Abstract
A measurement device (1) for measuring at least one vital parameter is provided. The measurement device (1) comprises a base body (2), a fixing means (10) and at least one sensor (5). The at least one sensor (5) is mounted in a damped manner, in particular actively damped, by a means for pressure regulation (7) in the base body (2), in particular in a recess (3) of the base body (2). Furthermore, a measurement system with a measurement device (1) according to the invention, a method for determining a pressure with which the sensor (5) of the measurement device lies on the skin of the patient, a method for measuring at least one vital parameter and a use of the measurement device for determining at least one vital parameter are provided.
Claims
1. Measurement device (1) for measuring vital parameters, comprising: a base body (2); a fixing means (10); and at least one sensor (5), characterized in that the at least one sensor (5) is mounted in a damped manner, in particular actively damped, by a means for pressure regulation (7) in the base body (2), in particular in a recess (3) of the base body (2).
2. Measurement device (1) according to claim 1, characterized in that the at least one sensor (5) is elastically mounted in the base body (2), in particular in the recess (3) of the base body (2).
3. Measurement device according to claim 1, characterized in that the level of damping or the elasticity of the mounting are adjustable by the means for pressure regulation (7).
4. Measurement device according to claim 3, characterized in that the damping is adjustable by the means for pressure regulation (7) in dependence of an external force (Fa) acting on the sensor (5), in particular automatically adjustable, in particular for reduction or elimination of an effect of the external force (Fa) on the sensor (5).
5. Measurement device according to claim 3, characterized in that the contact pressure of the at least one sensor (5) is adjustable in a measuring position by the means for pressure regulation (7), in particular automatically adjustable, further in particular in dependence of a or the external force (Fa).
6. Measurement device according to claim 4, characterized in that the measurement device, in particular the means for pressure regulation (7), comprise at least one further sensor for the determination of the external force (Fa) and/or the contact pressure, for example a force sensor, a pressure sensor, a movement sensor or acceleration sensor or a position sensor.
7. Measurement device according to claim 3, characterized in that the measurement device, in particular the means for pressure regulation (7), comprises at least one of the following for the adjusting of the level of damping or the elasticity of the mounting: servomotor (72), torsion bar, camshaft, spindle (73), eccentric disk, solenoid valve or solenoid and plunger, one or more magnets or electromagnets, electrode or electrode pair, in particular capacitor, tension spring, pressure spring, membrane, hydraulic or pneumatic element, such as e.g. a piston (74), a cylinder (75), a pressure chamber or air cushion, a gas spring, mechanical component made of an electrically deformable material, in particular made of an electroactive elastomer or piezo material.
8. Measurement device (1) according to claim 1, characterized in that the at least one sensor (5) comprises at least one pressure measurement unit.
9. Measurement device (1) according to claim 1, characterized in that the at least one sensor (5) is mounted in a or the recess (3) of the base body (2) by at least one spring element (6), in particular by two, three, four or more springs (6a), e.g. metallic helical springs.
10. Measurement device (1) according to claim 9, characterized in that the at least one spring element (6) is an elastic band and/or an elastomer, in which the at least one sensor (5) is embedded.
11. Measurement device (1) according to claim 1, characterized in that the at least one sensor (5) is plane, bent and/or flexible.
12. Measurement device set comprising at least one measurement device (1) according to claim 9 and at least one further spring element (6), which is configured to replace the available at least one spring element (6) or to mount with it the at least one sensor (5), in particular in series or parallel connection.
13. Measurement system (50) comprising a measurement device (1) according to claim 1 and a computer (51) connected to the measurement device (1) for entering of patient-related information and/or reading of measured vital parameters, wherein the patient-related information comprises in particular age, sex, fitness level, pre-existing conditions such as for example diabetes or COPD, or skin texture, and wherein the computer (51) is arranged either at the measurement device (1) or designed separately, in particular in form of a mobile phone.
14. Method for determining a pressure with which the sensor (5) of a measurement device of a measurement system (50) according to claim 13 lies on the skin of the patient, comprising: setting the pressure by the computer (51) based on an algorithm saved in the computer (51), in particular an iterative algorithm, optionally further based on at least one patient-related information, again optional further based on at least one value such as movement or acceleration, time, position of the sensor (5) relatively to the standard fixation to the body and gravity.
