Abstract
The invention relates to an article comprising an elongated pressure sensitive component in contact with a user. The pressure sensitive component forms a seal 7 between the user and the article when a minimum seal pressure is applied on the pressure sensitive component. The seal 7 comprises a signal pathway or an inductive loop indicative of a complete seal between user and article at the minimum seal pressure applied along the entire length of the pressure sensitive component.
Claims
1. An article comprising an elongated pressure sensitive component in contact with a user, wherein the pressure sensitive component forms a seal (7) between the user and the article when a minimum seal pressure is applied on the pressure sensitive component and wherein the seal (7) comprises a signal pathway or an inductive loop indicative of a complete seal along the entire length of the pressure sensitive component.
2. The article according to claim 1, wherein the signal of the signal pathway is based on electrical signals or on optical or acoustic waves, and wherein the signal of the inductive loop may be based on electrical inductance or inductive coupling of the closed inductive loop to an electric circuit.
3. The article according to claim 1, wherein the pressure sensitive component comprises a transmitter (36, 46, 56, 66) as well as a receiver (37, 47, 57, 67), or electrodes (6) or terminals.
4. The article according to claim 1, wherein the elongated pressure sensitive component comprises two opposing structures of aligned conductive patches (3) (opposing patch structures) wherein the two opposing patch structures are separated by an insulating material and as long as the minimum seal pressure is not applied onto the pressure sensitive component.
5. The article according to the claim 4, wherein under the minimum seal pressure applied on the pressure sensitive component each of the conductive patches (3) electrically bridges the opposing insulating material of the opposing patch structure and thereby forms a conductive signal pathway between the electrodes or closes to an inductive loop.
6. The article according to claim 1, wherein the elongated pressure sensitive component comprises a bridging structure that consists of an array of adjacent conductive lamellae (13) that are spaced apart from each other as long as the minimum seal pressure is not applied to the pressure sensitive component and that are designed such as to deform as soon as the minimum seal pressure is applied on the pressure sensitive component.
7. The article according to claim 6, wherein under the minimum seal pressure applied along the entire length of the pressure sensitive component the lamellae (13) of the bridging structure deform and thereby bridge the space between the lamellae resulting either in a complete conductive signal pathway between the electrodes (6) at each end of the bridging structure or in closing to an inductive loop in the pressure sensitive component.
8. The article according to claim 1, wherein the elongated pressure sensitive component comprises a compressible conductive foam (23) across the entire length of the elongated pressure sensitive component in the form of a closed inductive loop or with two embedded electrodes (6) at each end of the conductive foam.
9. The article according to claim 8, wherein under the minimum seal pressure applied along the entire length of the pressure sensitive component the conductive foam (23) generates an electrical signal, wherein the signal may be based on an electric current, a voltage, or a change of electrical impedance, due to change in electrical resistance and/or capacitance, between two electrodes (6) embedded in the foam (23), or a change of inductance in the inductive loop formed by the foam in the elongated pressure sensitive component.
10. The article according to claim 1, wherein the elongated pressure sensitive component comprises a conductive non-woven (33) across the entire length of the elongated pressure sensitive component in the form of a closed inductive loop or with two embedded electrodes (6) at each end of the conductive non-woven.
11. The article according to claim 10, wherein under the minimum seal pressure applied along the entire length of the pressure sensitive component the conductive non-woven (33) generates an electrical signal in, wherein the signal is be based on an electric current, a voltage, or a change of electrical impedance, due to a change in electrical resistance and/or capacitance, between two electrodes (6) embedded in the non-woven or a change of inductance in the inductive loop formed by the non-woven in the elongated pressure sensitive component.
12. The article according to claim 1, wherein the elongated pressure sensitive component comprises two opposing, complementary structures (33) that consist of a material that is optically transparent to the wave from an optical transmitter (36) or acoustically transparent to the wave from an acoustic transmitter (56), where the optical or acoustic transmitter and an optical or acoustic receiver are each embedded at the same end or opposite ends of one of the opposing, complimentary structures.
