Gas sensor, method for production and uses

Abstract

The present disclosure relates to a gas sensor, a method for production and uses thereof; namely a device comprising said gas sensor, preferably a coating plate, more preferably a ceramic plate. It is disclosed a gas sensor comprising at least one sensitive layer on top of at least one conductive layer, wherein the conductive layer comprises at least one interdigitate electrode, wherein the sensitive layer comprises 25% to 50% (w / w) of a metal-oxide semiconductor nanoparticle dispersed in 50% to 75% (w / w) of a polymeric matrix, with the incorporation of up to 1% (w / w) of a dispersing agent with respect to the mixture of the metal-oxide semiconductor nanoparticle and polymeric matrix; and a substrate to support the conductive layer.

Description

GAS SENSOR, METHOD FOR PRODUCTION AND USESTECHNICAL FI ELD

[0001] The present disclosure relates to a gas sensor, a method for production and uses thereof; namely an article comprising said gas sensor, preferably a coating plate, more preferably a ceramic plate.BACKGROU ND

[0002] The use of advanced sensing techniques for detecting, indicating, and monitoring gases, for example toxic gases in industry, and the environment is very important for health and safety.

[0003] It is very important that precise and rapid detection, alerting, and monitoring of gases should be available to prevent or minimise accidents involving poisoning or explosions. For example, toxic gases, such as carbon monoxide, carbon dioxide, hydrogen sulphide, chlorine, bromine, or others, are found in a wide variety of situations, varying from industry: chemical, heavy, petroleum, electronic, coal, gas, mines, to warehouses, enclosed parking areas, vehicles, sewerage, waste disposal, the atmosphere, houses, and even battle fields. In the past, certain colour changing reagents were adopted to detect these gases by tedious and time-consuming colorimetric, or more complicated chromatographic methods. However, in the last ten to twenty years techniques have progressed rapidly and more sensors have been developed for the fast precise detection of various toxic gases. Four kinds of sensors are widely available, such as electrochemical, semiconductor, catalytic field effect and catalytic gas sensors.

[0004] Document US20210041387A1 discloses a CO2 gas sensor based on carbon nanotubes (CNT). The disclosed structure is composed by a carbon nanotube film and an absorbing layer deposited over said CNT film. The ink formulation used is composed by branched polyethylenimine, polyethylene glycol, and poly[l-(4-vinylbenzyl)-3- methylimidazolium tetrafluoroborate] of the formula I:, wherein n ranges from 10-300. Also in this document, it is described several procedure steps for the production of each sensing part, involving chemical products with significant toxicity and need for special handling conditions, which provides a high level of complexity for production process.

[0005] Document US11275051B2 discloses metal oxide-based chemical sensors that are integrated using a hybrid polycrystalline gas-sensitive material to create an uniform and integrated sensory system. It is disclosed a chemical sensor platform comprising an oxidized silicon membrane, which comprises a silicon (Si) layer and a silicon oxide (SiOz) layer. The disclosed sensors were specifically studied for a hydrogen sulphide (H2S) concentration range 100 - 500 ppm. The design helped to improve selectivity, sensitivity, faster response time and lower power consumption.

[0006] Document US20220178856A1 discloses a catalyst for a gas sensor includes a support and a porous core-shell type complex contained in the support structure. The complex includes a gas sensor, manufactured in a micro electro-mechanical system (MEMS), that detects hydrogen and some variations, such as ethanol or formaldehyde, with a long sensor life and excellent durability. The support may be a ceramic containing a metal oxide and a carbon-based compound. This document does not refer or anticipate the detection of CO2 or the effect of the water vapour on its effectiveness.

[0007] These facts are described in order to illustrate the technical problem solved by the achievements of the present document.GENERAL DESCRIPTION

[0008] The present disclosure relates to a gas sensor, a method for production and uses thereof; namely an article comprising said gas sensor, preferably a coating plate, more preferably a ceramic plate.

[0009] In the development of this new product the aim was to develop a gas sensor that allows in real time and in a non-intrusive way, a rapid, non-invasive, and innovative way to measure the quantity of gases by measuring the variation of the sensor's resistance (chemirresistive-based mechanism), such as dangerous gases, such as CO2, and to signal the existence of a fire when the variation of resistance of the sensor correspond to high values of concentration of carbon dioxide and water, i.e. concentrations above 105pprriv, by passing a pre-defined limit, defined in the complementary electronic control system connected to the article where the gas sensor is integrated.

