WO2015140394A1

WO2015140394A1 - An apparatus and associated methods

Info

Publication number: WO2015140394A1
Application number: PCT/FI2015/050152
Authority: WO
Inventors: Jarkko Rouvinen; Matti Kosonen; Katri POHJONEN; Pekka KORPINEN; Kim BLOMQVIST
Original assignee: Nokia Technologies Oy
Priority date: 2014-03-19
Filing date: 2015-03-10
Publication date: 2015-09-24
Also published as: GB201404927D0; GB2524288A

Abstract

An apparatus comprising a sensing unit, the sensing unit comprising a plurality of laterally- spaced fluid-sensitive elements and at least one readout node associated with the plurality of laterally-spaced fluid-sensitive elements, wherein the fluid-sensitive elements are configured to exhibit a characteristic response to the presence of a fluid in their respective localities, and wherein the at least one readout node is configured to receive signalling from the associated fluid-sensitive elements indicative of the characteristic response, and transmit signalling to a reader to enable the presence and location of the fluid to be determined based on the signalling received from the fluid-sensitive elements.

Description

An apparatus and associated methods Technical Field

The present disclosure relates to the field of fluid sensors, associated methods and apparatus, and in particular concerns an apparatus for use in determining the presence and location of a fluid (e.g. liquid and/or gas) based on signalling received from a plurality of laterally-spaced fluid-sensitive elements. Certain disclosed embodiments have particular relevance to moisture detection in buildings and structures.

Certain disclosed example aspects/embodiments, with respect to a wired or wireless reader, relate to portable electronic devices, in particular, so-called hand-portable electronic devices which may be hand-held in use (although they may be placed in a cradle in use). Such hand-portable electronic devices include so-called Personal Digital Assistants (PDAs) and tablet PCs. The portable electronic devices/apparatus according to one or more disclosed example aspects/embodiments may provide one or more audio/text/video communication functions (e.g. tele-communication, video-communication, and/or text transmission, Short Message Service (SMS)/ Multimedia Message Service (MMS)/emailing functions, interactive/non-interactive viewing functions (e.g. web- browsing, navigation, TV/program viewing functions), music recording/playing functions (e.g. MP3 or other format and/or (FM/AM) radio broadcast recording/playing), downloading/sending of data functions, image capture function (e.g. using a (e.g. in-built) digital camera), and gaming functions.

Background

Research is currently being done to develop new fluid sensors (such as moisture sensors). One or more aspects/embodiments of the present disclosure may or may not address one or more issues associated with existing fluid sensors.

The listing or discussion of a prior-published document or any background in this specification should not necessarily be taken as an acknowledgement that the document or background is part of the state of the art or is common general knowledge.

Summary According to a first aspect, there is provided an apparatus comprising a sensing unit, the sensing unit comprising a plurality of laterally-spaced fluid-sensitive elements and at least one readout node associated with the plurality of laterally-spaced fluid-sensitive elements, wherein the fluid-sensitive elements are configured to exhibit a characteristic response to the presence of a fluid in their respective localities, and wherein the at least one readout node is configured to receive signalling from the associated fluid-sensitive elements indicative of the characteristic response, and transmit signalling to a reader to enable the presence and location of the fluid to be determined based on the signalling received from the fluid-sensitive elements.

The readout node may be a wireless readout node or a wired readout node, the latter requiring physical connection to the sensing unit, for example, using a port. In the case of a wireless readout node, there is provided an apparatus comprising a sensing unit, the sensing unit comprising a plurality of laterally-spaced fluid-sensitive elements and at least one wireless readout node associated with the plurality of laterally- spaced fluid-sensitive elements, wherein the fluid-sensitive elements are configured to exhibit a characteristic response to the presence of a fluid in their respective localities, and wherein the at least one wireless readout node is configured to receive signalling from the associated fluid-sensitive elements indicative of the characteristic response, and wirelessly transmit signalling to a wireless reader to enable the presence and location of the fluid to be determined based on the signalling received from the fluid-sensitive elements

The sensing unit, comprising a plurality of laterally-spaced fluid-sensitive elements and at least one readout node associated with the plurality of laterally-spaced fluid-sensitive elements, may comprise at least one of: a common readout node associated with a plurality of laterally-spaced fluid-sensitive elements; and a plurality of readout nodes, each readout node associated with one or more laterally-spaced fluid-sensitive elements.

The plurality of readout nodes may be electrically connected to one another such that one readout node can receive signalling from the fluid-sensitive elements associated with the other readout nodes. The apparatus may comprise a plurality of sensing units each having a common readout node associated with a plurality of laterally-spaced fluid-sensitive elements, and the common readout node of each sensing unit may be configured to: receive signalling from the fluid-sensitive elements associated with the common readout node; and relay signalling regarding the presence of fluid to one or more of the other common readout nodes.

The apparatus may comprise at least one signal line for receiving the signalling from the fluid-sensitive elements at the common readout node. The apparatus may comprise a communication line for relaying the signalling to the one or more other common readout nodes. The at least one signal line and the communication line may be the same line or different lines.

The common readout node may be configured to relay the signalling to other common readout nodes in one or more lateral directions. The common readout node may be configured to relay the signalling to its immediately adjacent common readout nodes.

The apparatus may comprise a plurality of readout nodes laterally spaced along an axial direction. One or more of the readout nodes may be configured to relay signalling from other readout nodes back in the axial direction to a preceding readout node such that the preceding readout node can provide signalling concerning the presence and location of fluid from fluid-sensitive elements associated with the readout nodes following the preceding node. The axial direction may be along a length or width direction of the apparatus.

