Description:TECHNICAL FIELD
[0001] Embodiments of the present disclosure relates generally sensors, and more specifically, to a porogen based sensor and method making the porogen based sensor for providing a highly efficient and cost-effective sensors.

BACKGROUND
[0002] Generally, porous elastomers find applications in a wide range of technical field in science and technology ranging from biology to electronics to avionics, and specifically find importance in the fields of bioelectronics and medical devices and wearable electronics for monitoring of various conditions. Normally, sensors can be made from porous elastomers, which are typically porous polydimethylsiloxane (PDMS)-based elastomers, and such porous elastomer-based sensors are used, for example, in the study of organism metabolism for biologists. Such sensors provide a localized region for intensive study and precise observation on a small scale and are scalable to large areas to be used in aircrafts or even space crafts and space stations.
[0003] Demand and application for high tech sensors has led to development of varied ways of preparing porous elastomer, which are used to form sensors and may be broadly classified as chemical methods and physical methods. Chemical methods relate to a modification of the resin in its uncured stage and incorporating pore creating templates that aid the resin take shape of the pore during its later stages of curing. Physical methods involve porous elastomer fabrication by direct impregnation of uncured resin into template obtained either by solid entities which are removed at later stage and by lithography techniques.
[0004] State of the art sensors, for example pressure sensors, are in the simplest way based on the principles of piezo-resistivity. A piezoresistive sensor is typically made from semiconductor material in which a p-type region has been diffused into an n-type base. The resistance of these sensors varies when the sensor is compressed or stretched, however the sensitivity of such sensor may not be efficient and effective to extremely light pressure measurements, though these type of sensors are typically used to reduce uncertainty in measurements. Different materials may be used to form such semiconductor piezoelectric sensors, depending on the intended use of the sensor and the cost associated with manufacturing these could be extremely high. A disadvantage of these sensors is the high dependence on temperature of the piezoresistive effect.
[0005] Such disadvantages can be normally overcome with capacitive sensor based on silicon technology consisting usually of a very fragile silicon membrane, which easily breaks at certain pressure levels. However, organic based elastomer (PDMS) might offer possibilities to resolve this disadvantage. To detect pressure forces with capacitive PDMS sensors it is necessary to develop a novel sensor design and to verify the PDMS technology. PDMS based sensors find use in the field of wearable highly sensitive flexible pressure sensors due to potential applications in electronic skin (e-skin), health monitoring devices, medical diagnostics, touch screens, smartphones, and robotics. Various wearable pressure sensors capable of detecting low-pressure ranges such as heart pulse measurements and high-pressure ranges such as ergonomic chairs have been reported. The wide variety of applications demands high sensitivity over a wide pressure range of 0 – 1000 kPa. Based on sensing mechanisms, pressure sensors can be classified as piezoresistive, capacitive, and piezoelectric. Among the different transduction mechanisms, capacitive pressure sensors are more practical with excellent sensitivity, stability, and response time required for different application. Thus, there is a need in the art for a better, efficient and cost effective sensing device.