[0010] The present technology is related with a method for providing a rapid, non- invasive, and innovative gas sensor for the detection of leakage of gases, preferably toxic gases, and infer possible fire and / or toxic atmospheres in real time. The gas sensor comprises a chemiresistive-based mechanism, where the sensitive layer can be printed in flexible and rigid substrates on top of at least one interdigitate electrode. The sensitive layer is produced, for example by deposition technologies, such as inkjet, screen printing, doctor blade, drop casting, slot die or additive manufacturing techniques, with a polymeric ink formulation. The metal-oxide semiconductor nanoparticle is dispersed in a polymeric matrix, with an incorporation of a dispersing agent. This optimized ink formulation allows to achieve a better dispersion and a higher number of adsorption sites for gas. The interdigitate electrode is the conductive layer, for monitoring of signals from the sensor, namely the change in resistance caused by a chemical reaction, preferably the chemisorption on the sensitive layer of the reactional products produced in the combustion reaction.

[0011] The sensitive layer of the metal-oxide semiconductor strongly depends on the amount of oxygen species adsorbed on its surface, which means that when the metal- oxide semiconductor is exposed to air, oxygen molecules in the air get adsorbed on its surface in the form of chemisorbed oxygen species, such as O2’, O’ and Oz’, by trappingelectrons from its conduction band. The adsorbed oxygen species induce, thus, an electron depletion region in the semiconductor thereby reducing the carrier concentration. This phenomenon has a directly influence in the adsorption of some gas molecules, for example, CO2, because higher number of oxygen adsorption results in high adsorption of gas molecules on the metal-oxide semiconductor surface. The metal- oxide semiconductor, which in an embodiment can be tin oxide, comprises a porous structure that favours the diffusion and transport of a target gas in and out of the sensitive layer.

[0012] In an embodiment, the disclosed gas sensor can be integrated in an article, where it is connected with an electronic control system that can be made by using a printed circuit board (PCB). This electronic control system transduces the signal obtained by the gas sensor and can also be associated with some communication system, which can generate a specific alert to the user, such as visual, sound, contact with authorities, or other suitable ways to alert the user.

[0013] In an embodiment, the PCB part comprises a dimension lower than 10 cm length x 10 cm width cm x 2.5 cm thickness, preferably less than 6 cm x 6 cm x 1.5 cm each side (square).

[0014] The disclosed gas sensor is connected to the electronic control system by means of a printed track, a flat cable, an electric wire, an electronic component, or any other suitable connection method.

[0015] The PCB is developed under the specific needs defined for the sensor response and integration, such as type of connection, data acquisition and communication protocol.

[0016] This fully sensing solution can be integrated in a constructive material, such as modular constructive systems plasterboard, a tile, among others, to monitoring and warning danger situations to improve life quality and autonomy of users. For that, the gas sensor needs to be located / placed in direct contact with air without the need of additional encapsulation of the sensitive layer.

[0017] One aspect of the present disclosure is a gas sensor comprising at least one sensitive layer on top of at least one conductive layer, wherein the conductive layer comprises at least one interdigitate electrode, wherein the sensitive layer comprises 25% to 50% (w / w) of a metal-oxide semiconductor nanoparticle dispersed in 50% to 75% (w / w) of a polymeric matrix, with the incorporation of 0.5% to 1% (w / w) of a dispersing agent with respect to the mixture of the metal-oxide semiconductor nanoparticle and polymeric matrix; and a substrate to support the conductive layer.

[0018] The gas sensor of the present disclosure surprisingly allows a better and easier detection of a gas presence directly on the sensitive layer without the need of any kind of encapsulation. More surprisingly, the gas sensor can still have a protective encapsulation layer against external agents, especially in washing processes, and still have a very accurate reading. Even more surprisingly, the now disclosed gas sensor does not need any preliminary activation, such as an activation using Ultraviolet-light.

[0019] Additionally, to improve the sensors' durability to usage conditions, a polymeric- based encapsulation membrane could be applied to overlap the sensor.

