Pressure distribution sensing device

Abstract

This disclosure relates to a device for measuring pressure distribution, also known as a pressure mapping device or pressure sensor mat, and a method for manufacturing it. The device comprises a first flexible substrate (10) and a second flexible substrate (20), and a spacer structure (30) extending between the substrates and a plurality of force-sensing sensor nodes. Each sensor node (40) comprises a first conductive element (41) attached to the first substrate and a second conductive element (42) attached to the second substrate facing the first conductive element, wherein the first conductive element is movable in use relative to the second conductive element, thereby changing the resistance of the force-sensing sensor node. The spacer structure (30) comprises a plurality of isolated spacer elements (31) distributed between adjacent sensor nodes, wherein the spacing between adjacent spacer elements provides an interconnected network of gas passages between the sensor nodes.

Description

Technical Field

[0001] The present disclosure relates to a flexible pressure sensor device and a method for manufacturing the same. Specifically, it relates to a device for measuring pressure distribution, also referred to as a pressure mapping device or a pressure sensor mat.

Background Art

[0002] Pressure distribution sensing devices are known.

[0003] CN113720501A discloses a flexible pressure sensor in which a porous interface of insulating fibers is provided between an array readout circuit and a piezoresistive sensing layer.

[0004] CN112067177A relates to a piezoresistive pressure sensing array. The sensor measures the resistance across a deformable micro-pattern relief between opposing electrodes. Patterned blocks are provided to limit the deformation of the relief and improve the life of the sensor.

[0005] EP3171146A1 discloses a flexible pressure sensor array, where each sensor comprises a (circular) cavity bounded by a chamber wall.

[0006] In scientific literature, textile-based pressure sensing arrays have been reported. H. Mei et al. show a flexible pressure sensing array based on a soft substrate having holes formed (laser cut) in each sensor node and an insulating (textile) layer adhered between electrode layers (Sensors and Actuators A 222(2015)80 - 86).

[0007] The reported solutions can provide several advantages, but there is still a desire for one or more of improved sensor performance, reduced hysteresis, and eased manufacturing, especially mass manufacturing.

Summary of the Invention

[0008] Aspects of this disclosure relate to pressure sensor devices. Specifically, the devices can be advantageously used to map pressure distributions. For example, pressure mapping devices, e.g., sensor mats.

[0009] The device comprises a first substrate, a second substrate, and a spacer structure. A sensor node comprises a first conductive element mounted on the first substrate and a second conductive element mounted on the second substrate at a position facing the first conductive element. The first and conductive elements are movable relative to each other during use, changing the resistance of the force-sensing sensor node. The spacer structure separates the first and second substrates when there is no external contact pressure. The spacer structure comprises a plurality of spacer elements distributed between adjacent sensor nodes, and the spacing between adjacent spacer elements provides an interconnected network of gas passages between the sensor nodes. The spacer elements are preferably isolated or laterally separated spacer elements, i.e., elements that are not directly interconnected.

[0010] The substrate can be a flexible foil, such as a plastic foil or a multilayer foil / laminated structure. The spacer structure extends between the first substrate and the second substrate. The device further comprises a plurality of force-sensing sensor nodes.

[0011] Typically, at least one of the substrates is a flexible substrate formed from, for example, an elastomer composition. If both substrates are flexible, the entire device can be made flexible, for example, bendable.

[0012] To enable reliable and repeatable activation of the sensor nodes, the system preferably includes stretchability. Thus, at least one of the foils can be made stretchable so that it can move toward each other when pressure is applied. Alternatively, or in addition, the pillars can be made flexible and / or stretchable.

[0013] The substrate is preferably airtight under normal operating conditions. Airtightness (on a measurement scale) can be particularly relevant to expandable substrates, as it has been found that airtightness facilitates the return of the foil to a non-contact position after pressure release. The sensor nodes can be distributed according to any predefined pattern known in the art, such as a regular (m × n) matrix, in order to tune the device to measure the pressure distribution.