15. Method for measuring at least one vital parameter comprising: arrangement of the measurement device (1) of a measurement system (50) according to claim 13 on the patient; entering of at least one patient-related information in the computer (51) of the measurement system (50) according to claim 13 or retrieving of at least one saved patient-related information from the computer (51) of the measurement system (50) according to claim 13; adjustment of the pressure with which the sensor (5) of the measurement device lies on the skin based on the at least one patient-related information.
16. Method according to claim 15, further comprising: carrying out at least one initial measurement of at least one vital parameter for obtaining at least one initial measurement value; adjustment of the pressure with which the sensor (5) of the measurement device lies on the skin based on the at least one patient-related information and the at least one initial measurement value.
17. Method for checking the setting of the pressure with which the at least one sensor (5) of a measurement device (1) according to claim 1 lies on the skin, comprising: determining a first measurement value of a vital parameter, while the at least one sensor (5) lies on the skin with a preset pressure. decreasing the preset pressure of the at least one sensor (5), in particular by lifting the at least one sensor (5) from the skin and/or by adjusting the level of the damping or the elasticity of the mounting of the sensor (5); determining a second measurement value of the vital parameter, while the at least one sensor (5) lies on the skin with the lowered pressure; increasing the lowered pressure of the at least one sensor (5), in particular to the preset pressure and/or in particular by lowering the at least one sensor (5) form the skin and/or by adjusting the level of damping or the elasticity of the mounting of the sensor (5); comparing the first measurement value and the second measurement value.
18. Method for calibrating and/or adjusting the pressure with which the at least one sensor (5) of the measurement device (1) according to claim 1 lies on the skin, comprising: determining a first measurement value of a vital parameter, while the at least one sensor (5) lies on the skin with a preset pressure. changing the preset pressure of the at least one sensor (5), in particular decreasing of the preset pressure of the at least one sensor (5), preferably by lifting the at least one sensor (5) from the skin and/or by adjusting the level of damping or the elasticity of the mounting of the sensor (5); determining a second measurement value of the vital parameter, while the at least one sensor (5) lies on the skin with the changed, or in particular lowered pressure; comparing the first measurement value and the second measurement value; adjusting the pressure with which the at least one sensor (5) of the measurement device lies on the skin based on the comparison of the first measurement value and the second measurement value, in particular by lowering the pressure in case of a deviation of the measurement values by 0.2% or more; and/or calibrating the pressure specified by an algorithm with which the at least one sensor (5) should lie on the skin based on the comparison of the first measurement value and the second measurement value, in particular by lowering the specified pressure in case of a deviation of the measurement values by 0.2% or more.
19. Method for calibrating and/or adjusting the pressure with which the at least one sensor (5) of the measurement device (1) according to claim 1 lies on the skin, comprising: determining a first measurement value of a vital parameter, while the at least one sensor (5) lies on the skin with a preset pressure. changing the preset pressure of the at least one sensor (5), in particular decreasing of the preset pressure of the at least one sensor (5), preferably by lifting the at least one sensor (5) from the skin and/or by adjusting the level of damping or the elasticity of the mounting of the sensor (5); determining a second measurement value of the vital parameter, while the at least one sensor (5) lies on the skin with the changed, or in particular lowered pressure; changing the changed pressure, in particular by increasing the changed, or lowered pressure of the at least one sensor (5), in particular to the preset pressure or a pressure deviating from it, preferably by lowering the at least one sensor (5) from the skin and/or by adjusting the level of the damping or the elasticity of the mounting of the sensor (5); determining a third measurement value of the vital parameter, while the at least one sensor (5) lies on the skin with the again changed, or in particular increased pressure; comparing the first measurement value and the second measurement value and/or comparing the first measurement value and the third measurement value; adjusting the pressure with which the at least one sensor (5) of the measurement device lies on the skin based on the comparison of the first measurement value and the second measurement value and/or based on the comparison of the first measurement value and the third measurement value, in particular by lowering the pressure in case of a deviation of the measurement values by 0.2% or more; and/or calibrating the pressure specified by an algorithm with which the at least one sensor (5) should lie on the skin based on the comparison of the first measurement value and the second measurement value and/or based on the comparison of the first measurement value and the third measurement value, in particular by lowering the specified pressure in case of a deviation of the measurement values by 0.2% or more.
