Nanocomposite sensor compositions, method of fabrication and sensor system for detecting and monitoring liquid water

Abstract

A liquid water sensing coating (thin film sensor) may be formed using conductive and / or semi-conductive nanomaterials and a fully hydrolyzed polyvinyl alcohol polymer with MW above 30000. The coating may be formed by dissolving the polymer in a mixed solvent system, dispersing the nanomaterials within the polymer, and applying the material to a heated substrate to form the coating on the substrate. A plurality of sensors may be controlled by sequential activation using circuit boards arranged in one or more chains. Alternatively, an area or volume of coating may be sampled by sequential activation of electrodes arranged in one or more chains.

Description

NANOCOMPOSITE SENSOR COMPOSITIONS, METHOD OF FABRICATION AND SENSOR SYSTEM FOR DETECTING AND MONITORING LIQUID WATERTECHNICAL FIELD

[0001] Electronic sensors, particularly for detecting water.BACKGROUND

[0002] Detection and monitoring of unwanted water presence are critical due to the health & safety, environmental, and financial costs associated with water damage. Any unwanted water presence over time can lead to i) health risks due to mold, mildew, and fungus, ii) deterioration of structure due to corrosion, iii) environmental damage particularly in case of leakage of produced water or wastewater in surrounding and iv) accidents in industrial and manufacturing environments.

[0003] Several water sensor systems have been implemented to determine water leaks. Typically, such systems consist of a sensor with electronics coupled to a controller which analyzes data from a sensor and provides alerts to a user. Most of these systems include two probes or conductors as a water sensor. When water flows through these probes or electrodes, a closed electrical path is created to alert an alarm. US Pat. No. 4,843,305 describes a spacer-separated liquid sensing device consisting of two conductors separated by an insulating spacer. A liquid or water leak is detected when any conductive liquid such as water is collected in between the connector, thus short-circuiting the conductors. US Pat. No. 5,661,405 also discloses a similar system where two flexible electrodes / conductor sleeves are made from silicone rubber material filled with conductive carbon particles. Then, two sleeves are braided with polyester materials to complete the liquid water detection sensor. When water or any conductive liquid passes through the sleeves it causes a short circuit detecting water presence. These devices cannot detect a small amount of water as it might not be enough to short-circuit the conductors and are not selective as any conductive material will short-circuit the conductors. More efficient water monitoring devices contain a plurality of water sensors located at different locations with central control apparatus with transmitter and communication devices for remote monitoring. US. Pat. 6,526,807 Bl and US Pat. 9.383,289 Bl discloses similar centralized systems. US Pat. No. 9,383,289 Bl highlights the importance of water leak detection inresidential and commercial buildings and presents a system consisting of plurality sensors including the two-conductor-based water sensor. However, none of them present any active and selective detection of liquid water.

[0004] Polymer nanocomposites are a new class of materials that have shown a lot of potential as active liquid leak detection sensors. US Pat. No. 11143610 B2 discloses a nanocomposite sensor composition comprising siloxane polymer admixed with carbon nanotube (CNT), graphene nanoplatelets (GNP), and / or metal oxide nanoparticles for liquid hydrocarbon detection. However, there is no such nanocomposite formulation for detecting liquid water or aqueous solutions.

[0005] US. Pat. No. 7,270,002 B2 discloses a humidity sensor device comprising carbon nanotube / perfluorinated polymer with acid functional groups in a weight ratio of 0.01-20. They report extremely sensitive humidity sensors with a minimum detection limit of l5.76 ppm. US Pat. No. 9,267,853 also discloses a nanocomposite sensor film that is one-micron thick containing CNT and a polymer for humidity and temperature sensing applications. This shows the potential of nanocomposite sensors to actively detect humidity. This reference uses a polymer that undergoes a phase change. These sensors are small in size (point sensors) and tend to disintegrate in high humidity conditions or the presence of liquid water. Thus, there remains a need for such water sensors that can withstand high humidity conditions and the presence of water sensors for long periods.SUMMARY

[0006] There is disclosed a nanocomposite sensor composition for detecting liquid water or aqueous solution. The composition may include an at least 98.5% hydrolyzed polyvinyl alcohol polymer with a molecular weight of at least 30,000, and a plurality of conductive or semi-conductive nanoparticles dispersed homogeneously within said polymer. Additional features may include: the polymer can be insensitive to high humidity levels and withstands multiple water exposures without degrading. The conductive or semiconductive nanoparticles can include for example carbon nanotubes, graphene nanoplatelets, carbon nanofilaments or carbon nanofibers. The conductive or semiconductive nanoparticles can include carbon nanotubes with an average aspect ratio greater than 100, 500 or 1000, which may be single-walled nanotubes, multi -wallednanotubes, or a mixture thereof. The conductive or semi-conductive nanoparticles may also or alternatively include graphene nanoplatelets. In an example, the polymer and the plurality of nanoparticles are present in the range of weight ratios from 90: 10 to 99: 1.

[0007] A nanocomposite sensor fdm may be formed using a sensor composition as described above including any combination, or none, of the additional features. In an embodiment, the nanocomposite sensor fdm has an average thickness in the range of 20 pm - 100 pm. The nanocomposite sensor fdm may be formed by a process comprising the steps of preparing a mixture dispersing an at least 98.5% hydrolyzed polyvinyl alcohol polymer with molecular weight (MW) greater than 30000 into one or more solvents at a mixture temperature greater than 80 °C, dispersing nanoparticles within the mixture to form an ink, and depositing the ink on a substrate through spray coating, silk screening, or spin coating. Additional features may include: The substrate may be heated to a substrate temperature of more than 60°C during the step of depositing the ink on the substrate. The nanoparticles may be dispersed within the mixture through by ultrasonicating the nanoparticles while also mixing the mixture at high speed. The one or more solvents may include one or more of water, dimethyl sulfoxide (DMSO), Dimethyl formamide (DMF), N-Methyl-2-pyrrolidone, ethylene glycol, or ethanol. The one or more solvents may be plural solvents including water in than range of 50 to 95 wt.%. The one or more solvents may be plural solvents including ethanol in the range of 0 to 50 wt.%. In the step of depositing the ink onto the substrate, the ink may be deposited using a computer-controlled spray coating system. For example, the spray coating system may include an ink reservoir containing the ink to be deposited, a spray valve connected to the ink reservoir, an air valve to control pressurized air to control airflow to trigger the spray valve, and a computer-operated XYZ - stage for positioning the spray valve relative to the substrate.

