay, the system effectively avoids the peak range of the background current during double-layer capacitor charging, and the extracted transient decay current sequence It exhibits a smooth, exponential decay characteristic.

[0031] For the quantification of performance criteria, the drift data of each sample group after 72.0 hours of continuous operation are recorded as follows: The control sample group, due to the lack of time-domain gating and decoupling correction, experienced a 12.4% drift in its output current reference, and its response curve showed significant hysteresis under humidity fluctuations; Test group one, within the same measurement cycle, utilized the operator matrix embedded in the non-volatile memory module. The signal is corrected in real time, and the drift of the output current reference is controlled within 0.42%, and the response time to the concentration change signal is maintained at 2.1s. In the extreme boundary conditions of 50.0ppm concentration and 95.0% high humidity, due to the introduction of Arrhenius temperature variability correction logic, the final calculated concentration output value still deviates from the calibration value within the engineering allowable range of ±3.8%.

[0032] Experimental results confirm that when the hydrogen sulfide concentration does not exceed the set upper limit of 50.0 ppm, the system can achieve signal discretization through differential extraction of the current sequence, thereby decoupling multi-component interference. When the interference concentration exceeds this physical extreme value, the key performance index data show an obvious nonlinear saturation trend, indicating that the catalytic sites under this ratio parameter have been completely occupied. This verifies the effective detection concentration range defined by the present invention. The above data show that the system successfully transforms the cross-sensitive coupling effect into a quantifiable characteristic current slope difference by changing the polarization process from a steady state to a non-equilibrium state, thereby achieving accurate decoupling measurement of component concentration under complex industrial conditions.

[0033] Example 3: In industrial monitoring scenarios involving high-concentration hydrogen sulfide gas exposure, to address the signal attenuation and nonlinear drift issues caused by reduced coverage of electrochemical active sites under long-term exposure, this system implements an adaptive compensation procedure based on dynamic polarization feature extraction. The electrochemical sensing module includes a gold nanoparticle-modified working electrode with an interfacial double-layer capacitance. With mass transfer resistance The sample exhibits dynamic evolution characteristics under sulfide adsorption conditions, which helps determine the sampling delay time constant. The engineering calibration values ​​were determined. In a laboratory environment, this system monitored the physical process of the current response by applying voltage step excitations of different amplitudes to the electrode surface. Experiments revealed that when the sampling delay time constant was set to [value missing], [the system achieved optimal performance]. At the same time, it can ensure the transient interference current generated during double-layer charging. Decay to Faraday current Below 1.0%, The numerical value is obtained by immersing the sensor in a standard test gas and calculating the first derivative of the current response in real time. Until the derivative enters the stable decay range and a certain engineering calibration point is determined, when the system performs mixed gas monitoring, the processors of multiple decoupling modules adjust the transient current input from the electrochemical sensing module. A feature analysis matrix is ​​dynamically constructed, and a compensation operator matrix based on the current decay slope is systematically solidified to address the adsorption poisoning phenomenon of active sites caused by hydrogen sulfide components. Operator matrix Each item Defined as: in the first Within a time window, components The weighted mapping coefficient between mass transfer flux and activation energy of catalytic interface reaction is used. When the system detects a lag in the working electrode potential response, the temperature feedforward compensation module calculates the change in charge transfer resistance. And based on the Arrhenius correction formula, the operator matrix is... Perform real-time weighted updates, and the updated operators Used for subsequent concentration output vector The solution.

[0034] To eliminate nonlinear interference from temperature and humidity fluctuations in the industrial environment, the detection system deploys thermistors around the working electrode to collect ambient temperature data in real time. The temperature feedforward compensation module, embedded within the multi-group decoupling module, captures temperature variability signals at a frequency of 10Hz. ,when When the absolute value exceeds 0.2℃ / s, the system triggers the temperature compensation algorithm, and based on the pre-stored temperature-potential sensitivity compensation curve, adjusts the compensation algorithm accordingly. Second-order polynomial calibration is performed to maintain the characteristic stability of the current decay slope under temperature-induced disturbances.

[0035] In the verification test where the hydrogen sulfide concentration jumped from 10.0 ppm to 50.0 ppm, the control group, under the influence of site poisoning, experienced a physical attenuation of the peak output current of 18.5%, while the system in this test... The dynamic feedback compensation of the matrix controls the stabilization time of the output concentration value to within 4.5 seconds, and the final calculated concentration deviation fluctuation value does not exceed 2.5%. The above experimental data clearly show that by constructing a matrix based on... Gating and With the decoupled closed-loop dynamic correction logic, the system achieved stable analysis of intrinsic mass transfer polarization signals under complex chemical interference, verifying the engineering reproducibility and data accuracy of the system under multidimensional physical interference environments.