SUMMARY
[0006] Embodiments of the present disclosure related to a sensor having a conducting sheet, the conducting sheet being made of a conducting material such as copper, nickel etc. The conducting sheet is perforated in a pre-determined pattern, the perforations essentially consisting of holes made in the conducting sheet either manually or by a machine. The conducting sheet is sandwiched between a first layer of an elastomer admixture formed on a first side of the conducting sheet and a second layer of the elastomer admixture formed on a second side of the conducting sheet. The elastomer admixture is poured on the first side of the conducting sheet and since the elastomer admixture is not hardened, the elastomer admixture percolates via the perforation to the second side of the conducting layer forming the second layer. Multiple layers may be formed in these patterns, and the sensor so formed may be inked with a particular ink (material) such that is becomes sensitive to different conditions. Other embodiments are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The detailed description is described with reference to the accompanying figures. Features, aspects, and advantages of the subject matter of the present disclosure will be better understood with regard to the following description and the accompanying drawings. The figures are intended to be illustrative, not limiting, and are generally described in context of the embodiments, and it should be understood that it is not intended to limit the scope of the disclosure to these particular embodiments. In the figures, the same numbers may be used throughout the drawings to reference features and components. In order that the present disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages.
[0008] Figure 1A is an illustration of an exemplary perforated conducting sheet in accordance with an embodiment of the present disclosure.
[0009] Figure 1B is an exemplary pictorial representation of a perforated conducting sheet of Figure 1A.
[0010] Figure 2A is an exemplary embodiment of a sensor formed by sandwiching a conducting sheet between the elastomer admixture in accordance with an embodiment of the present disclosure.
[0011] Figure 2B is an illustration of exemplary of a sensor formed by sandwiching multiple conducting sheets between the elastomer admixture in accordance with an embodiment of the present disclosure.
[0012] Figure 2C is a pictorial illustration of exemplary of a sensor formed by sandwiching multiple a perforated copper sheet between the PDMS layers in accordance with an embodiment of the present disclosure.
[0013] Figure 3A illustrates an exemplary array of sensors formed on a substrate, wherein the array of sensors includes multiple sensors of Figure 2A arranged in a predetermined manner in accordance with an embodiment of the present disclosure.
[0014] Figure 3B illustrates an exemplary pictorial representation of an array of sensors formed on a substrate, wherein the array of sensors includes multiple sensors of Figure 2A arranged in a predetermined manner in accordance with an embodiment of the present disclosure.
[0015] Figure 3C illustrates an exemplary array of sensors created using a mould in accordance with an embodiment of the present disclosure.
[0016] Figure 3D is an exemplary array of sensors created using the mould of Figure 3C in accordance with an embodiment of the present disclosure.
[0017] Figure 4A illustrates an exemplary process of inking the array of sensors, wherein the ink is sensitive of a certain parameter or condition in accordance with an embodiment of the present disclosure.
[0018] Figure 4B illustrates an exemplary array of inked sensors in accordance with an embodiment of the present disclosure.
[0019] Figure 5 illustrates exemplary multiple arrays of sensors formed in a re-determined orientations in accordance with an embodiment of the present disclosure.
[0020] Figure 6A illustrates an exemplary way of connecting the array of sensors to record information from the sensors for processing in accordance with an embodiment of the present disclosure.
[0021] Figure 6B illustrates another exemplary way of connecting the array of sensors to record information from the sensors for processing in accordance with an embodiment of the present disclosure.
[0022] Figure 7 illustrates a general process of forming the sensor in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0023] The following describes technical solutions in exemplary embodiments of the subject matter of the present disclosure with reference to the accompanying drawings. In this application as disclosed herein, "at least one" means one or more, and "a plurality of" means two or more. The term "and/or" describes an association relationship for describing associated objects and represents that three relationships may exist. For example, A and/or B may represent the following cases: Only A exists, both A and B exist, and only B exists, where A and B may be singular or plural. The character "/" usually indicates an "or" relationship between the associated objects. "At least one item (piece) of the following" or a similar expression thereof means any combination of the items, including any combination of singular items (piece) or plural items (pieces). For example, at least one item (piece) of a, b, or c may represent a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c each may be singular or plural.
[0024] It should be noted that in this application articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”. Throughout this specification defined above, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of elements or steps. The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably. In the structural formulae given herein and throughout the present disclosure, the following terms have been indicated meaning, unless specifically stated otherwise.
[0025] Unless otherwise defined, all terms used in the disclosure, including technical and scientific terms, have meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included for better understanding of the present disclosure. The term ‘about’ as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of ±10% or less, preferably ±5% or less, more preferably ±1% or less and still more preferably ±0.1% or less of and from the specified value, insofar such variations are appropriate to perform the present disclosure. It is to be understood that the value to which the modifier ‘about’ refers is itself also specifically, and preferably disclosed.
[0026] It should be noted that in this application, the term such as "example" or "for example" or “exemplary” is used to represent giving an example, an illustration, or descriptions. Any embodiment or design scheme described as an "example" or "for example" in this application should not be explained as being more preferable or having more advantages than another embodiment or design scheme. Exactly, use of the word such as "example" or "for example" is intended to present a related concept in only a specific manner.
[0027] It should be understood that in the embodiments of the present subject matter that "B corresponding to A" indicates that B is associated with A, and B can be determined based on A. However, it should be further understood that determining B based on A does not mean that B is determined based on only A. B may alternatively be determined based on A and/or other information.
[0028] In the embodiments of this application, "a plurality of" means two or more than two. Descriptions such as "first", "second" in the embodiments of this application are merely used for indicating and distinguishing between described objects, do not show a sequence, do not indicate a specific limitation on a quantity of devices in the embodiments of this application, and do not constitute any limitation on the embodiments of this application.
