Ammonia gas sensing method

Abstract

The invention discloses an ammonia gas sensing method, which is characterized in that a hollow liquid drop is utilized to drive a friction nanometer generator probe to generate electric signal response, and the principle of the method depends on hollow liquid drop preparation and liquid-solid friction electrification. The hollow liquid drops are prepared by adopting a coaxial injection system, and the ammonia loading capacity is controlled through the gas-liquid flow rate ratio. The hollow liquid drops loaded with ammonia gas strike the surface of the friction layer and are electrified by friction, the hollow liquid drops transfer electrons to the friction layer, and the electrons are transferred from the top electrode to the bottom electrode through the connecting circuit to form sensing current. Compared with an ammonia gas sensing method based on a solid response material, the functional liquid is used as a sensing base material, a chemical adsorption-desorption reaction process is not relied on, the response time is greatly shortened, the sensing timeliness and accuracy are remarkably improved, and the method is suitable for ammonia gas concentration sensing in multiple scenes.

Description

Technical Field

[0001] This invention relates to the field of gas sensing technology, specifically to an ammonia gas sensing method based on a probe driven by a hollow droplet-driven triboelectric nanogenerator. Background Technology

[0002] Globally, approximately 183 million tons of ammonia are produced annually, with about 80% ultimately released into the atmosphere. NH3 emissions are widespread in industry, agriculture, and medicine. Ammonia is a colorless gas with a strong, pungent odor, and is extremely corrosive and toxic. Long-term exposure to ammonia concentrations greater than 50 ppm can lead to serious respiratory illnesses and even death. Efficient and accurate detection of ammonia levels is of great significance to the ecological environment and human health.

[0003] Ammonia's unique boiling point (-33.3℃), refractive index (1.33), and dipole moment (1.42 D) make it a highly targeted gas. Based on these physical properties, various sensors based on resistance, optics, triboelectricity, and microbalance principles have been developed, with resistive sensing currently being the mainstream commercial technology. However, the physical principle of resistive sensing technology relies on the chemical reaction of ammonia on the surface of solid materials, changing the material's resistance through the adsorption-desorption of ammonia molecules, thereby achieving ammonia sensing. However, this dynamic transformation of chemical bonds involves a long reaction period, limiting the sensor's response speed. Therefore, response hysteresis has always been a difficult technical bottleneck to overcome in existing ammonia sensing technologies, limiting the application potential of various sensors in high-precision, fast-response scenarios. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for sensing ammonia concentration with fast response and stable detection.

[0005] The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] An ammonia gas sensing method includes the following steps:

[0007] S1. A functional liquid and ammonia are co-extruded using a coaxial injection system at a set gas-liquid flow rate ratio to prepare a core-shell hollow droplet loaded with ammonia. The ammonia loading is controlled by controlling the gas-liquid flow rate ratio. The outer shell of the hollow droplet is the functional liquid, and the inner core is ammonia. The functional liquid is an aqueous solution of sodium dodecylbenzenesulfonate.

[0008] S2. The hollow droplet is vertically dropped onto the surface of the triboelectric nanogenerator probe. Electron transfer is generated on the surface of the triboelectric layer by means of the liquid-solid triboelectric effect, forming a sensing current.

[0009] S3. By detecting the sensing current, a current signal corresponding to the ammonia concentration can be obtained, thereby realizing ammonia concentration sensing.

[0010] Furthermore, the aqueous solution of sodium dodecylbenzenesulfonate has a mass concentration of 0.1-2.0 wt%, the ammonia concentration is 50-200 ppm, and the gas-liquid flow rate ratio is 1:1-1:8.

[0011] Preferably, the gas-liquid flow rate ratio is 1:5, corresponding to an ammonia flow rate of 20 mL / h. -1 The functional liquid flow rate is 100 mL / h -1 .

[0012] Furthermore, the coaxial injection system includes a coaxial needle with an inner diameter of 0.86 mm and an outer diameter of 1.55 mm, and the functional liquid and ammonia gas are respectively connected to the two ends of the coaxial needle through syringes.