[0008] A sensor system may include a sensor element, the sensor element including a nanocomposite sensor fdm as described above or formed as described above including any combination of, or none, of the additional features, and a positive electrode and a passive electrode connected to the nanocomposite sensor fdm, the passive electrode being connected to the ground. The sensor system also includes a data acquisition system in communication with the positive electrode of the sensor element for receiving electrical signals. Additional features may include: At least one of the positive electrodeand the passive electrode comprise one or more of: silver, copper, gold, and platinum. The sensor element may be apply-able on to at least a portion of a transportation or storage structure for liquid water monitoring. The sensor element may be deposited on a, or the, substrate, and the substrate may be installable on at least a portion of the transportation or storage structure for liquid water monitoring. The substrate may comprise one or more of: polyimide, polyethylene terephthalate (PET), polycarbonate (PC), poly ether ether ketone (PEEK), and fluorene polyester polyimide.

[0009] A system may collect and process signals from a plurality of sensing elements, each of the sensing elements exhibiting a change in resistance in response to an influence. The system may comprise a voltage supply circuit connectable to the sensing elements for converting the change in resistance of each of the sensing elements into a respective voltage signal, a plurality of sequential sensor activation circuit boards, each sequential sensor activation circuit board of the plurality of sequential sensor activation circuit boards being connected to energize a respective sensing element of the plurality of sensing elements, the plurality of sequential sensor activation circuit boards being arranged in a chain, so that activation of each of the plurality of sequential sensor activation circuit boards triggers, with a delay, the activation of a successive sequential activation circuit board of the chain, up to a last sequential activation circuit board of the chain if there is a last element of the chain, each of the sequential sensor activation circuit boards energize the respective sensing element when activated; and a controller configured to activate a first sequential sensor activation circuit board of the chain, the controller being configured to receive and process the voltage signals to obtain data representative of the presence of the influence at the sensing elements.1. Additional features of the system may include: the sequential sensor activation boards may be sensitive to identifiers unique to each sensing element to locate the sensing elements within the chain, the sequential sensor activation boards energizing the respective sensing elements using respective analog switches in response to the unique identifiers. The sequential sensor activation circuit boards of the chain may each comprise a flip flop, the flip flops of the sequential sensor activation circuit boards of the chain being collectively connected to form a shift register, the delay being provided by a clock signal from the controller. The voltage supply circuit may comprise a current limiting resistance. The system may be capable of having sensor chain lengths of 100meters long or more. The controller may be configured to transmit the data representative of the presence of liquid water using a wireless communication protocol. The wireless communication protocol may be, for example Bluetooth®, or a cellular or satellite communication protocol. The sensor chain may be apply-able onto a surface of residential, industrial, or a commercial structure and / or transportation system for water monitoring. There may also be a further plurality of additional sensor elements and corresponding further plurality of sequential sensor activation circuit boards connected in one or more additional chains, the controller being configured to activate a respective first sequential sensor activation circuit board of each chain and being configured to receive and process the voltage signals to obtain data representative of the presence of the influence at the sensing elements of each chain. The influence may be the presence of liquid water.

[0010] A sensor for detecting an influence on or in a detection area of a sheet or volume of an at least partially conductive material may include the detection area of the sheet or volume of the at least partially conductive material, plural conductive contacts arranged in electrical contact with the sheet or volume of the at least partially conductive material around the detection area, a plurality of sequential sensor activation circuit boards, each sequential sensor activation circuit board of the plurality of sequential sensor activation circuit boards being connected to a respective conductive contact of the plural conductive contacts, the plurality of sequential sensor activation circuit boards being arranged in a chain, so that activation of each of the plurality of sequential sensor activation circuit boards triggers, with a delay, the activation of a successive sequential activation circuit board of the chain, up to a last sequential activation circuit board of the chain if there is a last element of the chain, each of the sequential sensor activation circuit boards energizing or connecting to ground the respective conductive contact when activated, and a controller configured to activate a first sequential sensor activation circuit board of the chain, the controller being configured to receive and process the voltage signals to obtain data representative of the presence of the influence on or in the detection area.2. Additional features of the sensor may include: the sequential sensor activation boards may be sensitive to identifiers unique to each conductive contact to locate the sensing elements within the chain, the sequential sensor activation boards energizing therespective conductive contacts using respective analog switches in response to the unique identifiers. The sequential sensor activation circuit boards of the chain may each comprise a flip flop, the flip flops of the sequential sensor activation circuit boards of the chain being collectively connected to form a shift register, such that the delay is provided by a clock signal from the controller. The voltage supply circuit may comprise a current limiting resistance. The controller may be configured to transmit the data representative of the presence of liquid water using a wireless communication protocol. The wireless communication protocol may be, for example Bluetooth®, or a cellular or satellite communication protocol. The at least partially conductive material may have a conductivity sensitive to the presence of liquid water and the influence may be the presence of liquid water.BRIEF DESCRIPTION OF THE FIGURES

[0011] Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:

[0012] Fig. 1 is a simplified diagram showing a sensor system connected to a wireless interface.

[0013] Fig. 2 is a schematic diagram showing nanotubes embedded in a polymer to form a sensor coating.

[0014] Fig. 3 is a schematic isometric view showing a spray coating apparatus for applying a sensor coating, such as the sensor coating of Fig. 2, to a substrate.

[0015] Fig. 4 is a top view of an exemplary sensor element, with a sensor coating removed from the ends.

[0016] Fig. 5 is a schematic diagram of an exemplary control system for plural sensor elements such as the element shown in Fig. 4.

[0017] Fig. 6 is a schematic diagram showing a chain of sensor elements controlled sequentially by a controller.

[0018] Fig. 7 is a schematic diagram showing components of a sensor system connected to a remote station.

[0019] Fig. 8 is a schematic diagram showing elements of an active board for a sensor and how they interact with a controller in an exemplary embodiment with a chain of sensors.

[0020] Fig. 9 is a schematic diagram showing multiple chains of sensors controlled by a single controller.

[0021] Fig. 10 is a top view of a wide area sensor using multiple contacts controlled using, in an embodiment, a chain arrangement as shown in Fig. 9.

[0022] Fig. 11 is a chart showing a graph of resistance change over time of a sensor after exposure to water.

[0023] Fig. 12 is a chart showing a graph of resistance change over time of a sensor exposed repeatedly to water.

[0024] Fig. 13 is a chart showing a graph of resistance change over time of a sensor exposed to gasoline and subsequently to water.

[0025] Fig. 14 is a picture of a sensor installed within an insulated pipe for a test.

[0026] Fig. 15 is a chart showing a graph of measurements from a sensor over time in a field test.DETAILED DESCRIPTION

[0027] Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.

[0028] The following description and the embodiments described herein are provided by way of illustration of an example, or examples, of particular embodiments of the principles of various aspects of the present invention. These examples are provided for the explanation, and not of limitation, of those principles and the invention in its various aspects. The drawings are not necessarily to scale, and, in some instances, proportions may have been exaggerated in order to depict certain features.