20. Use of a measurement device according to claim 1 for determining at least one of the following vital parameters: blood pressure; pulse; blood sugar; oxygen saturation; temperature; skin texture; moisture.
21. Use according to claim 20 for determining at least one of the following values: movement or acceleration; pressure of the sensor on the skin; time; position of the sensor (5) relatively to the standard fixation at the body; gravity.
Description
[0065] FIG. 1 a schematic depiction of a measurement device for vital parameters according to the state of the art;
[0066] FIG. 2 a schematic depiction of a measurement device for vital parameters according to the invention;
[0067] FIG. 3 a schematic depiction of an embodiment of a measurement device for vital parameters according to the invention;
[0068] FIG. 4 a schematic depiction of an embodiment of a measurement device for vital parameters according to the invention;
[0069] FIG. 5a a schematic side view of an embodiment of a measurement device for vital parameters according to the invention;
[0070] FIG. 5b a schematic longitudinal section of the embodiment of a measurement device for vital parameters shown in FIG. 5a;
[0071] FIG. 6a a schematic longitudinal section of a measurement device for vital parameters according to the invention in a first position of the sensor;
[0072] FIG. 6b a schematic longitudinal section of a measurement device for vital parameters according to the invention in a second position of the sensor;
[0073] FIG. 7a a schematic depiction of an embodiment of a measurement device for vital parameters according to the invention;
[0074] FIG. 7b a schematic longitudinal section of the embodiment of a measurement device for vital parameters according to the invention shown in FIG. 7a in a first position of the sensor;
[0075] FIG. 7c a schematic longitudinal section of the embodiment of a measurement device for vital parameters according to the invention shown in FIG. 7a in a second position of the sensor;
[0076] FIG. 7d a schematic longitudinal section analogous to FIG. 7b with forces drawn in;
[0077] FIG. 7e a schematic longitudinal section analogous to FIG. 7c with forces drawn in;
[0078] FIG. 8a a schematic depiction of a measurement system for vital parameters according to the invention;
[0079] FIG. 8b a schematic depiction of a pressure measurement sensor;
[0080] FIG. 9a a schematic longitudinal section of a measurement device for vital parameters according to the state of the art in which the sensor is rigidly connected with the case (or the base body);
[0081] FIG. 9b a schematic longitudinal section of an exemplary measurement device for vital parameters according to the invention with a servomotor-based means for pressure regulation;
[0082] FIG. 9c a schematic longitudinal section of an exemplary measurement device for vital parameters according to the invention with a piston-based means for pressure regulation;
[0083] FIG. 9d a schematic longitudinal section of an exemplary measurement device for vital parameters according to the invention with an air cushion-based means for pressure regulation;
[0084] FIG. 9e a schematic longitudinal section of an exemplary measurement device for vital parameters according to the invention with a solenoid valve-based means for pressure regulation;
[0085] FIG. 9f a schematic longitudinal section of an exemplary measurement device for vital parameters according to the invention with a capacitor-based means for pressure regulation;
[0086] FIG. 9g a schematic longitudinal section of an exemplary measurement device for vital parameters according to the invention with a membrane-based means for pressure regulation; and
[0087] FIG. 10 a schematic depiction of a comparative measurement between a measurement device 100 from the state of the art and a measurement device 1 according to the invention.