[0029] Exemplary embodiments of the present disclosure related to a sensor, wherein the sensor may include at least one conducting sheet sandwiched between layers of an elastomer admixture. In an exemplary embodiment, the conducting sheet may be perforated in a pre-determined pattern or a chosen pattern. In an exemplary embodiment, the sensor may be formed by pouring an elastomer admixture on one side of the conducting sheet, such that the elastomer admixture before hardening percolates to the other side via the perforations forming the second layer of elastomer admixture thereby sandwiching the conducting sheet in between the elastomer admixture layers. In an exemplary embodiment, the elastomer admixture on one side on hardening forms the first layer and the elastomer admixture layer which percolates to the other side on hardening forms the second layer. In an exemplary embodiment, the pattern of the perforations on the conducting sheet may be made manually or automatically by using a machine.
[0030] In an exemplary embodiment, the conducting sheet may be at least one of a metal or a non-metal or an alloy. In an exemplary embodiment, the metals may include at least one of copper or aluminium or nickel or iron or silver or gold or zinc or platinum or lead, the non-metal includes carbon, and the alloys include at least one of brass or bronze or steel. It should be obvious to a person or ordinary skill in the art the list is only exemplary in nature and not limiting in any manner, and other conducting material when used to form a sensor as described in the present disclosure fall within the scope of the present disclosure.
[0031] In an exemplary embodiment, the elastomer mixture may be formed by a mixture of an elastomer base and an elastomer curing agent mixed in a predetermined ration, for example in a ratio of 10:1, wherein 10 parts of the elastomer base may be mixed with 1 part of the elastomer curing agent. In an exemplary embodiment, a proportion of the elastomer curing agent used in forming the elastomer mixture may define the hardness of the elastomer mixture. In an exemplary embodiment, a solution of a porogen, for example yeast, may be added to the elastomer mixture to form the elastomer admixture, which is then poured on the conducting sheet. In an exemplary embodiment, the porogen, a solution of yeast, may be added to the elastomer mixture in order to generate a porous structure of the elastomer admixture on hardening. In an exemplary embodiment, the elastomer admixture formed by the elastomer mixture and the porogen ensure that on hardening the layers formed by the elastomer admixture may be porous in nature.
[0032] In an exemplary embodiment, the sensor formed by the conducting sheet sandwiched between the layers of the elastomer admixture may be cast with at least one ink, wherein ink may be sensitive to a particular parameter such as temperature or pressure or other measurable parameters. In an exe3mplary embodiment, each sensor may be inked with a plurality of inks, such that each sensor may be configured to measure a plurality of parameters. In an exemplary embodiment, when each sensor is inked with a plurality of inks, each of the sensors may be configured to measure multiple parameters such as temperature, pressure, weigh, force, direction, wavelength, composition, such as any chemical analyte like glucose, amines, pH, stress, motion, size, volume etc. It should be obvious to a person of ordinary skill in the art that different types of inks may be configured to measure different parameters and a technique of ink the sensor for measuring parameters falls within the scope of the present disclosure.
[0033] In an exemplary embodiment, each if the sensor may be configured to be coupled with a transmitter, wherein the transmitter may be configured to transmit the parameters measured by the sensor to an externally connected system. In an exemplary embodiment, the transmitter may be a wired transmitter or a wireless transmitter or a combination thereof.
[0034] In an exemplary embodiment, a plurality of sensors may be placed on an substrate to form an array of sensors and the each of the sensors forming the array of sensors may be coupled with a transmitter, wherein the transmitter may be configured transmit the measured parameters from the sensors to be recorded on an external device coupled to the sensors, which may include a simple memory device or a computing device. It should be obvious to a person of ordinary skill in the art that other devices which may be used for storing information may be used to record the parameters measured and may fall within the scope of the present disclosure. In an exemplary embodiment, the array of sensors may include plurality of sensors which may be placed at predetermined location and/or a predetermined configuration and/or a predetermined orientation.
[0035] In an exemplary embodiment an plurality of an array of sensors may be combined to form a multiple sensor array, wherein the multiple sensor array will cover a large dimension. In an exemplary embodiment, each of the sensors may be coupled to a transmitter configured to transmit the parameters to an externally connected system, wherein the transmitter may be a wired transmitter or a wireless transmitter or a combination thereof, and the externally connected system may be configured to record the parameters measured by the sensor with the location of the sensor providing the parameters.
[0036] In an exemplary embodiment, a method for forming the sensor may include selecting a material for the conducting sheet of the sensor and forming perforations on the conducting sheet. An exemplary embodiment may include pouring an elastomer admixture on a first side of the conducting sheet containing the perforation. An exemplary embodiment may include allowing the elastomer admixture to percolate via the perforations to the second side of the conducting sheet, thereby sandwiching the conducting sheet between a first layer of the elastomer admixture and a second layer of the elastomer admixture.
[0037] In an exemplary embodiment the elastomer admixture may include forming an elastomer mixture by mixing an elastomer base and a elastomer curing agent in a predetermined ration, as disclosed previously, wherein a proportion of the elastomer curing agent defines the hardness of the elastomer mixture. An exemplary embodiment may include adding a solution of a porogen to the elastomer mixture forming the elastomer admixture for the sensor. An exemplary embodiment may include placing a plurality of sensors at a predetermined orientation to form an array of sensors. An exemplary embodiment may include placing a plurality if array of sensors at a predetermined orientation forming a multiple array sensor.
[0038] An exemplary embodiment may include depositing each sensor with at least one ink or each sensor with a plurality of inks, wherein the at least one ink or the plurality of inks may be configured to be sensitive to measure at least one parameter, wherein the parameter includes at least one of a temperature or pressure or weight or force or direction or wavelength or composition or stress or motion or size or volume. In an exemplary embodiment, the conducting sheet may at least one of a metal or a non-metal or an alloy. In an exemplary embodiment, the metals may include at least one of copper or aluminium or nickel or iron or silver or gold or zinc or platinum or lead, the non-metal includes carbon, and the alloys include at least one of brass or bronze or steel.