The plurality of readout nodes may be laterally-spaced from one another such that the location of the fluid can be at least partly determined based on the location of the readout node from which the transmitted signalling is transmitted. The apparatus may comprise a respective electrical readout connection between each fluid-sensitive element and an associated readout node such that the location of the fluid can be at least partly determined based on the particular electrical readout connection via which the signalling is received. The apparatus may comprise a common electrical readout connection between each fluid- sensitive element and an associated readout node, and each fluid-sensitive element may be configured to provide uniquely-identifiable signalling to the associated readout node via the common electrical readout connection such that the location of the fluid can be at least partly determined based on the particular fluid-sensitive element with which the uniquely- identifiable signalling corresponds.

The fluid-sensitive elements may be electrically connected to an associated readout node such that the sensing unit remains functional when it is physically divided through a fluid- sensitive element or between adjacent fluid-sensitive elements to leave at least one fluid- sensitive element electrically connected to the associated readout node.

One or more of the fluid-sensitive elements and the readout nodes may be arranged to form a one or two dimensional array in the same lateral plane.

The fluid-sensitive elements may have a spaced apart or contiguous arrangement within the array.

The apparatus may comprise a sheet of material on which the fluid-sensitive elements and at least one readout node are formed. By virtue of the material being in sheet form, it may be considered to be substantially thin and flat. The fluid-sensitive elements and at least one readout node may be fully or partially printed onto the sheet of material. The sheet of material may be configured to be formed into a roll. The apparatus may comprise a plurality of sensing units formed on the sheet of material. The sheet of material may comprise perforation lines configured to allow the respective sensing units to be separated from the apparatus. The sheet of material may be flexible and/or stretchable. The sheet of material may be fluid-impermeable. The sheet of material may comprise an adhesive on a face thereof for attachment of the apparatus to a surface. The fluid-sensitive elements and at least one sensor node may be formed on the same face of the sheet of material as the adhesive. The sheet of material may comprise one or more of paper, Kapton™ and plastic foil or similar.

The characteristic response exhibited by the fluid-sensitive elements in the presence of a fluid may be a change in one or more of the following properties of the fluid-sensitive elements: real or imaginary impedance, DC resistance, effective dielectric constant, and conductance. At least one of the fluid-sensitive elements may comprise a layer of graphene oxide configured to exhibit a change in one or more electrical properties in response to the presence of the fluid. The fluid may comprise one or more of a liquid and a gas. The fluid may comprise one or more of water, ammonia and carbon monoxide. One or more of the at least one readout nodes may be wired or wireless. The at least one wireless readout node may be one or more of a radio transmitter/transceiver, a radio- frequency identification transmitter/transceiver and a near-field communication transmitter/transceiver. The radio-frequency identification transmitter/transceiver may be a passive radio-frequency identification transmitter/transceiver.

The apparatus may be one or more of a reinforcing mat, a supporting mat, a vapour barrier, and an adhesive tape for attaching and/or sealing one or more of the same.

According to a further aspect, there is provided a system comprising the apparatus described herein and the reader.

According to a further aspect, there is provided a method of making an apparatus,

the apparatus comprising a sensing unit, the sensing unit comprising a plurality of laterally-spaced fluid-sensitive elements and at least one readout node associated with the plurality of laterally-spaced fluid-sensitive elements, wherein the fluid-sensitive elements are configured to exhibit a characteristic response to the presence of a fluid in their respective localities, and wherein the at least one readout node is configured to receive signalling from the associated fluid-sensitive elements indicative of the characteristic response, and transmit signalling to a reader to enable the presence and location of the fluid to be determined based on the signalling received from the fluid- sensitive elements,

the method comprising forming the plurality of laterally-spaced fluid-sensitive elements and the at least one associated readout node. According to a further aspect, there is provided a method of using an apparatus,

the method comprising: receiving signalling at the at least one readout node from the plurality of associated fluid-sensitive elements indicative of a characteristic response to the presence of a fluid; and transmitting signalling to a reader to enable the presence and location of the fluid to be determined based on the signalling from the fluid-sensitive elements. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated or understood by the skilled person.

Corresponding computer programs (which may or may not be recorded on a carrier) for implementing one or more of the methods disclosed herein are also within the present disclosure and encompassed by one or more of the described example embodiments.

The present disclosure includes one or more corresponding aspects, example embodiments or features in isolation or in various combinations whether or not specifically stated (including claimed) in that combination or in isolation. Corresponding means for performing one or more of the discussed functions are also within the present disclosure.

The above summary is intended to be merely exemplary and non-limiting.

Brief Description of the Figures

A description is now given, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 shows the various sources of moisture within a typical building;

Figure 2a shows an apparatus according to one embodiment of the present disclosure;

Figure 2b shows an apparatus according to another embodiment of the present disclosure;

Figure 2c shows an apparatus according to another embodiment of the present disclosure;

Figure 2d shows an apparatus according to another embodiment of the present disclosure; Figure 2e shows an apparatus according to another embodiment of the present disclosure;

Figure 3a shows how the location of a fluid can be at least partly determined based on the location of a proximal wireless readout node;

Figure 3b shows how the location of a fluid can be at least partly determined based on the location of a neighbouring wireless readout node;

Figure 3c shows how the location of a fluid can be at least partly determined based on the location of a distant wireless readout node;

Figure 4a shows one example of how the fluid-sensitive elements and wireless readout nodes can be electrically connected to facilitate readout of the apparatus;

Figure 4b shows an example of the signalling associated with readout of the apparatus; Figure 5a shows an apparatus according to another embodiment of the present disclosure;

Figure 5b shows an apparatus according to another embodiment of the present disclosure;

Figure 5c shows an apparatus according to another embodiment of the present disclosure;

Figure 6a shows a roll of material comprising a plurality of sensing units;

Figure 6b shows a complete sensing unit separated from the roll of material;

Figure 6c shows a partial sensing unit separated from the roll of material;

Figure 6d shows another partial sensing unit separated from the roll of material;

Figure 7a shows the waterproofing layers incorporated into the walls and floor of a typical bathroom;

Figure 7b shows the cross-section of an exterior wall of a typical building;

Figure 8 shows one example of a wireless readout node of the apparatus described herein;

Figure 9 shows a system comprising the apparatus and wireless reader described herein; Figure 10a shows the main steps of a method of making the apparatus described herein; Figure 10b shows the main steps of a method of using the apparatus described herein; and

Figure 1 1 shows a computer-readable medium comprising a computer program configured to perform, control or enable one or more of the method steps of Figure 10a or 10b. Description of Specific Aspects/Embodiments Figure 1 shows the various sources of moisture to which a typical building is exposed. If the internal structure of a building cannot dry properly, it becomes moldy which can reduce the indoor air quality and cause health problems for people living or working in the building. Damp can also reduce the structural integrity of a building. Moisture-related problems are common and tend to increase with the age of a building. Furthermore, present-day building regulations demand greater insulation to satisfy energy efficiency requirements, which can exacerbate the problem.

