Claims:1. A gas sensor comprising,
a substrate;
an insulating layer configured on the substrate;
interdigitated electrodes configured on the insulating layer; and
a nanocomposite drop-deposited onto the gaps between the interdigitated electrodes, wherein the nanocomposite comprises a carbonaceous nanomaterial, a conducting polymer and a porous matrix.

2. The sensor according to claim 1, wherein the substrate is silicon.

3. The sensor according to claim 1, wherein the insulating layer comprises silicon dioxide.

4. The sensor according to claim 1, wherein the interdigitated electrodes comprise gold and chromium.

5. The sensor according to claim 1, wherein the carbonaceous nanomaterial is decorated with metal particles.

6. The sensor according to claim 5, wherein the metal is selected from the group consisting of Pd, Pt, Rh and Au.

7. The sensor according to claim 1, wherein the carbonaceous nanomaterial is selected from the group consisting of carbon nanotubes and graphene.

8. The sensor according to claim 7, wherein the carbonaceous nanomaterial is carbon nanotubes.

9. The sensor according to claim 8, wherein the carbon nanotubes is selected from the group consisting of single-wall carbon nanotubes and multi-wall carbon nanotubes.

10. The sensor according to claim 1, wherein the conducting polymer is selected from the group consisting of polyaniline (PANi) and ethylene diamine (EDA).

11. The sensor according to claim 1, wherein the porous matrix is polyvinylidene fluoride.

12. A method for making a gas sensor comprising the steps of:
Providing interdigitated electrodes;
drop-depositing a solution of a nanocomposite in a solvent onto the gaps between the electrode areas, wherein the nanocomposite comprises a carbonaceous nanomaterial, a conducting polymer and a porous matrix;
drying the drop-deposited solution to form a sensing film on the interdigitated electrodes; and
fabricating the interdigitated electrodes on an insulating layer positioned on a substrate.

13. The method according to claim 12, wherein the interdigitated electrodes comprise gold and chromium.

14. The method according to claim 12, wherein the substrate is silicon.

15. The method according to claim 12, wherein the insulating layer comprises silicon dioxide.

16. The method according to claim 12, wherein the interdigitated electrodes is fabricated on the insulating layer by lift-off process.

17. The method according to claim 12, wherein the nanocomposite comprises carbon nanotubes, polyaniline (PANi) and polyvinylidene fluoride.

18. The method according to claim 17, wherein the nanocomposite is produced by in-situ polymerization of aniline in carbon nanotubes to produce polyaniline coated carbon nanotubes; andmixing the polyaniline coated carbon nanotubes with polyvinylidene fluoride polymer to produce the nanocomposite.

