Electrochemical-mass spectrum combined device based on integrated electrode plate

Abstract

The invention provides an electrochemical-mass spectrometry device based on an integrated electrode plate, and relates to the technical field of analytical chemistry, the device comprises a mass spectrometer and an electrochemical reaction device, the mass spectrometer is provided with a sample inlet, and the electrochemical reaction device comprises an electrochemical workstation and an electrochemical reaction platform; the electrochemical reaction platform is a patterned electrode assembly and comprises an insulating base material with at least one hydrophilic sharp corner and three electrodes which are located in the hydrophilic sharp corner area and are electrically isolated from one another; the three electrodes are a working electrode, a counter electrode and a reference electrode, the working electrode is arranged at the tip of the hydrophilic sharp corner, and the tip of the hydrophilic sharp corner is arranged opposite to the sample inlet; the floating work station is connected with the patterned electrode assembly. The device provided by the invention can realize the combination of electrochemistry, electrospray and mass spectrum devices, is simple and convenient to operate, and can improve the electrochemical detection efficiency and detection accuracy.

Description

Technical Field

[0001] This application relates to the field of analytical chemistry technology, and in particular to an electrochemical-mass spectrometry device based on integrated electrode sheets. Background Technology

[0002] Electrospray ionization mass spectrometry (ESI-MS) has been widely used in small molecule analysis, biomarker detection, and identification of electrochemical reaction intermediates due to its high sensitivity, soft ionization properties, and adaptability to complex matrices. In recent years, in-situ electrochemical mass spectrometry coupled with other instruments has been used to capture short-lived reaction intermediates in real time, thereby revealing reaction mechanisms.

[0003] However, traditional electrochemical-mass spectrometry (ECMS) typically relies on bulk electrodes such as glassy carbon, gold, or platinum. This requires a mechanically assembled three-electrode system and support, a large reaction volume, and complex electrode pretreatment procedures. Electrode distance and layout are significantly affected by manual assembly, easily leading to electrode potential shifts and solution resistance changes, resulting in large experimental errors. It is also unsuitable for detecting trace samples and is difficult to achieve single-use. Furthermore, existing integrated electrode sheets are mostly used for routine electrochemical detection and lack direct coupling structures for electrospray mass spectrometry.

[0004] Therefore, there is still a lack of an integrated electrode spray interface that is compact, stable, low-cost, mass-producible, and simple and convenient. Summary of the Invention

[0005] This application provides an electrochemical-mass spectrometry device based on an integrated electrode sheet, which can realize the combined use of electrochemistry, electrospray ionization and mass spectrometry. It is simple and convenient to operate and can improve the efficiency and accuracy of electrochemical detection.

[0006] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application provides an electrochemical-mass spectrometry (EMS) device based on an integrated electrode sheet. The device includes a mass spectrometer and an electrochemical reaction apparatus. The mass spectrometer has an inlet. The electrochemical reaction apparatus includes an electrochemical workstation and an electrochemical reaction platform. The electrochemical workstation is a floating-ground workstation, comprising a battery power module, a high-voltage module, and an electrochemical measurement and control module. The electrochemical reaction platform is a patterned electrode assembly, including an insulating substrate with at least one hydrophilic tip, and three electrically isolated electrodes located in the region of the hydrophilic tip. The three electrodes are a working electrode, a counter electrode, and a reference electrode, with the working electrode disposed at the tip of the hydrophilic tip, the tip of which is opposite to the inlet. The floating-ground workstation is electrically connected to the patterned electrode assembly, wherein: The electrochemical workstation is used to provide the bias voltage required for the electrochemical reaction to the patterned electrode assembly, and to keep the working electrode, the counter electrode and the reference electrode at a floating high potential, so as to realize the controlled electrochemical reaction and electrospray ionization simultaneously at the hydrophilic sharp corner; The hydrophilic pointed tip is used to guide the ions generated by the electrospray ionization into the injection port.

[0007] In one possible implementation, the hydrophilic sharp corner is achieved in any of the following ways: Utilizing the hydrophilicity of the insulating substrate itself; Physical hydrophilic modification is performed on the sharp corner regions of the insulating substrate; The sharp corner regions of the insulating substrate are chemically hydrophilically modified. A hydrophilic layer is coated on the sharp corner areas of the insulating substrate.

[0008] In one possible implementation, the working electrode, the counter electrode, and the reference electrode are formed by a patterning process, which includes at least one of screen printing, inkjet printing, photolithography, laser etching, electroforming transfer, physical deposition, and chemical deposition.