[0013] Furthermore, the triboelectric nanogenerator probe is assembled from a bottom substrate, a bottom electrode, a friction layer, a top electrode, and a connection circuit; the bottom substrate provides mechanical support; the bottom electrode is stacked on the upper surface of the bottom substrate; the friction layer is stacked on the upper surface of the bottom electrode for contact friction with hollow droplets; the top electrode is stacked on the upper surface of the friction layer; the connection circuit has a first end and a second end, the first end being connected to the top electrode, and the second end penetrating the bottom substrate and being connected to the bottom electrode.

[0014] Furthermore, the bottom substrate is an organic glass plate, a silicone plate, a nylon plate, or a quartz plate; the bottom electrode and the top electrode are both copper, aluminum, iron, or indium tin oxide; the friction layer is a polytetrafluoroethylene film, a perfluoroethylene propylene film, or a polyvinyl chloride film; and the connecting circuit is a copper wire, an aluminum wire, a silver wire, or a carbon fiber.

[0015] Furthermore, the response time of the current signal generated by the hollow droplet impacting the surface of the friction layer is ≤1.4 s, and the ammonia sensing sensitivity is 3.5×10⁻⁶. -3 μA / ppm.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention realizes ammonia sensing based on the contact triboelectricity between hollow droplets and the friction layer. The ammonia sensing response time is only 1.4 s, which is tens of times faster than solid ammonia sensing response materials.

[0018] (2) The hollow droplets of the present invention effectively load ammonia gas and prevent leakage, and the ammonia gas sensing sensitivity is 3.5 × 10⁻⁶. -3 μA / ppm can be used to develop high-precision ammonia sensing technology.

[0019] (3) The sensing substrate proposed in this invention is a functional liquid. Compared with solid sensing response materials, it has low operating cost and excellent sustainability, and is more suitable for industrial production and medical health protection. Attached Figure Description

[0020] Figure 1 These are a schematic diagram of the device of the present invention and a physical image of the triboelectric nanogenerator.

[0021] Figure 2 This is a graph showing the response time of an ammonia gas sensor.

[0022] Figure 3 This is a sensitivity graph for ammonia gas sensing.

[0023] Among them, 1-coaxial injection system, 2-hollow droplet, 3-friction layer, 4-bottom electrode, 5-bottom substrate, 6-top electrode, and 7-connection circuit. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the invention. Simple modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and substance thereof are all within the scope of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0025] Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0026] like Figure 1 As shown, the triboelectric nanogenerator probe is assembled from a bottom substrate 5, a bottom electrode 4, a triboelectric layer 3, a top electrode 6, and a connecting circuit 7. The bottom substrate 5 provides mechanical support. The bottom electrode 4 is stacked on the upper surface of the bottom substrate 5. The triboelectric layer 3 is stacked on the upper surface of the bottom electrode 4 for contact and friction with the hollow droplet 2. The top electrode 6 is stacked on the upper surface of the triboelectric layer 3. The connecting circuit 7 has a first end and a second end, the first end being connected to the top electrode 6, and the second end penetrating the bottom substrate 5 and being connected to the bottom electrode 4.

[0027] Example 1: An ammonia sensing method of the present invention

[0028] (a) Preparation of hollow droplets

[0029] A 0.2 wt% functional liquid was prepared by adding sodium dodecylbenzenesulfonate to deionized water. The functional liquid was then drawn into a single-channel syringe using a 50 mL syringe. 50 ppm ammonia gas was drawn into another single-channel syringe using a different 50 mL syringe. Both syringes were connected to the two ends of a coaxial needle (inner diameter 0.86 mm, outer diameter 1.55 mm), and the gas-liquid flow rate ratio was set to 1:5 (ammonia flow rate 20 mL / h). -1 The functional liquid flow rate is 100 mL / h -1 Prepare hollow droplets with a core-shell structure.