Moisture detection systems have recently been developed to address this issue. There are currently two main approaches to moisture detection. The first approach involves the use of a transferable system which is brought in when there are already suspicions that damp has arisen. The second approach involves the use of an integrated sensor system which is incorporated within the building structure itself. Integrated systems can be installed when the building is first constructed or during a subsequent renovation project, and in some cases can be used for continuous monitoring of moisture levels within the building.

There will now be described an apparatus and associated methods that may or may not improve the areal coverage, size, conformity, power consumption, complexity and/or cost associated with fluid detection systems.

The following examples of various embodiments of the present disclosure will focus on particular embodiments with at least one wireless readout node. In other embodiments, one or more of the at least one readout nodes may be wired (or wireless). In the case of a wired readout node, a suitable connection would be required to provide for the physical wired connection e.g. a USB or other port.

Figures 2a and 2b show first and second embodiments of an apparatus according to the present disclosure. The present apparatus comprises a sensing unit 201 , the sensing unit 201 comprising a plurality of laterally-spaced fluid-sensitive elements 202 and at least one wireless readout node 203 associated with the plurality of laterally-spaced fluid-sensitive elements 202. The fluid sensitive elements 202 are configured to exhibit a characteristic response to the presence of a fluid in their respective localities, and the at least one wireless readout node 203 is configured to receive signalling from the associated fluid- sensitive elements 202 indicative of the characteristic response, and wirelessly transmit signalling to a wireless reader to enable the presence and location of the fluid to be determined based on the signalling received from the fluid-sensitive elements 202. In these embodiments, the nodes 203 and fluid-sensitive elements 202 are all aligned in an axial direction. In other embodiments, however, the fluid-sensitive elements 202 may not be aligned in an axial direction with the associated node 203, as shown in Figure 2c.

It will be appreciated that in wired readout node embodiments, the apparatus may comprise a sensing unit 201 , the sensing unit 201 comprising a plurality of laterally- spaced fluid-sensitive elements 202 and at least one wired readout node 203 associated with the plurality of laterally-spaced fluid-sensitive elements 202. The fluid sensitive elements 202 are configured to exhibit a characteristic response to the presence of a fluid in their respective localities, and the at least one wired readout node 203 is configured to receive signalling from the associated fluid-sensitive elements 202 indicative of the characteristic response, and by wiring transmit signalling to a wired reader to enable the presence and location of the fluid to be determined based on the signalling received from the fluid-sensitive elements 202.

The characteristic response exhibited by the fluid-sensitive elements 202 in the presence of a fluid may comprise a change in one or more physical or electrical properties of the fluid-sensitive elements 202, such as a change in real or imaginary impedance, DC resistance, effective dielectric constant, or conductance. For example, the fluid sensitive elements 202 may comprise a layer of graphene oxide configured to exhibit a change in one or more electrical properties in response to the presence of water, ammonia or carbon monoxide. Graphene oxide has recently been considered as a novel material for use in temperature and humidity sensors. The use of graphene oxide as the sensing material enables transparent, flexible sensors to be produced at low cost with improved sensitivity when compared to existing sensors. The impedance of graphene oxide has been found to be exponentially dependent upon the temperature and relative humidity of the environment in which it is located. The temperature and humidity dependence is not fully understood, but may relate to the layered structure of the material.

Graphene oxide comprises a stack of two-dimensional platelets which allow the permeation of water through the material. The permeation rate depends on both the temperature and relative humidity of the environment. At 100% relative humidity, the water penetrates through the graphene oxide as though the material wasn't there. One possible explanation for this behaviour is that the relative humidity (and also the temperature) of the surrounding environment affect the interstitial spacing of the graphene oxide platelets, which in turn dictates the amount of water that can be absorbed by the material. When water fills the space between the platelets, the thickness of the material increases and protons are dissociated from the graphene oxide. The protons and water molecules form a hydronium ion which is mobile within the graphene oxide-water complex resulting in the change in impedance.

In the apparatus of Figures 2a and 2c, the sensing unit 201 comprises a common wireless readout node 203 associated with a plurality of laterally-spaced fluid-sensitive elements 202. In the apparatus of Figure 2b, on the other hand, the sensing unit 201 comprises a plurality of wireless readout nodes 203 each associated with one (or more) laterally- spaced fluid-sensitive elements 202. By laterally spacing the fluid-sensitive elements 202 from one another, the apparatus is able to detect the presence of fluid at different points on a surface (e.g. wall, floor or ceiling). This aspect provides for greater areal coverage than some existing sensor systems. Furthermore, as shown in Figures 2d and 2e, any number of these sensing units 201 may be joined and/or connected together to form a larger sensor system. This may be used, for example, to monitor the moisture content across a complete stretch of wall, floor or ceiling rather than localised moisture detection.