[0029] Water is abundant on the earth and globally used / consumed in all aspects of society from household consumption to use in commercial and industrial processes. Because of its omnipresence, it can take a long time to identify water leaks. Any undetected / unresolved water leaks can lead to extensive water damage to buildings and structures, and any processed water leaks can significantly impact the environment and surrounding ecological systems. Most water sensors in the art fail to work in high humidity or selectively identify water and only do point detection. They are also difficult to instrument as most damaging water leaks happen out of sight, in hard-to-reach areas. The present invention aims to overcome these challenges by contemplating a sensor system foractive and selective detection of liquid water or other aqueous solutions over an area without getting affected by a high humidity environment and capable of withstanding water for a long time.

[0030] The present invention aims to overcome the challenges outlined above by providing a sensor system for direct and selective detection of water leakage monitoring through the use of nanocomposite sensor film and provides a complete system for remotely monitoring water issues. In one embodiment, one or more sensing elements are deposited on a sheet of material (also referred to as “substrate”) containing an electric response circuit connected to a battery-operated remote controller that can wirelessly communicate the sensor status to a user station. Fig. 1 shows the illustration of various components of the sensor system installed on the monitored surface or structure for water or aqueous solution detection. The nanocomposite sensor / s are deposited on a flexible substrate that can be fitted directly on a surface or structure to be monitored which is wire connected to a standalone battery-operated controller capable of wireless communication to a remote user. Suitable wireless communication protocols include cellular or satellite communication for long distance, or Bluetooth® where short range is sufficient. As shown in Fig. 1, a sensor element 10 comprises components 12 (including a sensor film, shown as the dark surface, and electrodes, not shown) mounted on a substrate 14. This substrate 14 is itself mounted to a surface 16 to be monitored by the sensor. The sensor element 10 may be connected to other sensor elements 10. A wired connection 18 connects the sensor(s) to a controller unit 21, here mounted to a wall 22 of a building, the wired connection 18 passing through the wall 22. The controller unit 21 may be battery operated and may be connected to the remote user for example by a cellular or satellite radio shown schematically by symbol 24. The control unit 21 also includes a controller 20, not separately shown in Fig. 1 but shown in other figures.

[0031] A nanocomposite sensor film is disclosed having sensitivity to liquid water and aqueous solution without getting affected by high humidity and having the capability to withstand liquid water for a long time. The nanocomposite sensor film comprises a water-swellable polymer admixed with a plurality of electrically conductive and / or semiconductive particles such as carbon-based nanoparticles, including Carbon nanofibers, Carbon nanotubes (CNT), Carbon nanofilaments, Graphene nanoplatelets (GNP), in any combination exceeding the percolation threshold. The percolation thresholdis a critical concentration of conductive particles required to form a conductive network within the otherwise insulating polymer. Fig. 2 schematically shows carbon-based nanoparticles, here nanotubes 26, embedded in a polymer 28 to form nanocomposite film 30.

[0032] Liquid water sensing film is configured to have a great affinity towards liquid water and aqueous solutions. The presence of liquid water can therefore be directly detected by detecting a change in the electrical conductivity of the sensor film resulting from the adsorption and desorption of water molecules on the surface of the sensing film.

[0033] The water-swellable polymer of the sensor film can be any polymer that readily absorbs the surrounding liquid at a rate relatively proportional to the concentration of water in the liquid. Thus, a correlation can be made between the quantity and quality of water present in the surrounding liquid. Compatible polymer for detecting liquid water includes many hydrophilic polymers such as polyethylene glycol, Polyvinyl pyrrolidone (PVP), Polyvinyl alcohol (PVA), Polyacrylic acid, Nafion Polyacrylamides, Polyoxazoline, etc. A variety of polymers are contemplated, and the preferred polymer is selected. Many of the polymers worked exceedingly well as humidity sensors. However, they failed to withstand liquid water exposure, and the mechanical integrity of these polymers was compromised during the water exposure. Thus, water swellable polymer selected for use with the present invention preferable can absorb and swell when exposed to liquid water or aqueous solution without degrading or dissolving, and is chemically inert and reversible, i.e. capable of recovering to its original physical and electrical properties once liquid water is removed therefrom. In the preferred embodiment, the water-swellable polymer is fully hydrolyzed polyvinyl alcohol (PVA) with a molecular weight of at least 30,000.

[0034] PVA is produced by the polymerization of vinyl acetate(CH3CO2CH=CH2) to polyvinyl acetate which is followed by its hydrolysis. Based on the extent of the hydrolysis reaction, various PVA grades with different hydrolysis degrees can be produced. The degree of hydrolysis and molecular weight of the PVA affects the water resistivity of the PVA. PVA with low hydrolysis degree (86-89%) contains a large amount of hydrophobic acetate groups (CH3-COO-) which create steric hindrance reducing the inter-and intra-molecular Hydrogen-bond (H-bond) interaction. This allows increased interaction between water and PVA molecules, thus reducing the water resistivity of thePVA. The fully hydrolyzed PVA (hydrolysis degree above 98.5) is significantly water resistant due to inter-and intra-molecular H-bonds that form between the hydroxyl groups (-OH) of the PVA chain.

[0035] The solubility of PVA in water is affected primarily by the degree of hydrolysis (DH) and to a secondary extent molecular weight (MW). If DH is less than 90% with MW of 25,000 to 100,000 PVA will dissolve in cold water. With the same PVA MW range but DH 95%, the PVA is insoluble in cold water but will dissolve at elevated temperature (65 C - 70 C). Fully hydrolyzed (DH greater than 98%) will require more than steaming (< 96C) temperature to dissolve. In order to obtain suitable water resistance, the PVA in the nanocomposite sensing fdm of the present disclosure may have a hydrolysis degree greater than 98.5, preferably greater than 99%. The PVA in the nanocomposite sensing fdm of the present disclosure may have a molecular weight greater than 30000, or for further water resistance above 35000. In an example, the molecular weight is in the range of 31000 to 50000, or in the range of 35000 to 50000 for further water resistance. The quantity of the PVA in the nanocomposite sensing fdm described herein may be from 80 to 95 wt. %, preferably 90 to 95 wt. %, based on the total weight of the composition.

[0036] The conductive particles selected for use with the present invention preferably have excellent electrical conductivity and are inert to water or moisture and other chemical contaminants. Examples of suitable conductive particles include gold, platinum, silver, copper, nickel, ferrite and electrically conductive carbon. Carbon-based conductive particles such as CNT and GNP are preferred due to their excellent electrical conductivity and large aspect ratios. The mechanical and thermal properties of carbon nanotubes and graphene nanoplatelets may provide thermal stability and durability to the polymer. Silver, copper, gold and platinum may also be used for the electrodes. In an embodiment, at least one of the positive electrode and the passive electrode comprises one or more of these metals.