[0014] Spacers and substrates can be understood as defining the interconnected structure of fluidly connected gas pockets. Since the spacer structure consists of multiple individual spacer elements separated from each other by a non-zero distance, the spacer can be understood as a porous spacer that allows for the distribution of gas across multiple sensor nodes. For example, the gas distribution when one or a subset is pressed advantageously allows for pressure distribution within the device. The inventors have found that spacers can advantageously provide negligible or controlled flow resistance, depending on, for example, the size of the spacer elements, the separation between elements, and / or the packing coefficient of the spacer elements.

[0015] In contrast to fibrous mats (e.g., laser-cut textile layers), this spacer configuration mitigates or eliminates problems related to aligning the spacer with the sensor node, and therefore improves the manufacturability, particularly for large-area sensor mats. Alternatively or in addition, this spacer configuration can improve the stability of the sensor in use by mitigating or even eliminating lateral shift of opposing conductive sensing elements, for example, during mat bending.

[0016] Furthermore, the inventors have found that advantageous gas distributions, such as those provided herein, can improve the performance and / or sensing repeatability, accuracy, and / or reduction of hysteresis or erroneous readings of the device. The inventors also find that the improved performance may relate to reducing, or even essentially eliminating, pressure buildup at the sensor node in use.

[0017] The sensing principle can be one known in the relevant art. For example, the sensor node can be based on a capacitive or force-sensing resistor. A sensor node based on a force-sensing resistor can be of the so-called through or shunting type.

[0018] In a preferred embodiment, the spacer element is an upright pillar. An upright pillar can be understood as an element extending from the substrate (between two substrates) at approximately a right angle, e.g., 90°±10°, 90°±5°, or even essentially right angle. This is in contrast to spacers such as textiles with randomly distributed fibers. Furthermore, the pillar, though not required, includes an essentially uniform cross-section over at least a portion of its length, e.g., over the majority. The cross-section can be square or rectangular (as illustrated). Of course, other cross-sections, such as circular, are also conceivable.

[0019] The pillars can be freestanding pillars that do not directly contact adjacent pillars. Upright pillars can be advantageously provided using additive manufacturing methods. For example, pillars can be provided by screen printing a suitable composition onto one or both of the substrates. Advantageously, pillars can be made of, for example, an elastomer composition, or essentially formed from an elastomer composition, and be flexible. As mentioned above, some or all of the spacer elements (e.g., pillars) may be substantially rigid, especially if one or more of the substrates are flexible and expandable.

[0020] A pillar can extend from one of the first and second substrates toward the other of the first and second electrical measuring substrates. For example, a pillar can connect opposing elastomer substrates that provide an air-filled gap between them. For example, a spacer (e.g., a pillar) can directly interconnect opposing substrates.

[0021] In another or further preferred embodiment, an adhesive layer is provided between one of the substrates and the spacer element. The adhesive can fix the relative (lateral) position of the substrates and mitigate the detrimental effects on sensor node performance caused by lateral shifts between substrates during use. Advantageously, the adhesive can be limited to the end faces of isolated spacer elements. The adhesive can be provided to all isolated spacer elements, e.g., the end faces of pillars. Depending on the application, the adhesive can be applied to a subset of spacers, elements, e.g., the subset of pillars closest to each outer periphery of the sensor node.

[0022] In some embodiments, a plurality of spacer elements, for example, a plurality of upright pillars, include subsets of different types of spacer elements (e.g., pillars). For example, in some embodiments, the isolated spacer elements comprise at least a first subset of a first type of upright pillar and a second subset of a second type of upright pillar having different design / anodic or structural qualities from the first subset. In a preferred embodiment, the first pillars are distributed in a first zone surrounding the periphery of the sensor node, while a subset of second upright pillars, different from the first pillars, is distributed in a second zone relatively further away from the sensor node. Preferably, the second zone covers an area of ​​substrate between the first zones. The type of pillar can be a mutually different geometric shape, including but not limited to height, lateral dimensions, and shape (e.g., cross-section). Alternatively or in addition, the pillars can be formed from the same or different composition as the second pillars, for example, a thermoplastic elastomer. By changing the pillar type and / or filling coefficient, the sensor device can be tailored to specific needs / applications. Advantageously, adjusting the pillar quality can alter the performance or device operation in different zones of the sensing device. For example, the type, dimensions, and / or filling coefficient can be used to adjust the local or overall air volume within the system.