When the apparatus comprises a plurality of wireless readout nodes 203 as shown in Figures 2b, 2d and 2e, the plurality of wireless readout nodes 203 may be laterally-spaced from one another such that the location of the fluid can be at least partly determined based on the location of the wireless readout node 203 from which the wirelessly transmitted signalling is transmitted. This is illustrated in Figures 3a to 3c in which the wireless reader 304 is a mobile device configured to receive the signalling from the wireless readout nodes 303 (e.g. via radio-frequency identification (RFID) or near-field communication (NFC)), and display corresponding data 305 to the user via an installed application. In these examples, the apparatus comprises three sensing units 301 a-c each comprising a plurality of fluid-sensitive elements 302 associated with a common wireless readout node 303.

In Figure 3a, some fluid-sensitive elements 302a within the first sensing unit 301 a have detected the presence of moisture 306 in their respective localities and generated corresponding signalling for transmission by the associated readout node 303a. As can be seen, the mobile device 304 has received the signalling from the wireless readout node 303a and has displayed a message 305 for the user indicating that moisture 306 has been detected within a distance of 10cm. In this case, the signal strength indicates that the transmitting node 303a and associated fluid-sensitive elements 302a are in close proximity to the mobile device 304.

In Figure 3b, some fluid-sensitive elements 302b within the second sensing unit 301 b have detected the presence of moisture 306 in their respective localities and generated corresponding signalling for transmission by the associated readout node 303b. This time, the signal strength at the mobile device 304 is weaker than in Figure 3a due to the greater distance between the transmitting node 303b and the mobile device 304. The signal strength indicates to the mobile device 304 that the signalling originated from a neighbouring node 303b rather than a proximal node 303a immediately adjacent to the mobile device 304. In this example, however, the mobile device 304 has not been preprogrammed with the specific layout of the sensing units 301 a-c, which could be arranged in one or two lateral dimensions (including a radial arrangement). As a result, the mobile device 304 displays a user message 305 which indicates that moisture 306 has been detected more than 10cm away, and suggests that the user moves the mobile device 304 by 10cm to try to determine the location of the transmitting node 303b. If the user then moves the mobile device 10cm to the right, the wireless device 304 will detect the stronger signal strength from the second node 303b and be able to confirm the approximate location of the moisture 306. If the user moves the mobile device 304 in another direction, however, a decrease in detected signal strength will indicate that the mobile device 304 is moving further away from the transmitting node 303b (and therefore the moisture 306). A corresponding message 305 displayed on the mobile device 304 would prompt the user to try moving the mobile device 304 in a different direction until the approximate location of the moisture 306 is determined.

In Figure 3c, some fluid-sensitive elements 302c within the third sensing unit 301 c have detected the presence of moisture 306 in their respective localities and generated corresponding signalling for transmission by the associated readout node 303c. This time, the distance between the transmitting node 303c and the mobile device 304 is sufficiently great that the mobile device 304 is outside the transmission range of the wireless readout node 303c. The lack of signalling indicates to the mobile device 304 that there is no moisture 306 in its vicinity. As a result, the mobile device 304 displays a corresponding message 305 prompting the user to move the mobile device 304 by 50cm to check for signalling transmitted by more distant readout nodes 303c. In some cases, the mobile device 304 may be pre-programmed with the specific layout of the sensing units 301 . This feature (not dissimilar to the storage of street maps on a satellite navigation device), would enable the mobile device 304 to better guide the user to the next-nearest readout node 303. For example, in Figure 3b, the mobile device 304 would know that the neighbouring node 303b was located to the right of the proximal node 303a and could therefore tell the user to move the device 10cm to the right. This would help to remove some of the guess work associated with locating the transmitting node 303b.

The apparatus may also be configured such that the plurality of wireless readout nodes 303a-c are electrically connected to one another such that one wireless readout node 303a can receive signalling from the fluid-sensitive elements 302b, c associated with some or all of the other wireless readout nodes 303b, c. This feature could enable the user to determine whether or not there is fluid present at respective fluid-sensitive elements 302b, c associated with other wireless readout nodes 303b, c using signalling received from a single wireless readout node 303a. For example, the apparatus may comprise a plurality of wireless readout nodes 303a-c laterally spaced along an axial direction. One or more of these wireless readout nodes 303b may be configured to relay signalling from other wireless readout nodes 303c back in the axial direction to a preceding wireless readout node 303a. In this way, the preceding wireless readout node 303a could provide signalling concerning the presence and location of fluid 306 from fluid-sensitive elements 302c associated with the wireless readout nodes 303c following the preceding node 303a. In this scenario, the axial direction could be a length or width direction of the apparatus.

Figure 4a illustrates one example of how the wireless readout nodes 403 and associated fluid-sensitive elements 402 could be electrically connected to achieve this functionality. In this example, the apparatus comprises a plurality of sensing units 401 each having a common wireless readout node 403 associated with a plurality of laterally-spaced fluid sensitive elements 402. The common wireless readout node 403 of each sensing unit 401 is configured to receive signalling from the associated fluid-sensitive elements 402, and relay signalling regarding the presence of fluid to one or more of the other common wireless readout nodes 403. The common wireless readout node 403 may be configured to relay the signalling to all of the other nodes, to nodes in one or more lateral directions, or only to its immediately adjacent nodes. Furthermore, the relay of signalling could occur in the forward and/or backward directions (e.g. the length or width directions of the apparatus as mentioned above).

As shown in this figure, the apparatus comprises at least one signal line (Signaljn [1]-[k]) for receiving the signalling from the fluid-sensitive elements 402 at the common wireless readout node 403, and a communication line (Comm) for relaying the signalling to the one or more other common wireless readout nodes 403. There is also a power line (Power) for providing each of the nodes 403 and fluid-sensitive elements 402 with electrical power, an interrogation line (Signal_out [0]) for requesting a readout from each of the fluid- sensitive elements 402, and a common ground line (Ground). In this example, the power line, communication line, interrogation line and signal lines are separate from one another, but two or more of these lines could be combined. In the latter scenario, a field-effect transistor or other isolator may be required to separate the various signals from one another.