[0037] In a sample embodiment, the liquid water sensing fdm comprises of fully hydrolyzed PVA polymer with MW greater than 30000 and a plurality of nanoparticles homogenously dispersed in the polymer. The nanoparticles comprise CNTs and exfoliated GNPs.

[0038] Due to their tubular structure, CNTs have a large surface area having high electrical conductivity and high aspect ratio which help reduce the concentrationrequired to achieve the percolation threshold. Thus, a tow concentration of CNTs is required to achieve the same conductivity as that of other conductive particles. CNTs also have high chemical inertness. These properties make CNTs an ideal nanoparticle reinforcement for sensing film. The sensing mechanism is attributed to the effect on the inter-CNT conductivity from the physical absorption of water molecules between CNTs. The change in the resistance of the sensing film is due to the charge transfer between chemical molecules and CNTs, which varies based on the concentration of chemicals absorbed in the nanocomposite sensing film. As the polymer swells upon absorption of water molecules, the increased volume of the polymer increases the distance between adjacent nanotubes, thereby decreasing the chance of electron transfer. Consequently, with fewer conducting paths available, the resistance of the nanocomposite sensing film increases.

[0039] Exfoliated GNP nanoparticles have a smaller size and more planar structure compared to materials disclosed in the prior art. These features facilitate electron transport and increase conductivity at tower concentrations, as compared to, for example, carbon black. It also has a higher strength-to-weight ratio compared to carbon black, which may provide higher mechanical and thermal stability to the polymer composite. In a preferred embodiment, exfoliated GNP is used in combination with CNT and / or the other particle types in the nanocomposite sensing film, to help expand the range and sensitivity of the sensing element.

[0040] The sensing film in some embodiments comprises at least one electrically conductive carbon nanostructure in an amount of 1% to 10% by weight based on the total weight of the composition. The sensing film according to the present invention may comprise at least one additional electrically conductive carbon nanostructure up to 5 wt. %, preferably 1 to 3 wt.%. Preferably, the sum of the electrically conductive plurality of carbon nanostructures is less than 10 wt.%, more preferably less than 8 wt.%. Other proportions may also be used, including less than 1% or greater than 10%. The resistance of a sensor depends on the size of the sensor and resistivity. Resistivity depends on various factors including percolation threshold. Higher aspect ratios of electrically conductive structures within the material enable smaller amounts of the electrically conductive structures to be used. In an example, the average aspect ratio is greater than 500. In another example, an aspect ratio of greater than 100 may be sufficient. In another example, anaspect ratio of over 1000 may be used for beter conductivity for the amount of nanotubes used. The amount used may be enough to cause the material to exceed the percolation threshold in all conditions expected to be encountered, or may be such that the percolation threshold will be exceeded in some and not exceeded in others. Any given electronic system connected to the material may be able to handle a range of resistances, such that a higher resistivity (for example, due to a smaller quantity of nanotubes) may require the sensor to be smaller or adjustments to the electronics. A very small sensor, for example, may be able to use a very low percentage of carbon nanotubes while still using electronics as described in this document.

[0041] The sensing film according to the present invention can be fabricated by admixing carbon nanoparticles discussed above with PVA polymer in one or more solvents such as water, dimethyl sulfoxide (DMSO), Dimethyl formamide (DMF), N-Methyl-2- pyrrolidone, ethylene glycol or ethanol to form a coating composition for the printing of sensing film. This coating composition is referred to hereinafter as the “ink”.

[0042] Water is extensively used as a solvent for PVA. But it is difficult to dissolve fully hydrolyzed PVA with high molecular weight in water. The temperature has to be increased to greater than 80 °C. Microgelling and aggregation also make it difficult to dissolve PVA. US. Pat. No. 10,332,651 discloses a method of making PVA / CNT nanocomposite film with water as solvent. PVA was completely dissolved in deionized water at 98C and then CNT was added and dispersed using an ultrasonic probe. The nanocomposite film was fabricated using the evaporative casting method which took 6 days to dry. The method proposed here is time-consuming and not suitable for scale-up manufacturing. Hence, a plurality of solvent systems is preferred.

[0043] The nanocomposite ink according to the present invention comprises at least one solvent, preferably water. The nanocomposite ink according to an embodiment comprises at least one additional organic solvent. PVA responds to polar solvents and many polar solvents can be used for PVA. In an example, the additional organic solvent is selected from the group consisting of dimethyl sulfoxide (DMSO), Dimethyl formamide (DMF), N-Methyl-2-pyrrolidone, ethylene glycol and ethanol.

[0044] In preferred embodiments, the quantity of one solvent, preferably water, in an amount of 50 to 95 wt.% based on the total weight of the ink, preferably 60 to 80 wt.%. Further, the additional solvent described herein, for example ethanol, is from 0 to 50wt.% of the total weight of the ink, more preferably 20 to 40 wt.% of the total weight of the ink.

[0045] The ink according to the invention can be obtained by dissolving PVA into a plurality of solvent system described above at a temperature higher than 80 C, preferably above 90 C. Further, the plurality of nanoparticles is dispersed in dissolved PVA solution using one or more suitable dispersing methods. Any type of high-speed mixing equipment may be used including a high-speed magnetic stir rod, high-speed dispenser, ultrasonic probe, centrifuge, vortex mixture and ball milling. In an example, a high-speed mixture using a magnetic stir rod and ultrasonic probe are used in combination to achieve uniform dispersion of nanoparticles in the ink. The term “high speed” may be used to indicate a speed equivalent to at least 500 rpm of mixing with a magnetic stir rod. A speed equivalent to at least 750 rpm of mixing with a magnetic stir rod may be of further benefit.

[0046] Examples of suitable ink-based fabrication processes include spray coating, silk screening, spin coating, inkjet printing, casting, doctor blade coating, and syringe pump deposition. In one embodiment, a fabrication process using a spray coating technique comprising a compressed air nozzle is developed to manufacture nanocomposite film as shown in Fig. 3. The spray coating system 40 comprises a computer-controlled dynamically movable three-axis stage and drive system containing an air-controlling valve, for example a solenoid valve (not shown), that controls a nozzle 42 connected to the ink source. In one embodiment, the nanocomposite ink of the invention is siphoned through a tube into a spray valve assembly 46 where ink is atomized into fine droplets and delivered to the nozzle 42. Further, pressurized air enters into the nozzle through a pressure inlet, thereby increasing the pressure inside the nozzle. The increase in pressure is accompanied by the atomization of the ink, and causes the ink 44 to exit through the nozzle.