[0009] In one possible implementation, the patterned electrode assembly further includes a conductive layer located outside the hydrophilic pointed region and an insulating layer covering the conductive layer.

[0010] In one possible implementation, the insulating substrate is a flexible insulating substrate or a rigid insulating substrate.

[0011] In one possible implementation, the flexible insulating substrate is a polymer film or a paper base.

[0012] In one possible implementation, the polymer film is made of any one of polyethylene terephthalate, polyimide, polypropylene, polyethylene, polydimethylsiloxane, or hydrogel.

[0013] In one possible implementation, the paper base includes any one of filter paper, chromatography paper, hydrophobic paper, nanocellulose paper, polymer-impregnated paper, bio-paper, and natural fiber paper.

[0014] In one possible implementation, the rigid insulating substrate is any one of silicon, glass, or ceramic.

[0015] In one possible implementation, the working electrode, the counter electrode, and the reference electrode are made of any one of carbon black, silver-silver chloride, gold, silver, platinum, or a conductive polymer.

[0016] The beneficial effects of the technical solutions provided in this application include at least the following: This application provides an electrochemical-mass spectrometry (ESS) device based on an integrated electrode sheet. The device includes a patterned electrode assembly comprising a working electrode, a reference electrode, and a counter electrode disposed on an insulating substrate; an electrochemical reaction region, located at the tip of the patterned electrode, which is the area containing the three electrodes and used to hold the target solution to be reacted. The three electrodes are in contact with the target solution, and a sample droplet covers the three electrodes. An external floating electrochemical workstation applies a working voltage, causing the entire device to float on high voltage, allowing the target molecules to undergo oxidation or reduction reactions to form reaction intermediates. The intermediates are connected to the electrochemical workstation via an adapter; and a mass spectrometry injection interface is provided, with the tip of the patterned electrode maintained at a certain distance from the injection cone to achieve stable spraying. The patterned electrode-based electrochemical spray ion source device provided in this application can achieve online coupled detection of electrochemistry and mass spectrometry, simultaneously performing both detections and improving detection efficiency. Furthermore, compared to existing technologies, this application features an extremely simple structure, requiring only a single patterned electrode to achieve a three-electrode system and spray function; the integrated electrode sheet eliminates the need for separate electrodes, electrochemical cells, and metal nozzles, simplifying the assembly process of traditional electrochemical cells and electrodes; it can be used once, avoiding polishing contamination and improving repeatability; the flexible insulating substrate ensures the integrity of the conductive layer of the electrode assembly and the stability of the electrochemical interface, thereby significantly improving the structural stability and electrochemical response repeatability of the electrode; stable electrospraying can be achieved with micro-sizing samples; it saves samples and is suitable for the analysis of biological and precious samples; because the working electrode is fixedly set at the tip of the hydrophilic apex, the electrochemical reaction occurs at the spray tip and the electrode will not fall off, thus achieving in-situ electrochemical reaction-spray-mass spectrometry coupling while ensuring stability, and can capture substances that are difficult to detect by traditional methods, such as short-lived free radicals and oxidative intermediates; it has strong scalability and can be used in scenarios such as enzyme conversion, redox kinetics, and biomarker analysis. Attached Figure Description

[0017] Figure 1 A schematic diagram of the overall structure of an electrochemical-mass spectrometry device based on an integrated electrode sheet provided in an embodiment of this application; Figure 2 A partially enlarged view of an electrochemical-mass spectrometry device based on an integrated electrode sheet provided in an embodiment of this application; Figure 3 A schematic diagram of the hydrophilic region, wire, and insulating region of a patterned electrode assembly provided in an embodiment of this application; Figure 4 A hierarchical structure diagram of a patterned electrode assembly provided in an embodiment of this application; Figure 5 This is a schematic diagram illustrating the surface hydrophilicity of an existing sharp corner without modification, as provided in an embodiment of this application. Figure 6 A schematic diagram illustrating the surface hydrophilicity of a hydrophilic sharp corner after plasma treatment and gelatin modification, provided as an embodiment of this application; Figure 7 This is a graph showing the change of ion current intensity over time in a dopamine oxidation process provided in an embodiment of this application.

