CA2801809A1 - Multiplexing mosaic sensor array - Google Patents

Abstract

A sensor array system capable of using electrical means to detect primarily the presence of, but not limited to, defects and leaks present in a structure and allowing for the localization thereof. The system is comprised of two networks of conductors separated by a composite, multipurpose interlayer, which is supported by a grid substructure. These components are arranged to form a grid of intersecting conductive elements where intersections between said elements from separate networks contain portions of the functional interlayer, whose electrical properties change upon exposure to a predetermined effect.
Detection of such changes is enabled as the networks of elements are affixed to signal processing devices.

Description

BACKGROUND OF INVENTION
Field of Invention This invention is to be used for the detection of physical and chemical changes regarding, in particular, but not limited to, defects within a structure.
Description of Related Art The problem this invention aims to remedy is the inability to conveniently detect and locate minor material deterioration as a result of water infiltration in a home.
However, defects in the home also include, but are not limited to, structural failure of load bearing elements, obscure perforations that can result in temperature instability or increased heating costs during the winter, as well as natural gas leaks. These defects are often detected too late, only after substantial damage is sustained.
Visual inspection of difficult to access areas, followed by testing with handheld instruments is routine when a defect or flaw is suspected. Some instruments used for leak detection, such as sensitive voltmeters consisting of two conductive leads, identify the presence of the flaw by measuring physical properties of the materials, such as resistance, and their changes when exposed to moisture.
These handheld devices have a limited area of detection; they require an experienced operator and methods can become invasive if the location of the defect has not been precisely determined.
There are preemptive measures used to detect water infiltration, structural deformation and other physical or chemical effects on materials. Because of the need to cover a large area, convenient arrangements of conductors and non-conductors in a grid-like fashion are used both for detection and ease of localization.

Canadian patent application 2689196 is a detector system, which provides suitable detection of environmental effects. The grid-arranged sensing element is constructed with tracks of two separate conductive pathways, printed on an insulated non-conductive core whose properties change when exposed to a predetermined effect. The grid arrangement allows for localization of a change.
US patent 5081422, describes a water detector which uses pairs of laterally spaced parallel conductors, in two directions normal to one another, arranged in a grid fashion. Each pair is sequentially tested and the location of a leak is pinpointed through association between detection by a pair of conductors in the x-direction and another pair in the y-direction.
Canadian patent 2599087 details a leak detection method by apply traversing conductive wires in a grid fashion and separated from each other by a nonconductive material at their intersections only, in proximity of an electrically conductive surface. There exists a relay whereby each wire is tested individually for a leak, which is indicated in the event that current is allowed to pass through the electrically conductive surface and through the water into the conductive wire in the event of a leak.
Although the aforementioned patents allow localization of defects, their design and method of function may restrict their usage to horizontal surfaces or detecting a single type of defect. Furthermore, regarding water detection in particular, prior art may require large amounts of water for detection due to the poor sensitivity of the detectors. In all cases, the amount of wiring could be reduced; these include tracks comprised of two conductive elements printed on a nonconductive core, parallel spaced pair of conductors and an electrically conductive surface, which are not wholly required. The same applies to the number of periphery devices required for implementation. Increasing in the amount of wiring and connectors to peripheral devices increases the risk for failure or breaks to occur within the detector system due to a higher number of possible failure points. The invention described here-in addresses the above-mentioned shortcomings.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide a means of detection of not only water infiltration, but also a variety of defects within a structure.
It is another object of the invention to provide a means of localization of a defect in the event of detection.
It is a further object of the invention to provide a detection method that is simple to implement and reliable.
To achieve the aforementioned objectives, a sensor array system has been designed which is comprised of two pluralities of electrically conductive elements separated at their crossing points by one functional constituent of a mosaic film interlayer. This will permit the detection of multiple defects mediated by multiplexing and signal processing circuitry. The configuration of the networks of conductive elements not only allows detection but localization of a defect.
The mosaic interlayer contains many constituents. Each constituent may differ from another and its electrical properties change when subject to a predetermined condition to allow the detection thereof. Multiple physical and chemical effects outside the realm of leak detection are possible with such a detector and are all included as preferred embodiments in this present invention.
The mosaic film interlayer, in a typical embodiment, is supported upon a thin non-conductive grid substructure with continually spaced and ideally square perforations forming a series of rows and columns. Each perforation contains protrusions to allow housing of one constituent of the interlayer. Different constituents arranged as repeating modules over the entirety of the interlayer allow for multiple physical and chemical effects to be probed across an area of varying size.
Regarding the configuration of the networks of conductive elements of a typical embodiment, the invention comprises of one plurality of non-intersecting conductors travelling longitudinally on one side of the interlayer and a second plurality of non-intersecting conductors travelling in preferably a direction orthogonal to the first on the opposite face of the interlayer. This configuration forms a grid of conductive elements where intersections between an element of the first network and elements in the second network contain a functional constituent of the interlayer. Unlike prior art, because the network elements are brought into proximity as a thin interlayer only separates them, large amounts of water are not required for detection of a leak and the detector still functions when deployed in any orientation.
The wiring and interrogation of the detector involves pulse signaling coupled with time-division multiplexing (TDM), which probes one element of the first network and another element from the second network at predetermined times. One end of each element from one plurality of elements is affixed to a signal-generating device and one end of each element from the second network is affixed to a signal-receiving device. Due to the arrangement of elements as discussed previously, the position along one axis and the position along the perpendicular axis allows for localization of the predetermined effect. The use of pulse signaling is adaptive to monitoring changes in electrical properties of the constituents of the interlayer and the coupling with TDM reduces the amount of wiring and periphery devices required for the sensors. The aforementioned design allows easier installation, even in areas of limited space, and reduces the number of failure points within the system that would otherwise cause areas to lack detection.