[0088] FIG. 1 shows a measurement device for vital parameters 100 known from the state of the art, shown in a view that allows the view on the site of the measurement device 100 which for the measurement is laid onto the skin of the patient, the so-called underside. The measurement device 100 comprises a base body 2 in which the at least one sensor 5 is embedded for measuring at least one vital parameter and rigidly connected. For example, the sensor 5 can be screwed with the base body 2 or glued in a recess in the base body 2 adapted to the form of the sensor. To at least temporary attach the measurement device 100 to the arm or any another body part of the patient, such as for example of the trunk, the measurement device 100 further comprises a fixing means 10, such as here for example an elastic two-piece band, which can be closed to a ring by a two-piece fastening 21,22. The fastening depicted here corresponds to an eyelet as first fastening piece 21 and a hook as second fastening piece 22. The total length of the measurement device 100 including base body 2, band 10 and the fastening pieces 21,22 is chosen in such a way that it sits tightly or fixed at the specified body part in closed state, so that it cannot slip, optimally also not while moving, as e.g. a physical activity such as jogging or the like. Alternatively, the measurement device 100 can also have a means for the adjustment of the total length of the measurement device 100. For example, at least one or both pieces of the band 10 are adjustable in length (note: it is not the case in the shown measurement device 100). The fixed sit of the measurement device 100 at a body part of the patient ensures that not only the band 10 and the base body 2 of the measurement device 100 are tightly pressed onto the skin of the corresponding body part, but that also the sensor 5 presses on it with the same force.
[0089] Consequently, the resulting interaction between the measurement device and the system to be measured ensures that an intervention in the system takes place changing it, so that measurement device 100 determines a value for a vital parameter which maybe would be correct as single value, but which does not correspond to the measurement value present in the rest of the body, and which is intended to be measured. The actual value is after all the one that is present in the body when no interaction takes place.
[0090] FIG. 2 shows a measurement device for vital parameters 1 according to the invention. The latter is also shown in a view that allows the view on the site of the measurement device 1 which for the measurement is laid onto the skin of the patient, the so-called underside. The measurement device 1 comprises a base body 2 at which, on two opposite sides, an elastic two-piece band 10 is arranged for the fixation at a body part. This two-piece band 10 can be for example closed by a hook-and-eyelet closure 21,22. On the contrary to the previously known measurement device shown in FIG. 1, the sensor 5 of the measurement device according to the invention of FIG. 2 is not rigidly connected with the base body 2. Moreover, the sensor 5 is elastically mounted in a recess 3 in the base body 2 by four spring elements 6 (for the sake of clarity only two of the four springs are marked by reference signs). In the shown embodiment the recess 3 has a rectangular ground view and the springs 6 are tensioned starting from the edges of the recess 3 up to the here round sensor 3. In an alternative embodiment the sensor 5 can be mounted with also e.g. 1, 2, 3, 4, 5, 6 etc. spring elements 6. The spring elements 6 illustrate here a movable and elastic element, which could also be an elastomer etc.
[0091] FIG. 3 shows an embodiment of a measurement device for vital parameters 1 according to the invention. The latter is also shown in a view that allows the view on the site of the measurement device 1 which for the measurement is laid onto the skin of the patient, the so-called underside. The measurement device 1 comprises a base body 2 at which, on two opposite sides, an elastic two-piece band 10 is arranged for the fixation at a body part. This two-piece band 10 can be for example closed by a snap-fit 21,22. Also here the sensor 5 is not rigidly connected with the base body 2. Moreover, the sensor 5 is elastically mounted by a spring element 6. In the shown embodiment the recess 3 has a round ground view in which the spring element 6, here a mass of an elastomer, is recessed, in which mass the sensor 5 is embedded.
[0092] FIG. 4 shows an embodiment of a measurement device for vital parameters 1 according to the invention. The latter is also shown in a view that allows the view on the site of the measurement device 1 which for the measurement is laid onto the skin of the patient, the so-called underside. The measurement device 1 comprises a base body 2 at which, on two opposite sides, an elastic two-piece band 10 is arranged for the fixation at a body part. This two-piece band 10 can be for example be closed by a velcro 21,22. Also here the sensor 5 is not rigidly connected with the base body 2. Moreover, the sensor 5 is elastically mounted in a recess 3 in the base body 2 by two spring elements 6 in form of two elastic bands. These are terminally connected with the recess 3 and centrally connected with the sensor 5, behind which they pass through. Instead of a band 6 that passes behind the sensor 5 also two elastic bands 6 can be applied, which then are arranged each via one site at the base body 2 and each via the other site at the sensor 5. In this way the elastic band 6 does not have to be passed behind the sensor 5.