[0020] In an embodiment, the polymeric-based encapsulation membrane is porous, hydrophobic, and chemically and mechanically resistant to external agents, such as detergents. In an embodiment, the material of the polymeric-based encapsulation membrane may be selected from a list consisting of polyethylene, polyvinylidene fluoride-trifluoroethylene, polytetrafluoroethylene, polycarbonate, polyester, or their combinations.

[0021] In an embodiment, the polymeric-based encapsulation membrane comprises a porous surface with a diameter between 0.5 and 25 pm, more preferably between 3 and 15 pm. The porosity may be calculated by the methods of microscopy techniques using SEM or AFM, by physical adsorption of a gas using BET analysis, by mercury porosimetry or helium pycnometry.

[0022] In an embodiment, the polymeric based membrane protects the said sensor while cleaning. Different cleaning processes were tested, cleaning with a soft dry cloth, with water and / or with water with degreasing liquid. Cyclic events of cleaning and activation of the sensor had been realized and showed the reproducibility of the sensor.

[0023] In an embodiment, the dispersing agent of the gas sensor is selected from a list consisting of a modified styrene maleic acid, poly(acrylic acid-co-maleic acid), poly(acrylic acid-co-hydroxyethyl methacrylate), polyoxyethylene sorbitan monooleate, or their combinations thereof.

[0024] In an embodiment, the sensitive layer of the gas sensor comprises 25% to 33% (w / w) of the metal-oxide semiconductor nanoparticle, 67% to 75% (w / w) of the polymeric matrix and 0.5 to 1% (w / w) of the dispersing agent with respect to the mixture of the metal-oxide semiconductor nanoparticle and polymeric matrix.

[0025] In an embodiment, the metal-oxide semiconductor nanoparticle of the gas sensor is selected from a list consisting of: titanium oxide, zinc oxide, bismuth oxide, tin oxide, or their combinations thereof.

[0026] In an embodiment, the material of the polymeric matrix of the gas sensor is selected from a list consisting of: carboxymethyl cellulose, hydroxyethyl cellulose, aliphatic polyester polyurethane, or their combinations thereof.

[0027] In an embodiment, the metal-oxide semiconductor nanoparticle used in the gas sensor is tin oxide.

[0028] In an embodiment, the polymeric matrix used in the gas sensor is aliphatic polyester polyurethane.

[0029] In an embodiment, the particle diameter of the metal-oxide semiconductor nanoparticle of the gas is below 100 nm, preferably from 10 to 100 nm, more preferably from 15 to 90 nm and even more preferably from 20 to 80 nm.

[0030] In an embodiment, the metal-oxide semiconductor nanoparticle of the gas sensor comprises a size distribution with a D50 from 50 to 250 nm, preferably from 50 to 100 nm and a D90 from 10 to 500 nm, preferably from 30 to 300 nm.

[0031] The measurement of the particle size and its distribution can be accessed by laser diffraction analysis, dynamic light scattering (DLS) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) or by using the standard method ASTM D6128-16 - 2016: Standard Test Method For Shear Testing Of Bulk Solids Using The Jenike Shear Tester, for a more precise analysis.

[0032] In an embodiment, the conductive layer of the gas sensor is deposited over a substrate made of a material selected from a list consisting of a polymer, a composite, a ceramic, a glass, a lignocellulosic, an insulating material, a semiconductor material, or their combinations.

[0033] In an embodiment, the gas sensor is obtained by the use of inkjet, screen printing, spray coating, spin coating, doctor blade, drop casting, slot die or additive manufacturing techniques.

[0034] The present disclosure also discloses an article comprising the gas sensor previously mentioned.

[0035] In an embodiment, the article comprises an electronic control system.

[0036] In an embodiment, the gas sensor used in the article is connected to the electronic control system through a connection selected from a list comprising a printed track, a flat cable, an electric wire, an electronic component, or their combinations thereof.

[0037] In an embodiment, the article is a coating plate, preferably a ceramic plate.

[0038] The present disclosure also relates to the use of the mentioned gas sensor in constructive materials, preferably in a modular constructive panel, plasterboard, tile, among others.

[0039] The present disclosure also discloses a method for production of the gas sensor comprising the following steps: preparing an ink for deposition of the sensitive layer; depositing the conductive layer over a substrate; depositing the sensitive layer over the conductive layer.