[0047] In a sample embodiment, the distance between the nozzle and substrate resting on the spray system base is adjustable to get uniform ink deposition. The spray system is connected to a 3-axis stage. The nozzle is attached to the stage which is movable in a z direction substantially orthogonal to the plane of the substrate 14 and base of the spray system and the stage is movable in the x and y direction on the plane to cover the large area substrate. The driving system containing the solenoid valve controls when the spray nozzle is active.

[0048] To fabricate sensor film, the nanocomposite ink may be spray painted on a substrate using the spray coating system shown in Fig. 3 or the like. Many polymer materials are being used as substrate and could be used for the sensor film. Examples of suitable substrates for sensor film include polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), poly ether ether ketone (PEEK), fluorene polyester polyimide, polytetrafluoroethylene (PTFE), Bismaleimide Triazine (BT), and epoxy resin based substrates. In a sample embodiment, nanocomposite ink is spayed on the PI substrate to form a sensor film. In a preferred embodiment, the substrate is heated more than 60°C, preferably 80°C during the spraying process. Heated substrate flashes of excess solvent, creating solid nanocomposite film instantly. The sensor film preferably has a thickness of less than 100 pm, and more preferably between about 20 to 60 pm, and has substantially uniform thickness throughout. The combination of a heated substrate and a surface-based manufacturing technique such as spray coating, silk screening or spin coating is particularly beneficial in reducing time taken to form the material.

[0049] The roll-to-roll process can deposit large numbers of nanocompositesensing film elements on a substrate. All the substrate examples mentioned above can be used in a roll to roll process. In an example, a polyimide substrate is used. The roll to roll process can also control the thickness and geometry of the nanocomposite sensor film elements, thereby allowing any desired configuration of the sensing element to be produced. Further, the computer-controlled system may allow the process to be carried out accurately and efficiently.

[0050] Three installation methods for the nanocomposite sensor film are provided herein. 1) The first installation method comprises a smaller sensor film (a single sensing element) that may be deployed on an accident-prone area of the structure such as solder joint, elbows, and flanges as shown in Fig. 4. As illustrated in Fig. 4, an exemplary simple sensing element 11 comprises a sensor film 30 on a substrate 14. For clarity, the sensor film 30 is shown removed from the ends of the sensing element 10. A positive electrode 50 and passive electrode 52 are provided. In this embodiment, both electrodes connect to terminals 54, 56 on a single end of the element for convenience of wiring, but the electrodes 50, 52 themselves are on opposite ends of the element so that current between them can flow the length of the sensor film 30. In this embodiment, one electrode is connected to a terminal 56 on an opposite end from the corresponding electrode usingvias 56 to connect to a conductor (not shown) not in contact with the sensor film 30, in this case because it is on the opposite side of the substrate 14. Both electrodes 50, 52 would be under the sensor film 30 if the sensor film were not shown with ends removed. The finger like structure of the electrodes 50, 52 are made to improve adhesion of the sensor material, This simple sensor element 11 does not require additional circuitry as is required for a sensor element 10 as used in a sequential chain, and as will be described further in relation to Figs. 6 and 8. In an example, the substrate has electronic components, for example the electrodes, present before the film is attached. For example, the electrodes may be preprinted on a printed circuit board to which the film is applied over the electrodes. Wires for connecting the electrodes to other electronic components may also be pre-printed. Such pre-printing, for example of electrodes and / or wires, may be used whether or not a roll-to- roll process is used.

[0051] There is disclosed a system for collection and processing signals from a sensor film having two electrodes, the system comprising: a voltage divider circuit connected to each of the sensing elements for converting the change in resistance therein into a voltage signal, the voltage divider circuit comprising a current limiting resistance connected in series to sensing element; a controller in communication with the voltage divider circuit, for detecting and analyzing the voltage signals; in communication via cellular or satellite networks to a remote user station sending alarms and warning information related to the status of the sensor. Fig. 5: illustrates a controller system that can communicate multiple single-element sensors. In this embodiment, each simple sensor element 11 is directly energized by a controller 20 via a general purpose I / O pin 60 which generates an output reduced by resistor 62, which then passes through an individual sensor element 11 to ground 64. A voltage on line 66 supplying current through the sensor is measured by analog input 68 of the controller. The same is duplicated for every sensor element in this embodiment. In an example, resistors 62 have 47kQ each.

[0052] 2) The second installation method comprises a long chain containing multiple sensor elements with nanocomposite film (Fig. 6) which can be applied along long pipelines or any large structure.

[0053] In an aspect of the present invention, there is a system for collection and processing signals from a chain of multiple sensor elements comprising: a chain of sensor elements each connected to a sequential sensor activation board (hereinafter referred to as“active board”), a controller controlled by a custom software program to provide activating signals sent to the active board that can be varied based on several parameters. A software program that collects and analyzes signals from the chain of sensor elements and then communicates the status of the monitored surface / structure to a communication module with wireless communication capability via cellular or satellite networks to a secure webbased user interface. As shown in Fig. 6, simple sensor elements 11 may extend between, and be controlled by, active boards 82. The combination of a simple sensor element 11 and an active board 82 forms a sensor element 10 as shown in Fig. 1. Wires (not shown in this figure, but shown in Fig. 8) extend the length of the chain 80 to control the active boards and supply power to and retrieve data from the active boards and / or sensor elements 11. The wires may extend to the controller (not shown in Fig. 6) from one end 84 of the chain 80.

[0054] Fig. 7 illustrates the overall sensor system divided into three segments.First, a chain 80 of nanocomposite sensor elements 11 each joined together using an active board 82 applied to any monitoring surface or structures which has a wired interface with a battery-operated standalone controller unit 21 with a wireless module 24. The controller provides four functionalities: 1) activation signal to active boards, 2) measuring voltage signals coming from the chain of sensor elements, 3) analyzing the sensor data and determining warnings or alarms messages based on an algorithm and, 4) sending out the warnings and / or alarms messages to a wireless module which relays the messages to a remote user station 90. The remote user station may display a web interface 92 for a user to view the data sent by the controller unit and send commands to the controller.

[0055] If direct sensing from individual sensing elements is employed for a large number of sensing elements, the sensor system would require crowded electric wiring to communicate with all the elements, and large computer power is required to monitor all the sensing elements. This approach is infeasible for the monitoring of pipelines and large surfaces / structures. Long lengths create considerable challenges with reliability, signal loss, signal degradation, and signal propagation. It would also make connecting the various sensor elements nearly impossible and negatively impact reliability. To address these issues, the present invention uses an active board connecting sensor elements in a chain configuration every 2 m. The active board circuit comprises a Schmitt trigger to provide hysteresis for noise immunity and an analog switch to energize the particular sensingelements it is connected. The illustration of the components of an active board is shown in Fig. 8.