[0093] FIG. 5a shows an embodiment of a measurement device for vital parameters 1 according to the invention in a side view. This measurement device 1 is especially suitable for the measurement on the finger of a patient. Base body 2 and fixing means 10 are here one and are formed by the upper site and the underside of a clamp which can be opened and closed as closure by a spring 20. The elements which actually would not be visible in the side view are dashed. Hereto count, next to the material recess for the insertion of the finger (without reference sign), the recess 3 in which the sensor 5 is elastically mounted by e.g. two spring elements 6.
[0094] FIG. 5b shows the embodiment of a measurement device for vital parameters 1 according to the invention, shown in FIG. 5a, in a longitudinal view. Especially easy to see are in this depiction the recess 3 in which the sensor 5 is elastically mounted by two spring elements 6. Also, the anchoring of the spring elements 6 in the recess 3 of the bottom part of the clamp alias base body 2 and fixing means 10, schematically depicted as two eyelets, are clearly visible.
[0095] FIG. 6a shows a measurement device 1 according to the invention in a first position of the sensor 5 in a longitudinal view. FIG. 6b however shows the same measurement device 1, also in longitudinal view, but the sensor 5 is here in a second position. The measurement device 1 is comparable to the one in FIG. 2 with the difference that the sensor 5 is elastically mounted in the recess 3 of the base body 2 not only by four but by eight spring elements 6, wherein in the longitudinal view only four of these spring elements 6 are visible. The spring elements 6 are arranged in a manner that four of the spring elements 6 generate a pull up (so from the underside, that is away from the site of the measurement device 1 which contacts the skin while using) and four of the spring elements 6 generate a pull down (so to the underside). The base body 2 at which, on two opposite sides, an elastic two-piece band 10 is arranged for the fixation at a body part, appears in the longitudinal view as two pieces because of the recess 3, but in reality, it is formed as one piece. Unlike in FIG. 2, the elastic two-piece band 10 is not depicted in full length, as illustrated by the frayed ends. Accordingly, the closure is not visible. In said first position the spring elements 6 (here in the picture at the bottom), which are facing the skin of the patient (skin surface is schematically depicted as dotted line) are more tensioned than in the second position shown in FIG. 6b. Consequently, while wearing the measurement device 1 in the first position a stronger contact pressure is applied onto the skin of the patient than in the second position. In other words, the measurement device 1 with a sensor 5 mounted in the first position (sensor 5 at the same height as the base body 2 referenced to the site facing the skin of the patient) is more suitable for e.g. younger patients or while physical activities, that is in the case of a higher venous pressure. The measurement device 1 with the sensor 5 in the second position (sensor 5 pressed inwards resp. in the drawing pressed up, so with distance to the base body 2 and not flush with the base body 2 referenced to the site facing the skin of the patient) is however better suitable for e.g. older or resting patients with a lower venous pressure. The reason therefor is that the skin can expand in the generated recess (sensor 5 is pressed inwards) and thus the pressure under the sensor decreases.
[0096] FIG. 7a shows an embodiment of a measurement device for vital parameters 1 according to the invention. The latter is shown in a view that allows the view on the site of the measurement device 1 which for the measurement is laid onto the skin of the patient, the so-called underside. The measurement device 1 comprises a base body 2 at which, on two opposite sides, an elastic two-piece band 10 is arranged for the fixation at a body part. This two-piece band 10 can be for example closed by a hook-and-eyelet closure 21,22. The sensor 5 is elastically mounted in a recess 3 in the base body 2 by a spring element 6. The spring element 6 is dashed becauseviewed from the bottomit is behind the sensor 5 and connects there the sensor 5 with the base body 2 via the recess 3. Also dashed is a second sensor 5 which is e.g. a movement sensor and is not elastically mounted but rigidly embedded in the base body 2.