[0040] In an embodiment, the step of preparing the ink for deposition comprises the following steps: dispersing the metal-oxide semiconductor nanoparticles in the polymeric matrix until complete homogenization; incorporating the dispersing agent; curing process.

[0041] In an embodiment, the dispersion of the metal-oxide semiconductor nanoparticles in the polymeric matrix is produced using a device for mix or stir liquidsolutions with a rotation comprised from 200 to 350 rpm at a temperature range of 20 to 30°C for 2 to 3 hours.

[0042] In an embodiment, the device for mix or stir liquid solutions is selected from a list consisting of a stirrer plate, a magnetic stir bar and a magnetic stir bar retriever, an overhead stirrer and stirrer shaft, a vortex mixer, shaking incubator, or their combinations.

[0043] In an embodiment, the rotation of the device for mix or stir liquid solutions is comprised from 220 to 300 rpm, preferably from 240 to 270 rpm.

[0044] In an embodiment, the temperature range of the device for mix or stir liquid solutions is comprised from 22°C to 27°C, preferably from 22°C to 24°C.

[0045] In an embodiment, the curing process is performed at a temperature comprised from 80°C to 150°C during 5 to 10 minutes.BRIEF DESCRI PTION OF TH E DRAWI NGS

[0046] The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention.

[0047] Figure 1: Schematic representation of an embodiment of the gas sensor.

[0048] Figure 2: Schematic representation of an embodiment of the gas sensor with the polymeric based membrane.

[0049] Figure 3: Graphic representation of the variation of the sensor resistance in an environment where it has been added CO2 and CO2 + H2O and the comparison with the usual behaviour of a sensor from the prior art. The gas sensor is not incorporated with a porous polymeric based membrane.

[0050] Figure 4: Graphic representation of the variation of the sensor resistance in an environment where it has been added CO2 + H2O and the comparison with the usual behaviour of a sensor from the prior art. The gas sensor isn't incorporated with a porous polymeric based membrane.

[0051] Figure 5: Graphic representation of the variation of the sensor resistance with the variation of the CO2 + H2O rate with two cycles in an environment. The gas sensor isn't incorporated with a porous polymeric based membrane.

[0052] Figure 6: Graphic representation of the variation of the sensor resistance with the variation of the CO2 + H2O rate with multiple cleaning cycles: dry, with water and with water and degreasing cleaning. The gas sensor is incorporated with a porous polymeric based membrane.

[0053] Throughout the figures indicated above, the following elements are indicated with the respective references:1 - sensitive layer;2 - substrate;3 - conductive layer;4 - polymeric-based encapsulation membrane.DETAI LED DESCRI PTION

[0054] The present disclosure relates to a gas sensor, a method for production and uses thereof; namely an article comprising said gas sensor, preferably a coating plate, more preferably a ceramic plate.

[0055] In an embodiment, the gas sensor detects the adsorption by a variation of resistance, being chemiresistor sensors.

[0056] In an embodiment, illustrated in Figure 1, the gas sensor now disclosed comprises at least one sensitive layer (1) on top of at least one conductive layer (3), wherein the conductive layer (3) comprises at least one interdigitate electrode, wherein the sensitive layer (1) comprises 25% to 50% (w / w) of a metal-oxide semiconductor nanoparticle dispersed in 50% to 75% (w / w) of a polymeric matrix, with the incorporation of up to 1% (w / w) of a dispersing agent with respect to the mixture of the metal-oxide semiconductor nanoparticle and polymeric matrix; and a substrate (2) to support the conductive layer (3).

[0057] In an embodiment, the dispersing agent of the gas sensor is selected from a list consisting of a modified styrene maleic acid, poly(acrylic acid-co-maleic acid), poly(acrylic acid-co-hydroxyethyl methacrylate), polyoxyethylene sorbitan monooleate, or their combinations thereof, for better results.

[0058] In an embodiment, the sensitive layer (1) of the gas sensor comprises 25% to 33% (w / w) of the metal-oxide semiconductor nanoparticle, 67% to 75% (w / w) of the polymeric matrix and 0.5 to 1% (w / w) of the dispersing agent with respect to the mixture of the metal-oxide semiconductor nanoparticle and polymeric matrix, for better results.