[0039] Reference is made to Figure 1A which is an illustration of an exemplary perforated conducting sheet in accordance with an embodiment of the present disclosure. The conducting sheet 110 chosen is made up of at least one of a metal or a non-metal or an alloy. The metals may include at least one of copper or aluminium or nickel or iron or silver or gold or zinc or platinum or lead, the non-metal includes carbon, and the alloys include at least one of brass or bronze or steel. The conducting sheet 110 is perforated, and the perforations 120 may be made in a pre-determined manner. In the exemplary conducting sheet 110 the perforations 120 are shown to be evenly spaced, however the conducting sheet 110 may have perforations in any predefined manner. In an exemplary case the perforations may be input to a CNC machine and the conductive sheet 110 may be provided with perforations in the pre-determined manner. In an exemplary case, the perforations 120 may be evenly or unevenly spaced or may be shaped in a particular geometrical pattern. The perforations 120 in the conducting sheet 110 form an important part of forming the sensor 200A and will be described subsequently.
[0040] Reference is made to Figure 1B which is an exemplary pictorial representation of a perforated conducting sheet of Figure 1A. The conducting sheet 110 is chosen to be of a conducting material, such as copper and the conducting sheet 110 illustrated herein is dimensionally created for a lab scale. It should be obvious to a person of ordinary skill in the art that the conducting sheet 100 may be made of any size from small sizes to large size, and all sizes of the conducting sheet 100 with perforations 120 fall within the scope of the present disclosure. As illustrated in the pictorial representation of the conducting sheet 110, the perforations 120 may be almost evenly spaced. In an exemplary embodiment, in accordance with the present disclosure, the perforation 120 are evenly spaced on the conducting sheet 110, which is copper in this exemplary case. However, it should be obvious to a person of ordinary skill in the art that the conducting sheet 110 can be chosen to be of a conducting material as disclosed previously, and the perforations 120 may be formed in an evenly manner or a random manner on the conducting sheet 110. In an exemplary embodiment, the perforations may be formed in a triangular pattern or a circular pattern or a rectangular pattern or any polygonal shape. In an exemplary embodiment, care should be taken that the distance between the perforations is not too far apart, as the elastomer admixture (PDMS with the porogen) needs to percolate to a second side (opposite side) when poured on a first side (top side). Alternatively, the conducting sheet 110 may be immersed in the elastomer admixture to form the structure as disclosed in Figure 1A, by placing the conducting sheet 110 in the elastomer admixture solution and allowing the elastomer admixture solution to harden.
[0041] Reference is made to Figure 2A which is an exemplary embodiment of a sensor 200A formed by sandwiching a conducting sheet between the elastomer admixture in accordance with an embodiment of the present disclosure. As illustrated in Figure 2A, a conducting sheet 210 (the same as the conducting sheet 110 of Figure 1A), is sandwiched between a first layer 220 and a second layer 225 of an elastomer admixture, which is preferably a porogen infused PDMS. The elastomer admixture is prepared by mixing an elastomer base with an elastomer curing agent in a predetermined ration, such as 10:1. As disclosed previously, the amount of elastomer curing agent added to the elastomer base defines the curing time for the elastomer. Once the elastomer mixture is prepared, an amount of porogen, such as a solution of yeast mixed in water, is added to the elastomer mixture to form the elastomer admixture.
[0042] The elastomer admixture (porogen infused PDMS) is then poured on a first side (top side) of the conducting sheet 210, allowing the elastomer admixture to pass through the perforations on the conducting sheet 210 and move to a second side (bottom side) and completely cover the bottom side of the conducting sheet. Part of the elastomer admixture which remains on the top side from the first layer 220 and part of the elastomer admixture that follow through the perforations from the second layer 225. Alternatively, the conducting sheet 210 may be dipped or placed in a solution of the elastomer admixture such that the elastomer admixture flows through the perforations in the conducting sheet 210 and on hardening form the first layer 220 and the second layer 225, sandwiching the conducting sheet 210 in between the first layer 220 and the second layer 225. The thickness of the first layer 210 and the second layer 220 may be made according to a predetermined design and requirement, by removing away the extra thickness from the layers by shaving or cutting or any other technique and all such techniques for removing the additional thickness fall within the scope of the present disclosure.
[0043] Reference is made to Figure 2B which is an illustration of exemplary of a sensor 200B formed by sandwiching multiple conducting sheets between the elastomer admixture (hereinafter also referred to as the porous PDMS or any reference to PDMS should be read as porous PDMS) in accordance with an embodiment of the present disclosure. As disclosure in Figure 2A, a conducting sheet 210 (hereinafter reference to conducting sheet 210 made refers to the perforated conducting sheet 210), is sandwiched between a first layers 220 and a second layer 225 of a porous PDMS. The same technique described above may be used to form multiple layers of conducting sheets sandwiched between layers of the porous PDMS. In an exemplary case, as disclosed in Figure 2B, a first conducting sheet 210 is formed between a first layer 220 and a second layer 225. The thickness of the layer is predetermined. A second conducting sheet 215 can be placed over either the first layer 220 or the second layer 225, as illustrated here, the second conducting sheet 215 is placed over the second layer 225 and is then sandwiched between the second layer 225 and a third layer 230. In this manner multiple layers may be formed.
[0044] In an alternate exemplary case, multiple conducting sheets, for example a first conducting sheet 210 and a second conducting sheet may be placed at a certain distance separating then. The multiple conducting sheets 210, 215 may be placed in a solution of an elastomer admixture (porous PDMS), such that the elastomer admixture fills the separation gap between the first conducting sheet 210 and the second conducting sheet 215 and also forms the outer layers, first layer 220 and the third layer 230, after the elastomer admixture is hardened. The outer layers 220, 230 may be shaved or cut to remove the additional hardened elastomer admixture. It should be obvious to a person of ordinary skill in the art that various other methods and techniques may be used to produce such a sensor 200B consisting of multiple layers and all such methods and techniques fall within the scope of the present disclosure. It should also be obvious to a person of ordinary skill in the art that the sensor may be formed in various other shapes using the similar methodology and all such variations fall within the scope of the present disclosure