[0097] FIG. 7b shows a longitudinal view of the measurement device 1 depicted in FIG. 7a in a first position of the sensor 5. FIG. 7c however shows a comparable measurement device 1, also in longitudinal view, but the sensor 5 is here in a second position. The base body 2 does not seem like it is divided into two parts also in the longitudinal view despite the recess 3 because the recess 3 of this measurement device 1 is not a continuous opening in form of a clearance hole, but it only represents kind of a notch in the bottom part of the base body 2, in which notch the spring element 6 and then the sensor 5 were introduced. However, the second sensor 5 is directly framed in the base body 2 and it is not mounted in the recess 3. The elastic and two-pieced band 10 is only partially depicted, comparable to the FIGS. 6a and 6b. In said first position (see FIG. 7b) the spring element 6 is a strongly resp. stronger adjusted means for pressure regulation, the sensor 5 reaches up to the edge of the bottom part respectively the skin surface (dashed line). If the measurement device 1 is applied to the patient, the base body 2 presses with a first pressure onto the skin surface. However, the sensor 5, which is elastically mounted, only presses with a second, lower pressure onto the skin surface because thanks to the spring element 6 (e.g. a spherical elastomer) not the full fixing force of the base body 2 is transferred to the sensor 5 and thus pressure is taken away from the skin area where the at least one vital parameter should be measured. The choice of the spring element 6 can be used to set the contact pressure with which the sensor 5 finally lies on the skin.
[0098] The round spring 6, as depicted in FIG. 7b, corresponds to a strongly resp. strong adjusted means for pressure regulation (7) so that the measurement device 1 is suitable for higher venous pressures, and the oval spring 6, as depicted in FIG. 7c, corresponds to a weakly resp. weaker adjusted means for pressure regulation (7) so that the measurement device 1 in this case is suitable for lower venous pressures.
[0099] The FIGS. 7d and 7e show the measurement device 1 with sensor in a first and a second position analogous to the FIGS. 7d and 7e but the present force relationships, which define the contact pressure, are marked, the rest of the reference signs was not depicted for the sake of clarity. Marked are force F (force from the toparrow points downwards) and counterforce F (force from the bottomarrow points upwards), which are defined by applying the measurement device 1 to the patient and the strength of its fixation. Additionally, force and counterforce F.sub.s which are present in the area of the sensor are marked. With a relaxed spring element (FIG. 7d) the forces and counterforces F.sub.s are evenly distributed across the whole measurement device 1. So the same pressure prevails in the area of the sensor, as it is predefined by applying the measurement device 1. It is visible in FIG. 7e that the force and counterforce F.sub.s, and thus also the contact pressure is lower in the area of the sensor than the force and counterforce F in the area of the rest of the base body 2. By pressing together the spring element, the latter absorbs a part of the force F predefined by applying the measurement device 1 and so enables a lower contact pressure below the sensor.
[0100] FIG. 8a shows a measurement system for vital parameters 50 according to the invention. The shown embodiment of the measurement device 1 according to the invention of this measurement system 50 comprises a base body 2, which by fixing means 10 (only partially depicted, as illustrated by the jagged terminal lines) is attachable to the body of a patient. The base body 2 comprises a recess 3 in which the sensor 5 is elastically mounted by a spring element 6. The spring constant of the spring element 6 is adjustable, as symbolically implied by the screwdriver. Below the sensor 5, so between the sensor 5 and the skin surface of the patient (dashed line), another sensor 5 is arranged. The latter is a pressure measurement sensor 5 which can determine the contact pressure of the sensor 5. The pressure measurement sensor 5 can extend along the whole surface facing the skin surface of the patient or else only along a part of this surface (note: optical measurements through a measurement pressure sensor 5 as depicted in FIG. 8b are possible without any problems). The measurement pressure sensor 5 can also be formed as a pressure measurement unit comprised in the sensor 5. Connected to the measurement pressure sensor 5 and the spring element 6, or the apparatus for adjusting the spring constant of the spring element and also the sensor 5 (here depicted by physical connectionsof course any kind of wireless communication is also possible) is a computer 51, here exemplary represented by a mobile phone 51. The latter is capable of setting the contact pressure of the sensor 5 by the spring element 6 based on the patient-related information deposited in the mobile phone 51 and the provided algorithm. Moreover, the mobile phone 51 can read or save and/or depict the at least one measured vital parameter via the connection to the sensor 5. Because of the measurement pressure sensor 5, which is optional in the shown embodiment, and the connection to this measurement pressure sensor 5, the mobile phone 51 can also monitor the actual prevailing contact pressure and if necessary, correctively intervene. If the predetermined contact pressure and the actual prevailing contact pressure are different, the spring constant of the spring element 6 can be adjusted accordingly, so that actual value and nominal value do match.