[0059] In an embodiment, the metal-oxide semiconductor nanoparticle of the gas sensor is selected from a list consisting of: titanium oxide, zinc oxide, bismuth oxide, tin oxide, or their combinations thereof, for better results.

[0060] In an embodiment, the material of the polymeric matrix of the gas sensor is selected from a list consisting of: carboxymethyl cellulose, hydroxyethyl cellulose, aliphatic polyester polyurethane, or their combinations thereof, for better results.

[0061] In an embodiment, the metal-oxide semiconductor nanoparticle used in the gas sensor is tin oxide, for better results.

[0062] In an embodiment, the polymeric matrix used in the gas sensor is aliphatic polyester polyurethane, for better results.

[0063] In an embodiment, the particle diameter of the metal-oxide semiconductor nanoparticle of the gas is below 100 nm, preferably from 10 to 100 nm, more preferably from 15 to 90 nm and even more preferably from 20 to 80 nm, for better results and easily detection of lower gas concentrations.

[0064] In an embodiment, the metal-oxide semiconductor nanoparticle of the gas sensor comprises a size distribution with a D50 from 50 to 250 nm, preferably from 50 to 100 nm and a D90 from 10 to 500 nm, preferably from 30 to 300 nm, for better results, i.e. a better detection of gas.

[0065] In an embodiment, the conductive layer (3) of the gas sensor is deposited over a substrate (2) made of a material selected from a list consisting of a polymer, acomposite, a ceramic, a glass, a lignocellulosic, an insulating material, a semiconductor material, or their combinations, for better results.

[0066] In an embodiment, the gas sensor is obtained by the use of inkjet, screen printing, spray coating, spin coating, doctor blade, drop casting, slot die or additive manufacturing techniques. In a more specific embodiment, and for better results, the conductive layer (3) and / or the sensitive layer (1) is deposited over a substrate (2) using the same deposition technologies.

[0067] In an embodiment, the gas sensor further comprises a polymeric-based encapsulation membrane, for better results and higher resistance against external agents.

[0068] In an embodiment, the polymeric-based encapsulation membrane of the gas sensor comprises a porous surface with a diameter between 0.5 and 25 pm, more preferably between 3 and 15 pm, for better and more accurate results. The porosity may be calculated by the methods of microscopy techniques using SEM or AFM, by physical adsorption of a gas using BET analysis, by mercury porosimetry or helium pycnometry.

[0069] The present disclosure also discloses an article comprising the gas sensor previously mentioned. In an embodiment, the article comprises an electronic control system. In an embodiment, the gas sensor is connected to the electronic control system through a connection selected from a list comprising a printed track, a flat cable, an electric wire, an electronic component, or their combinations thereof. In an embodiment, the article is a coating plate, preferably a ceramic plate.

[0070] The present disclosure also discloses a method for production of the gas sensor comprising the following steps: preparing an ink for deposition of the sensitive layer (1); depositing the conductive layer (3) over a substrate (2); depositing the sensitive layer (1) over the conductive layer (3).

[0071] In an embodiment, the step of preparing the ink for deposition comprises the following steps: dispersing the metal-oxide semiconductor nanoparticles in the polymeric matrix until complete homogenization; incorporating the dispersing agent; curing process.

[0072] In an embodiment, the dispersion of the metal-oxide semiconductor nanoparticles in the polymeric matrix is produced using a device for mix or stir liquid solutions with a rotation comprised from 200 to 350 rpm at a temperature range of 20 to 30°C for 2 to 3 hours.

[0073] In an embodiment, the device for mix or stir liquid solutions is selected from a list consisting of a stirrer plate, a magnetic stir bar and a magnetic stir bar retriever, an overhead stirrer and stirrer shaft, a vortex mixer, shaking incubator, or their combinations.

[0074] In an embodiment, the rotation of the device for mix or stir liquid solutions is comprised from 220 to 300 rpm, preferably from 240 to 270 rpm.

[0075] In an embodiment, the temperature range of the device for mix or stir liquid solutions is comprised from 22°C to 27°C, preferably from 22°C to 24°C.

[0076] In an embodiment, the curing process is performed at a temperature comprised from 80°C to 150°C during 5 to 10 minutes.

[0077] In an embodiment, the method further comprises a step of encapsulation of the gas sensor by applying a polymeric-based encapsulation membrane, for better results and higher resistance against external agents.