[0056] In one embodiment of the present invention, a battery-operated standalone controller 20 provides an activation bit that is clocked through the length of the chain to select only one sensor element at a time via an analog switch 106 located on the active board 82 allowing tag and uniquely identify the location of each sensor element on the chain. As shown in Fig. 8, The signal from the sensor element is placed on the single data line connected to the controller. A current limiting resistance 100 is a part of the controller circuit connected to a single data receiving line 102 of the sensor elements 11 in the series with voltage (VDD) 104 supplied to it creating a voltage divider circuit, converting sensor resistance signals into the voltage signals. This configuration of the active board allows fabrication of a sensor chain adding up to 100 sensing elements that can have a length of 100 meters or more. The analog switch 106 may be controlled by circuitry in response to a unique identifier. In the particular case shown, each board contains a flip flop 108, and the flip flops 108 are wired together and to the controller 20 to act collectively as a shift register. The shift register shifting a bit to a sensor’s board is the unique identifier in this case that leads to activation of the corresponding sensor. Each board supplies the signal to the next, after a delay supplied by a clock signal sent on delay line 110. The activation bit is sent along data activation line (DIN, DOUT) 112. Each activation board may have a Schmitt trigger 114 on the data activation line 112, delay line 110, or both to help prevent noise from changing the state of the flip flop 108.

[0057] As illustrated in Fig. 9 multiple sensor chains can be added to a controller controlled by a custom software program to provide activating signals sent to the active boards along the chains. A software program that collects and analyzes signals from the chain of sensor elements 80 and then communicates the status of the monitored surface / structure to a communication module with wireless communication capability via cellular or satellite networks to a secure web-based user interface 92. Each individual chain may be controlled similarly to as shown in Fig. 8. In Fig. 9, the sensor elements 10 are shown as including the active boards; the separate simple sensor elements 11 and active boards 82 are not shown. Ground connections 64 may also be considered part of the sensor elements 10 and not shown separately. In addition, Fig. 9 shows two data activation lines 112 and 113 along with the delay (clock) line 110. This allows two sensor chains to becontrolled by the same controller (more than two may be present if desired) and, in the embodiment shown, the same pulse can trigger each chain simultaneously and do data reading, though separate clock lines may be used if desired.

[0058] Fig. 10 illustrates a large area sensor that is fabricated with a similar software system for sending activating signals to conductive elements distributed outside of the conductive area of a 2 D nanocomposite coated surface that can be influenced by liquid water. The conductive elements are activated in a particular sequence and the changes in the surface are interpreted by software such that a map can be drawn of that surface and the location of the liquid water on that surface can be determined. As shown in Fig. 10, a sensor 120 for detecting liquid water includes a detection area 122 of a sheet or volume of an at least partially conductive material. In order to detect water, the material may have resistance sensitive to water, such as the materials disclosed in this document. Plural conductive contacts 124 are arranged in electrical contact with the sheet or volume of the at least partially conductive material around the detection area. The detection area 122 may comprise the entire sheet or volume of the at least partially conductive material, for example on a substrate 14, or be a portion of a larger sheet or volume, the portion defined by the arrangement of conductive contacts 124 around it. The sensor also comprises a plurality of sequential sensor activation circuit boards 126, each sequential sensor activation circuit board of the plurality of sequential sensor activation circuit boards being connected to a respective conductive contact of the plural conductive contacts, the plurality of sequential sensor activation circuit boards being arranged in a chain (connected using wires, not shown, but may be for example as shown in Fig. 9 or Fig. 8). As with the other chain embodiments, it may be the case that activation of each of the plurality of sequential sensor activation circuit boards triggers, with a delay, the activation of a successive sequential activation circuit board of the chain, up to a last sequential activation circuit board of the chain if there is a last element of the chain, each of the sequential sensor activation circuit boards energizing or connecting to ground the respective conductive contact when activated. The system may also comprise a controller configured to activate a first sequential sensor activation circuit board of the chain, the controller being configured to receive and process the voltage signals to obtain data representative of the presence of liquid water on or in the detection area.

[0059] Unlike in the other chain embodiments disclosed in this document, for the wide area sensor two contacts are separately activated in different combinations. One contact is connected to an electrical source and another to ground, or differing source, in order to measure resistance between the contacts in the detection area. This may be achieved, for example, by separate chains controlling the connection of the contacts to source and ground wires; the separate chains may share circuit boards or use different ones, or could even operate entirely different conductive contacts. Another way is to use two data lines (as shown in Fig. 9) clocked by a single delay line; the signals in the data lines in this case remain a fixed number of circuit boards apart, but once they have gone around the circle the controller may send another pair of signals a different number of circuit boards apart to probe different pairs of conductive contacts. Other methods of uniquely identifying a contact to connect to the active or ground lines may also be used. As with other embodiments, a current limiting resistance may be used, and data may be transmitted by the controller wirelessly, such as via Bluetooth® or cellular or satellite communication.

[0060] The controller described herein can be used for any type of resistive sensor including herein described water sensing nanocomposites, hydrocarbon sensing nanocomposites described in US US11143610B2, etc.

[0061] The examples below are intended to further illustrate protocols for fabricating nanocomposite sensor film for liquid water detection of the present disclosure described herein. Further, they are intended to illustrate assessing the liquid water sensitivity of the film without getting affected by high humidity. Examples also show various applications of these liquid water sensors. They are not intended to limit the scope of the claims.

[0062] Example 1

[0063] Preparation of water-sensing nanocomposite ink

[0064] The ink of PVA and carbon-based nanoparticles was prepared using the solution mixing method. 2g of fully hydrolyzed PVA with a molecular weight of 31000 to 50000 was dissolved in a certain amount of water / ethanol solution system at 90 C overnight. Carbon nanoparticles were added to the solution that was mixed magnetically for 30 minutes and then ultrasonicated for 5 minutes using an ultrasonic probe. Various formulations are listed in Table 1. The substrate was heated to 90 C and the solution was sprayed to fabricate liquid water sensors.

[0065] Table 1: Solvent systems used for Ink formulation for liquid water sensors.

[0066]

[0067] Example 2

[0068] Moisture and liquid water testing of PVA nanocomposite sensors

[0069] The sensors were exposed to various humidity levels and finally immersed in the water. Table 2 shows the response of the sensors at different levels.

[0070] Table 2: PVA nanocomposite sensor response to humidity and liquid water

[0071] The sensor shows very little response to humidity levels. However, as soon as it was immersed in the water the response was significant. After 30 seconds of immersion, the percentage change in the electrical resistance of the sensor is 260% and within a minute the resistance change is higher than 500%.