[0045] Reference is made to Figure 2C which is a pictorial illustration of exemplary of a sensor 200C formed by sandwiching multiple a perforated copper sheet between the porous PDMS layers in accordance with an embodiment of the present disclosure. The exemplary pictorial illustration of the sensor 200C with multiple layers illustrates two conducting sheets sandwiched between the porous PDMS. A first conducting sheet 210 is sandwiched between a first porous PDMS layer 220 and a second porous PDMS layer 225. A second conducting sheet 215 is sandwiched between a second porous PDMS layer 225 and a third porous PDMS layer 230. The exemplary case illustrated two conducting sheets sandwiched between the porous PDMS layers, and it should be obvious to a person of ordinary skill in the art that multiple layers of conducting sheets may be sandwiched between porous PDMS layers. In an exemplary embodiment, the conducting copper sheet may be chosen to be in a range of 100 – 300 microns in thickness and the PDMS layer may be in a range of around 2mm – 1cm in thickness or as required for any specific application The thickness of the conducting sheet and the thickness of the porous PDMS layers may vary. In some exemplary embodiments, the thickness of the porous PDMS layers may vary. In an exemplary case, the first PDMS layer 220 may be of a first thickness, the second PDMS layer 225 may be of a second thickness that is not the same as the thickness of the first PDMS layer 210, and the third PDMS layer may be of a third thickness, where the third thickness may be different from the first thickness and the second thickness or may be the same as either the first thickness or the second thickness or may be the same as either one of the first thickness or the second thickness. In a preferred exemplary embodiment, the thickness of all conducting sheet and the thickness of all porous PDMS layers may be uniform to the extent possible. Different variations may be possible with the conducting sheets and the PDMS layers and all such variations fall within the scope of the present disclosure. Different designs of the sensor, for example triangular, rectangular, polygonal may be made, and all variations of designs of a sensor formed with conducting sheets sandwiched between porous PDMS layers fall within the scope of the present disclosure. It should be obvious to a person of ordinary skill in the art that the thickness and shape of the electrodes may vary depending on the application and/or use and various different shapes of the electrodes may be used to create sensors of different shapes.
[0046] Reference is made to Figure 3A which illustrates an exemplary array of sensors 300A formed on a substrate, wherein the array of sensors includes multiple sensors of Figure 2A arranged in a predetermined manner in accordance with an embodiment of the present disclosure. As illustrated in exemplary Figure 3A, a plurality of sensors 200B can be arranged in a predetermined manner on a substrate 340, wherein the substrate is a conducting material. Each of the plurality of sensors 200B can be of a different shape and/or size or may be of the same shape and size so as to cover the substrate 340. The sensor 200B is configured to pick up signals, specifically directed to pressure, temperature, pH and other parameters and via the substrate, provide the parameters collected to an external device for processing. The array of sensors 300A may be prefabricated to any size depending on the requirement design and use.
[0047] In an exemplary embodiment, the sensor 300A may be a relatively large panel of 10Ft X 10Ft, and may be placed on a spacecraft or an airplane or a ship or submarine. In another exemplary case, relatively smaller panels of may be a 1Ft X 1Ft may be placed on a building or an automobile to determine various parameters. In an exemplary embodiment, the sensors 300B may be placed on the outside of an aircraft to measure various parameters and transmit them to a external processing system, within the aircraft or to a ground control system monitoring the aircraft. In an exemplary embodiment, the sensors 300A may be placed in the bonnet of a car to measure various parameters and transmit them to an onboard computing system to analyse the parameters and detect any untoward incident that may occur.
[0048] The sizes indicated are only exemplary in nature and it should be obvious to a person of ordinary skill in the art that the array of sensor 300A may be fabricated or manufactured to any size or shape and may be configured to measure various parameters and all such variations of the sensor 300A fall within the scope of the present disclosure, essentially containing porous PDMS layers encompassing a conducting sheet which are made sensitive to determine specific parameters. It should be obvious to a person of ordinary skill in the art that various other shapes and sizes of the array of sensors, where the sensors themselves may have different shapes and sizes may be formed, and all such variations fall within the scope of the present disclosure.
[0049] Reference is made to Figure 3B which illustrates an exemplary pictorial representation of an array of sensors 300B formed on a substrate, wherein the array of sensors includes multiple sensors of Figure 2A arranged in a predetermined manner in accordance with an embodiment of the present disclosure. As illustrated with respect to Figure 3A, the array of sensors 300B may be of any shape and size, but the exemplary illustration of Figure 3B shows square sensors 200B placed on a substrate 340. As illustrated in the pictorial representation the substrate 340 contains a plurality of sensors 200B that have multiple layers of conducting sheet 310 sandwiched between the porous PDMS layers 320. As described previously, these sensors can be fabricated to any dimension or shape depending on the design requirements and the plurality of sensors 200B forming the array of sensor 300B may also have different shapes and dimensions. Each of the plurality of sensors is coupled to a transmitter such that the parameter recorded by the sensor 200B in the array of sensors, may be transmitted to an external device for further processing. The sensors 200B may be coupled by wired means or wireless means or a combination thereof.
[0050] Reference is made to Figure 3C which illustrates an exemplary array of sensors created using a mould in accordance with an embodiment of the present disclosure. A conducting substrate 340 first taken. The conducting substrate has a certain thickness “t”. A layer of porous PDMS is coated on the conducting substrate. A mould 345 having predefined shapes for creating the sensor is prepared and placed above the conducting sheet, where in this exemplary embodiment the sensors to be prepared are shown to be circular. A perforated conducting sheet 350 is then placed in the plurality of holes 347 and the porous PDMS (admixture of PDMS with yeast in a predetermined proportion) is poured into the holes 347. The admixture percolates through the perforated conducting sheet 350 in the hole 347 and the admixture is allowed to harden, thereby forming the porous PDMS layer above and below the perforated conducting sheet.
[0051] In an exemplary case the height of the conducting substrate 340 and the mould 345 may be in the range of 3 mm to about 8 mm. It should be obvious to a person skilled in the art that the thickness could be more than 8mm and all such variations fall within the scope of the present disclosure. The height of the mould could be in the range of about 2mm to 5 mm. Again, it should be obvious to a a person skilled in the art that the thickness could be more than 5mm and all such variations fall within the scope of the present disclosure. In a preferred embodiment, the thickness of the mould was chosen as 3mm and the thickness of the conducting substrate to be about 2 mm, such that the total thickness of the array of sensors was about 5 mm. The holes 347 can be evenly spaced or randomly spaced in accordance with a design requirement of the sensor. In this manner a plurality of sensors can be designed to make an array of sensors 200B.