[0023] In a preferred embodiment, the pressure sensor device can have relatively higher structural rigidity in the area corresponding to the second zone than in the area corresponding to the first zone, for example, by providing pillars having a larger cross-sectional area, by providing pillars of a relatively high rigidity composition, and / or by having locally higher area coverage (filling coefficient). Having relatively high structural rigidity in the zones between sensor nodes is advantageous in that it allows for the incorporation of further electronic components, such as temperature sensors or fragile elements, while maintaining the overall flexibility and / or expandability of the entire pressure sensor device and reducing exposure of such elements to potentially undesirable contact pressures during operation. For example, both SMD components and other printed functions can be realized.

[0024] Therefore, in some variations, a device can be provided that includes one or more additional sensor nodes located in a second zone.

[0025] Alternatively, or in addition, the spacer elements surrounding the sensor nodes may have different qualities for specific individual sensor nodes or subsets within a group of sensor nodes. For example, the height of the pillars may vary around the sensor nodes to adjust for offsets.

[0026] The height of the spacer element, at least the spacer element directly surrounding the sensor node, will preferably exceed the combined thickness with the adhesive layer, provided that it is provided to ensure an approximate distance between the first conductive element, the second conductive element, and the stationary second conductive element.

[0027] Furthermore, it will be understood that the spacer elements can preferably be distributed to reduce the anisotropy of inter-layer flow resistance by providing, for example, a uniform packing coefficient, uniform lateral distribution, spacing, and / or height throughout the device.

[0028] Furthermore, it will be appreciated that the first and second substrates are connected around the outer periphery of the spacer structure, thereby enabling the sealing of the interconnected network of gas passages from the surroundings. Sealing the internal network of gas passages from direct exchange with the surroundings can prevent the intrusion of contaminants and / or reduce changes in device performance due to ambient changes such as air pressure and / or temperature variations. Additionally, it has been found that the hysteresis time is shortened after pressure release because the air trapped in the mat flows back into the area that was pressed when released. This relaxation process can be severely hindered if air needs to return from the environment (e.g., through holes).

[0029] According to a further aspect, a method of manufacturing a pressure sensor device, such as a pressure mapping device as disclosed herein, is provided. The method includes: i) providing a first substrate; ii) providing a second substrate; iii) providing a plurality of force sensing sensor nodes, each sensor node comprising a first conductive element attached to the first substrate and a second conductive element attached to the second substrate facing the first conductive element, the first conductive element being movable relative to the second conductive element during use and changing the resistance of the force sensing sensor node; and iv) providing a spacer structure extending between the first substrate and the second substrate, the spacer structure comprising a plurality of isolated spacer elements distributed between adjacent sensor nodes, the spacing between adjacent spacer elements providing an interconnected network of cavities of the air passages between the sensor nodes.

[0030] Advantageously, more of i) to iv) can be provided by common additive manufacturing methods, including known printing methods such as screen printing. Furthermore, the method can be fully compatible with high-volume production methods, advantageously including but not limited to (semi) continuous roll-to-roll processing.

[0031] In some embodiments, the step of providing the spacer structure includes printing, preferably screen printing.

[0032] Alternatively or in addition, the step of providing multiple force-sensing sensor nodes may include printing. For example, printing a first conductive element and a second conductive element onto their respective substrates before providing the spacer structure.

[0033] Advantageously, the method may further include the step of v) overprinting an adhesive layer onto the spacer structure. Advantageously, the adhesive layer may be provided specifically only to the end faces or subsets thereof of isolated spacer elements (e.g., pillars). Limiting adhesion to spacer elements (at least during manufacturing) is advantageous in that it can mitigate the adverse effects on internal airflow caused by excess glue, as opposed to providing, for example, a continuous glue layer.