19. The method according to claim 17, wherein the carbon nanotubes are decorated with metal particles.

20. The method according to claim 19, wherein the metal is selected from the group consisting of Pd, Pt, Rh and Au.

21. The method according to claim 12, wherein the nanocomposite is dispersed in dimethyl formamide (DMF) solvent to provide the solution thereof.
, Description:FIELD OF THE INVENTION
[0001] The present disclosure pertains to technical field of chemical gas detection. In particular, the present disclosure relates to a nanocomposite for detection of natural gas under ambient conditions, and a method of preparing the same.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Methane, propane and butane are the main components of Natural Gas which are commonly found in wastelands, landfills and pockets in the earth's crust. Human activities such as fossil fuel production and intensive livestock farming are the primary causes of increased methane concentrations in the atmosphere. Together, these two sources are responsible for 60% of all human methane emissions. It is important to continually sense methane to provide safeguards for the employees who work in areas like petrochemical and coal mines where methane is released during coal extraction. In recent years, with the rise of biogas and natural gas usage in household and automobiles, leakage detection of methane has become much more important. Very recently methane leakage in coal mines and natural gas pipelines has led to death of several lives. So there are rising concerns regarding methane gas leakage in industries and coal mines where a small spark can trigger an explosion leading to casualties.
[0004] Conventional sensors for sensing compressed natural gas (methane under high pressure) utilize metal oxides as sensing material which require higher operating temperature i.e. around 200-300oC because they work on the principle of decomposition or chemical oxidation of methane at high temperature (Bhattacharyya et al. Sens. Actuators B Chem. 124 (2007) 62-67). Such sensors exhibit maximum sensitivity only at elevated temperatures, and at this elevated temperature, irreversible reactions can take place between the gas and the sensing layer, which affects the long-term stability of the sensor. Further, these sensors lack sensitivity and selectivity towards gaseous hydrocarbons such as methane, propane and butane, and degrade in presence of moisture. Furthermore, these metal oxide based sensors require integration of heater with the sensor, thus leading to higher power consumption and pose a risk in explosive environments.
[0005] In addition to elevated operation temperature, the metal oxide based sensors are capable of detecting only higher concentration of target gas molecules present in an atmosphere. For example, Quaranta et al.(Sens. Actuators B Chem. 58 (1999) 350-355) reports that osmium doped tin dioxide thin films prepared by sol-gel technique detects 1000 ppm methane at a working temperature of 250-300oC. Further, Ghosh et al. (ACS applied materials and interfaces, 6, (2014), 3879-3887)reports that Pd-Ag activated ZnO films detects 1% methane with a sensitivity of 80%at an operating temperature of 100oC.Therefore, it is very difficult to positively detect methane gas of low concentration using these known sensors.
[0006] Single-wall carbon nanotubes(SWCNTs) and multi-wall carbon nanotubes (MWCNTs) based nanocomposites have been developed in the art for sensing gaseous molecules. Carbon nanotubes (CNTs) functionalized with metal nanoparticles have also been reported for selective sensing of gas. For example, Lu et al. (Chemical Physics Letters, 391 (2004), 344-348) discloses Pd loaded SWCNTs for detecting 6-100 ppm methane. However, in this composite, desorption results in a time span of 45 minutes with heater and ultra violet light as desorption aids. Li et al. (Sensors and Actuators B, 13 (2008), 155-158) discloses Pd loaded MWCNTs (1:1) for detecting methane gas. This composite material exhibits a good sensitivity toward methane gas, but is capable of detecting only 2% methane with a sensitivity of 4.5%.
[0007] Moreover, the preparation of nanocomposites with precise chemical composition, nanostructures, surface area and interfacial characteristics is a challenging task. Therefore, development of nanocomposites with consistent behavior and reproducibility is of prime importance for their use in active sensing materials. Further, degradation of the nanocomposites due to the aggregation of nanosized components as well as the exposure to heat/moisture has to be carefully evaluated.
[0008] Infra red and laser based methane detectors are also reported in the art for detection of methane gas at low temperature but they are too bulky and expensive (Matveev et al. Sens. Actuators B Chem. 51 (1998) 233-237).
[0009] Accordingly, there exists a need in the art for a nanocomposite based sensor for performing highly sensitive detection of natural gas at ambient temperature, and for positively detecting natural gas of ultra-low concentration. There also exists a need for a nanocomposite based sensor that has greater stability, high specificity, fast reset time and high reproducibility.
[0010] The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

OBJECTS OF THE INVENTION
[0011] It is an object of the present disclosure to provide an improved nanocomposite for performing highly sensitive detection of natural gas at ambient temperature.
[0012] It is a further object of the present disclosure to provide a nanocomposite that can respond to ultra-low concentration of natural gas to be detected.
[0013] It is another object of the present disclosure to provide a nanocomposite thatis stable under different weathering conditions.
[0014] It is another object of the present disclosure to provide a nanocomposite that can detect a broad range of natural gas with high sensitivity and selectivity.
[0015] It is another object of the present disclosure to provide a nanocompositethat is extremely reproducible and achieves very uniform responses.
[0016] It is another object of the present disclosure to providea sensor system with the nanocomposite.
[0017] It is another object of the present disclosure to provide a nanocomposite based sensor which is capable of sensing a natural gas under different atmospheric conditions.
[0018] It is another object of the present disclosure to provide a nanocomposite based sensor having faster response time for detection of natural gas and a shorter recovery time for enabling subsequent detection.
[0019] It is another object of the present disclosure to provide a method for making a gas sensor for sensing natural gas.