[0018] Figure label: 1~Mass spectrometer and sample inlet cone; 2~Patterned electrode assembly; 3~Electrochemical workstation adapter interface; 4~Electrochemical workstation; 5~Moving alignment platform; 6~Base; 2-1 Working electrode; 2-2 Counter electrode; 2-3 Reference electrode; 2-4 Wire; 2-5 Hydrophilic region; 2-6 Wire and insulating region; 2-7 Insulating substrate; 2-8 Wire layer; 2-9 Three-electrode layer; 2-10 Insulating layer. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0021] In addition, the use of “based on” or “according to” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” or “according to” one or more conditions or values ​​can in practice be based on additional conditions or values ​​beyond those conditions.

[0022] To address the aforementioned issues, this application proposes an electrochemical-mass spectrometry (EMS) device based on integrated electrode sheets. Patterned electrode assemblies are characterized by high integration, customizable structure, high consistency in batch preparation, no need for polishing, low cost, and single-use capability. This application constructs hydrophilic sharp corners with specific geometries at the front end of the patterned electrode, enabling sample droplets to form a stable electrospray under high voltage in the tip region after the electrochemical reaction, thus directly entering the mass spectrometry analysis. Furthermore, this application simultaneously integrates a three-electrode system and the spray geometry on a composite substrate, achieving seamless connection between the reaction zone and the electrospray zone, significantly reducing the size and complexity of the coupled device.

[0023] Furthermore, by applying an external potential to the working electrode, this application can control the redox process within a micro-level system and generate short-lived intermediates. Subsequently, through high-voltage electrospray scattering, these intermediates are introduced into the mass spectrometer before decay, thereby achieving real-time capture and analysis of short-lived active species. This application is not only applicable to research on fundamental electrochemical reactions but also to research scenarios requiring the monitoring of transient species, such as drug oxidation, neurotransmitter metabolism, and biomolecular modification.

[0024] The following examples use dopamine oxidation as a model system to illustrate the structure, operation, and mass spectrometry response of this application.

[0025] The device includes a mass spectrometer and an electrochemical reaction unit. The mass spectrometer has a sample inlet, and the electrochemical reaction unit includes an electrochemical workstation and an electrochemical reaction platform. The electrochemical workstation is a floating workstation, which includes a battery power module, a high-voltage module, and an electrochemical measurement and control module. The electrochemical reaction platform is a patterned electrode assembly, which includes an insulating substrate with at least one hydrophilic tip, and three electrically isolated electrodes located in the hydrophilic tip region. The hydrophilic tip is the reaction cell for carrying the electrochemical reaction. The three electrodes are a working electrode, a counter electrode, and a reference electrode, with the working electrode located at the tip of the hydrophilic tip, which is opposite to the sample inlet. The floating workstation is connected to the patterned electrode assembly. The electrochemical workstation provides the bias voltage required for the electrochemical reaction to the patterned electrode assembly and keeps the working electrode, counter electrode, and reference electrode at a floating high potential, so that controlled electrochemical reaction and electrospray ionization can be simultaneously achieved at the hydrophilic tip. The hydrophilic tip is used to guide ions generated by electrospray ionization into the sample inlet.

[0026] The three-electrode layer comprises a working electrode, a reference electrode, and a counter electrode, all printed on the same plane to form a micro-electrochemical reaction zone. It should be noted that the patterned electrode assembly here may include an insulating substrate with one or more hydrophilic tips. With multiple hydrophilic tips, a set of electrically isolated three electrodes can be disposed in each hydrophilic tip region. For example, if there are two hydrophilic tips, A and B, a set of three electrodes can be disposed in region A, with the working electrode positioned at the tip of hydrophilic tip A. Similarly, a set of three electrodes can be disposed in region B, with the working electrode positioned at the tip of hydrophilic tip B. This application does not specifically limit the number of hydrophilic tips.

[0027] The tip structure of the hydrophilic apex can be machined into a cone angle of 15°-60°. After physical and chemical modification, the hydrophobic angle of the tip surface is less than 30°. This geometry ensures that droplets can gather at the tip to generate a Taylor cone and form a stable electrospray.

[0028] The online electrochemical reaction zone can cover the working electrode with 20–50 μL sample droplets. The working voltage is applied by an external electrochemical workstation, and the entire device is then floated on high voltage, causing the target molecules to undergo oxidation or reduction reactions and form short-lived reaction intermediates.

[0029] The high-voltage electrospray interface allows the entire device to float on a high voltage of 3-6 kV. In-situ electrospray is formed at the tip 5-10 mm away from the interface, allowing the reaction products to be directly analyzed by mass spectrometry.

[0030] In addition, the patterned electrode assembly is equipped with an electrochemical workstation adapter that connects to the electrochemical reaction zone and is connected to the electrochemical workstation through the conductive layers of the working electrode, reference electrode, and counter electrode.