Using water infiltration as an example of a predetermined effect to be detected, one constituent of the mosaic interlayer could be comprised of a non-conductive material that when soaked in water becomes conductive. For instance, the constituent could comprise of a water-absorbent film impregnated with salt. If one element from the first network and another element from the second network are probed by the signal-processing device and at their intersection is this particular constituent of the interlayer, in the event of water infiltration, the constituent becomes wet and changes the characteristics of the pulses being transmitted across the elements. These changes allow processing and interpretation thereof by the signal-processing device as means of detection of the leak. Transmitted signals in the form of pulses will change depending on the electrical properties of the constituents that make up the interlayer. These electric properties include impedance, resistance, capacitance and inductance; for many materials these characteristics change selectively to a predetermined physical or chemical condition allowing further applications of detection besides leak detection.
The following example illustrates the above-mentioned extension of application. If a constituent of the interlayer contains a piezoresistive material, instead of a salt-impregnated sheet, whose electrical resistance changes significantly upon changes in pressure, physical stress such as snow atop of a roof could be monitored. Physical strain that would cause deformation of the invention will result in a change in the electrical properties of the particular constituent, resulting in a change in the transmission of a signal between elements that intersect at the constituent to be realized.
If another constituent were a thin-filmed semiconductor, such as a metal oxide, whose electrical properties change significantly upon adsorption of a gas, transmission of the pulse will change allowing for embodiments of the invention to also act as a detector of gases such as propane, naphtha or natural gas.

Using different constituents of the mosaic interlayer arranged systematically as modules across the sensor array in repeated fashion, as demonstrated, may allow for detection and localization of many predetermined effects simultaneously across an area of predetermined size.
DESCRIPTION OF DRAWINGS
In order to visualize the aforementioned and the way objects of the invention are fulfilled, an in-depth description of a specific embodiment will be rendered with reference to illustrations thereof in the appended figures. These drawings illustrate only a typical embodiment and are not therefore considered limiting of its scope. The present invention will be described with greater detail through the use of the accompanying drawings wherein:
Figure 1 displays a top view of the non-conductive grid substructure in the preferred embodiment.
Figure 2 displays a bottom view of the non-conductive grid substructure shown in Figure 1.
Figure 3 displays a top view of the grid substructure with the mosaic interlayer installed.
Figure 4 displays a bottom view of the grid substructure with the mosaic interlayer installed.
Figure 5 shows an isometric view of a singular empty unit of the grid substructure that houses a singular constituent of the interlayer.