[0034] In some preferred embodiments, the process for providing a spacer structure includes: iiia) printing a first set of pillar elements distributed in a first zone surrounding the outer periphery of a sensor node; and iiib) printing a second set of pillar elements, different from the first set of pillar elements, distributed in a second zone adjacent to the first zone.

[0035] To seal the internal structure of the device from direct contact with the surroundings, the method may further include interconnecting the first substrate and the second substrate around the outer periphery of the spacer structure, thereby sealing the interconnected network of gas passages from the surroundings. [Brief explanation of the drawing]

[0036] These and other features, aspects, and advantages of the apparatus, systems, and methods of this disclosure will be better understood from the following description, the appended claims, and the appended drawings.

[0037] [Figure 1] A partial cross-sectional side view of a flexible pressure sensor device is provided. [Figure 2] A partial cross-sectional side view of a flexible pressure sensor device is provided. [Figure 3A] Detailed configuration of the spacer. [Figure 3B] Detailed configuration of the spacer. [Figure 4A] Further detailed embodiments of the spacer configuration. [Figure 4B] Further detailed embodiments of the spacer configuration. [Figure 5] A partial plan view of a flexible pressure sensor device is provided. [Figure 6] A top view of a flexible pressure sensor device under manufacture is provided. [Figure 7A] The manufacturing method will be explained in general terms. [Figure 7B] The manufacturing method will be explained in general terms. [Figure 7C] The manufacturing method will be explained in general terms. [Figure 7D] The manufacturing method will be explained in general terms. [Figure 8] A cross-sectional side view of a flexible pressure sensor device is provided. [Figure 9] We will provide the experimental results. [Figure 10] A plan view of a flexible pressure sensor layout manufactured for testing is provided. [Figure 11] Further experimental results will be provided. [Figure 12] Further experimental results will be provided. [Modes for carrying out the invention]

[0038] The terms used to describe specific embodiments are not intended to be limitations of the invention. Where used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context otherwise clearly indicates. The terms “and / or” include any combination of one or more of the associated enumerated items. The terms “comprises” and / or “comprising” are understood to specify the presence of the described features but not to exclude the presence or addition of one or more other features. Where a particular step of a method is said to follow another step, unless otherwise specified, it is further understood that it may follow directly to the other step or that one or more intermediate steps may take place before the particular step. Similarly, where a connection between a structure or component is described, it is understood that this connection may be established directly or through an intermediate structure or component, unless otherwise specified.

[0039] The present invention is described in full below with reference to the accompanying drawings illustrating embodiments of the invention. In the drawings, absolute and relative sizes of systems, components, layers, and areas may be exaggerated for clarity. Embodiments may be described with reference to, in some cases, idealized embodiments and schematic and / or cross-sectional views of intermediate structures of the invention. In the description and drawings, similar figures refer to similar elements throughout. Relative terms and their derivatives should be interpreted as referring to orientations such as those described below or shown in the drawings considered. These relative terms are for illustrative purposes only and do not require the system to be constructed or operated in a particular orientation unless otherwise specified.

[0040] Figure 1 provides a partial cross-sectional side view of a flexible pressure sensor device 1 according to the present disclosure. As shown in the figure, the device comprises a first flexible substrate 10, a second flexible substrate 20, a spacer structure 30, and a plurality of sensor nodes 40 (only one is shown).

[0041] The substrate can be foil or polymer-based. Preferably, at least one of the substrates is stretchable, most likely at least 5%, without losing its essential function. For example, the substrate can be formed from an elastomer composition, such as elastomer foil. For example, a polyurethane-based foil such as thermoplastic polyurethane. Typically, the foil is airtight. The thickness of the foil is preferably in the range of 25 to 300 micrometers, most preferably in the range of 50 to 200 micrometers. Foil that is too thick may be undesirable from a practical or aesthetic standpoint. Foil that is too thin may be undesirable because it becomes increasingly difficult to handle during manufacturing.