As indicated by the dashed lines, the apparatus may comprise a respective electrical readout connection (Signaljn [1]-[k]) between each fluid-sensitive element 402 and an associated wireless readout node 403. This feature enables the location of the fluid to be at least partly determined based on the particular electrical readout connection via which the signalling is received. In this way, the location of the fluid can be determined to the nearest fluid-sensitive element 402 rather than just to the nearest readout node 403. In some cases, the wireless readout nodes 403 may not be connected to one another. In this situation, the location of the associated readout node 403 may also be required in order to determine the absolute location of the fluid.

An alternative option is to use a common electrical readout connection (Signal_out [0]) between each fluid-sensitive element 402 and an associated wireless readout node 403, and configure each fluid-sensitive element 402 to provide uniquely-identifiable signalling to the associated wireless readout node 403 via the common electrical readout connection. The use of uniquely-identifiable signalling allows the location of the fluid to be at least partly determined based on the particular fluid-sensitive element 402 with which the uniquely-identifiable signalling corresponds. In some cases, the signalling from each fluid-sensitive element 402 may be uniquely identifiable within a particular sensing unit 401 , but in other cases, it could be uniquely identifiable within the complete apparatus (i.e. across all sensing units 401 ). In the former scenario, the location of the associated readout node 403 may also be required in order to determine the absolute location of the fluid.

Each wireless readout node 403 may comprise any transmitter configured to receive signalling from the associated fluid-sensitive elements 402, and transmit corresponding signalling to the wireless reader. In some embodiments, the transmitters may be configured to receive and transmit the signalling continuously or intermittently regardless of whether the wireless reader is present or not (i.e. active transmission). In other embodiments, however, the transmitters may be transceivers configured to receive and transmit the signalling only on receipt of interrogation signalling from the wireless reader. The power saving associated with the latter scenario is advantageous for battery-powered devices, as it reduces the frequency of battery replacement. If the apparatus is to be integrated within a wall, floor or ceiling cavity, however, then a passive transceiver may be desirable. Such transceivers are inductively powered by the interrogation signalling from the wireless reader thus removing the need for batteries.

Figure 4b shows an example of the signalling associated with a passive system comprising three connected sensing units 401 a-c. In this example, some of the fluid- sensitive elements 402b of the second sensing unit 401 b are in contact with moisture 406, and the wireless readout node 403a of the first sensing unit 401 a has received interrogation signalling from the wireless reader. The interrogation signalling is relayed to the readout nodes 403b, c of the second 401 b and third 401 c sensing units and is used to determine the state (i.e. whether or not any of the fluid-sensitive elements 402a-c exhibit the characteristic response) of each respective associated fluid-sensitive element 402a-c. The wireless readout nodes 403a-c then receive signalling from their associated fluid- sensitive elements 402a-c in response to the interrogation signalling, which is relayed to the readout node 403a of the first sensing unit 401 a for transmission to the wireless reader. The presence or absence of moisture 406 (and possibly also the amount of moisture 406) can be determined from the shape of the signalling received from the fluid- sensitive elements 402a-c.

Figure 5a shows another embodiment of the present apparatus, with two sensing rows each with respective nodes. In this example, the apparatus comprises a plurality of sensing units 501 (each can be considered to be a sensing chain [n]) each having a common wireless readout node 503 and a plurality of associated fluid-sensitive elements 502. The fluid-sensitive elements 502 of each sensing unit 501 are arranged to form a one-dimensional array, and the sensing units 501 themselves are arranged to form a two- dimensional array (two rows), in the same lateral plane. The fluid-sensitive elements 502 can be seen to have a slightly space-apart arrangement within the array, but they could be contiguous for greater surface coverage. Furthermore, the wireless readout nodes 503 of the apparatus are spaced apart from one another to increase the chance of the wireless reader being within the transmission range of at least one of the nodes 503 regardless of where it is positioned in proximity to the apparatus.

Figure 5b shows a further embodiment of the present apparatus. Unlike the example shown in Figure 5a, the fluid-sensitive elements 502 of each sensing unit 501 are arranged to form a two-dimensional sensor array (comprising rows and columns of fluid- sensitive elements). This arrangement may provide a similar areal coverage at lower cost than the example of Figure 5a due to the smaller number of wireless readout nodes 503, but may not guarantee that the wireless reader is within the transmission range of any of the nodes 503.

The wireless readout nodes and associated fluid-sensitive elements are not limited to horizontal and vertical lateral arrangements. For example, as shown in Figure 5c, the nodes and fluid-sensitive elements could be arranged radially.

Regarding fabrication of the present apparatus, the fluid-sensitive elements 602 and associated readout nodes 603 could be formed on a sheet of material 607 using a printing process (for example). Currently, the fluid-sensitive elements and wireless readout nodes lend themselves particularly suitable to printing.

The sheet of material 607 may be sufficiently flexible that it can be formed into a roll as shown in Figure 6a. Suitable materials may include paper, Kapton™ or plastic foil or similar. The apparatus comprises a plurality of sensing units 601 , and the sheet of material 607 may comprise perforation lines (i.e. small holes to ease cutting/separation) configured to allow the respective sensing units 601 to be separated from the apparatus (e.g. by cutting). Furthermore, the fluid-sensitive elements 602 of each sensing unit 601 are electrically connected to an associated wireless readout node 603 such that the sensing unit 601 remains functional when it is physically divided through a fluid-sensitive element 602, or between adjacent fluid-sensitive elements 602, to leave at least one fluid- sensitive element 602 electrically connected to the associated wireless readout node 603. This aspect is illustrated in Figures 6b-6d. In Figure 6b, the sheet of material 607 has been divided between the last fluid-sensitive element 602a of one sensing unit 601 a and the first wireless readout node 603b of an adjacent sensing unit 601 b (comprising a plurality of readout nodes 603b and associated fluid-sensitive elements 602b). In this example, both of the resulting sensing units 601 a, b have at least one fluid-sensitive element 602a, b electrically connected to an associated readout node 603a, b and are therefore functional.