[0036] Example 4: In industrial online monitoring scenarios involving long-term exposure to high concentrations of hydrogen sulfide gas, the electrochemical sensing module experiences charge transfer resistance due to the continuous adsorption of sulfides at its electrode catalytic sites. With electrochemical double layer capacitance As the system experiences nonlinear drift during its service life, a dynamic compensation calibration procedure is implemented during the offline calibration phase to ensure long-term detection accuracy. Under a constant 10.0 ppm hydrogen sulfide standard gas flow, the system performs a polarization excitation response scan every 24.0 hours. The processor records the transient current response curves of the working electrode at different potential steps and fits the interface dynamics model at that moment. This is achieved by measuring the charge transfer resistance at different service time points. Compared with the initial calibration value Compare and calculate the attenuation coefficient. The time evolution function ensures that the system maintains an accurate mapping of the characteristic current slope during sensor aging.

[0037] To eliminate signal nonlinear interference caused by temperature and humidity fluctuations in the industrial environment, the detection system deploys thermistors around the working electrode to collect ambient temperature data in real time. The temperature feedforward compensation module, consisting of multiple decoupled modules, calculates the transient temperature change rate at a frequency of 10.0 Hz. ,when When the absolute value exceeds 0.05℃ / s, the system triggers a temperature compensation algorithm, which, based on the pre-stored temperature-potential sensitivity compensation curve, adjusts the transient decay current sequence. Polynomial calibration is performed to eliminate aliasing interference caused by temperature changes on resistive characteristic parameters. The data acquisition module detects the rising edge of the potential step signal through a hardware trigger and locks the sampling trigger delay at [time value missing]. The engineering calibration points, the timer / counter module calibrates the trigger window according to the system clock frequency to ensure that the acquisition start time error is less than 1.0μs, and the multi-group decoupling module utilizes discrete operator matrices. For the calibrated feature vector Perform matrix multiplication and output a vector of component concentrations. ,vector Each discrete term in the equation represents the absolute volume percentage concentration of each harmful gas component under industrial conditions.

[0038] In the verification test where the hydrogen sulfide concentration jumped from 10.0 ppm to 50.0 ppm, the control group, under the influence of site poisoning, showed a 5.2% decrease in peak output current compared to the initial state. This system compensated by calling the attenuation coefficient. Normalization was performed on the original feature vector to maintain the judgment deviation at a concentration of 30.0 ppm within ±1.5%. The experimental results confirmed that by incorporating the evolution of the charge transfer resistance at the electrode interface into the kinetic correction model, the system achieved online restoration of the in-service performance of the electrochemical sensing module, ensuring stable identification of each gas component through the transient current decay ratio coefficient in an environment where the physical coverage of the catalytic site is constantly changing.

[0039] Example 5: In an online detection scenario involving multiple batches of mixed gas production lines and frequent changes in environmental baseline parameters, the system executes a standardized procedure that includes offline equipment calibration and real-time adaptive calibration during operation. Before accessing the mixed gas detection process, the system performs an offline calibration procedure, using a standard gas of known concentration to perform a full-range polarization scan of the sensor array under test, obtaining the charge transfer resistance of the working electrode in its initial state. With double-layer capacitance The calibration procedure involves applying a small sinusoidal voltage perturbation signal with a frequency ranging from 0.1 Hz to 100 kHz and an amplitude of 5.0 mV to the electrode using an electrochemical workstation, and then calculating the equivalent complex impedance of the electrode interface. The data is stored in a non-volatile memory module as in-service reference calibration data. To safely perform impedance calibration without disrupting the sensor's polarization, the system's internal hardware switching circuit consists of a high-speed solid-state analog switch array controlled by the central processing unit. The main input of this analog switch array is connected to the working electrode, reference electrode, and counter electrode, respectively. Its two branch output channels point to the conventional time-domain excitation data acquisition loop and the online impedance calibration loop, respectively. During continuous operation, the system maintains a 24-hour timed maintenance resting counter through the processor. When the counter reaches a set threshold, and When the processor determines that the rate of change of the transient decay current is less than 0.01 microamps per second for 10 consecutive seconds, proving that the gas response is in a quasi-steady-state equilibrium with extremely low fluctuations, the safety switching criterion is triggered. The central processing unit issues a switching command to control the solid-state analog switch array to switch the entire three-electrode network to the impedance online calibration loop within 5 microseconds. Since the amplitude of the sinusoidal AC perturbation voltage is strictly limited to within 5 millivolts, this weak energy input will not cause destructive disturbance to the diffusion layer limit already established on the electrode surface. After the calibration scan is completed, the switch array seamlessly switches back, ensuring the in-situ safe operation of the zero-point long-term anti-drift self-reconfiguration channel.