13. The article according to claim 12, wherein the space between the two opposing, complementary structures (33) is filled with a fluid or a gas wherein the fluid or gas between the complementary structures (33) has a refractive index that is different from the refractive index of the material of the complementary structures (33) at the wavelength of an optical or acoustic transmitter (36) or wherein the fluid or gas between the complementary structures (33) has a mass density and bulk modulus that is different from the mass density and bulk modulus of the material of the complementary structures (33) and/or wherein under the minimum seal pressure applied along the entire length of the pressure sensitive component the opposing, complementary structures (33) engage with each other, thereby displacing the fluid or gas, producing a waveguide for optical or acoustic waves.
14. The article according to claim 1, wherein the elongated pressure sensitive component comprises a porous structure (43), made of a material with low enough optical absorption or low enough acoustic attenuation for optical or acoustic waves that are transmitted from an optical or acoustic transmitter to an optical or acoustic receiver over the entire length of the pressure sensitive component and/or wherein the pores in the porous structure (43) are filled with a fluid or a gas, wherein the fluid or gas has a refractive index that is different from the refractive index of the material of the porous structure (43) at the wavelength of an optical or acoustic transmitter (46), or wherein the fluid or gas has a mass density or bulk modulus that is different from the mass density or bulk modulus of the material of the porous structure.
15. The article according to claim 14, wherein under the minimum seal pressure applied along the entire length of the pressure sensitive component the porous structure (43) gets compressed thereby displacing the fluid or gas and producing a waveguide for optical or acoustic waves.
Description
[0054] The invention will now be described in more detail with reference to the following Figures exemplifying particular embodiments of the invention:
[0055] FIG. 1 a schematical view of a seal or gasket placed onto a skin of a user;
[0056] FIG. 1A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with two opposing structures of conductive patches;
[0057] FIG. 1B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 1a;
[0058] FIG. 2A cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 1a with a force F1 applied to it;
[0059] FIG. 2B cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 1a with a force F2 applied to it;
[0060] FIG. 3A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with a structure of parallel conductive lamellae;
[0061] FIG. 3B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 3a;
[0062] FIG. 4A cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 3a with a force F1 applied to it;
[0063] FIG. 4B cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 3a with a force F2 applied to it;
[0064] FIG. 5A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with a conductive foam structure;
[0065] FIG. 5B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 5a;
[0066] FIG. 6A cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 5a with a force F1 applied to it;
[0067] FIG. 6B cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 5a with a force F2 applied to it;
[0068] FIG. 7A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with conductive non-woven;
[0069] FIG. 7B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 7a;
[0070] FIG. 8A cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 7a with a force F1 applied to it;
[0071] FIG. 8B cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 7a with a force F2 applied to it;
[0072] FIG. 9A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with two opposing complementary zigzag structures made of acoustically transparent material with a force F2 applied to it;
[0073] FIG. 9B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 9a;
[0074] FIG. 10 cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 9a with a force F1 applied to it;
[0075] FIG. 11A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with acoustically transparent foam material with a force F2 applied to it;
[0076] FIG. 11B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 11a;
[0077] FIG. 12 cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 11a with a force F1 applied to it;
[0078] FIG. 13A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with two opposing complementary zigzag structures made of optically transparent material;
[0079] FIG. 13B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 13a;
[0080] FIG. 14A cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 13a with a force F1 applied to it;
[0081] FIG. 14B cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 13a with a force F2 applied to it;
[0082] FIG. 15A cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with two parallel waveguides made of optically transparent material and a divider;
[0083] FIG. 15B cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 14a showing the two parallel waveguides and the mechanical divider;
[0084] FIG. 16A cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 15a with a force F1 applied to it,
[0085] FIG. 16B cross-sectional view along the longitudinal axis of the elongated pressure sensitive component of FIG. 15a with a force F2 applied to it, and
[0086] FIG. 17 a diagram showing typical pressure response curves of different materials over compressive stress.
[0087] Herein below various embodiments of the present invention are described and shown in the drawings wherein like elements are provided with the same reference numbers.