In Figure 6c, the sheet of material 607 is divided between adjacent fluid-sensitive elements 602a of the same sensing unit 601 a to leave a first functional sensing unit 601 a comprising a wireless readout node 603a and one associated fluid-sensitive element 602a, and a second functional sensing unit 601 b comprising a plurality of readout nodes 603b with associated fluid-sensitive elements 602b. As a result of the division, the "orphan" elements 609 which were previously associated with the wireless readout node 603a of the first sensing unit 601 a may no longer be functional (unless, for example, the orphan elements 609 were also connected to node 603b in the forward axial direction).

In Figure 6d, the sheet of material 607 is divided through a fluid-sensitive element 602a to leave a first functional sensing unit 601 a comprising two and a half fluid-sensitive elements 602a and an associated readout node 603a, and a second functional sensing unit 601 b comprising a plurality of readout nodes 603b and associated fluid-sensitive elements 602b. As a result of the division, both the "orphan" 609 and partial 610 fluid- sensitive elements may no longer be functional (unless, for example, the orphan elements 609 were also connected to node 603b and the fluid-sensitive elements 602a were configured to remain operable when cut).

In the examples shown in Figures 6a to 6d, each sensing unit 601 a, b may be considered to comprise one or more sensor chains, each comprising respective fluid-sensitive elements 602a, b and an associated readout node 603a, b. Furthermore, in sensing units 601 b comprising multiple sensor chains, the readout node 603b of one or more sensor chains may be configured to relay signalling regarding the presence of fluid to the readout node 603b of another sensor chain. For example, the readout nodes 603b of the middle and right sensor chains in Figure 6b may be configured to relay the signalling to the readout node 603b of the left sensor chain. Although Figures 6a to 6d show the sheet of material 607 being cut across its width (i.e. to form particular lengths), it could also be cut along its length to form particular widths or shapes. For example, the apparatus of Figure 5a could be cut lengthwise to form two narrower sensor arrays). This ability to cut the sheet of material 607 into a functional sensor system of a chosen size and shape allows the apparatus to be tailored to a particular surface. This feature is particularly advantageous for use in buildings where the specific size of each wall, floor and ceiling can vary enormously.

One application of the present apparatus is bathrooms, an example of which is illustrated in Figure 7a. A bathroom is one of the most critical rooms of a building for waterproofing. For this reason, bathrooms typically comprise a layer of waterproofing compound 71 1 under the floor and wall tiles, with additional reinforcing 712 and supporting 713 mats to seal corners and joints to prevent leakage in the event that the wall or floor panels move over time. The apparatus described herein could be used as a fluid-sensitive reinforcing 712 or supporting 713 mat for a bathroom. For this purpose, the sheet of material on which the sensing units are formed would typically comprise an adhesive for attachment of the apparatus to the wall or floor underneath the layer of waterproofing compound 71 1 .

To enable the detection of moisture within the wall or floor panels, the fluid-sensitive elements should be formed on the same face of the sheet of material as the adhesive used to attach the apparatus to the surface (i.e. in contact with the wall or floor). The associated wireless readout nodes, on the other hand, could be formed on either surface of the sheet of material provided that they are electrically connected to the fluid-sensitive elements to enable the state of the fluid-sensitive elements to be read out. Furthermore, the sheet of material should ideally be fluid-impermeable to prevent exposure of the fluid- sensitive elements to any moisture absorbed by the apparatus itself.

The present apparatus could also be used as a vapour barrier. Vapour barriers are often used within the exterior walls and ceilings of buildings to prevent water vapour condensing onto insulating materials. Figure 7b shows a cross-section of an exterior wall comprising a vapour barrier 714. As shown, the vapour barrier 714 is located between the insulating material 715 and the interior wall panel 716, and is typically attached and sealed to the insulating material 715 using an adhesive tape. The fluid-sensitive elements and associated wireless readout nodes could be formed on a fluid-impermeable sheet of material (e.g. a plastic sheet such as polyethylene) to produce a fluid-sensitive vapour barrier 714, or they could be formed on an adhesive tape to produce a fluid-sensitive adhesive tape for attaching and/or sealing a vapour barrier 714 to the insulating material 715. In both scenarios, the fluid-sensitive elements should be located on the surface of the sheet or tape which faces the insulating material 715 (i.e. in contact with the insulating material 715).

Figure 8 shows one example of a wireless readout node 803 of the present apparatus. The wireless readout node 803 comprises a transmitter/transceiver 817, a processor 818 and a storage medium 819, which are electrically connected to one another by a data bus 820. The transmitter/transceiver 817 is configured to receive signalling from the associated fluid-sensitive elements, and transmit signalling to a wireless reader to enable the presence and location of a fluid to be determined. The transmitter/transceiver 817 may be an RFID or NFC transmitter/transceiver, and may be passive, active or battery- assisted. The processor 818 is configured for general operation of the wireless readout node 803 by providing signalling to, and receiving signalling from, the other components to manage their operation. In particular, the processor 818 is configured to receive signalling from the fluid-sensitive elements, and generate corresponding signalling for transmission to the wireless reader. The processor 818 may also be configured to receive interrogation signalling from the wireless reader, and transmit said interrogation signalling to the fluid- sensitive elements to read out the state of the fluid-sensitive elements. The storage medium 819 is configured to store computer code configured to perform, control or enable operation of the wireless readout node 803. The storage medium 819 may also be configured to store settings for the other components. The processor 818 may access the storage medium 819 to retrieve the component settings in order to manage the operation of the other components. The storage medium 819 may also be configured to store calibration data (e.g. predetermined characteristic response measurements) for use by the processor 818 in determining the presence of a fluid. The processor 818 may be a microprocessor, including an Application Specific Integrated Circuit (ASIC). The storage medium 819 may be a temporary storage medium such as a volatile random access memory. On the other hand, the storage medium 819 may be a permanent storage medium such as a hard disk drive, a flash memory, or a non-volatile random access memory. Figure 9 shows a system comprising the apparatus described herein and a wireless reader 904. The wireless reader 904 is configured to receive signalling transmitted by the wireless readout nodes 903 of the apparatus to enable the presence and location of a fluid 906 to be determined. The wireless reader 904 may be one or more of an electronic device, a portable electronic device, a portable telecommunications device, and a module for any of the aforementioned devices.