[0040] During system online operation, the processors of multiple decoupling modules extract the steady-state polarization current of the working electrode in real time. And calculate the dynamic decay rate of the current within adjacent sampling periods. ,in, For dynamic decay rate, For the sampling time increment, when When the deviation exceeds a preset deviation threshold of 15.0%, the processor determines that the sensor has undergone microscopic physical aging and immediately calls the preset feedback calibration weight coefficient. Calculate operator update amount for matrix Perform linear correction, and the corrected operator matrix The weighting coefficient here The method originates from the statistical fitting of the evolution trend of electrode impedance spectrum at different aging stages in the laboratory environment in the early stage, which ensures that the correction parameters accurately correspond to the physical decay trend of electrode activity.

[0041] The system is executing the mixed gas concentration... During the calculation, ambient temperature variability compensation logic is applied synchronously. When the internal temperature change rate of the cavity... When the absolute value is within the engineering stability range of 0.05℃ / s, the system directly calls the matrix. Output concentration; when the rate of change exceeds this critical point, the system adjusts the operator matrix according to a preset Arrhenius temperature correlation model. The activity mapping coefficient is dynamically compensated to maintain the detection accuracy deviation of each gas component concentration output value within the engineering control range of 2.0% within the temperature window of 10.0℃ to 45.0℃. At the end of each monitoring cycle, the system automatically updates the latest operator matrix. Compared with the current reference current response Synchronously updated to the non-volatile storage module, enabling real-time tracking and quantitative compensation of electrode interface activity throughout its entire lifecycle, including concentration vectors. The output values ​​show that this system eliminates the reference potential drift during long-term sensor operation through closed-loop compensation of physical impedance evolution logic, ensuring the engineering reproducibility of gas component concentration data under complex industrial interference environments.

[0042] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A mixed gas composition detection system based on electrochemical sensing, characterized in that, include: An electrochemical sensing module is used to contact the gas mixture to be measured and generate a mass transfer polarization current response. The time-domain excitation module is electrically connected to the electrochemical sensing module and is used to apply an asymmetric time-domain electrode step excitation sequence containing voltage transition actions to the electrochemical sensing module to change the electrochemical polarization state of the gas component at the catalytic interface. The data acquisition module, electrically connected to the electrochemical sensing module, is used to acquire the transient decay current sequence caused by voltage transition. The data acquisition module includes a low-noise transimpedance amplification module, a high-order analog-to-digital conversion module, a timing and counting module, and a high-frequency sampling channel module. It also has a built-in sampling delay time constant, which is used to forcibly suspend the conversion action of the high-order analog-to-digital conversion module at the moment the voltage transition occurs, keeping the data acquisition in a paused state until the holding time of the timing and counting module crosses the critical point of the sampling delay time constant. Then, the high-frequency sampling channel module is activated to digitally extract the transient decay current sequence that reflects the Faraday characteristics. Multiple decoupling modules are connected to the data acquisition module to receive transient decay current sequences. The multiple decoupling modules include a non-volatile storage module and a microprocessor module. The non-volatile storage module contains a decoupling correction coefficient matrix. The microprocessor module is used to retrieve the decoupling correction coefficient matrix, and the transient decay current sequence is stripped of nonlinear cross-sensitive overlapping components through first-order differential processing to output the concentration of each gas component. The flow rate adaptive compensation module is connected to the time-domain excitation module. The front end of the detection chamber module has an intake pipe module with fixed flow resistance, and the intake pipe module contains a micro-pressure difference measurement module. The micro-pressure difference measurement module monitors local fluid pressure changes caused by external airflow fluctuations in real time and converts the micro-pressure difference parameters into input data for the flow rate adaptive compensation module. The flow rate adaptive compensation module uses the micro-pressure difference parameters collected by the micro-pressure difference measurement module to calculate the airflow velocity deflection in real time, and sends a timing fine-tuning command to the time-domain excitation module when the external fluid transport conditions deviate from the steady-state boundary. This dynamically adjusts the pulse duration of the asymmetric time-domain electrode step excitation sequence in the next polarization cycle, achieving dynamic offsetting of the unsteady diffusion layer thickness on the time axis. The feedforward of the unsteady diffusion layer thickness in the time domain compensates for convective mass transfer losses caused by airflow velocity disturbances, preventing local fluid dissipation distortion from spreading to the transient decaying current sequence. It also includes: a temperature feedforward compensation module, which is electrically connected to multiple decoupling modules, used to obtain the real-time temperature in the detection chamber module and retrieve the activation energy balance constant of the solidified module. The activation energy balance constant is an algebraic weighting coefficient obtained in advance based on the correspondence between the intrinsic activation energy of each gas component to be tested at the catalytic interface and the molecular diffusion coefficient with temperature. It is used to characterize the linear intervention weight of temperature change on the attenuation slope of Faraday characteristic current. The temperature correction coefficient is calculated by multiplying the real-time temperature and the constant of the activation energy, and then embedded into the transient decay current sequence to offset the exponential interference of temperature changes on the interfacial multiphase catalytic rate constant and the intrinsic diffusion coefficient of gas molecules.