[0052] Reference is made to Figure 3D which illustrates an exemplary array of sensors created using the mould of Figure 3C in accordance with an embodiment of the present disclosure. As illustrated above, once the admixture is cured, the area of the perforated conducting sheet where the admixture was poured will form the sensor 200B. Advantageously, after the formation of a single layer, multiple layers may be formed in the same manner, wherein the conducting substrate 340 is covered with a PDMS layer and the layer is infused with the sensor 200B. It should be obvious to a person of ordinary skill in the art that various designs of the array of sensors may be formed depending on the design requirements and the pattern of the moulds created to form the array of sensors.
[0053] Reference is made to Figure 4A which illustrates an exemplary process of inking the array of sensors 400A, wherein the ink is sensitive of a certain parameter or condition in accordance with an embodiment of the present disclosure. In an exemplary embodiment, on formation of the array of sensors, each sensor may be made to measure a particular parameter like pressure, temperature, pH, chemical composition etc. For achieving this, each of the sensor 200B on the substrate 440 may be inked with a marker ink 407 configured to measure a certain parameter. In an exemplary embodiment, a carbon based ink may be used measure applied pressure and a thermoelectric ink such as PEDOT:PSS may be used measure change in temperature of the sensor. It should be obvious to a person of ordinary skill in the art that various other inks may be used to measure various other parameters and each sensor may be inked with multiple inks to measure and/or monitor different parameters, and all such variations fall within the scope of the present disclosure. Further, each sensor 200B may be inked with multiple inks 407, wherein each different type of ink 407 is configured to measure a particular parameter. In an exemplary embodiment, when a pressure sensitive ink 407 is used to ink the sensors 200B, the ink 407 is absorbed into the porous PDMS. The ink is a conducting material and on sensing a pressure immediately transmits a signal via the conducting sheet to the transmitter, and the signal is provided to an external computing device for analysis. Signal processing has not been discussed in detail as this is not a part of the present disclosure, however it should be obvious to a person of ordinary skill in the art that signals from the sensors 200B are recorded and transmitted to a computing device, for example a computer, which is external to the array of sensors and the data provided by the sensors are recorded and analysed..
[0054] Reference is made to Figure 4B which illustrates an exemplary array of inked sensors 400B in accordance with an embodiment of the present disclosure. As disclosure previously with respect to the embodiments of Figure 4A, the array of sensors 200B may be inked with a single type of ink or multiple inks depending on the requirements and use of the sensors, and the inked sensor 200B-1 is essentially laid out on a substrate 440, which is a conducting material. The inked sensors 200B-1 records either a single parameter like pressure or may be configured to record multiple parameters like pressure, temperature, pH, chemical composition etc., and provide each of the recorded parameters to a computing device, where the computing device may record these parameters and analyse these parameters.
[0055] Figure 5 illustrates exemplary multiple arrays of sensors 500 formed in a predetermined orientations in accordance with an embodiment of the present disclosure. As disclosed previously, the multiple array of sensors 500 essentially can be fabricated or made from an array of sensors 400B. The array of sensors 400B contain a plurality of sensors 200B.
[0056] In an exemplary embodiment, each of the array of sensor 510 may contain a plurality of sensors 200B, wherein each of these plurality of sensors 200B is inked with different inks for measuring different parameters. In an exemplary embodiment, as illustrated the array of sensors in block 510 may be built to monitor different parameters. In an exemplary case, a first sensors 200B-1 may be inked with an ink that is configured to pressure, a second sensors 200B-2 may be inked with an ink to monitor temperature, a third sensor 200B-3 may be inked with an ink to monitor viscosity and so on. Each sensor 200B of the plurality of sensors in block 510 may be inked to measure a particular parameter.
[0057] In an alternate embodiment each of the sensor 500A forming the array of sensors 400B may be inked with multiple inks, wherein each different ink may be configured to measure a different parameter. As illustrated the entire array of sensors in block 510 may be inked with multiple inks such that each sensor 200-B is configured to measure multiple parameters from each of the sensors 200-B.
[0058] In an exemplary alternate embodiment, the multiple array of sensors in block 520 may contain a mix of the two exemplary embodiments disclosed above, with sensors 200B configured to measure specific parameters, which are inked with a specific ink related to the parameter and with sensors configured to measure multiple parameters, wherein sensors 200-B in the array of sensors in block 520 may be inked with multiple inks such that the multiple inks are configured to measure multiple parameters. Various alternate combination may be designed by a person of ordinary skill in the art and all these combinations will fall within the scope of the present disclosure. In an exemplary embodiment, each of the sensor is also configured to transmit the recorded parameter a computing device, which may be done at the instant the parameter is recorded or at periodic time intervals. In an exemplary embodiment, the parameters (data from the sensor) may be transmitted by wired means, wireless means or a combination thereof.
[0059] Figure 6A illustrates an exemplary way of connecting the array of sensors to record information from the sensors for processing in accordance with an embodiment of the present disclosure. Once the array of sensors is prepared, each of the sensor 200B as illustrated is placed over a conducting sheet 610 in a certain pattern that may be in accordance with the design requirements. Each of the sensor 200B may be connected to a circuit 640 via a wire 620 that is concealed in the porous PDMS layer and each of wire 620 from the sensor to the circuit 640 has a transistor 630. The sensors in each row or the sensors in each column may be wired together. Any alternate form of connection may also be made, and it should be obvious that all these connected falls within the scope of the present disclosure. In an exemplary embodiment, each of the sensors may coupled/connected to a transistor and a wireless transmitting circuit (not shown) which may transmit the data from the sensor 200B to an external computing system.
[0060] On detection of a change in the parameter being monitored, the transistor may switch ON and the relevant parameters with the coordinates may be collected by the circuit 640, which may then be coupled to an external computing system (not shown) to perform analysis on the data related to the parameter collected. In an exemplary embodiment, each sensor may be configured to monitor multiple parameters depending on the conducting ink type and all the parameters being monitored will be collected by the circuit 640 and either processed at the circuit 640 or by an external computing device coupled to the circuit 640.
[0061] In an exemplary embodiment the sensor 200B may monitor pressure and temperature. When the sensor S1 senses a change in the pressure or temperature the transistor T1 is switched ON, and data from the sensor S1 is transmitted to the circuit 640 which is recorded and processed. Similarly, all other sensors in the array of sensors may be configured to transmit data to the circuit 640, and the data from all the sensors 200B are collectively analysed and processed. In another exemplary embodiment, specific sensors 200B may be considered for specific data and such specific data may be analysed and processed.