The main steps 1021 -1022 of a method of making the apparatus are shown schematically in Figure 10a. Similarly, the main steps 1023-1025 of a method of using the apparatus to determine the presence and location of a fluid are shown schematically in Figure 10b.

Figure 1 1 illustrates schematically a computer/processor readable medium 1 126 providing a computer program according to one embodiment. In this example, the computer/processor readable medium 1 126 is a disc such as a digital versatile disc (DVD) or a compact disc (CD). In other embodiments, the computer/processor readable medium 1 126 may be any medium that has been programmed in such a way as to carry out an inventive function. The computer/processor readable medium 1 126 may be a removable memory device such as a memory stick or memory card (SD, mini SD, micro SD or nano SD).

The computer program may comprise computer code configured to perform, control or enable one or more of the method steps 1021 -1022, 1023-1025 of Figure 10a or 10b. In particular, the computer program may be configured to determine the presence and location of a fluid using signalling received from the fluid-sensitive elements. In this scenario, the computer program may be stored on the storage medium of the wireless readout node and/or on a storage medium of the wireless reader. Additionally or alternatively, the computer program may be configured to control the fabrication processes used to form the fluid-sensitive elements and associated wireless readout nodes of the apparatus.

Other embodiments depicted in the figures have been provided with reference numerals that correspond to similar features of earlier described embodiments. For example, feature number 1 can also correspond to numbers 101 , 201 , 301 etc. These numbered features may appear in the figures but may not have been directly referred to within the description of these particular embodiments. These have still been provided in the figures to aid understanding of the further embodiments, particularly in relation to the features of similar earlier described embodiments.

It will be appreciated to the skilled reader that any mentioned apparatus/device and/or other features of particular mentioned apparatus/device may be provided by apparatus arranged such that they become configured to carry out the desired operations only when enabled, e.g. switched on, or the like. In such cases, they may not necessarily have the appropriate software loaded into the active memory in the non-enabled (e.g. switched off state) and only load the appropriate software in the enabled (e.g. on state). The apparatus may comprise hardware circuitry and/or firmware. The apparatus may comprise software loaded onto memory. Such software/computer programs may be recorded on the same memory/processor/functional units and/or on one or more memories/processors/functional units. In some embodiments, a particular mentioned apparatus/device may be pre-programmed with the appropriate software to carry out desired operations, and wherein the appropriate software can be enabled for use by a user downloading a "key", for example, to unlock/enable the software and its associated functionality. Advantages associated with such embodiments can include a reduced requirement to download data when further functionality is required for a device, and this can be useful in examples where a device is perceived to have sufficient capacity to store such pre-programmed software for functionality that may not be enabled by a user.

It will be appreciated that any mentioned apparatus/circuitry/elements/processor may have other functions in addition to the mentioned functions, and that these functions may be performed by the same apparatus/circuitry/elements/processor. One or more disclosed aspects may encompass the electronic distribution of associated computer programs and computer programs (which may be source/transport encoded) recorded on an appropriate carrier (e.g. memory, signal).

It will be appreciated that any "computer" described herein can comprise a collection of one or more individual processors/processing elements that may or may not be located on the same circuit board, or the same region/position of a circuit board or even the same device. In some embodiments one or more of any mentioned processors may be distributed over a plurality of devices. The same or different processor/processing elements may perform one or more functions described herein. It will be appreciated that the term "signalling" may refer to one or more signals transmitted as a series of transmitted and/or received signals. The series of signals may comprise one, two, three, four or even more individual signal components or distinct signals to make up said signalling. Some or all of these individual signals may be transmitted/received simultaneously, in sequence, and/or such that they temporally overlap one another.

With reference to any discussion of any mentioned computer and/or processor and memory (e.g. including ROM, CD-ROM etc), these may comprise a computer processor, Application Specific Integrated Circuit (ASIC), field-programmable gate array (FPGA), and/or other hardware components that have been programmed in such a way to carry out the inventive function. The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole, in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that the disclosed aspects/embodiments may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the disclosure.

While there have been shown and described and pointed out fundamental novel features as applied to different embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods described may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. Furthermore, in the claims means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

Claims

1 . An apparatus comprising a sensing unit, the sensing unit comprising a plurality of laterally-spaced fluid-sensitive elements and at least one readout node associated with the plurality of laterally-spaced fluid-sensitive elements, wherein the fluid-sensitive elements are configured to exhibit a characteristic response to the presence of a fluid in their respective localities, and wherein the at least one readout node is configured to receive signalling from the associated fluid-sensitive elements indicative of the characteristic response, and transmit signalling to a reader to enable the presence and location of the fluid to be determined based on the signalling received from the fluid- sensitive elements.

2. The apparatus of claim 1 , wherein the sensing unit, comprising a plurality of laterally-spaced fluid-sensitive elements and at least one readout node associated with the plurality of laterally-spaced fluid-sensitive elements, comprises at least one of:

a common readout node associated with a plurality of laterally-spaced fluid- sensitive elements; and

a plurality of readout nodes, each readout node associated with one or more laterally-spaced fluid-sensitive elements.

3. The apparatus of claim 2, wherein the plurality of readout nodes are electrically connected to one another such that one readout node can receive signalling from the fluid-sensitive elements associated with the other readout nodes.