[0042] The spacer structure comprises multiple isolated spacer elements. The spacer elements are distributed between adjacent sensor nodes. The spacer structure separates the substrates by a certain distance when there is no external force. The sensor node 40 comprises a first conductive element 41 mounted on a first substrate and a second conductive element 42 mounted on a second substrate facing the first conductive element. The first conductive element is movable relative to the second conductive element during use, changing the resistance of the force-sensing sensor node.

[0043] As is most commonly seen in Figures 2 to 6, the spacing between adjacent spacer elements provides openings that form an interconnected network of pockets connected by gas passages between sensor nodes.

[0044] As illustrated in the figure, the sensor node 40 may be what is known in the field as a force-sensing resistor type (FSR) sensor. For these sensors, one of the conductive elements typically comprises a pair of conductive leads 42-1, 42-2. In a preferred modification (see, for example, Figure 3), the leads may be part of a comb-type finger electrode. The leads may be any preferably conductive composition, such as a metal. For example, a trace formed by a printed conductive ink composition. The other conductive element typically comprises a layer of a composition having relatively high resistance, typically having a resistance range of kOhm~MOhm, for example, an FSR layer. When one or both of the substrates are bent inward over a distance of at least the initial separation distance, the opposing elements can come into contact, which results in an observable change in resistance between the leads. Advantageously, the resistance can scale with the applied pressure. For example, one or more of the following, the contact area between the elements, and the specific resistance of the FSR can vary as a function of the applied pressure:

[0045] When the pressure is released, the sensor can return to its initial state. For further details regarding the composition and / or layout of the FSR-based sensor node, specifically the substrate and conductive elements, see WO2020 / 214037, which is incorporated herein by reference.

[0046] Due to the openness of the spacer structure (see WO2020 / 214037 with restricted flow spacers), air between opposing elements can be freely depleted within the device. Relatively greater free air redistribution compared to known devices with closed or restricted spacer structures significantly improves the sensor node response. Figure 9 illustrates experimental traces (a, b) of two devices obtained from modeling. Each device has a 100 μm high spacer surrounding a circular sensor node with a diameter of 5 mm. The devices differ in the presence or absence of air within the sensor node. In the device without air within the sensor node (trace a), the maximum vertical displacement (d) of the upper substrate (first substrate) relative to the lower substrate (second substrate) is not inherently hindered by the accumulation of internal pressure. As shown, the substrates can already contact each other at a relatively low external pressure of about 70 Pa, such as applied to the center, after which the maximum separation remains 100 μm, but the contact area increases. In contrast, devices in which air within the node is restricted from redistribution require a much higher force for initial contact (reaching an offset of approximately 11,000 Pa).

[0047] In relation to specific spacer configurations such as those disclosed herein, it will be understood that the FSR-based configurations of specific shunting types as shown herein are not particularly limited. The benefits of free air redistribution within a system can be applied to devices having different types of other types of sensor nodes or combinations of sensor types, e.g., capacitive sensors, as is known in the field. Figures 3A and 3B provide detailed embodiments of exemplary pillar configurations. As can be seen in the clear figures, a plurality of pillars 32 surround the central area of ​​the sensor node 40. As shown, the pillars can partially overlap the conductive element 42 (finger electrode) or the wiring 42a connected to the element. As shown, both the spacing and dimensions of the pillars can be varied. The same is true for the composition of the pillars (not visualized).

[0048] Similarly, it will be understood that the exact number, size, and / or layout of the sensor nodes may depend on the intended application, e.g., pressure-sensing mats, shoe inlays, bedding underlays, etc. In some variations, the sensor nodes may be provided in a regular MXN grid, for example, in combination with a grid, preferably a matrix readout, most preferably a passive matrix readout.