[0031] Alternatively, the hydrophilic sharp corner can be achieved in any of the following ways: Utilizing the hydrophilicity of the insulating substrate itself; Physical hydrophilic modification of the sharp corner areas of the insulating substrate; Chemical hydrophilic modification of the sharp corner areas of the insulating substrate; A hydrophilic layer is coated on the sharp corner areas of the insulating substrate.

[0032] Among them, physical and chemical modification can be carried out by 120s of maximum power plasma treatment and soaking in 0.01% gelatin, followed by drying at 37°C, maintaining a static hydrophobic angle of less than 30°, and the hydrophilic effect can be maintained for one month.

[0033] In some alternative embodiments, the working electrode, counter electrode, and reference electrode are formed by a patterning process, which includes at least one of screen printing, inkjet printing, photolithography, laser etching, electroforming transfer, physical deposition, and chemical deposition.

[0034] In some alternative embodiments, the patterned electrode assembly, in addition to the insulating substrate and the three electrodes, also includes a conductive layer located outside the hydrophilic sharp corner region and an insulating layer covering the conductive layer to prevent the conductive layer from participating in the electrochemical reaction.

[0035] In some alternative embodiments, the insulating substrate is a flexible insulating substrate or a rigid insulating substrate.

[0036] Optionally, the flexible insulating substrate is a polymer film or a paper base.

[0037] In some alternative embodiments, the polymer film is made of any one of polyethylene terephthalate, polyimide, polypropylene, polyethylene, polydimethylsiloxane, or hydrogel.

[0038] In some alternative embodiments, the paper base includes any one of filter paper, chromatography paper, hydrophobic paper, nanocellulose paper, polymer-impregnated paper, bio-paper, and natural fiber paper.

[0039] Optionally, the rigid insulating substrate can be any one of silicon, glass, or ceramic.

[0040] In some alternative embodiments, the working electrode, counter electrode, and reference electrode are made of any one of carbon black, silver-silver chloride, gold, silver, platinum, and conductive polymer.

[0041] It should be noted that the above embodiments are all illustrative examples and can be adapted to the actual situation. The embodiments of this application do not specifically limit the selection of patterning process, insulating substrate, patterned electrode assembly material, spray ionization method, etc.

[0042] Specifically, such as Figure 1 and Figure 2 As shown, Figure 1 This is a schematic diagram of the overall structure of an electrochemical-mass spectrometry device based on an integrated electrode sheet, provided in an embodiment of this application. Figure 2 This is a partially enlarged view of an electrochemical-mass spectrometry device based on an integrated electrode sheet, provided as an embodiment of this application.

[0043] The device includes a mass spectrometer and sample inlet cone 1, a patterned electrode assembly 2, an electrochemical workstation adapter interface 3, an electrochemical workstation 4, a movable alignment platform 5, and a base 6. In practical applications, the movable alignment platform 5 can be mounted on the base 6, with the hydrophilic patterned electrode tip aligned with the mass spectrometer sample inlet cone, 10 mm away from the cone. The working electrode, counter electrode, and reference electrode of the floating electrochemical workstation are connected via the electrochemical workstation adapter. The 5.5 kV high voltage of the mass spectrometer is connected to the grounding terminal of the electrochemical workstation. 50 μL of reaction solution is added to the tip using a pipette, and mass spectrometry scanning and electrochemical workstation scanning are started to achieve simultaneous electrochemical reaction and spray ionization.

[0044] The patterned electrode assembly 2 includes a working electrode 2-1, a counter electrode 2-2, a reference electrode 2-3, and a wire 2-4 printed on an insulating substrate. It should be noted that the three electrodes described below refer to the working electrode 2-1, the counter electrode 2-2, and the reference electrode 2-3. The patterned electrode assembly 2 can be used by directly inserting it into the electrochemical workstation adapter interface 3. After the electrochemical workstation 4 is connected to floating ground, three BNC connecting wires with alligator clips are led out through the corresponding electrode ports. The alligator clips clamp the three wires of the electrochemical workstation adapter interface 3, respectively, to achieve communication with the three electrodes in the patterned electrode assembly 2.

[0045] The device may also include a tip electrochemical reaction zone, which is the area where the three electrodes are located, for holding the target solution to be reacted and for contacting the target solution; an electrochemical workstation adapter that connects to the three-electrode electrochemical reaction zone and connects to the electrochemical workstation; and a mass spectrometer injection interface.