SUMMARY OF THE INVENTION
[0020] The present disclosure provides a nanocomposite based sensor that can facilitate highly sensitive detection of natural gas such as, but not limited to, methane, propane and butane at ambient temperature, and can respond to target gas of ultra-low concentration.
[0021] According to embodiments of the present disclosure, the nanocomposite that can detect ultra-low concentration of natural gas under ambient conditions can include a carbonaceous nanomaterial, conducting polymer and a porous matrix.
[0022] In an embodiment, the carbonaceous nanomaterial can preferably be decorated with metal particles such as, but not limited to, Pd, Pt, Rh and Au.
[0023] In another embodiment, the carbonaceous nanomaterial can be chosen from carbon nanotubes or graphene. In a more preferred embodiment, the carbonaceous nanomaterial can be single-wall carbon nanotubes or multi-wall carbon nanotubes.
[0024] According to embodiments, the conducting polymer that can functionalize the carbonaceous nanomaterialcan be selected from the group consisting of polyaniline (PANi) and ethylene diamine (EDA), and the porous matrix can be polyvinylidene fluoride.
[0025] In an aspect, the present disclosure provides a gas sensor with the nanocomposite, wherein the sensor can include (a) a substrate; (b) an insulating layer configured on the substrate; (c) interdigitated electrodes configured on the insulating layer; and (d) a nanocomposite drop deposited onto the gaps between the interdigitated electrodes, wherein the nanocomposite can include components such as a carbonaceous nanomaterial, conducting polymer and a porous matrix.
[0026] In an embodiment, the interdigitated electrodes of the sensor can be formed of gold and chromium.
[0027] In another aspect, the present disclosure provides a method for making a gas sensor, wherein the method can include the steps of: (a) providing interdigitated electrodes; (b) drop-depositing a solution of a nanocomposite in a solvent onto the gaps between the electrode areas, wherein the nanocomposite comprises a carbonaceous nanomaterial, a conducting polymer and a porous matrix; (c) drying the drop-deposited solution to form a sensing film on the interdigitated electrodes; and (d) fabricating the interdigitated electrodes on an insulating layer positioned on a substrate.
[0028] In an embodiment, the nanocomposite can be dispersed in dimethyl formamide (DMF) solvent to provide a solution thereof, and the resulting solution can be drop-deposited onto the gaps between the electrode areas.
[0029] In an embodiment, the interdigitated electrodes can be fabricated on the insulating layer by lift-off process.
[0030] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0032] FIG.1A illustrates an optical image of interdigitated electrodes having nanocomposite network on its surface in accordance with embodiments of the present disclosure
[0033] FIG.1B illustrates optical image of an exemplary gas sensor including the nanocomposite in accordance with embodiments of the present disclosure.
[0034] FIGs. 2A and 2B are graphs illustrating sensor response from an exemplary nanocomposite containing Pd decorated carbon nanotubes (CNTs), wherein the ratio of Pd to CNTs is 1:2 and 2:1 respectively.
[0035] FIGs. 3A, 3B and 3C are graphs showing methane, propane and butane gas sensing results obtained using a nanocomposite that comprises Pd decorated CNTs, polyaniline and polyvinylidene fluoride, wherein the ratio of Pd to CNTs is 2:1 in accordance with embodiments of the present disclosure.
[0036] FIG. 4 illustrates block diagram of a signal conditioning and data acquisition circuit in accordance with embodiments of the present disclosure.
[0037] FIG. 5 illustrates block diagram of an analog front end circuit in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0038] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0039] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0040] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0041] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0042] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
[0043] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0044] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0045] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0046] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0047] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0048] The present disclosure provides a nanocomposite based sensor that can facilitate highly sensitive detection of natural gas such as, but not limited to, methane, propane and butane at ambient temperature, and can respond to target gas of ultra-low concentration.
[0049] According to embodiments of the present disclosure, the nanocomposite that can detect ultra-low concentration of natural gas under ambient conditions can include a carbonaceous nanomaterial, conducting polymer and a porous matrix.
[0050] In an embodiment, the carbonaceous nanomaterial used to formulate the nanocomposite of the present disclosure can be selected from the group consisting of carbon nanotubes and graphene. The carbonaceous nanomaterial can have particle size less than 500 nm, preferably less than 100 nm, more preferably less than 50 nm. In a more preferred embodiment, the carbonaceous nanomaterial can be carbon nanotubes which can be single-wall carbon nanotubes or multi-wall carbon nanotubes.