[0072] In other tests, only 5% of the sensor area was exposed to liquid water for a minute. Fig. 11 shows the response of the sensor to the liquid water.

[0073] The response shows that the sensor has a high sensitivity to the water and shows very high resistance change (>2000%).

[0074] The sensors were also tested with various aqueous solutions where 5% sensor area was exposed to said aqueous solution and the results are shown in Table 3.

[0075] Table 3: PVA nanocomposite sensor response to an aqueous solution

[0076]

[0077] In one embodiment, the nanocomposite sensors described in the present disclosure were repeatedly immersed in water and then removed and allowed to dry naturally. The response of the sensor from multiple exposures is shown in Fig. 12. It shows present sensor can survive multiple exposures without a reduction in its performance.

[0078] Example 3

[0079] Monitoring of liquid and aerosol leaks in Pharmaceutical and biotech manufacturing plants:

[0080] In one embodiment, the nanocomposite sensor fdm of the present disclosure is envisioned to find use as a small-volume leak detector in pharmaceutical and biotech manufacturing plants.

[0081] The monitoring of liquid and aerosol leaks in tube / small pipe connections is a major concern in drug production plants. Interconnected equipment is used for the manufacturing of drug substances in a flexible multi-product facility. Manufacturing may require one or more large pieces of equipment that are connected via sterile tubing and associated connectors. These connections are one of the major concerns of small leaks such as 1 -3 mm liquid drops. These liquids are either pure liquid water or water-based solutions (>90% water) containing sugars, salts, and / or organic compounds including biological material. Early detection of the presence of these drops and liquid puddles in their initial formation can prevent environmental, personnel, and equipment contamination.

[0082] To showcase the effectiveness of the present disclosure, the nanocomposite sensor film was tested with the most commonly used liquids: ultra-pure water, Phosphate Buffer solution, and Isopropyl alcohol in the pharmaceutical and biomanufacturing plant. The results are shown in Table 4.

[0083] Table 4:PVA nanocomposite sensor response to pharmaceutical plant liquids

[0084]

[0085] Example 4

[0086] Monitoring of liquid water in hydrocarbon storage and distribution facilities

[0087] In one embodiment, the nanocomposite sensor fdm of the present disclosure is envisioned to be used as a water detector in the hydrocarbon storage tanks and / or under insulation in the insulated hydrocarbon pipes.

[0088] Storing hydrocarbon fuel / oil in a dry tank and keeping the insulation dry on the insulated hydrocarbon pipeline is critical. The source of the water can be rain or condensation and may enter into to tank or insulation through vent lines, faulty inlet caps or seals, weld joints, flanges, and / or some other integrity issues with the oil and gas infrastructure.

[0089] Water in the hydrocarbon storage or distribution facility is the main cause of corrosion and microbial activities. If undetected water can cause significant damage to the storage tanks and insulated pipe leading to costly equipment and / or infrastructure replacement costs, hydrocarbon leaks causing environmental damage.

[0090] To showcase the effectiveness of the present disclosure in water detection for hydrocarbon storage tanks, the nanocomposite sensor film described herein was tested under the gasoline and then water was slowly introduced to the gasoline, and the response of the sensor film was measured. Fig. 13 shows the graph of the sensor response. The graph shows nanocomposite sensor film didn’t respond to gasoline but as soon as water was introduced the sensor gave an instant response with close to 200% change in 10 minutes.

[0091] Example 5

[0092] Corrosion under insulation (CUI) is one of the major concerns for the oil and gas industry. It is common practice to wrap or insulate a pipe with insulation or cladding. The insulation material may provide the space for retention and accumulation of water contributing towards corrosion of the pipeline. CUI stays hidden under the insulationand cannot be easily detected by surface measurement methods. The wet-dry cycles can further accelerate the rate of CUI as chloride ions can diffuse deeper through insulation material during these cycles.

[0093] To showcase the effectiveness of present disclosure in water detection for insulated pipe, the nanocomposite sensor fdm described herein was tested on insulated 2-inch pipe sections. Nanocomposite sensors were installed inside the glass wool insulation on two plastic pipes as shown in Fig. 14. Three holes were drilled in the top surface of each pipe to allow water ingress into the pipe, one pipe also had a drain hole drilled into the bottom of the pipe to allow for more rapid draining of any rainwater. The two pipes were mounted next to a roof exposed to the weather. Monitoring over 94 days is shown in Fig. 15, the sensors picked up rain events by showing an increase in resistance. The sensor mounted in the pipe with the drain hole (sensor 3) had a faster sensor recovery after a prolonged rain event indicating a more rapid drying out of the insulation.

[0094] In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVEPROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A nanocomposite sensor composition for detecting liquid water or aqueous solution comprising: an at least 98.5% hydrolyzed polyvinyl alcohol polymer with a molecular weight of at least 30,000; and a plurality of conductive or semi-conductive nanoparticles dispersed homogeneously within said polymer.

2. The nanocomposite sensor composition according to claim 1, wherein the polymer is insensitive to high humidity levels and withstands multiple water exposures without degrading.

3. The nanocomposite sensor composition according to claim 1 or claim 2, wherein said conductive or semiconductive nanoparticles include particles of one or more of the types of particles of the group of types of particles consisting of carbon nanotubes, graphene nanoplatelets, carbon nanofilaments and carbon nanofibers.

4. The nanocomposite sensor composition according to any one of claims 1-3, wherein is the conductive or semiconductive nanoparticles include carbon nanotubes with an average aspect ratio greater than 100 and selected from the group consisting of singlewalled nanotubes, multi-walled nanotubes, and a mixture thereof.

5. The nanocomposite sensor composition according to any one of claims 1-4, wherein the conductive or semi-conductive nanoparticles comprise graphene nanoplatelets.

6. The nanocomposite sensor composition according to any one of claims 1-5, wherein the nanocomposite sensor film comprises the polymer and the plurality of nanoparticles in the range of weight ratios from 90: 10 to 99: 1.

7. A nanocomposite sensor film comprising the sensor composition according to any one of claims 1-6.

8. The nanocomposite sensor film of claim 7, wherein the nanocomposite sensor film has an average thickness in the range of 20 pm - 100 pm.

9. The nanocomposite sensor film of claim 7 or claim 8 formed by a process comprising the steps of: preparing a mixture dispersing an at least 98.5% hydrolyzed polyvinyl alcohol polymer with molecular weight (MW) greater than 30000 into one or more solvents at a mixture temperature greater than 80 °C, dispersing nanoparticles within the mixture to form an ink, and depositing the ink on a substrate through spray coating, silk screening, or spin coating.

10. The nanocomposite sensor film formed according to claim 9, wherein the substrate is heated to a substrate temperature of more than 60°C during the step of depositing the ink on the substrate.