[0088] FIG. 1 a schematical view of a seal or gasket 2 placed onto a skin 5 of a user. The gasket 2 provides a hollow space in between two layers. In areas A, where the two layers 2 of the gasket are spaced apart from each other a minimum seal pressure zone is established. In areas B, where the two layers 2 of the gasket are positioned close to each other a maxim seal pressure is established. The minimal and maximal seal pressure of the pressure-sensitive seal component depend not only on the force applied across the area of the seal, but also locally on the anatomical shape in contact with the gasket. Using the pressure-sensitive component to determine fit of the seal the minimum pressure is essential to determine a complete seal of the gasket. Hence the minimum pressure is used for the seal pressure threshold.
[0089] FIG. 1A is a cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with two opposing structures of conductive patches. The elongated pressure sensitive component may for example be a seal for sealing the gap between a personal protective device, such as for example a respirator mask, a hearing protector or eyewear, and a person's skin or any other kind of seal (see FIGS. 17A through 18C). FIG. 1A shows part of the protection device 1 to which the pressure sensitive component is attached to. The protection device 1 is followed by a first gasket layer 2. Next to the gasket or seal layer 2 a first layer of subsequent conductive patches 3 is arranged wherein the conductive patches 3 are flat and spaced apart from each other. With a certain distance a second layer of subsequent conductive patches 3 is arranged wherein the conductive patches 3 of the second layer are also spaced apart from each other. The space between the patches 3 as well as the space between the first layer of patches 3 and the second layer of patches 3 is filled with a non-conductive material, such as a gas for example air. The two layers of conductive patches 3 may be held apart from each other through compressible spacer elements 4 that can be seen in FIG. 1B and that are positioned on each side of it. The two layers of conductive patches 3 are arranged such relative to each other that each conductive patch 3 is arranged opposite of a space between two conductive patches 3. Also, the extension of the space between two patches 3 is smaller than the extension of the patches 3. The second layer of conductive patches 3 is again followed by a second gasket layer 2 which is in contact with skin 5 of a person. The first gasket layer 2, the first layer of conductive patches 3, the spacer 4, the second layer of conductive patches 3 and the second gasket layer 2 may form a seal 7 of a personal protection device 1. The seal may also be a closed seal on the sides of the spacer elements 4, such that it would show with a squared cross section in FIG. 1B. On both ends of the elongated pressure sensitive component a terminal 6 is positioned. Each of the terminals 6 is in contact with one conductive patch 3. The terminals themselves are separated from each other.
[0090] FIG. 1B, which is a cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 1A, shows that the compressible spacers 4, that are arranged on both sides of the conductive patches 3, keep the conductive patches apart as long as no pressure is applied onto the elongated pressure sensitive component. The compressible spacers 4 may be also the sidewalls of the gasket.
[0091] As soon as a pressure in form of a force F is applied onto the elongated pressure sensitive material, the spacer elements 4 get compressed and the two layers of conductive patches 3 get closer to each other. Upon a certain force F1 (see FIG. 2A) all conductive patches 3 get in contact with each other thereby building a conductive path between the two terminals 6 through the elongated pressure sensitive component, which can trigger a signal directly at the terminals 6 or by forming an inductive loop (not shown) that is coupled to a remote resonant circuit. This conductive path may be used directly as an electric circuit via the terminals 6 and is able to trigger a visual or audible indication of a complete seal without the need of multiplexing or micro-processing the signal. A time event may be communicated to an internal or wireless data logging device.
[0092] If the pressure sensitive material shown in the FIGS. 1A to 2B is used as a seal 7 for example for a personal protection device the force F may get applied onto the seal upon skin contact and may exert a compressive stress to the gasket 2 and the spacer 4 within the seal 7. Due to the alignment of spacer 4 and electrode patches 3 the stresses in the spacer 4 need to be large enough to compress the spacer 4 by nearly 100% in order for the conductive patches 3 to be able to form an electrical contact. The compressive and flexural modulus and thickness of the spacer 4 and seal layer 2 allow control of the compressive strain as result of the compressive stress. A partial gasket 2 skin 5 contact due to human factors such as body shape, movement, or hair on the skin surface would—as for example shown in FIG. 2B—result in a reduction of the compressive stress and consequently the strain in the spacer 4 so that not all conductive patches 3 are able to form an electrical contact with the according opposite conductive patches 3. As a result, the electrode patches 3 cannot form a complete electrical conduction path and the circuit across the terminals remain open (see FIG. 2B).