[0078] Fourier-transform infrared (FT-IR) spectroscopy analysis was performed to evaluate the structural characterization of the ink. The FTIR spectra was obtained between 4000-700 cm4, using 16 scans per measurement at a resolution of 8 cm1with the equipment PerkinElmer Spectrum 100. The equipment was equipped with an Attenuated Total Reflectance (ATR) accessory of diamond crystal. The films of sensitive layer spectra were collected under room temperature (22°C) / humidity control (50 %) after background correction.

[0079] The morphological characterization of the thin films of sensitive layer was performed by Ultra-high-resolution field-emission Scanning Electron Microscopy (FEI Nova 200 and Pegasus X4M form) with integrated microanalysis X-ray system (EDS - energy dispersive spectrometer) and Electron Backscatter Diffraction (EBSD). The images were obtained with a tension of 10 kV.

[0080] The X-ray spectroscopy (XRD) analysis was performed to evaluate the differences in the crystal lattices of the metal-oxide semiconductor nanoparticle in the polymeric dispersion. The X-ray spectra was obtained by Bruker D8 with Cu-Ka radiation from 10° to 90°, with a step of 0.02 s and an exposition time of 1 s / step.

[0081] For these tests, it was used an embodiment using tin oxide as metal-oxide semiconductor nanoparticle, where it was very clear that there were no changes in crystal lattices of the tin oxide dispersed in polymeric matrix.

[0082] It was also very clear that with the presence of the dispersing agent, the metal- oxide semiconductor nanoparticle has a reduced diameter that promote the highest adsorption sites for gas.

[0083] The gas characterization of the sensor was evaluated by placing the sensor inside a testing chamber, adding a controlled gas flux, at a rate of 0.2 L / min, and at constant pressure of 0.8 Pa.

[0084] The tested gas sensor was placed in different locations inside of the chamber, and the variation of the resistance of the gas sensor with concentration of the gas is followed, on time, outside the chamber. All experiments were performed at room temperature. As can be seen on Figures 2, 3 and 4, positive and negative variations of resistance were achieved with the increase of gas mixture, CO2, and CO2+H2O. The gas sensor detects CO2 values up to 4 X 105ppm, in the test chamber.

[0085] The tested gas sensor was not affected by relative humidity in the range 20% to 80% of relative humidity.

[0086] As can be seen in Figure 5, the tested gas sensors present a cyclic behaviour with the same variations in resistance.

[0087] This work was co-financed by the Operational Program for Competitiveness and Internationalization (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF).

[0088] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude thepresence or addition of one or more other features, integers, steps, components or groups thereof.

[0089] The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof.

[0090] The above-described embodiments are combinable.

[0091] The following claims further set out particular embodiments of the disclosure.

Claims

C L A I M S1. A gas sensor comprising at least one sensitive layer on top of at least one conductive layer, wherein the conductive layer comprises at least one interdigitate electrode, wherein the sensitive layer comprises 25% to 50% (w / w) of a metal-oxide semiconductor nanoparticle dispersed in 50% to 75% (w / w) of a polymeric matrix, with the incorporation of 0.5% to 1% (w / w) of a dispersing agent with respect to the mixture of the metal-oxide semiconductor nanoparticle and polymeric matrix; and a substrate to support the conductive layer.

2. The gas sensor according to the previous claim, wherein the dispersing agent is selected from a list consisting of a modified styrene maleic acid, poly(acrylic acid- co-maleic acid), poly(acrylic acid-co-hydroxyethyl methacrylate), polyoxyethylene sorbitan monooleate or their combinations thereof.

3. The gas sensor according to any of the previous claims, wherein the sensitive layer comprises 25% to 33% (w / w) of the metal-oxide semiconductor nanoparticle, 67% to 75% (w / w) of the polymeric matrix and 0.5 to 1% (w / w) of the dispersing agent with respect to the mixture of the metal-oxide semiconductor nanoparticle and the polymeric matrix.

4. The gas sensor according to any of the previous claims, wherein the metal-oxide semiconductor nanoparticle is selected from a list consisting of: titanium oxide, zinc oxide, bismuth oxide, tin oxide, or their combinations thereof.