[0051] In another embodiment, a metal-decorated carbonaceous nanomaterial can be used to produce the nanocomposite. The carbonaceous nanomaterial may preferably be decorated with metal particles such as, but not limited to, Pd, Pt, Rh and Au. The metal-decorated carbonaceous nanomaterial can enhance the sensitivity of a sensor by virtue of the catalytic activity provided the metal particles. The ratio of metal particles to carbonaceous nanomaterial can range from 1:2 to 2:1. In an embodiment, the sensitivity of a gas sensor can be increased by increasing the metal particle concentration in the metal-decorated carbonaceous nanomaterial.
[0052] In a more preferred embodiment, Pd decorated multi-wall carbon nanotubes, in a weight ratio of 2:1,can be used to formulate the nanocomposite of the present disclosure.
[0053] Although any conductive polymer can be used to prepare the nanocomposite of the present disclosure, examples of preferred polymers can include polyaniline (PANI) and ethylene diamine (EDA). The conducting polymer can contain polyconjugated bond systems and it may be doped with electron donor dopants or electron acceptor dopants to form an ionic pairing complex. The conducting polymer when combined with the carbonaceous nanomaterial can form a polymer-nanomaterial composite. Further, the conducting polymer can functionalize the carbonaceous nanomaterial, and thereby enhance the gas sensing capability of the nanocomposite due to p- p conjugation exhibited between the conducting polymer and the carbonaceous nanomaterial.
[0054] In a more preferred embodiment, the conducting polymer used to formulate the nanocomposite can be polyaniline, and it can present in the nanocomposite at a concentration of from about 1 to about 100 wt %.
[0055] The nanocomposite of the present disclosure can further include a polymer matrix that provides enhanced strength, elasticity, and toughness to the sensing film formed on the electrode surfaces. In an embodiment, polyvinylidene fluoride can serve as a polymer matrix, and it can present in the nanocomposite at a concentration of from about 1 to about 100 wt % based on the total weight of the composition.
[0056] In a more preferred exemplary embodiment, the nanocomposite can include Pd decorated carbon nanotubes, polyaniline (PANi) as conducting polymer and polyvinylidene fluoride as polymer matrix.
[0057] In another exemplary embodiment,the nanocomposite can be produced by in-situ polymerization of aniline monomer in a solution of carbon nanotubes (CNTs) to yield a polyaniline coated carbon nanotubes (i.e. PANi-CNTs composite) which in turn can be mixed with polyvinylidene fluoride (PVDF) to afford the nanocomposite of the present disclosure. Preferably, the weight ratio of PANi : CNTs : PVDF can be 50 : 50 : 5 based on the total weight of the composition.
[0058] In an embodiment, the nanocomposite can be evenly dispersed in a solvent to provide a solution thereof, and the resulting nanocomposite solution can be drop-deposited onto the gaps between interdigitated electrode areas to form a sensing film thereon. The sensing film formed of the nanocomposite can exhibit high sensitivities and short response time; especially, these feathers are ensured at room temperature.
[0059] In an embodiment, the solvent used to provide a solution of nanocomposite can be any polar solvent, for example dimethyl formamide (DMF).
[0060] In an embodiment, the present disclosure provides a gas sensor with the nanocomposite for performing highly sensitive detection of natural gas at ambient temperature, wherein the sensor can include (a) a substrate; (b) an insulating layer configured on the substrate; (c) interdigitated electrodes configured on the insulating layer; and (d) a nanocomposite drop deposited onto the gaps between the interdigitated electrodes, wherein the nanocomposite can include components such as a carbonaceous nanomaterial, conducting polymer and a porous matrix.
[0061] In an embodiment, the substrate can be silicon which can be deposited onto its surface with an insulating layer. In an embodiment, a layer of silicon dioxide can be deposited onto a silicon substrate.
[0062] In an embodiment, the interdigitated electrodes can be formed by sputtering gold and chromium. The interdigitated electrodes can have finger gap in the range of from 1 to 10 µm. In a more preferred embodiment the interdigitated electrodes can be formed by sputtering 90um of gold and 10um of chromium, with a finger gap 5 µm.
[0063] In an embodiment, the nanocomposite can be dispersed in dimethyl formamide (DMF) solvent and the resulting nanocomposite solution can be drop-deposited onto the gaps between the interdigitated electrode areas. After deposition, the solvent can be evaporated to form a network i.e. a sensing film on the interdigitated electrodes.
[0064] In an embodiment, the interdigitated electrodes can be fabricated on the insulating layer by lift-off process to provide a sensor which is capable of detecting a change in conductivity in the sensing film formed of the nanocomposite.
[0065] In an exemplary embodiment, the present disclosure provides a method for making a gas sensor, wherein the method can include the steps of: (a) providing interdigitated electrodes; (b) drop-depositing a solution of a nanocomposite in a solvent onto the gaps between the electrode areas, wherein the nanocomposite comprises a carbonaceous nanomaterial, a conducting polymer and a porous matrix; (c) drying the drop-deposited solution to form a sensing film on the interdigitated electrodes; and (d) fabricating the interdigitated electrodes on an insulating layer positioned on a substrate.