2. The mixed gas composition detection system based on electrochemical sensing according to claim 1, characterized in that, In the data acquisition module, the low-noise transimpedance amplification module includes a microampere-level low-noise amplification unit, and the voltage output terminal of the low-noise transimpedance amplification module is electrically connected to the analog input terminal of the high-order analog-to-digital converter module. The data acquisition module is signal-connected to the time-domain excitation module, which is used to forcibly suspend the conversion action of the high-order analog-to-digital converter module at the instant when the voltage transition action is determined, and keep the data acquisition paused until the maintenance time of the timing counting module crosses the critical point of the sampling delay time constant. Then, the high-frequency sampling channel module is activated to digitally extract the transient decay current sequence reflecting the Faraday characteristics, and block the double-layer capacitor charging background current generated by the inherent capacitance polarization of the electrochemical sensing module interface at the moment of transition.

3. The mixed gas composition detection system based on electrochemical sensing according to claim 1, characterized in that, In the multi-group decoupling module, the decoupling correction coefficient matrix is ​​a constant weighted algebraic mapping array pre-embedded in the specified sector address of the non-volatile storage module of the multi-group decoupling module. The decoupling correction coefficient matrix is ​​calculated based on the standard mass transfer decay current curves corresponding to each single pure working condition gas characteristic component collected in the standard gas calibration test before leaving the factory. After the nonlinear cross-sensitive overlapping components are removed by first-order differential, it is used to directly convert the collected transient decay current sequence into the concentrations of each gas component that do not interfere with each other through matrix multiplication.

4. The mixed gas composition detection system based on electrochemical sensing according to claim 1, characterized in that, The electrochemical sensing module includes a working electrode module, a counter electrode module, and a reference electrode module located inside the detection chamber module. The catalyst surface of the working electrode module is used to allow multiple gas components in the gas mixture to undergo redox reactions simultaneously. The time-domain excitation module is electrically connected to the working electrode module and is used to apply an asymmetric time-domain electrode step excitation sequence to the working electrode module, so that the molecules of different characteristic gas components in the early stage of catalytic reaction establishment produce heterogeneous mass transfer attenuation resistance characteristics on the time axis, which are determined by their intrinsic mass transfer rate and reaction activation energy level.

5. The mixed gas composition detection system based on electrochemical sensing according to claim 1, characterized in that, The asymmetric time-domain electrode step excitation sequence delivered by the time-domain excitation module contains multiple pulse signals with different potential amplitudes, and there is a voltage transition action between two adjacent pulse signals; the sampling delay time constant solidified in the data acquisition module is in the range of 10μs to 500μs, which is used to avoid the peak range of the background current of the double-layer capacitor charging, so that the transient decay current sequence extracted by the high-frequency sampling channel module is completely composed of Faraday characteristic currents that reflect the real electrochemical multiphase catalytic rate.

6. The mixed gas composition detection system based on electrochemical sensing according to claim 1, characterized in that, In the multi-group decoupling module, the non-volatile storage module is a flash memory storage unit, and the microprocessor module is a central processing unit. The decoupling correction coefficient matrix is ​​pre-programmed into a fixed sector of the flash memory storage unit as a constant weighted algebraic mapping array. The central processing unit is used to read the digitized discrete current data sequence from the data acquisition module, and to perform constant weighted matrix multiplication operation through the decoupling correction coefficient matrix to remove the cross-sensitive coupling components caused by high potential overlap, and output the concentration of each gas component after separation in an independent channel.

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