[0030] (II) Preparation of Triboelectric Nanogenerator Probes

[0031] A copper sheet is attached to an acrylic glass plate as a bottom electrode, followed by a polytetrafluoroethylene film as a friction layer, and then a copper sheet is attached to the friction layer as a top electrode. The bottom electrode and the top electrode are connected by copper wires to obtain a triboelectric nanogenerator probe.

[0032] (III) Testing of Ammonia Sensing Performance

[0033] The triboelectric nanogenerator probe was positioned directly below a coaxial needle, allowing a hollow droplet to fall vertically onto the surface of the triboelectric layer. The prepared hollow droplet generated a current of 1.5 μA and an ammonia response time of 1.4 s on the surface of the triboelectric nanogenerator probe. Figure 2 ).

[0034] Example 2: An ammonia sensing method of the present invention

[0035] (a) Preparation of hollow droplets

[0036] A 0.1 wt% functional liquid was prepared by adding sodium dodecylbenzenesulfonate to deionized water. The functional liquid was then drawn into a single-channel syringe using a 20 mL syringe. 150 ppm ammonia gas was drawn into another single-channel syringe using a different 20 mL syringe. Both syringes were connected to the coaxial needle ends (inner diameter 0.86 mm, outer diameter 1.55 mm), and the gas-liquid flow rate ratio was set to 1:1 (ammonia flow rate 20 mL / h). -1 The functional liquid flow rate is 20 mL / h -1 Prepare hollow droplets with a core-shell structure.

[0037] (II) Preparation of Triboelectric Nanogenerator Probes

[0038] An aluminum sheet is attached to a quartz plate as a bottom electrode, followed by a polytetrafluoroethylene (PTFE) film as a friction layer, and then an aluminum sheet is attached to the friction layer as a top electrode. The bottom electrode and the top electrode are connected by aluminum wires to obtain a triboelectric nanogenerator probe.

[0039] (III) Testing of Ammonia Sensing Performance

[0040] A triboelectric nanogenerator probe was placed directly below a coaxial needle, allowing a hollow droplet to fall vertically onto the surface of the triboelectric layer. The prepared hollow droplet generated a current of 0.6 μA on the surface of the triboelectric nanogenerator probe.

[0041] Example 3: An ammonia sensing method of the present invention

[0042] (a) Preparation of hollow droplets

[0043] A 1.0 wt% functional liquid was prepared by adding sodium dodecylbenzenesulfonate to deionized water. The functional liquid was then drawn into a single-channel syringe using a 50 mL syringe. 100 ppm ammonia gas was drawn into another single-channel syringe using a 10 mL syringe. Both syringes were connected to the two ends of a coaxial needle (inner diameter 0.86 mm, outer diameter 1.55 mm), and the gas-liquid flow rate ratio was set to 1:8 (ammonia flow rate 20 mL / h). -1 The functional liquid flow rate is 160 mL / h -1 Prepare hollow droplets with a core-shell structure.

[0044] (II) Preparation of Triboelectric Nanogenerator Probes

[0045] A silver sheet was attached to an plexiglass plate as the bottom electrode, followed by a polytetrafluoroethylene film as the friction layer, and then a silver sheet was attached to the friction layer as the top electrode. The bottom electrode and the top electrode were connected by carbon fiber to obtain a triboelectric nanogenerator probe.

[0046] (III) Testing of Ammonia Sensing Performance

[0047] A triboelectric nanogenerator probe was placed directly below a coaxial needle, allowing a hollow droplet to fall vertically onto the surface of the triboelectric layer. The prepared hollow droplet generated a current of 0.8 μA on the surface of the triboelectric nanogenerator probe.

[0048] Example 4: An ammonia sensing method of the present invention

[0049] (a) Preparation of hollow droplets

[0050] A 2.0 wt% functional liquid was prepared by adding sodium dodecylbenzenesulfonate to deionized water. The functional liquid was then drawn into a single-channel syringe using a 30 mL syringe. 200 ppm ammonia gas was drawn into another single-channel syringe using a 50 mL syringe. Both syringes were connected to the two ends of a coaxial needle (inner diameter 0.86 mm, outer diameter 1.55 mm), and the gas-liquid flow rate ratio was set to 1:2 (ammonia flow rate 20 mL / h). -1 The functional liquid flow rate is 40 mL / h -1 Prepare hollow droplets with a core-shell structure.