[0062] Figure 6B illustrates an illustrates another exemplary way of connecting the array of sensors to record information from the sensors for processing in accordance with an embodiment of the present disclosure. Once the array of sensors is prepared, each of the sensor 200B as illustrated is placed over a conducting sheet 610 in a certain pattern that may be in accordance with the design requirements. Each row or column of the array of sensor 200B may be connected to a circuit 640 via a wire 620 that is concealed in the porous PDMS layer and each of the sensor line to the circuit 640 has a transistor 630, which is connected to the wired line 620. On detection of a change in the parameter being monitored, the transistor 630 may switch ON and the relevant parameters with the coordinates may be collected by the circuit 640, which may then be coupled to an external computing system (not shown) to perform analysis on the data related to the parameter collected. In an exemplary embodiment, each sensor may be configured to monitor multiple parameters depending on the conducting ink type and all the parameters being monitored will be collected by the circuit 640 and either processed at the circuit 640 or by an external computing device coupled to the circuit 640. In an exemplary case the sensors 200B may be coupled wirelessly as disclosed previously.
[0063] Figure 7 illustrates a general process of forming the sensor in accordance with an embodiment of the present disclosure. As illustrated are only the exemplary steps of creating a sensor and the method steps disclosed in Figure 7 should not be read as a limitation to the method of making or producing or fabricating the sensor. In step 710, an electrode is created with perforations. As discussed previously, in an exemplary embodiment, a conducting sheet is first taken, and the perforations are made on the conducting sheet. The conducting sheet may be from Copper, Nickel, Aluminium or any other conducting material. The conducting sheets are perforated either with a fixed pattern or any predetermined pattern, wherein the perforations may be evenly spaced or unevenly spaced and may form a desired patter, for example a triangular pattern, or a rectangular pattern or a square pattern or a polygonal pattern. The conducting sheet with perforations may be referred to as an electrode.
[0064] In step 720, a PDMS porogen solution is poured over the conducting sheet and the PDMS porogen solution is allowed to spread uniformly over the poured surface and also percolate to the other surface via the perforations. The conducting sheet is sandwiched between a first layer and a second layer of the PDMS porogen solution. In an exemplary embodiment, the PMDS porogen solution is prepared by first taking an elastomer base and mixed with an elastomer curing agent in a predetermined ration, forming an elastomer mixture, wherein the ratio of the curing agent determines the hardness of the PDMS formed. Before the elastomer mixture hardens, a porogen, such as yeast is mixed in water and a predetermined quantity of the porogen is poured into the elastomer mixture to form the elastomer admixture. In an exemplary case, a food grade porogen, such as active dry yeast, may be used. In an exemplary case, the concentration of yeast may be varied for obtaining a desired porosity and may be typically in a range of 0.5 – 3 gm in 3 mL of deionized water. In an exemplary case, this elastomer admixture is referred to as the PDMS porogen solution is poured over the conducting sheet such that the PDMS porogen spread over the first surface and percolates spreading over the second surface. The conducting sheet is referred to as an electrode as a signal from the electrode may be recorded and transmitted to a computing device for recording and processing. Either a single conducting sheet with PDMS porogen layers on both sides or multiple layers of conducting sheets and PDMS porogen layers on either side of the conducting sheets may be formed.
[0065] In an alternate exemplary embodiment, the PDMS porogen solution may be kept in a tank, and the conducting sheet may be dipped into the tank and removed to cure the PDMS porogen layer to form the sensor with the conducting sheet sandwiched between the PDMS porogen layers. In an alternate exemplary embodiment, multiple conducting sheets may be separated by a gap, i.e., kept at an even distance or uneven distance and dipped into the tank of PDMS porogen solution to form the PDMS porogen layer between the conducting sheets and on the outer sides of the conducting sheets. In an exemplary embodiment, the PDMS porogen layer may be pruned to any desired thickness. Various possibilities of creating the sensor by sandwiching the conducting sheet (electrode) between the PDMS porogen layer may be possible, and all such method of forming a sensor as disclosed above fall within the scope of the present disclosure.
[0066] In step 730, multiple such sensors may be grouped together to form an array of sensor, by placing the sensors in a predetermined manner in a substrate. The substrate is a conducting material, and the sensors are placed in a predetermined orientation on the substrate as has been disclosed previously.
[0067] In step 740, the array of sensor are inked. In an exemplary embodiment, each sensor may be inked with a single ink to which may be sensitive to one parameter, or each sensor may be inked with multiple inks, where each ink is configured to be sensitive to different parameters. The ink is absorbed into the PDMS porous layer, and for example if the sensors is inked to measure pressure, on application of pressure at the sensor, the sensor detects the applied pressure and transmits the reading via a signal attached to the sensor to an external device for recording and analysis. In an exemplary embodiment, each sensor may be configured to monitor and measure a single parameter or multiple parameters. Each of the parameters may be transmitted by a wired means or a wireless means or a combination thereof.
[0068] In step 750, multiple sensors may be coupled to form an array of sensors as illustrated with respect to Figure 3A and more specifically as disclosed with respect to Figure 5. Each of the sensors may monitor different parameters and transmit the monitored parameters to a device for recording and analysis.
[0069] Although the present disclosure has been described with reference to several preferred embodiments, it should be understood that the present disclosure is not limited to the preferred embodiments disclosed here. Embodiments of the present disclosure are intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims. Although the foregoing disclosure has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practised within the scope of the appended claims. Examples of the present disclosure have been described in language specific to structural features and/or methods. It should be noted that there are many alternative ways of implementing both the process and apparatus of the present invention. Accordingly, embodiments of the present disclosure are to be considered illustrative and not restrictive, and the invention is not to be limited to the details given herein but may be modified within the scope and equivalents of the appended claims. It should be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present disclosure.
, Claims:WE CLAIM:
1. A sensor 200A, the sensor 200A comprising:
a conducting sheet 210, the conducting sheet 210 being perforated in a pre-determined pattern, and the conducting sheet 210 sandwiched between a first layer 230 of an elastomer admixture formed on a first side of the conducting sheet 210 and a second layer 235 of the elastomer admixture formed on a second side of the conducting sheet 210.