Figure 6 shows an isometric view of a singular unit of the sensor containing portions of the grid substructure installed with a constituent of the mosaic interlayer and portions of a conductive element from each network.
Figure 7 shows a cross section of the unit in Figure 6 along the centerline defined by the lower wire in Figure 6.
Figure 8 displays top views of both pluralities of conductive elements of the preferred embodiment along with their associated signal-processing devices.
Figure 9 displays an isometric view of the final assembly of the two networks of Figure 8 and the interlayer and its substructure from Figure 4.
Figure 10 displays a schematic diagram of the grid of electrical conductors containing a leak that describes the means of interrogation of a predetermined physical or chemical effect.
Figure 11 displays a schematic representation of the pulse signaling and TDM
used to interrogate the sensor array.
DESCRIPTION OF THE INVENTION
A sensor array system for detecting and localizing multiple predetermined effects as a result of, in particular, but not limited to, defects within a structure.
The system comprises two pluralities or networks of conductive elements. The conductive elements in both networks are electrically separated and run in one direction with one end only of each element affixed to a signal-processing device.
The two networks are arranged such that elements are ideally orthogonal to one another and separated by a mosaic interlayer of several varying constituents.
The interlayer typically has the form of a thin film supported upon a non-conductive grid substructure. A functional constituent of the interlayer is sandwiched at the intersection between an element from one network and elements from the second. These constituents of the interlayer have electric properties that are altered when subject to a predetermined effect which allows detection by probing elements with the signal processing devices to which the elements are affixed to, in particular, possessing pulse signaling and TDM
capabilities. The sensor array is meant to, but not limited to, cover or be adhered to a surface, placed in between layers of construction or embedded within a structure. The sizing of the sensor array can be accommodated for small or large areas of detection dependent upon sizing and spacing of the components of the device.
Preferred embodiments of the invention as discussed will be described in detail, by means of reference to relevant accompanying drawings, where in Figure 1, the top view of an empty thin grid substructure (1) without the functional interlayer that it facilitates the support thereof is shown. In typical embodiments this grid substructure could be composed of an artificial elastomer or synthetic rubber, without exception a polymer that is relatively non-conductive in nature.
This would allow flexibility of the sensor array to accommodate surfaces of irregular geometries. The grid substructure will also serve as mechanical support for a structure in which the sensor array is embedded, if the substructure is made of a more durable material. The substructure contains a series of continuously spaced square perforations (2) forming a grid of columns and rows that contain protrusions from all faces of the perforation that enable support of the functional interlayer for which more detail is provided in Figure 5. Indents (3) are a guide to the placement of the conductive elements from one network where elements run in one direction. The size of the perforations dictates the resolution for detection.
In the case of small sized perforations arranged continuously, greater resolution of detection and localization will be achieved. Although the typical embodiment contains only a single continuous substructure, alternative embodiments can use multiple interspersed smaller grid substructure units to accommodate different geometries or to selectively probe specific areas.

Regarding Figure 2, the bottom view of the empty, thin grid substructure shows indents (5) that act as a guide for placement of conductive elements from the second network that traverse elements from the first network. As illustrated, conductive elements of the second network cross elements from the first network over the perforations (2).
A filled grid substructure (10) with the multi-functional mosaic interlayer installed is shown in Figure 3. The bottom view of the filled grid substructure (15) is shown in Figure 4. Perforations (2) are overlaid with several constituents (11) that make up the mosaic interlayer. The constituents' electrical properties change when subject to a predetermined effect and can be monitored by configuration of the network of conductive elements and probing thereof through signal processing as illustrated in Figures 10 and onwards. One constituent could be used to detect water infiltration, which can be facilitated by it being a film or sheet of water absorbent and salt-impregnated material. Another constituent could be used to detect changes in temperature such as thermosistors made generally of ceramic or a polymer whose resistance varies significantly as a function of temperature.
This would be useful to detect obscure perforations within a structure that would cause increase of heating costs and fluctuations in temperature.
Alternatively, when a piezoelectric constituent is used, the electrical resistance is altered when subject to mechanical stress such as pressure. An example of such piezoresistive material is silicon. If another constituent such as a thin-film semiconductor, such as a metal oxide, whose electrical properties change significantly upon adsorption of a gas, the sensor array will allow detection of natural gas from defective heating systems. These four constituents in the invention, although the invention is not limited to only these constituents, will be used further in description of the proceeding figures to explain functioning of the sensor array.