[0046] Optionally, the patterning process can employ laser etching and chemical deposition processes, meaning the three electrodes in the patterned electrode assembly 2 are fabricated using laser etching and chemical deposition. Specifically, a polyimide (PI) film can be used as a substrate. After setting the electrode pattern outline in the software, a laser with 96% power and 71% scanning speed is used for point-by-point or line-by-line etching. Under the local high temperature and instantaneous reduction effect of the laser, the PI surface undergoes carbonization and graphitization, generating laser-induced graphene (LIG) with a porous structure and high conductivity in situ. The conductive framework of the working electrode, counter electrode, and reference electrode is formed in one step through a pre-designed pattern.

[0047] Subsequently, a heat-curable silver paste was uniformly sprayed onto the reference electrode area. The paste was then heated at 120–150°C for several minutes using a hot air gun to cause solvent evaporation and particle sintering, forming a continuous and dense silver conductive layer. Based on this, the cured silver electrode was immersed in a FeCl3 solution for about 5 minutes. Through chemical deposition, the surface of the metallic silver was transformed in situ into an Ag / AgCl layer, thereby obtaining an Ag / AgCl reference electrode with a stable potential. Finally, the electrode was thoroughly rinsed with deionized water and dried, thus completing the fabrication process of the graphene working electrode, counter electrode, and reference electrode based on laser-etched PI.

[0048] To ensure good conductivity, the resistance between the working electrode and the counter electrode is controlled within tens of ohms. The potential difference between the reference electrode and the standard Ag / AgCl electrode is verified to ensure the accuracy of the reference electrode's reference potential. The potential difference between the reference electrode and the standard Ag / AgCl electrode is measured in a saturated KCl solution using an open-circuit voltage test in an electrochemical workstation. If the measured potential difference between the two is less than 5mV, then the reference electrode is a high-performance reference electrode that can provide a correct potential reference.

[0049] Optionally, the patterning process can employ physical deposition and chemical deposition processes, meaning the three electrodes in the patterned electrode assembly 2 are prepared using physical deposition and chemical deposition processes. Specifically, a clean, dry filter paper can be used as a substrate. The hollowed-out electrode pattern is placed on the paper substrate and fixed on the sample stage of an ion sputtering instrument. Under vacuum conditions, inert argon gas is introduced, and the sputtering current is set to 20 mA and the sputtering time to 120 s. The gold target is bombarded with ions, causing gold atoms to be sputtered from the target surface and uniformly deposited on the surface of the filter paper and in the gaps between its fibers, forming a continuous conductive gold thin film. This yields the conductive layers of the paper-based working electrode, the gold counter electrode, and the gold-based reference electrode.

[0050] Subsequently, a heat-curable silver paste was uniformly coated onto the surface of the reference electrode area by spraying, and then heated at 120–150°C with a hot air gun until the silver paste was completely cured. On this basis, the reference electrode area with the formed silver layer was immersed in FeCl3 solution for about 5 minutes, so that silver and FeCl3 could undergo a surface chemical reaction and a stable Ag / AgCl interface was deposited in situ on the surface of the silver layer, thereby obtaining a paper-based Ag / AgCl reference electrode with a stable potential.

[0051] When the resistance of the prepared working electrode and counter electrode reaches within tens of ohms, it indicates good electrode conductivity, meeting the requirements for low internal resistance and stable signal output in subsequent electrochemical tests. To verify the potential difference between the reference electrode and the standard Ag / AgCl electrode and ensure the accuracy of the reference electrode's reference potential, the potential difference between the reference electrode and the standard Ag / AgCl electrode is measured in a saturated KCl solution using an open-circuit voltage tester in a commercial electrochemical workstation. If the measured potential difference between the two is less than 5mV, then the reference electrode is a high-performance reference electrode that can provide a correct potential reference.

[0052] Optionally, the patterning process can employ screen printing. The insulating substrate 2-7 of the patterned electrode assembly 2 is made of polyethylene terephthalate (PET), the conductive layer 2-8 is made of conductive ink, the working electrode 2-1 and counter electrode 2-2 of the three-electrode layer 2-9 are carbon electrodes, the reference electrode 2-3 is printed with Ag / AgCl, and the insulating layer 2-10 is made of PET. The hydrophilic pointed structure has a 30° cone angle, with the tip being the region for the droplet addition of the reaction liquid and the electrochemical reaction.

[0053] Based on this, the sharp corners of the patterned electrode assembly are hydrophilic areas, while the rest are wire and insulating areas.