2. The sensor 200A as claimed in claim 1, wherein the conducting sheet is at least one of a metal or a non-metal or an alloy.

3. The sensor 100A as claimed in claims 2, wherein the metal comprise:
at least one of copper or aluminium or nickel or iron or silver or gold or zinc or platinum or lead, the non-metal includes carbon, and the alloys include at least one of brass or bronze or steel.

4. The sensor 100A as claimed in claim 1, wherein the elastomer admixture comprises:
an elastomer mixture formed by mixing an elastomer base and an elastomer curing agent in a predetermined ration, wherein a proportion of the elastomer curing agent defining the hardness of the elastomer mixture; and
a solution of a porogen added to the elastomer mixture to form the elastomer admixture.

5. The sensor 100A as claimed in claim 4, wherein the solution of porogen added to the elastomer mixture is configured to generate a porous structure of the elastomer admixture on hardening.

6. The sensor 100A as claimed in claim 1, wherein the sensor 100A is cast with at least one ink 407.

7. The sensor 100A as claimed in claim 1, wherein the sensor 100A may comprise a plurality of inks 407.

8. The sensor 100A as claimed in claim 6 or 7, wherein the at least one ink 407 or the plurality of inks may be sensitive to at least one measurable parameter.

9. The sensor as claimed in claim 8, wherein the measurable parameter includes at least one of a temperature or pressure or weight or force or direction or wavelength or composition (any chemical analyte such as glucose, amines etc.) or stress or motion or size or volume.

10. The sensor 100A as claimed in claim 9, the sensor 100A comprising:
a transmitter configured to transmit the parameters to an external computing system, wherein the external computing system is configured to record and perform analysis on the parameter, and wherein the transmitter may be a wired transmitter or a wireless transmitter or a combination thereof.

11. A sensor array 400B formed on a substrate by placing by a plurality of sensors 100A as claimed in any of the claim 1 to 10, wherein the substrate is a conducting material.

12. The sensor array 400B as claimed in claim 11, wherein the plurality of sensors 100A being placed at predetermined location or a predetermined configuration or predetermined orientation on the substrate.

13. The sensor array 400B as claimed in claim 11, the sensor array 400B comprising a transmitter coupled to each of the plurality of sensors 100A, the transmitter configured to transmit measured parameters to an external computing system, wherein the external computing system is configured to record and perform analysis on the measured parameter, and wherein the transmitter may be a wired transmitter or a wireless transmitter or a combination thereof.

14. A multiple sensor array 500 comprising a plurality of sensor array 400B as claimed in claims 1 and 11.

15. The multiple sensor array 500, the multiple sensor array 500 comprising a transmitter coupled to each of the plurality of sensors 100A, the transmitter configured to transmit measured parameters to an external computing system, wherein the external computing system is configured to record and perform analysis on the measured parameter, and wherein the transmitter may be a wired transmitter or a wireless transmitter or a combination thereof.

16. A method of forming a sensor 100A, the method comprising:
- forming perforations on a sheet, wherein the sheet comprises a conducting material;
- forming a sandwich of the conducting sheet between two layers of the elastomer admixture.

17. The method as claimed in claim 16, wherein the sandwich may be
- pouring an elastomer admixture on a first side of the conducting sheet containing the perforation;
- allowing the elastomer admixture to percolate via the perforations to the second side of the conducting material, thereby sandwiching the conducting sheet between a first layer 230 and a second layer 235 of the elastomer admixture.

18. The method as claimed in claim 16, wherein the sandwich may be
- placing the conducting sheet in a tank containing the elastomer admixture thereby forming the layers on both sides of the conducting sheet.

19. The method as claimed in claim 16, wherein the elastomer admixture comprises:
- forming an elastomer mixture by mixing an elastomer base and a elastomer curing agent in a predetermined ration, wherein a proportion of the elastomer curing agent defines the hardness of the elastomer mixture
- adding a solution of a porogen to the elastomer mixture thereby forming the elastomer admixture.

20. The method as claimed in claim 16, comprising:
- placing a plurality of sensors 100A in a predetermined orientation to form an array of sensors 400B.

21. The method as claimed in claim 15, comprising:
- placing a plurality of array of sensors 400B in a predetermined orientation forming a multiple array sensor 500.

22. The method as claimed in claim 16, comprising:
- depositing each sensor 100A with at least one ink or depositing each sensor with a plurality of inks, wherein the at least one ink or the plurality of inks is configured to be sensitive to monitor or measure at least one parameter, wherein the monitored or measured parameter include at least one of a temperature or pressure or weight or force or direction or wavelength or composition or stress or motion or size or volume.

23. The method as claimed in claim 16, wherein the conducting sheet is at least one of a metal or a non-metal or an alloy.

24. The method as claimed in claims 23, wherein the metals include at least one of copper or aluminium or nickel or iron or silver or gold or zinc or platinum or lead, the non-metal includes carbon, and the alloys include at least one of brass or bronze or steel.

Dated this 09th day of November 2023
Indian Institute of Science
By their Agent & Attorney

Dr. Eric W B Dias
Reg No IN/PA- 1058
of Khaitan & Co