[0093] FIG. 3A is a cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with a structure of essentially parallel conductive lamellae 13. The elongated pressure sensitive component may for example be a seal for sealing the gap between a personal protective device, such as for example a respirator mask, a hearing protector or eyewear, and a person's skin. FIG. 3A shows part of the protection device 1 to which the pressure sensitive component is attached to. The protection device 1 is followed by a first gasket layer 2. Next to the gasket or seal layer 2 the structure of conductive lamellae 13 is arranged wherein the lamellae 13 are arranged parallel and spaced apart from each other such that the lamellae—when no pressure is applied on the elongated pressure sensitive component—do not touch each other. The lamellae 13 may consist of a mechanically compliable and electrically conductive polymer compound as explained in the general part of the description. The space between the lamellae 13 is filled with a non-conductive gas or fluid, such as air for example. The lamellae 13 extend between the first gasket layer 2 and a second parallel gasket layer 2. They may be fixed with their upper most end to the first gasket layer 2 and with their lower end to the second gasket layer 2. In the uncompressed state the two layers of gasket 2 may be held apart by the lamellae themselves or through compressible spacer elements 14 that can be better seen in FIG. 3B. The second gasket layer 2 is in contact with skin 5 of a person. The first gasket layer 2, the structure of lamellae 13, the spacer elements 14 and the second gasket layer 2 may form a seal 7 of a personal protection device 1. On both ends of the elongated pressure sensitive component a terminal 6 is positioned. Each of the terminals 6 is in contact with one lamella 13 of the lamellae structure. Also, in this embodiment the seal 7 may be closed at the sides of the spacer elements 14.
[0094] FIG. 3B, which is a cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 3A, shows that the spacers 14 that are arranged on both sides of the lamellae 13 to keep the two gasket layers 2 apart as long as no force is applied to the elongated pressure sensitive component. The spacers 14 may also act as sidewalls of the gasket.
[0095] As soon as a pressure in form of a force F is applied onto the elongated pressure sensitive material, the spacers 14 get compressed and the lamellae 13 get bended. The higher the applied force F is the more the lamellae 13 are bent. Upon a certain force F1 all lamellae 13 are bent so much that they get in contact with each other thereby building a conductive path through the elongated pressure sensitive component between the two terminals 6, which can trigger a signal directly at the terminals 6 or by forming an inductive loop (not shown) that is coupled to a remote resonant circuit (see FIG. 4A). This conductive path may be used directly as an electric circuit via the terminals 6 and is able to trigger a visual or audible indication of a complete seal without the need of multiplexing or micro-processing the signal. A time event may be communicated to an internal or wireless data logging device.
[0096] If the pressure sensitive material shown in the FIGS. 3A to 4B is used as a seal 7 for a personal protection device the force F may get applied onto the seal upon skin contact and may exert a compressive stress to the gasket 2 and the spacer elements 14 within the seal 7. Due to the alignment of spacers 14 and the lamellae structure 13 the stresses in the spacers 14 needs to be large enough to compress the spacers 14 in order for the lamellae 13 to be able to contact each other and to form an electrical path. The compressive and flexural modulus and thickness of the spacers 14 and gasket materials 2 allow control of the compressive strain as result of the compressive stress. A partial gasket 2 to skin 5 contact due to human factors such as body shape, movement, or hair on the skin surface would result in a reduction of the compressive stress and consequently the strain in the spacers 14 so that not all lamellae 13 are able to form an electrical contact with the according adjacent lamellae 13. As a result, the lamellae structure 13 cannot form a complete electrical conduction path and the circuit across the terminals remains open (see FIG. 4B).