4. The apparatus of any preceding claim, wherein the apparatus comprises a plurality of sensing units each having a common readout node associated with a plurality of laterally-spaced fluid-sensitive elements, and wherein the common readout node of each sensing unit is configured to:

receive signalling from the fluid-sensitive elements associated with the common readout node; and

relay signalling regarding the presence of fluid to one or more of the other common readout nodes.

5. The apparatus of claim 4, wherein the apparatus comprises at least one signal line for receiving the signalling from the fluid-sensitive elements at the common readout node, and a communication line for relaying the signalling to the one or more other common readout nodes.

6. The apparatus of claim 5, wherein the at least one signal line and the communication line are the same line or different lines.

7. The apparatus of any of claims 4 to 6, wherein the common readout node is configured to relay the signalling to other common readout nodes in one or more lateral directions.

8. The apparatus of any of claims 4 to 7, wherein the common readout node is configured to relay the signalling to its immediately adjacent common readout nodes.

9. The apparatus of any preceding claim, wherein the apparatus comprises a plurality of readout nodes laterally spaced along an axial direction, and wherein one or more of the readout nodes are configured to relay signalling from other readout nodes back in the axial direction to a preceding readout node such that the preceding readout node can provide signalling concerning the presence and location of fluid from fluid-sensitive elements associated with the readout nodes following the preceding node.

10. The apparatus of claim 9, wherein the axial direction is a length or width direction of the apparatus.

1 1 . The apparatus of any of claims 2 to 10, wherein the plurality of readout nodes are laterally-spaced from one another such that the location of the fluid can be at least partly determined based on the location of the readout node from which the transmitted signalling is transmitted.

12. The apparatus of any preceding claim, wherein the apparatus comprises a respective electrical readout connection between each fluid-sensitive element and an associated readout node such that the location of the fluid can be at least partly determined based on the particular electrical readout connection via which the signalling is received.

13. The apparatus of any preceding claim, wherein the apparatus comprises a common electrical readout connection between each fluid-sensitive element and an associated readout node, and wherein each fluid-sensitive element is configured to provide uniquely-identifiable signalling to the associated readout node via the common electrical readout connection such that the location of the fluid can be at least partly determined based on the particular fluid-sensitive element with which the uniquely- identifiable signalling corresponds.

14. The apparatus of any preceding claim, wherein the fluid-sensitive elements are electrically connected to an associated readout node such that the sensing unit remains functional when it is physically divided through a fluid-sensitive element or between adjacent fluid-sensitive elements to leave at least one fluid-sensitive element electrically connected to the associated readout node.

15. The apparatus of any preceding claim, wherein one or more of the fluid-sensitive elements and the readout nodes are arranged to form a one or two dimensional array in the same lateral plane.

16. The apparatus of claim 15, wherein the fluid-sensitive elements have a spaced apart or contiguous arrangement within the array.

17. The apparatus of any preceding claim, wherein the apparatus comprises a sheet of material on which the fluid-sensitive elements and at least one readout node are formed.

18. The apparatus of claim 17, wherein the fluid-sensitive elements and at least one readout node are printed onto the sheet of material.

19. The apparatus of claim 17 or 18, wherein the sheet of material is configured to be formed into a roll.

20. The apparatus of any of claims 17 to 19, wherein the apparatus comprises a plurality of sensing units formed on the sheet of material, and wherein the sheet of material comprises perforation lines configured to allow the respective sensing units to be separated from the apparatus.

21 . The apparatus of any of claims 17 to 20, wherein the sheet of material is flexible and/or stretchable.

22. The apparatus of any of claims 17 to 21 , wherein the sheet of material is fluid- impermeable.

23. The apparatus of any of claims 17 to 22, wherein the sheet of material comprises an adhesive on a face thereof for attachment of the apparatus to a surface.

24. The apparatus of claim 23, wherein the fluid-sensitive elements and at least one sensor node are formed on the same face of the sheet of material as the adhesive.

25. The apparatus of any of claims 17 to 24, wherein the sheet of material comprises one or more of paper, Kapton™ and plastic foil.

26. The apparatus of any preceding claim, wherein the characteristic response exhibited by the fluid-sensitive elements in the presence of a fluid is a change in one or more of the following properties of the fluid-sensitive elements: real or imaginary impedance, DC resistance, effective dielectric constant, and conductance.

27. The apparatus of any preceding claim, wherein at least one of the fluid-sensitive elements comprises a layer of graphene oxide configured to exhibit a change in one or more electrical properties in response to the presence of the fluid.

28. The apparatus of any preceding claim, wherein the fluid comprises one or more of a liquid and a gas.

29. The apparatus of any preceding claim, wherein the fluid comprises one or more of water, ammonia and carbon monoxide.

30. The apparatus of any preceding claim, wherein one or more of the at least one readout node is a wireless readout node comprising one or more of a radio transmitter/transceiver, a radio-frequency identification transmitter/transceiver and a near- field communication transmitter/transceiver.

31 . The apparatus of claim 30, wherein the radio-frequency identification transmitter/transceiver is a passive radio-frequency identification transmitter/transceiver.

32. The apparatus of any preceding claim, wherein the apparatus is one or more of a reinforcing mat, a supporting mat, a vapour barrier, and an adhesive tape for attaching and/or sealing one or more of the same.

33. A system comprising the apparatus of any preceding claim and the reader.

34. A method of making an apparatus,

the method comprising forming the plurality of laterally-spaced fluid-sensitive elements and the at least one associated readout node.

35. A method of using an apparatus,

the method comprising: receiving signalling at the at least one readout node from the plurality of associated fluid-sensitive elements indicative of a characteristic response to the presence of a fluid; and transmitting signalling to a reader to enable the presence and location of the fluid to be determined based on the signalling from the fluid-sensitive elements.

36. A computer program comprising computer code configured to perform the method of claim 34 or 35.