Regarding Figure 5, a singular unit (20) of the empty grid substructure (1) containing its perforation (21) is displayed. An improved view of the protrusions (22) contained on the faces of the square perforations that allow housing of one constituent (11) of the interlayer and indents (23, 24, 25, 26) on both surfaces of the unit that function as a guide for elements from either network of conductive elements is shown. Different geometries for the singular unit (20) are possible, so long as the arrangement of each and every unit that make up the grid substructure (10) facilitates proper intersection of elements from the two networks of the sensor array.
A filled unit (30) is shown in Figure 6, where the perforation has been overlaid by a varying constituent (31) of the mosaic interlayer and the two intersecting elements (32, 33) belonging to separate networks enables detection of a predetermined physical or chemical effect. A cross section of the unit in Figure 6 along the centerline with respect to the long axis of the bottom conductive element is displayed in the figure that follows.
Regarding Figure 7, the top element (35) from one network runs in a direction in and out of the plane of the paper, with respect to the drawing and the bottom element (36) that traverses the top element (35). Sandwiched at the intersection of these traversing elements is a constituent (37) of the mosaic interlayer supported by the protrusions (38, 39) of the perforated grid substructure walls (40). As an example, water infiltration will be used to illustrate detection by the unit, where its corresponding constituent may be a salt impregnated material.
In the event of a water leak in the vicinity of the intersection of two elements with the aforementioned constituent, absorption of water by the constituent actuates change in electrical properties and transmission of electric pulse through elements (35, 37) allowing probing by signal processing purposes for detection and localization. In a typical embodiment the intersection between the top element (35) and the bottom element (36) is at right angles; however, as long as there is at least one intersection between the elements the intersection may vary from 90 degrees.
Regarding Figure 8, a top view of one plurality of elements (45) and second plurality of elements (46) are shown. The elements (47) of the first network (45) travel in the latitudinal direction where one end of each element (47) terminates at a face corresponding to the signal-generating portion of a signal-processing device (48). The elements (49) of the second network (46) travel in the longitudinal direction where each element (49) also terminates at a signal-processing device but at the signal-receiving portion (50). The other end of each element is free. Although within the preferred embodiment each element (47, 49) is electrically separated from each other as they are arranged such that they are parallel and evenly spaced apart, any arrangement as long as the elements are laterally spaced apart is adequate for detection. The two networks are superimposed with the mosaic interlayer grid substructure (10) separating the two and displayed as such in Figure 9 to form the preferred embodiment of the invention; a sensor array where elements from both networks form a grid and intersect above and below a constituent of the mosaic interlayer.
Figure 9, as mentioned displays the superposition of one network (56) of latitudinal directed elements over another network (57) of longitudinally directed elements with a mosaic interlayer supported by a grid substructure (59) separating the two networks and is the preferred embodiment of the invention.
In this figure, the signal-processing device (59) may be one device, contrary to the depiction in Figure 8. Such device (59) or devices (48, 50) could be a microcontroller that may be associated with numerous auxiliary devices (not shown) to allow additional functions. These functions include and are not limited to, alarming and wireless communications to other devices.
Figure 10 shows a schematic diagram of the grid of elements formed by superposition of networks in the preferred embodiment of the invention (55). A

node (60) represents a terminal at the pulse-generating device of the first element (61) in the first network travelling along the ordinate and another node (62) represents a terminal of the first element (63) in the second network below travelling along the abscissa at the pulse-receiving device. Solid lines of elements represent elements on the plane of the paper, whereas dashed lines of elements represent elements some distance into the plane of the paper to signify the two networks' superposition and their physical separation by the interlayer (10). The space between each element will define the resolution of detection, whereby larger lengths will generate lower resolution. The length of each element travelling along the ordinate (62) will define size of area of detection, where larger lengths will allow a larger area of detection. The same can be said with elements travelling along the abscissa (63).
As discussed previously, the sensor array (55) can be arranged as an organization of repeated modules (64) where each module (64) comprises of multiple but possibly different constituents and their associated intersection of elements (64a, 64b, 64c, 64d) allow for detection of multiple predetermined effects across the area of detection. For the sake of clarifying the concept of a module (64), the sensor array could be used to detect four predetermined physical or chemical conditions discussed previously. One module will require at least four constituents and thus four intersections (64a, 64h, 64c, 64d), preferably in a 2x2 grid. This module (64) or 2x2 grid is repeated over the entirety of the sensor array (55). For instance, the constituent corresponding to the intersection (64a) at the upper right corner of the module (64) is temperature sensing, and that of the intersection (64b) at the upper left corner is methane gas sensing and that of the intersection (64c) at the bottom left corner is pressure sensing and that of the intersection (64d) at the bottom right corner is water sensing. In the case where a water leak is to be probed, a systematic check is performed of all elements that intersect at the constituent located at the bottom right corner of every module (64). This includes every other element beginning from the second element (65) that travels along the ordinate and every other element beginning from the first element (63) that travels along the abscissa. Other configurations for a module (64) are possible and are not limited to intersections forming a square grid, as in the aforementioned case.
In the event of a leak (68) occurring at intersection between elements (66, 67), detection is possible because the intersection corresponds to the lower left corner (69d) of a module (69), which is able to detect water. Said detection is mediated through signal transmission in the form of a pulse from the pulse-generating device across the two elements and analyzing changes thereof.
Probing of elements, where one element that travels along the abscissa and one element along the ordinate, is done in a systematic manner at predetermined times so as to monitor the entire array for all predetermined effects. Changes that occur with transmission of a signal associated with two elements, each associated with a position along the abscissa and the ordinate allow for localization of the affected area.
A simplified schematic representation of the means by which selective probing of one element from one network and another element through pulse signaling and TDM is illustrated in Figure 11. The sensor array is represented by a network of two elements (75, 76) associated with the pulse generating device (77) corresponding to different nodes (78, 79) of a circuit switch apparatus (80) and a second network of two elements (81, 82) associated with a pulse-receiving-device (83) corresponding to nodes (84, 85) of a second circuit switch apparatus (86). Each circuit switch apparatus (80, 86) can be represented as containing a switch (87, 88) that revolves around at different frequencies so as to allow all combinations of two different elements (75, 76, 81, 82), where a connection with an element (75, 76, 81, 82) is made when the switches (87, 88) come into contact with corresponding element nodes (84, 85, 78, 79). When contact is made by the two switches (87, 88) the elements (76, 81) are connected. The pulse-generating device (77) creates an electrical pulse (89), in this case a square pulse. In the event that the constituent at the intersection (91) of the two elements (76, 81) is not subject to its corresponding physical or chemical effect, a normal pulse (90) is received at the pulse-receiving device. In the event that the constituent at the intersection (91) is subject to its corresponding physical or chemical effect an altered pulse (92) is transmitted as a result of change in its electrical properties. Pulse signaling provides a robust and quick way to observe changes within the sensor array. Furthermore the use of TDM and multiple configurations thereof minimizes requirements for gratuitous amounts of wires and periphery devices that would otherwise increase the number of failure points and malfunctions that could occur, as well as reducing difficulty of installation. In addition once installed, other networks of conductors could easily be installed to the same signal-processing and multiplexing device in case multiple networks are required for geometries or several areas at of detection are needed, for example in artificial environments or structures resident in geographical sites with seismic activity and faults. This pulse signaling and multiplexing could be facilitated by a microcontroller to which other devices may be connected to allowing some form of output to a user in the event of detection.