[0097] FIG. 5A is a cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with a conductive foam structure 23. The conductive foam structure 23 may consist of a mechanically compliable polymer that comprises an electrically conductive filler material 25, such as micro-particles, nanotubes or nanofibers. The elongated pressure sensitive component may for example be a seal for sealing the gap between a personal protective device, such as for example a respirator mask, a hearing protector or eyewear, and a person's skin. FIG. 5A shows part of the protection device 1 to which the pressure sensitive component is attached to. The protection device 1 is followed by a first gasket layer 2. Next to the gasket layer 2 the conductive foam structure 23 is arranged wherein the foam structure 23 extends parallel to the first gasket layer 2. The cells within the foam structure 23 are filled with a non-conductive gas or fluid, such as for example air. The conductive foam structure 23 extends between the first gasket layer 2 and a second parallel gasket layer 2. The two layers of gasket 2 may be held apart from each other through the gasket sidewalls in FIG. 5b, the compressible, conductive foam structure 23 and/or through additional spacers as in the other embodiments (not shown in the drawings). The second gasket layer 2 is in contact with skin 5 of a person. The first gasket layer 2, the conductive foam structure 23 and the second gasket layer 2 may form a seal 7 of a personal protection device 1. On both ends of the elongated pressure sensitive component a terminal 6 is positioned. The two terminals 6 are in contact with the conductive foam structure 23. The gasket 2 may also comprise a hollow space filled with the conductive foam structure 23 as can be seen in FIG. 5B.
[0098] FIG. 5B, which is a cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 5A, shows that the conductive foam structure 23 is surrounded by gasket sidewalls 2 also on the left and right. The gasket sidewalls, the conductive foam structure 23 and/or additional spacer material as in the other embodiments (not shown in this drawing) keeps all the gasket layers 2 separated from each other in the uncompressed state.
[0099] As soon as a pressure in form of a force F is applied onto the elongated pressure sensitive material, the conductive foam structure 23 gets compressed thereby reducing the size of its cells and contacting the electrically conductive filler material 25 within the foam structure 23 and therewith reducing the electrical resistance of the foam structure 23 which closes the circuit between the two terminals 6. The higher the applied force F is the more the foam structure 23 gets compressed. Upon a certain force F1 a conductive path through the elongated pressure sensitive component is build, which can trigger a signal directly at the terminals 6 or by forming an inductive loop (not shown) that is coupled to a remote resonant circuit (see FIG. 6A). This conductive path may be used directly as an electric circuit via the terminals 6 and is able to trigger a visual or audible indication of a complete seal without the need of multiplex or micro-processing the signal. A time event may be communicated to an internal or wireless data logging device.
[0100] If the pressure sensitive material shown in the FIGS. 5A to 6B is used as a seal 7 for a personal protection device the force F may get applied onto the seal upon skin contact and may exert a compressive stress to the gasket 2 and the conductive foam structure 23 within the seal 7. The compressive and flexural modulus and thickness of the foam structure 23 and gasket materials 2 allow control of the compressive strain as result of the compressive stress. A partial gasket 2 to skin 5 contact due to human factors such as body shape, movement, or hair on the skin surface would result in a reduction of the compressive stress and consequently the strain in conductive foam structure 23 so that less filler material is able to form an electric contact. This increases the electrical resistance in the foam 23 again, which opens the circuit between the terminals (see FIG. 6B).
[0101] The embodiment shown in FIGS. 7A to 8B differs from the embodiment shown in the FIGS. 5A to 6B in that the gasket 2 is not filled with a conductive foam 23 but with an electrically conductive non-woven 33 that has been coated with an electrically conductive material. The electrically conductive non-woven 33 forms an electrical conduction path along the gasket 2 as soon as the gasket is in complete contact with the skin 5 of a person. Just as in the other embodiments in FIGS. 1A to 6B this conduction path is created due to the electrical impedance change of the compressed nonwoven and may be measured directly via a voltage and current transient by an electric circuit at two terminals 6 or indirectly if the conductive path forms an inductive loop that is coupled to a resonant circuit. The measured signals can be used to trigger a visual or audible fit indication if the electrical impedance exceeds the threshold impedance at the minimum seal pressure determined in a fit test.