[0049] In a preferred modification, the spacer element may be, for example, an upright pillar formed from an elastomer composition, which extends from one of the first and second electrical measuring substrates toward the other of the first and second electrical measuring substrates. The pillar can be advantageously provided by a common deposition method, such as screen printing a suitable comparison onto one of the substrates, after which the second substrate can be assembled on top of the pillar.

[0050] To limit the lateral shift of the substrate, an adhesive can be provided. In a preferred embodiment, for example, as shown in Figure 2, an adhesive layer 50 can be provided, limited to the end faces 33 of the isolated spacer elements or a subset thereof. As best seen in Figure 8, the first and second substrates can be connected around the outer periphery of the spacer structure by a seal 60 that separates direct fluid contact between the interconnected network of gas passages and the surroundings. The seal can be provided by a glue layer, which can have the same composition as on the pillar and can be advantageously provided during a single overprint step. Alternatively or in addition, a thermoseal can be used.

[0051] As illustrated in Figure 1, the height (h) of the spacer preferably exceeds the combined thickness of the first conductive element, the second conductive element, and the adhesive layer. Table 1 provides numerical values ​​for the elements used in the manufactured device.

[0052] [Table 1]

[0053] In some variations, the spacer elements may include a subset of the first upright pillars 34 and a subset of the second upright pillars 35 that are different from the subset of the first upright pillars. As illustrated in Figure 4A, the pillars 34, 35 may be distributed in separate zones. For example, a first zone (z1) that is in direct proximity to (e.g., surrounding) the first conductive element 41, and a second zone that is relatively farther from the sensor node 40, for example, between adjacent first zones.

[0054] As illustrated in Figure 4B, the first and second types of pillars 34, 35 can be varied in size, number, and / or spacing. Alternatively or in addition, the pillars can be varied in height and / or composition (not illustrated). In some embodiments, for example, as shown, an additional electronic component 70 can be provided in the second zone (z2).

[0055] Figures 7A, 7B, 7C, and 7D schematically illustrate the manufacturing method. As shown, the method is i) To provide a first substrate, preferably an elastomer substrate, ii) To provide a second substrate, preferably an elastomer substrate, iii) To provide multiple force sensing sensor nodes, iv) Providing a spacer structure, Each sensor node comprises a first conductive element mounted on a first substrate and a second conductive element mounted on a second substrate facing the first conductive element, wherein the first conductive element is movable relative to the second conductive element during use, changing the resistance of the force-sensing sensor node, and the spacer structure consists of a plurality of isolated spacer elements extending between the first and second substrates and distributed between adjacent sensor nodes, wherein the spacing between adjacent spacer elements provides an interconnected network of cavities for air passages between sensor nodes.

[0056] The steps of providing a spacer structure and / or providing a plurality of force-sensing sensor nodes may include printing. For example, providing a plurality of force-sensing sensor nodes, as illustrated in Figure 7B, may include substeps iiia and iiib of printing (e.g., screen printing) first and second conductive elements onto each substrate before providing the spacer structure. Similarly, the spacer structure may be printed on one or both of the substrates. As previously mentioned, the pillars may be made of an elastomer composition.

[0057] In some embodiments, the method further includes step (v) of overprinting an adhesive layer onto a spacer structure, as illustrated in Figure 7C, for example.

[0058] Advantageously, the production process is perfectly suited to mass production methods. In some embodiments, the production process can be implemented as a roll-to-roll process.

[0059] A specific manufacturing method is described in detail with reference to Figure 7D. In steps i) and ii), sheets of suitable substrates 10, 20 are supplied, for example, from separate feed rollers. Foil 10 is processed in a station (e.g., a screen printing station) configured to apply a first conductive element 41 (e.g., FSR). Foil 20 is processed in a station configured to apply a corresponding second conductive element 42 (e.g., a comb-type finger electrode). A spacer (e.g., pillar) structure is applied to one of the foils (step iv), followed in step v) by applying a glue rubber (adhesive 50) to the end face in a step rather than (e.g., by screen printing), e.g., by overprinting v). In the final step, the foils are assembled on top of each other to obtain an assembled flexible pressure sensor device.