11. The nanocomposite firm formed according to claim 9 or claim 10, wherein the nanoparticles are dispersed within the mixture by ultrasonicating the nanoparticles while also mixing the mixture at high speed.

12. The nanocomposite sensor film formed according to any one of claims 9-11, wherein the one or more solvents include one or more of water, dimethyl sulfoxide (DMSO), Dimethyl formamide (DMF), N-Methyl-2-pyrrolidone, ethylene glycol, or ethanol.

13. The nanocomposite sensor film formed according to any one of claims 9-12, wherein the one or more solvents are plural solvents including water in than range of 50 to 95 wt.%.

14. The nanocomposite sensor film formed according to any one of claims 9-13, wherein the one or more solvents are plural solvents including ethanol in the range of 0 to 50 wt.%.

15. A nanocomposite sensor film formed according to any one of claims 9-14 as dependent on claim 10, and in which in the step of depositing the ink, the ink is deposited on the substrate using a computer-controlled spray coating system.

16. A sensor system comprising: a sensor element, the sensor element comprising: the nanocomposite sensor film according to any one of claims 7-15, and a positive electrode and a passive electrode connected to the nanocomposite sensor film, the passive electrode being connected to the ground; and a data acquisition system in communication with the positive electrode of the sensor element for receiving electrical signals.

17. The sensor system of claim 16 wherein at least one of the positive electrode and the passive electrode comprise one or more of: silver, copper, gold, and platinum.

18. The sensor system of claim 16 or claim 17, wherein the sensor element is applyable on to at least a portion of a transportation or storage structure for liquid water monitoring.

19. The sensor system of claim 17 as dependent on claim 9, or as not dependent on claim 9 but wherein the sensor element comprises a substrate onto which the nanocomposite film is deposited, and the substrate is installable on at least a portion of the transportation or storage structure for liquid water monitoring.

20. The sensor system of claim 19 wherein the substrate comprises one or more of: polyimide, polyethylene terephthalate (PET), polycarbonate (PC), poly ether ether ketone (PEEK), and fluorene polyester polyimide.

21. A system for collecting and processing signals from a plurality of sensing elements, each of the sensing elements exhibiting a change in resistance in response to an influence, the system comprising: a voltage supply circuit connectable to the sensing elements for converting the change in resistance of each of the sensing elements into a respective voltage signal; a plurality of sequential sensor activation circuit boards, each sequential sensor activation circuit board of the plurality of sequential sensor activation circuit boards being connected to energize a respective sensing element of the plurality of sensing elements, the plurality of sequential sensor activation circuit boards being arranged in a chain, so that activation of each of the plurality of sequential sensor activation circuit boards triggers, with a delay, the activation of a successive sequential activation circuit board of the chain, up to a last sequential activation circuit board of the chain if there is a last element of the chain, each of the sequential sensor activation circuit boards energize the respective sensing element when activated; and a controller configured to activate a first sequential sensor activation circuit board of the chain, the controller being configured to receive and process the voltage signals to obtain data representative of the presence of the influence at the sensing elements.

22. The system of claim 21, wherein the sequential sensor activation boards are sensitive to identifiers unique to each sensing element to locate the sensing elements within the chain, the sequential sensor activation boards energizing the respective sensing elements using respective analog switches in response to the unique identifiers.

23. The system of claim 21 or claim 22 wherein the sequential sensor activation circuit boards of the chain each comprise a flip flop, the flip flops of the sequential sensor activation circuit boards of the chain being collectively connected to form a shift register, and the delay is provided by a clock signal from the controller.

24. The system of any one of claims 21-23 wherein the voltage supply circuit comprises a current limiting resistance.

25. The system of any one of claims 21-24 being capable of having sensor chain lengths of at least 100 meters long.

26. The system of any one of claims 21-25 in which the controller is configured to transmit the data representative of the presence of the influence using a wireless communication protocol.

27. The system of claim 26 in which the wireless communication protocol is Bluetooth®.

28. The system of claim 26 in which the wireless communication protocol is a cellular or satellite communication protocol.

29. The system of any one of claims 21-28, wherein the sensor chain is apply-able onto a surface of residential, industrial, or a commercial structure and / or transportation system for water monitoring.

30. The system of any one of claims 21-29 further comprising a further plurality of additional sensor elements and corresponding further plurality of sequential sensor activation circuit boards connected in one or more additional chains, the controller being configured to activate a respective first sequential sensor activation circuit board of each chain and being configured to receive and process the voltage signals to obtain data representative of the presence of the influence at the sensing elements of each chain.

31. The system of any one of claims 21-30 in which the influence is the presence of liquid water.

32. A sensor for detecting an influence on or in a detection area of a sheet or volume of an at least partially conductive material, the sensor comprising; the detection area of the sheet or volume of the at least partially conductive material;plural conductive contacts arranged in electrical contact with the sheet or volume of the at least partially conductive material around the detection area; a plurality of sequential sensor activation circuit boards, each sequential sensor activation circuit board of the plurality of sequential sensor activation circuit boards being connected to a respective conductive contact of the plural conductive contacts, the plurality of sequential sensor activation circuit boards being arranged in a chain, so that activation of each of the plurality of sequential sensor activation circuit boards triggers, with a delay, the activation of a successive sequential activation circuit board of the chain, up to a last sequential activation circuit board of the chain if there is a last element of the chain, each of the sequential sensor activation circuit boards energizing or connecting to ground the respective conductive contact when activated; and a controller configured to activate a first sequential sensor activation circuit board of the chain, the controller being configured to receive and process the voltage signals to obtain data representative of the presence of the influence on or in the detection area.

33. The system of claim 32, wherein the sequential sensor activation boards are sensitive to identifiers unique to each conductive contact to locate the sensing elements within the chain, the sequential sensor activation boards energizing the respective conductive contacts using respective analog switches in response to the unique identifiers.

34. The system of claim 32 or claim 33 wherein the sequential sensor activation circuit boards of the chain each comprise a flip flop, the flip flops of the sequential sensor activation circuit boards of the chain being collectively connected to form a shift register, and the delay is provided by a clock signal from the controller.

35. The system of any one of claims 32-34 wherein the voltage supply circuit comprises a current limiting resistance.

36. The system of any one of claims 32-35 in which the controller is configured to transmit the data representative of the presence of the influence using a wireless communication protocol.

37. The system of claim 36 in which the wireless communication protocol is Bluetooth®.

38. The system of claim 36 in which the wireless communication protocol is a cellular or satellite communication protocol.

39. The system of any one of claims 32-38 in which the at least partially conductive material has a conductivity sensitive to the presence of liquid water and the influence is the presence of liquid water.

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