[0051] (II) Preparation of Triboelectric Nanogenerator Probes

[0052] A copper sheet is attached to a silicone plate as a bottom electrode, followed by a polytetrafluoroethylene film as a friction layer, and then a copper sheet is attached to the friction layer as a top electrode. The bottom electrode and the top electrode are connected by carbon fiber to obtain a triboelectric nanogenerator probe.

[0053] (III) Testing of Ammonia Sensing Performance

[0054] A triboelectric nanogenerator probe was placed directly below a coaxial needle, allowing a hollow droplet to fall vertically onto the surface of the triboelectric layer. The prepared hollow droplet generated a current of 0.3 μA on the probe surface. Under various ammonia concentrations, the output response of the triboelectric nanogenerator was obtained as 3.5 × 10⁻⁶ μA through linear fitting. -3 Sensing sensitivity in μA / ppm ( Figure 3 ).

Claims

1. A method for sensing ammonia gas, characterized in that, Includes the following steps: S1. A functional liquid and ammonia are co-extruded using a coaxial injection system at a set gas-liquid flow rate ratio to prepare a core-shell hollow droplet loaded with ammonia. The ammonia loading is controlled by controlling the gas-liquid flow rate ratio. The outer shell of the hollow droplet is the functional liquid, and the inner core is ammonia. The functional liquid is an aqueous solution of sodium dodecylbenzenesulfonate. S2. The hollow droplet is vertically dropped onto the surface of the triboelectric nanogenerator probe. Electron transfer is generated on the surface of the triboelectric layer by means of the liquid-solid triboelectric effect, forming a sensing current. S3. By detecting the sensing current, a current signal corresponding to the ammonia concentration can be obtained, thereby realizing ammonia concentration sensing.

2. The ammonia sensing method according to claim 1, characterized in that, The aqueous solution of sodium dodecylbenzenesulfonate has a mass concentration of 0.1-2.0 wt%, the ammonia concentration is 50-200 ppm, and the gas-liquid flow rate ratio is 1:1-1:

8.

3. The ammonia sensing method according to claim 2, characterized in that, The preferred gas-liquid flow rate ratio is 1:5, corresponding to an ammonia flow rate of 20 mL / h. -1 The functional liquid flow rate is 100 mL / h -1 .

4. The ammonia sensing method according to claim 1, characterized in that, The coaxial injection system includes a coaxial needle with an inner diameter of 0.86 mm and an outer diameter of 1.55 mm. The functional liquid and ammonia are respectively connected to the two ends of the coaxial needle via syringes.

5. The ammonia sensing method according to claim 1, characterized in that, The triboelectric nanogenerator probe is assembled from a bottom substrate, a bottom electrode, a friction layer, a top electrode, and a connection circuit. The bottom substrate provides mechanical support. The bottom electrode is stacked on the upper surface of the bottom substrate. The friction layer is stacked on the upper surface of the bottom electrode for contact friction with hollow droplets. The top electrode is stacked on the upper surface of the friction layer. The connection circuit has a first end and a second end, the first end being connected to the top electrode, and the second end penetrating the bottom substrate and being connected to the bottom electrode.

6. The ammonia sensing method according to claim 5, characterized in that, The bottom substrate is an organic glass plate, a silicone plate, a nylon plate, or a quartz plate; the bottom electrode and the top electrode are both made of copper, aluminum, iron, or indium tin oxide; the friction layer is a polytetrafluoroethylene film, a perfluoroethylene propylene film, or a polyvinyl chloride film; and the connecting circuit is made of copper wire, aluminum wire, silver wire, or carbon fiber.

7. The ammonia sensing method according to claim 1, characterized in that, The response time of the current signal generated by the hollow droplet impacting the friction layer surface is ≤1.4 s, and the ammonia gas sensing sensitivity is 3.5×10⁻⁶. -3 μA / ppm.

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