[0054] The following example illustrates the use of screen printing for patterning processes. Figure 3 As shown, Figure 3 This is a schematic diagram of the hydrophilic region, wires, and insulating region of a patterned electrode assembly provided in an embodiment of this application. The hydrophilic region 2-5, formed after the aforementioned hydrophilic treatment, is the reaction region of the patterned electrode assembly 2. The hydrophilic treatment of this region ensures that the electrochemical reaction takes place at the tip, and after high voltage, it quickly forms a spray that enters the mass spectrometer for detection. The insulating layer 2-10 covering the wires formed by the wire layers 2-8 and the insulating region 2-6 ensures that the reaction liquid can be dripped onto the tip and does not flow to the electrochemical workstation adapter interface 3 at the rear end, preventing short circuits of the three electrodes, the wire layers 2-8 participating in the reaction, and leakage damage to the floating electrochemical workstation.

[0055] Figure 4 This is a layered structural diagram of a patterned electrode assembly provided in an embodiment of this application. The insulating substrate 2-7 provides mechanical support and chemical stability, serving as the carrier for all functional layers. The conductor layer 2-8 enables conductive connections between the electrodes and an external floating electrochemical workstation, ensuring reliable signal transmission. Here, the conductor layer 2-8 is the plane containing the three parallel conductors 2-4 mentioned above. The three-electrode layer 2-9, composed of the working electrode 2-1, the counter electrode 2-2, and the reference electrode 2-3, is the core area where electrochemical reactions occur and signals are generated. The insulating layer 2-10 covers the conductors and defines the effective exposed area of ​​the electrodes, preventing short circuits, reducing background current, and improving the reproducibility and structural stability of the electrodes.

[0056] Figure 5 This is a schematic diagram illustrating the surface hydrophilicity of an existing sharp corner without modification, as provided in an embodiment of this application. Figure 6 This is a schematic diagram illustrating the hydrophilicity of a droplet with hydrophilic pointed corners after plasma treatment and gelatin modification, provided as an embodiment of this application. Specifically, as shown... Figure 5 The static hydrophobic angle of the untreated three electrodes is 124.8°.

[0057] Physical modification involves plasma treatment of the surface. However, if the treatment time is too long, the three electrodes are prone to bending and detachment. Therefore, a modification treatment with a maximum power of 120 seconds can significantly change the surface's hydrophilicity, but its stability is poor and its storage time is short.

[0058] Plasma treatment with a maximum power of 120 s, followed by chemical modification with 0.01% gelatin and drying at 37°C, resulted in a static hydrophobic angle of 22.4° for the plasma-treated and gelatin-modified droplets. Figure 6 The three electrodes treated with plasma and modified with 0.01% chemical treatment can be stably stored for one month without changing their hydrophilicity.

[0059] In addition, based on the electrochemical-mass spectrometry device based on integrated electrode sheet (hereinafter referred to as the device) provided in the embodiments of this application, the following tests and verifications were also conducted in this application.

[0060] Example 1: In positive ion mode, a voltage of 0.0~1 V was applied to monitor the oxidation of dopamine.

[0061] Research on dopamine oxidation provides crucial support for the biomedical field: it reveals the pathogenesis of neurodegenerative diseases such as Parkinson's disease, lays the foundation for targeted drug development and early diagnostic technology optimization, and also helps to innovate clinical protocols related to neurofunctional regulation.

[0062] Specifically, an electrochemical linear voltammetric scan was performed using a 1 mM dopamine hydrochloride solution (dissolved in a 10 mM lithium chloride electrolyte solution (methanol / water = 1 / 1)). The scan rate was 0.05 V / s, the scan range was 0-1 V, the scan interval was 0.001 V, and the number of scan segments was 1. Mass spectrometry parameters were set as follows: ion transfer tube temperature was set to 275 °C; S-lens energy was set to 60%; the number of scans was set to 1; and the mass spectrometer resolution was set to 60000. The results showed that the oxidation peak potential of dopamine on the integrated three-electrode plate was approximately 0.6 V.

[0063] Figure 7The graph shows the change in ion current intensity over time during the dopamine oxidation process provided in this application embodiment. The horizontal axis represents time, and the vertical axis represents the normalized strength of the mass spectrometry ion signal. m / z 154 and m / z 152 represent ions with two different mass-to-charge ratios. Initially, 154 is present in large quantities as a reaction precursor, while 152 is absent. At 0.2 min, 152 begins to appear in large quantities. At 0.2 min, the protonation of dopamine begins the first step of the reaction, producing the 152 intermediate, which corresponds to the decrease in the 154 reaction precursor at 0.2 min. After 1.2 min, the dopamine 154 ion current decreases to 0, corresponding to the oxidation product 152 remaining stable and no longer increasing.