Claims (14)

1) A sensor array for simultaneous monitoring of multiple predetermined physical and chemical effects comprised of two superposed networks of traversing non-insulated conductive elements with crossing points of network elements containing functional constituents of a mosaic interlayer that separate the two networks and are supported by a grid substructure, whereby detection and localization of said physical and chemical effects are mediated by signal processing and TDM devices to which elements of both networks are affixed.

2) A sensor array as claimed in Claim 1 whereby conductive elements in each network never intersect by being spaced apart.

3) A sensor array as claimed in Claim 2 wherein conductive elements are corrosion proof.

4) A sensor array as claimed in Claim 3 whereby mediation of signal processing for detection and localization is facilitated through one end of each conductive element (47) in one network being affixed to a pulse generating device and one end of each conductive element in the second network being affixed to a pulse receiving device.

5) A sensor array as claimed in Claim 4 whereby one element from one network and one element from the second network are selectively probed by multiplexing capabilities of the signal-generating and signal-receiving device.

6) A sensor array as claimed in Claim 5 whereby probing of two elements from separate networks involves transmission of pulses across them from the signal-generating device to the signal-receiving device.

7) A sensor array as claimed in Claim 6 wherein detection and localization of a physical or chemical effect is based upon monitoring changes in the electric pulses through two elements from separate networks.

8) A sensor array as claimed in Claim 7 wherein changes in the electric pulses transmitted across two elements from separate networks occurs because of the electric properties of the functional constituent of the mosaic interlayer that separates the elements when subject to a physical or chemical effect.

9) A sensor array as claimed in Claim 8 wherein changes of electrical properties of the constituents of the mosaic interlayer comprises of at least one of electrical capacitance, inductance, resistance and impedance when subject to a physical or chemical effect.

10) A constituent whose electrical properties as claimed in Claim 9 change when exposed to electromagnetic radiation.

11) A constituent whose electrical properties as claimed in Claim 9 change when exposed to at least one of these three phases: liquid, solid and gas.

12) A constituent whose electrical properties as claimed in Claim 9 change when exposed to heating, cooling and exposure to any temperature.

13) A constituent whose electrical properties as claimed in Claim 9 change when exposed to compression, deformation, mechanical stress, stretching and pressure.

14) A sensor array as claimed in Claims 1 to 9 comprised of an interlayer containing at least one constituent claimed in Claims 10, 11, 12 and 13.