[0060] Figure 5 illustrates the first flexible substrate 10 after printing of the first conductive element 41 (comb-shaped finger electrodes) and screen printing of multiple isolated upright pillars 32. Wiring 49 to the second conductive element 42 is arranged in a matrix configuration (marked by horizontal and vertical gray bands in the image). As is best seen in the detail image (bottom left), the glue layer 50 is overprinted on the end faces 33 of the pillars. The positioning of the FSR layer 42 (after assembly of the second foil) is indicated by a dashed rectangular box.

[0061] Figure 6 shows an image of a substrate having multiple wired comb-type finger electrodes, thereby the spacer structure includes a subset of first pillars 34 spaced apart around the outer circumference of each sensor node and a subset of second pillars 31 provided in the area between the first pillars. Note the different spacing in different zones. The substrate can be the lower substrate of a flexible pressure sensor device, as shown in Figure 2.

[0062] Figure 10 illustrates a modification that differs from the modification depicted in Figure 6, primarily in that the pillars are anisotropically distributed. Specifically, there is a zone (z, vertical in the figure) where no pillars are provided. Hysteresis evaluation was performed in a dynamic measurement setting. Small (approximately A4 size) pressure sensor mats were fabricated with two different pillar designs, as shown in Figures 6 and 10. The design in Figure 10 strokes vertically where no pillars are present, while the design in Figure 6 is fairly homogeneously covered with pillars. All pillars were similarly covered with glue. The mats were positioned on a 1 cm thick yoga mat, and a bowling ball was rolled across the mat while simultaneously reading the pressure sensors on the mat. The mat fabricated with an anisotropic distribution clearly showed more hysteresis when the ball was rolled horizontally (as opposed to vertically). In the more homogeneous, distrustful design, the response did not change with the direction of the bowling ball's roll.

[0063] The effect of pillar height was evaluated for systems with and without airflow. As discussed in relation to Figure 9, the threshold pressure (defined as the pressure at which the FSR first contacts the comb-shaped silver fingers, causing a resistance reduction of several decades) was found to depend on whether the sensor node was closed or not. In addition, it was confirmed that in the case of a closed sensor node (filled with air but without air exchange between adjacent nodes), the threshold may depend on the pillar height.

[0064] Figure 11 illustrates the response traces of nodes fabricated using PEN foil as the support material. Traces 101 (red), 102 (blue), 104 (green), and 106 (yellow) use printed spacers and adhesives. Traces 105 (orange) and 103 (purple) use the same support material, but with PSA and TPU-based foils used as spacers and adhesives.

[0065] The nominal thicknesses of the closed spacers are 11, 23, 50, 60, 60, and 89 μm (in ascending order from 101 to 106), respectively.

[0066] Additionally, the simulation clearly demonstrated the dependence of threshold pressure on pillar height for an airflow-free sensor printed on a TPU substrate. Figure 12 provides simulation results illustrating contact area versus applied pressure (normalized with respect to device area). Curves are obtained for a device radius of 5 mm and for different spacer thicknesses. The normalized contact area (A) is defined as the surface of the FSR-printed TPU in contact with the TPU having printed comb-shaped fingers. The contact area corresponds to the current flowing through the sensor and therefore the sensor's resistance.

[0067] The next step involved using pressure sensors printed on a stretchable TPU substrate. Here, pillars were used according to the spatial concept to create airflow in a larger sensor mat. In these samples, no experimental dependence of threshold pressure on pillar height was observed.

[0068] For the purpose of clarification and concise explanation, features are described herein as part of the same or distinct embodiments; however, it will be understood that the scope of the invention may include embodiments having all or some combinations of the described features.