[0064] The above-mentioned dopamine oxidation experiment shows that the device provided in this application can perform correct electrochemical-mass spectrometry studies. It is a faster, more accurate, more convenient, and lower-cost device that can be used in the field of analytical chemistry research.

[0065] The above examples fully demonstrate that the electrochemical-mass spectrometry device based on integrated electrode sheets provided in the embodiments of this application can monitor the electrochemical reaction process and capture and identify the active intermediates and products in the reaction process.

[0066] This application proposes an electrochemical-mass spectrometry device based on an integrated electrode sheet. Through a three-electrode coupled spray structure design, it realizes in-situ electrochemical reactions in a micro-level reaction system and directly electrosprays them into the mass spectrometer for capturing short-lived redox intermediates and rapid chemical analysis.

[0067] Compared to the traditional manual mechanical assembly of the separation electrode, carrier, and electrochemical cell, the relative positions, immersion depths, and spacing are difficult to maintain consistently, leading to instability in the electric field distribution and diffusion structure of the electrochemical reaction. This results in poor measurement repeatability and increased experimental errors. Secondly, the distance and geometric layout between electrodes are significantly affected by manual placement, easily causing problems such as reference electrode potential drift, changes in solution resistance, and inconsistent effective areas of the working electrode. Furthermore, traditional systems typically rely on large glass or plastic electrochemical cells, requiring large sample volumes (often in the mL range), making them unsuitable for micro-samples or one-time analyses.

[0068] Taking screen printing as an example, controlling the materials and processes to be consistent during the preparation and application of screen-printed integrated electrode sheets can minimize the aforementioned problems. Specifically, the screen printing process involves the coupling of multiple factors such as paste viscosity, screen structure, squeegee pressure, and curing temperature. It is necessary to avoid uneven electrode layer thickness, uncontrollable pore structure, and conductivity fluctuations, which would affect electrochemical repeatability. Secondly, the proportions of binders, solvents, and fillers in conductive pastes (such as carbon ink and silver ink) need to be strictly controlled. Insufficient dispersibility or unstable film formation may lead to electrode microcracks, insufficient interfacial adhesion, or large batch-to-batch differences. Therefore, the manufacturing process requires strict control of consistent materials and processes. Furthermore, screen printing can produce electrodes with slightly rough surfaces, thereby increasing the effective specific surface area and improving the electrochemical reaction current and mass spectrometry signal intensity.

[0069] The core advantage of integrated electrode sheets lies in their low cost and mass production capability. They can integrate working electrodes, counter electrodes, reference electrodes, and even microchannels into a single flexible substrate. This not only greatly simplifies the sensor assembly process and reduces volume and material consumption, but also significantly improves the consistency and stability between electrodes. They are particularly suitable for disposable biosensors, point-of-care testing devices, and wearable electronic products, achieving an effective combination of high performance and large-scale production.

[0070] In addition, the flexible insulating substrate has higher dielectric breakdown strength, making the electrode edges safer and more reliable under the high voltage of electrospraying, which can significantly reduce the risk of discharge and breakdown; at the same time, the flexible film supports pattern printing process, which can realize large-area production and single use, improving the universality and cost advantage of the device.

[0071] Specifically, flexible substrates possess excellent mechanical flexibility and bendability, maintaining high structural stability even under repeated bending, twisting, or stretching. This helps ensure the integrity of the conductive layer and the stability of the electrochemical interface in the electrode assembly, thereby significantly improving the structural stability and electrochemical response repeatability of the electrode. Secondly, the materials themselves have good electrical insulation properties, providing a stable support structure for the conductive layer, electrode materials, or sensitive film, avoiding leakage or short circuit problems that may occur during electrochemical testing. Furthermore, these substrates typically have relatively smooth surfaces, allowing for uniform coverage of functional materials through printing, electrochemical deposition, evaporation, spraying, and other methods, which helps ensure the reproducibility of the electrode assembly's performance.

[0072] If the electrode assembly substrate is a rigid insulating material, its structural stability can ensure the stability and consistency of the electrode geometry and electrochemical interface, thereby significantly improving the repeatability of experiments and signal reliability. This can provide important support for the fabrication of high-performance electrodes and the realization of micro- and nano-scale electrochemical electrode assemblies.