[0102] FIG. 9A is a cross-sectional view along the longitudinal axis of an elongated pressure sensitive component with two opposing complementary zigzag structures of acoustically transparent material. The elongated pressure sensitive component may for example be a seal for sealing the gap between a personal protective device, such as for example a respirator mask, a hearing protector or eyewear, and a person's skin. FIG. 9A shows part of the protection device 1 to which the pressure sensitive component is attached to. The protection device 1 is followed by a first gasket layer 2. Next to the gasket layer 2 a first zigzag structure of acoustically transparent material 33 is arranged. A second corresponding zigzag structure of acoustically transparent material 33 is arranged parallel to the first structure 33 wherein the two structures also are arranged parallel and spaced apart from each other such that they—when no pressure is applied on the elongated pressure sensitive component—do not touch each other or do not engage with each other. The space between the zigzag structures 33 is filled with a fluid or gas such as for example air. The second zigzag structure 33 of acoustically transparent material is followed by a second gasket layer 2, followed by skin 5. The two layers of gasket 2 may be held apart from each other through compressible spacers 34 that can be seen in FIG. 9B and/or gasket sidewalls (not shown in this figure). The second gasket layer 2 is in contact with skin 5 of a person. The first gasket layer 2, the two zigzag structures 33, the spacers 34 and the second gasket layer 2 may form a seal 7 of a personal protection device 1. On both ends of the elongated pressure sensitive component a transmitter 36 and a receiver 37 are positioned that are embedded in the first zigzag structure 33.
[0103] FIG. 9B, which is a cross-sectional view along the transvers axis of the elongated pressure sensitive component of FIG. 9A, shows that the spacer elements 34 that are arranged on both sides of the zigzag structures 33 to keep the two gasket layers 2 with the zigzag structures 33 apart from each other as long as no force is applied to the elongated pressure sensitive component. The spacers can also have the function of gasket sidewalls.
[0104] As soon as a pressure is applied onto the elongated pressure sensitive material by a force F, the spacers 34 get compressed thereby bringing the two zigzag structures 33 closer to each other and finally into engagement. The higher the applied force F is the closer the zigzag structures get until they are in final engagement with each other. Final engagement means that the two zigzag structures 33 fully engage with each other such that their entire surfaces touch each other, and no gas or fluid is being entrapped between them. In final engagement the two zigzag structures 33 build a waveguide for acoustic waves.
[0105] Upon a certain force F1 the two zigzag structures 33 fully engage with each other thereby building the above-mentioned waveguide through the elongated pressure sensitive component (see FIG. 10). The acoustic path in the waveguide may be used for guiding acoustic waves from a transmitter 36 to a receiver 37 embedded in the gasket 2. The receiver's response can trigger a visual or audible fit indication without the need of multiplexing or micro-processing the signal. A time event may be communicated to an internal or wireless data logging device.
[0106] If the pressure sensitive material shown in the FIGS. 9A to 10 is used as a seal 7 for a personal protection device the force F may get applied onto the seal upon skin contact and may exert a compressive stress to the gasket 2 and the spacer elements 34 within the seal 7. Due to the alignment of spacers 34 and the zigzag structure 33 the stresses in the spacers 34 need to be large enough to compress the spacers 34 in order for the zigzag structure 33 to be able to engage with each other to form an acoustic waveguide. The compressive and flexural modulus and thickness of the spacers 34 and gasket materials 2 allow control of the compressive strain as a result of the compressive stress. A partial gasket 2 to skin 5 contact due to human factors such as body shape, movement, or hair on the skin surface would result in a reduction of the compressive stress and consequently the strain in the spacers 34 so that there is no engagement over the entire length of the two zigzag structures 33. As a result, the zigzag structures 33 cannot form a complete acoustic waveguide and no response can be generated by the acoustic receiver 37 (see FIG. 9A).