[0069] When interpreting the attached claims, it should be understood that the word “comprising” does not exclude the existence of other elements or actions other than those enumerated in the given claims, the word “a” or “an” preceding an element does not exclude the existence of multiple such elements, any reference numerals in the claims do not limit their scope, some “means” may be represented by the same or different items or structures or functions implemented, and any or part of the disclosed devices may be combined together or separated into further parts unless otherwise specifically stated. Where one claim refers to another, this may indicate a synergistic benefit achieved by the combination of their respective features. However, the mere fact that certain measures are enumerated in different claims does not mean that combinations of these measures cannot be used to their advantage. Thus, this embodiment may include all functional combinations of claims, where each claim may, in principle, refer to any prior claim unless explicitly excluded by context.

Claims

1. A pressure sensor device (1), The first substrate (10) and The second substrate (20) and A spacer structure (30) extending between the first substrate and the second substrate, Equipped with multiple force sensing sensor nodes, Each sensor node (40) comprises a first conductive element (41) attached to a first substrate and a second conductive element (42) attached to a second substrate facing the first conductive element, wherein the first conductive element is movable relative to the second conductive element during use, and changes the resistance of the force sensing sensor node. The device comprises a spacer structure (30) comprising a plurality of isolated spacer elements (31) distributed between adjacent sensor nodes, wherein the spacing between adjacent spacer elements provides an interconnected network of gas passages between the sensor nodes.

2. The device according to claim 1, wherein the spacer element is an upright pillar (32) formed from an elastomer composition.

3. The device according to claim 1 or 2, further comprising an adhesive layer (50) limited to the end face (33) of the isolated spacer element or a subset thereof.

4. The aforementioned plurality of spacer elements, A subset of first upright pillars (34) distributed in a first zone (z1) surrounding the outer periphery of the sensor node (40), The device according to any one of the prior claims, comprising: a subset of second upright pillars (35) distributed in a second zone (z2) adjacent to the first zone, which is different from the subset of first upright pillars.

5. The device according to claim 4, wherein the pressure sensor device has relatively higher structural rigidity in the area corresponding to the second zone (z2) than in the area corresponding to the first zone (z1).

6. The device according to claim 4 or 5, further comprising one or more additional sensor nodes (60) disposed in the second zone.

7. The device according to any one of the prior claims, wherein the height of the spacer element exceeds the combined thickness of the first conductive element, the second conductive element, and the adhesive layer.

8. The device according to any one of the prior claims, wherein the first substrate and the second substrate are connected around the outer periphery of the spacer structure, thereby sealing the interconnected network of gas passages from the periphery.

9. A method (200) for manufacturing a pressure sensor device, i) To provide a first substrate, ii) To provide a second substrate, iii) To provide multiple force sensing sensor nodes, Each sensor node comprises a first conductive element mounted on a first substrate and a second conductive element mounted on a second substrate facing the first conductive element, wherein the first conductive element is movable relative to the second conductive element during use, thereby changing the resistance of the force-sensing sensor node. iv) To provide a spacer structure, A method comprising providing, the spacer structure comprising a plurality of isolated spacer elements extending between the first substrate and the second substrate and distributed between adjacent sensor nodes, wherein the spacing between adjacent spacer elements provides an interconnected network of gas passage cavities between the sensor nodes.

10. The method according to claim 9, wherein the step of providing the spacer structure includes printing.

11. The method according to claim 9 or 10, wherein the step of providing a plurality of force-sensing sensor nodes includes printing the first conductive element and the second conductive element onto the respective substrates before providing the spacer structure.

12. The method according to any one of claims 9 to 11, further comprising the step (v) of overprinting an adhesive layer onto the spacer structure, wherein the adhesive is limited to the end faces or subsets thereof of the isolated spacer elements.

13. The step of providing the spacer structure is, A substep of printing a set of first pillar elements distributed in a first zone surrounding the outer periphery of the sensor node, The method according to any one of claims 9 to 12, comprising the substep of printing a second set of pillar elements, which is different from the first set of pillar elements, distributed in a second zone adjacent to the first zone.

14. The method according to any one of claims 9 to 13, further comprising interconnecting the first substrate and the second substrate around the outer periphery of the spacer structure, thereby sealing the interconnected network of gas passages from the periphery.

Images