5. The gas sensor according to any of the previous claims, wherein the material of the polymeric matrix is selected from a list consisting of: carboxymethyl cellulose, hydroxyethyl cellulose, aliphatic polyester polyurethane, or their combinations thereof.

6. The gas sensor according to any of the previous claims, wherein the metal-oxide semiconductor nanoparticle is tin oxide.

7. The gas sensor according to any of the previous claims, wherein the material of the polymeric matrix is aliphatic polyester polyurethane.

8. The gas sensor according to any of the previous claims, wherein the particle diameter of metal-oxide semiconductor nanoparticle is below 100 nm, preferably from 10 to 100 nm, more preferably from 15 to 90 nm and even more preferably from 20 to 80 nm.

9. The gas sensor according to any of the previous claims, wherein the metal-oxide semiconductor nanoparticle comprises a size distribution with a D50 from 50 to 250 nm, preferably from 50 to 100 nm and a D90 from 10 to 500 nm, preferably from 30 to 300 nm.

10. The gas sensor according to any of the previous claims, wherein the conductive layer is deposited over a substrate made of a material selected from a list consisting of a polymer, a composite, a ceramic, a glass, a lignocellulosic, an insulating material, a semiconductor material, or their combinations.

11. The gas sensor according to any of the previous claims, wherein said gas sensor is obtained by the use of inkjet, screen printing, spray coating, spin coating, doctor blade, drop casting, slot die or additive manufacturing techniques.

12. The gas sensor according to any of the previous claims, further comprising a polymeric-based encapsulation membrane.

13. The gas sensor according to the previous claim, wherein the polymeric-based encapsulation membrane comprises a porous surface with a diameter between 0.5 and 25 pm, more preferably between 3 and 15 pm.

14. The gas sensor according to any of the previous claims, wherein the material of the polymeric-based encapsulation membrane is selected from a list consisting of polyethylene, polyvinylidene fluoride-trifluoroethylene, polytetrafluoroethylene, polycarbonate, polyester, or their combinations.

15. Article comprising the gas sensor according any of the previous claims.

16. Article according to the previous claim, comprising an electronic control system.

17. Article according to any of the previous claims 15 to 16, wherein the gas sensor is connected to the electronic control system through a connection selected from a list comprising a printed track, a flat cable, an electric wire, an electronic component, or their combinations thereof.

18. Article according to any of the previous claims 15 to 17, wherein said article is a coating plate, preferably a ceramic plate.

19. Use of the gas sensor described in any of the claims 1 to 14 in a constructive material, preferably a modular constructive panel, plasterboard or tile.

20. A method for production of the gas sensor described in any of the previous claims 1 to 14, comprising the following steps:- Preparing an ink for deposition of the sensitive layer;- Depositing the conductive layer over a substrate;- Depositing the sensitive layer over the conductive layer.

21. The method according to the previous claim, where in the step of preparing the ink for deposition comprises the following steps:- Dispersing the metal-oxide semiconductor nanoparticles in the polymeric matrix until complete homogenization;- Incorporating the dispersing agent;- Curing process.

22. The method according to the previous claims 20 to 21, wherein the dispersion of the metal-oxide semiconductor nanoparticles in the polymeric matrix is produced using a device for mix or stir liquid solutions with a rotation comprised from 200 to 350 rpm at a temperature range of 20 to 30°C for 2 to 3 hours.

23. The method according to any of the previous claims 20 to 22, wherein the device for mix or stir liquid solutions is selected from a list consisting of a stirrer plate, a magnetic stir bar and a magnetic stir bar retriever, an overhead stirrer and stirrer shaft, a vortex mixer, shaking incubator, or their combinations.

24. The method according to any of the previous claims 20 to 23, wherein the rotation of the device for mix or stir liquid solutions is comprised from 220 to 300 rpm, preferably from 240 to 270 rpm.

25. The method according to any of the previous claims 20 to 24, wherein the temperature range of the device for mix or stir liquid solutions is comprised from 22°C to 27°C, preferably from 22°C to 24°C.

26. The method according to any of the previous claims 20 to 25, wherein the curing process is performed at a temperature comprised from 80°C to 150°C during 5 to 10 minutes.

27. The method according to any of the previous claims 20 to 26, further comprising a step of encapsulation of the gas sensor by applying a polymeric-based encapsulation membrane.

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