[0107] The embodiment shown in FIGS. 11A to 12 differs from the embodiment shown in the FIGS. 9A to 10 in that the construction comprises a porous structure in form of a foam 43 that forms an optical or acoustic waveguide upon complete skin contact of the gasket 2 between the first and second gasket layer 2 instead of the two opposing zigzag structures 33. The foam or porous structure may consist of an optically or acoustically transparent polymer, such as a silicone, thermoplastic resin, or other. The voids in the porous structure are filled with a gas or fluid, such as for example air. The embodiment also comprises spacer elements 44 and/or two gasket sidewalls (not shown in this figure) arranged on both sides of the foam or porous structure 43.
[0108] The system also includes an optical or acoustic transmitter 46 as well as an optical or acoustic receiver 47. Without any pressure applied to the elongated pressure sensitive material, the foam or porous structure 43 is in an expanded state, in which it is unable to guide an optical or acoustic wave from the transmitter 46 due to scattering of the optical wave at the gas or fluid filled voids or due to insufficient bulk modulus and mass density in the foam or porous structure for the acoustic wave so that no signal is obtained by the receiver 47. As soon as a minimum seal pressure is applied on the elongated pressure sensitive material, an optical or acoustic waveguide is formed by the displaced gas or fluid in the compressed foam or porous structure 43 which may guide optical waves so that the receiver 47 receives signals through the optical waveguide from the transmitter 46. As soon as the receiver 47 receives the signal it may trigger a visual or audible fit indication without the need of multiplexing or micro-processing the signal.
[0109] The embodiment shown in FIGS. 13A to 14B resembles the embodiment shown in FIGS. 9A to 10. The only difference is that in FIGS. 13A to 14B optical waves are guided from a transmitter to a receiver instead of acoustic waves. The material used in the embodiment of FIGS. 13A to 14B are optically transparent materials instead of acoustically transparent materials.
[0110] In FIGS. 15A to 15B another embodiment using optical waves is described. The embodiment again comprises an elongated pressure sensitive component that may be used as seal for a gap between a personal protection equipment and skin of a person. The gasket comprises a first gasket layer 2 attached to the protection device 1 as well as a second gasket layer 2 next to the skin 5 of a person. Within the gasket 2 two parallel optically transparent waveguides 63 are arranged and extend parallel to the extension of the pressure sensitive component. Within the first optically transparent waveguide 63 an optical transmitter 66 is embedded and within the second optically transparent waveguide 63 an optical receiver 67 is embedded. The two parallel waveguides touch each other along their entire length. The gasket 2 further comprise a separator 68 with for example a triangular cross-section as in FIG. 15B, which is positioned in the gasket opposite of the two waveguides 63. As soon as a force is applied onto the elongated pressure sensitive component, the gasket 2 gets compressed, thereby moving the separator 68 towards the two parallel waveguides 63 and separating them such that they do not touch each other anymore. And finally, the gasket 2 may comprise two spacers 64, each spacer 64 being arranged on one side of the two waveguides 63.
[0111] An optical wave, that is generated and send out by the transmitter 63 may move through the first waveguide 63 and as long as the two waveguides touch each other also through the second waveguide 63, where it may be detected through the receiver 67. As soon as the separator 68 separates the two waveguides 63, the receiver 67 may not detect any optical wave from the transmitter 66 anymore which may be an indication of an applied pressure that has forced the separator between the two waveguides 63. As in all the other embodiments the material and dimensions of the components (gasket 2, spacer 64 etc.) of the system need to be selected such that the receiver 67 gets a signal only if the gasket is not completely sealing the skin towards the personal protection device.
[0112] FIG. 17 a diagram showing typical pressure response curves of different materials over compressive stress. The pressure response of the pressure-sensitive component is designed to be highly non-linear with regard to the compressive stress from the seal pressure in the pressure-sensitive component. The Young's Modulus of the pressure-sensitive component can be used to match the pressure response of the pressure-sensitive component with the minimum seal pressure threshold of a group of subjects. The midpoint of the pressure response curve is considered to be the optimal match with the minimum seal pressure threshold.