EXAMPLES
[0066] The present invention is further explained in the form of following examples. However it is to be understood that the foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.

Example 1: Preparation of nanocomposite
[0067] Polyaniline coated multi-wall carbon nanotubes (PANi-MWCNTs) were first produced by in-situ polymerization of aniline in a solution of multi-wall carbon nanotubes (MWCNTs). The MWCNTs were previously loaded with Pd particles, wherein the ratio of Pd to MWCNTs is 2:1. Then, X mg of polyaniline coated MWCNTs (herein after referred to as Pd-MWCNTs-PANi) and X mg of polyvinylidene fluoride (PVDF) were blended and then dispersed in 20ml of dimethyl formamide (DMF) and ultrasonicated for 6 hours to provide a nanocomposite solution.

Example 2: Fabrication of sensor
[0068] A layer of silicon oxide was deposited onto a silicon substrate. On the other hand, interdigitated electrodes (IDEs) were formed by sputtering 90um of gold and 10um of chromium. Chromium was used to promote better adhesion to the substrate. Then, 2 µl of the nanocomposite solution as obtained in Example 1 was drop deposited onto the gaps between the IDEs having a finger gap of approximately 5 µm. The IDEs was then fabricated on the silicon dioxide layer (Si/SiO2 substrate) by lift-off process. FIG. 1A illustrates optical image of the interdigitated electrodes having the nanocomposite network on its surface. FIG. 1B illustrates optical image of the sensor assembly having interdigitated electrodes with electrical contacts.
Example 3: Detection of methane gas using the nanocomposite based sensor
[0069] Gas sensing experiments were carried out in air tight custom built gas chamber having electrical feed through which enabled to perform in situ electrical measurements on the samples during methane exposure. The resistances across the samples were monitored in real time using Keithley source and measurement unit. Methane cylinder containing 100% methane and 1000 PPM were involved during the measurement process. Mass flow controller was used to control the flow rate of the gas which after initial optimization was finalized to be 400 sccm. The exposure time and desorption time was maintained to be 5 min each. Sensitivity of the sample in each case was calculated using the formula i.e. (Rair-Rgas)/Rair * 100. FIG. 3A shows the methane gas sensing results obtained using the sensor as produced in example 2.Highly reversible response was observed at room temperature without any additional input for the gas desorption. It was also noted that the sensor was responsive to 2% methane .FIGs. 2A and 2B illustrate sensor response from the nanocomposite containing Pd decorated carbon nanotubes (CNTs), wherein the ratio of Pd to CNTs is 1:2 and 2:1 respectively.
[0070] Similarly, the sensor was exposed to 1000ppm of propane and butane gas separately and the gas sensing results are shown in FIGs. 3B and 3C respectively. It was observed that the sensor provided highly reversible responses for propane and butane gas as well at room temperature without any additional input for the gas desorption.

Example 4: Signal conditioning and data acquisition circuit of the sensor for methane detection
[0071] FIG. 4 illustrates block diagram of a signal conditioning and data acquisition circuit designed to operate the sensor for detecting methane gas. The Signal conditioning part consists of constant current source circuit to power the sensor, Analog front end to increase the signal to noise ratio (SNR) of the signal and Ardunio microcontroller for data acquisition and methane detection. The sensor was powered by LM334, which is a 3-terminal adjustable current source. A current of 100uA flowed through the sensor. The raw signal tapped across the sensor was fed to an active filter and amplifier stage to boost the SNR of the signal. The first stage was a non-inverting buffer used to isolate the sensor from the rest of the circuitry. This stage was followed by a low pass filter of 10Hz to remove high frequency noise. The filtered signal was then fed to a difference amplifier. A reference signal was fed to its inverting input and the filtered signal to its non-inverting input. This stage had a gain of 330. This stage was used to amplify the signal to an extent so that the response can be measured by the 10bit ADC present on the microcontroller. The microcontroller was used for data acquisition and gas detection. It sampled data every 1ms and a moving average algorithm was implemented to further reduce the noise in the signal. The response was then calculated by the microcontroller upon exposure to methane and based on a pre-set threshold it confirmed the presence of methane in the environment.FIG. 5 illustrates block diagram of an analog front end circuit.

ADVANTAGES OF THE PRESENT INVENTION
[0072] The present disclosure provides a nanocomposite that facilitates highly sensitive detection of natural gas at ambient temperature.
[0073] The present disclosure provides a nanocomposite that is capable of detecting natural gas of ultra low concentrations.
[0074] The present disclosure provides a nanocomposite that is stable under different weathering conditions.
[0075] The present disclosure provides a highly accurate and inexpensive method for detection of natural gas.
[0076] The present disclosure provides a nanocomposite that is extremely reproducible and achieves very uniform responses.
[0077] The present disclosure provides a nanocomposite based sensor which is capable of sensing a natural gas under different atmospheric conditions.
[0078] The present disclosure provides a nanocomposite based sensor that reduces power consumption and enables safer detection of combustible gas.
[0079] The present disclosure provides a nanocomposite that is capable of detecting gas molecules within a short period of time.
[0080] The present disclosure provides a nanocomposite that exhibits excellent specificity to the gas to be detected.
[0081] The present disclosure provides a method of sensing natural gas that overcomes the drawbacks of the prior art.