[0073] Furthermore, hydrophilic treatment can enable the sample solution to form a uniform and stable liquid film at the spray tip, which helps to quickly establish the Taylor cone and improve spray stability; edge hydrophobic treatment can concentrate droplets in the sharp corner area of ​​the spray tip, further improving spray focusing and droplet reduction effect.

[0074] Furthermore, the spray tip is equipped with a hydrophilic pointed tip with specific geometric features. Through the combined effect of the tip effect and the wettability of the adhering liquid, the sample liquid is more easily concentrated at the tip, achieving stable electrospraying under low flow conditions. The enhanced local electric field at the tip can significantly reduce the spray initiation voltage; the liquid automatically gathers in the pointed tip region, forming a more stable Taylor cone; it can generate finer spray droplets, improving the mass spectrometry ionization efficiency and signal-to-noise ratio; the pointed tip geometry can be further fine-tuned through the aforementioned patterning process and surface treatment, improving the repeatability of the device.

[0075] Furthermore, by integrating the three electrodes onto a flexible substrate and using an adapter to set up a "floating workstation" for electrode fixation and mechanical support, this structure avoids the problems of traditional electrochemical cells, such as mechanical assembly, large size, unstable contact, and difficult positioning. It allows for highly precise control of electrode spacing and relative positions, improving the reproducibility of electrochemical reactions; the overall structure is compact and modularly assembled, significantly enhancing the system stability of electrochemistry-mass spectrometry.

[0076] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An electrochemical-mass spectrometry device based on integrated electrode sheets, characterized in that, The device includes a mass spectrometer and an electrochemical reaction device. The mass spectrometer is equipped with a sample inlet. The electrochemical reaction device includes an electrochemical workstation and an electrochemical reaction platform. The electrochemical workstation is a floating workstation and includes a battery power module, a high-voltage module, and an electrochemical measurement and control module. The electrochemical reaction platform is a patterned electrode assembly. The patterned electrode assembly includes an insulating substrate with at least one hydrophilic tip and three electrically isolated electrodes located in the region of the hydrophilic tip. The three electrodes are a working electrode, a counter electrode, and a reference electrode, and the working electrode is disposed at the tip of the hydrophilic tip, which is opposite to the sample inlet. The floating workstation is connected to the patterned electrode assembly, wherein: The electrochemical workstation is used to provide the bias voltage required for the electrochemical reaction to the patterned electrode assembly, and to keep the working electrode, the counter electrode and the reference electrode at a floating high potential, so as to realize the controlled electrochemical reaction and electrospray ionization simultaneously at the hydrophilic sharp corner; The hydrophilic pointed tip is used to guide the ions generated by the electrospray ionization into the injection port.

2. The apparatus according to claim 1, characterized in that, The hydrophilic pointed corner is achieved by any of the following methods: Utilizing the hydrophilicity of the insulating substrate itself; The sharp corner regions of the insulating substrate are physically hydrophilically modified; The sharp corner regions of the insulating substrate are chemically hydrophilically modified. A hydrophilic layer is coated on the sharp corner areas of the insulating substrate.

3. The apparatus according to claim 1, characterized in that, The working electrode, the counter electrode, and the reference electrode are formed by a patterning process, which includes at least one of screen printing, inkjet printing, photolithography, laser etching, electroforming transfer, physical deposition, and chemical deposition.

4. The apparatus according to claim 1, characterized in that, The patterned electrode assembly also includes a conductive layer located outside the hydrophilic pointed region and an insulating layer covering the conductive layer.

5. The apparatus according to any one of claims 1-4, characterized in that, The insulating substrate is a flexible insulating substrate or a rigid insulating substrate.

6. The apparatus according to claim 5, characterized in that, The flexible insulating substrate is a polymer film or a paper base.

7. The apparatus according to claim 6, characterized in that, The polymer film is made from any one of polyethylene terephthalate, polyimide, polypropylene, polyethylene, polydimethylsiloxane, and hydrogel.

8. The apparatus according to claim 6, characterized in that, The paper base includes any one of filter paper, chromatography paper, hydrophobic paper, nanocellulose paper, polymer-impregnated paper, bio-paper, and natural fiber paper.

9. The apparatus according to claim 5, characterized in that, The rigid insulating substrate is any one of silicon, glass, or ceramic.

10. The apparatus according to any one of claims 1-4, characterized in that, The working electrode, the counter electrode, and the reference electrode are made of at least one of carbon black, silver-silver chloride, gold, silver, platinum, and conductive polymer.

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