[0101] FIG. 8b shows an embodiment of a measurement pressure sensor 5 as it can e.g. be applied in a measurement device according to the invention.
[0102] FIG. 9a shows a schematical longitudinal view of a measurement device 100 for vital parameters as known from the state of the art, in which the sensor 5 is rigidly connected with the casing (or the base body 2). The fixing means 10 are not marked in the FIG. 9a. In measurement devices 100 according to the state of the art the sensor 5 protrudes from the base body 2 and is, as visible in FIG. 9a, flush with the underside of the base body 2, which is laid on the skin. If an external force F.sub.a acts on the base body 2, this external force F.sub.a will be transferred to the underside of the base body 2 incl. to the sensor 5, where it acts as force F.sub.a on the skin surface. In this way the underside of the base body 2 is pressed together with the within rigidly arranged sensor 5 in the skin 8 lying below, resulting in that the vein 9 is squeezed and the blood flow through the vein 9 is affected or even stopped. Thereby also a measurement of vital values which are dependent from (largely undisturbed) blood flow through the vein 9 will be falsified, which of course is extremely undesirable.
[0103] In the following, solutions according to the invention are described, in which the sensor is mounted in an actively damped manner in the base body by the means for pressure regulation, in particular in a recess of the base body. The active damping of the sensor ensures that the contact pressure of the sensor onto the skin in the measurement area is (mostly) adjustable independently from an external force acting on sensor, or it is adjustable depending on the latter. Therefor e.g. the contact pressure is continuously monitored by a sensor and accordingly adjusted by an actuator of the means for pressure regulation. It means that a regulator ensures that the contact pressure remains constant, (mostly) independent from an external force acting on the base body, or it is always equal to a desired (e.g. adjustable) value. Alternatively, several components of the external force in the three spatial directions can be detected and equilibrated or eliminated e.g. by a triaxial (3D) acceleration sensor.
[0104] FIG. 9b schematically illustrates a longitudinal view of an exemplary measurement device 1 for vital parameters according to the invention in which the above-mentioned problem of the transfer of an external force F.sub.a to the sensor 5 is reduced, or even completely avoided by providing a means for pressure regulation 7 to the measurement device 1 according to the invention with which the sensor 5 is damped mounted in the base body 2, or as shown in FIG. 9b, it is damped arranged in a recess 3 of the base body 2. In the example of FIG. 9b a trapezoidal construction 71 is used as means for pressure regulation 7.sub.1, of which the height is adjustable by a servomotor 72 via a spindle 73, similar to a scissor jack. The contact pressure of the sensor 5 onto the skin 8 is measured by the sensor 5 or by a separate pressure sensor and depending on whether this contact pressure is above or below the desired contact pressure the position of the sensor 5 will be accordingly adjusted within the recess 3, it is the distance of the sensor 5 to the ceiling of the recess 3 is accordingly decreased or increased. As soon as an external force F.sub.a acts on the base body 2 it is automatically registered and the means for pressure regulation 7.sub.1 ensures that the contact pressure always corresponds to a desired (predetermined or adjustable) value. As visible in the FIG. 9b, the base body 2 is pressed, because of the external force F.sub.a, with the force F.sub.a on the edge of the base body 2 on the skin, so that the edge of the base body 2 protrudes into the skin. In order that the external force F.sub.a is not transferred to the sensor 5, the latter must be pulled in the recess 3 by the height h=d.sub.1d.sub.2 by the means for pressure regulation 7.sub.1. As soon as the external force F.sub.a is no longer present the sensor 5 is again driven down by h by the means for pressure regulation 7.sub.1. In this way the contact pressure of the sensor 5 onto the skin 8 is continuously monitored and always kept at the desired nominal value with the help of the means for pressure regulation 7.sub.1.
[0105] At this point it should be noticed that when multiple sensors 5 in the measurement device 1, it is, are arranged in the base body 2 by damped mounting, for every single each sensor 5 a means for pressure regulation 7 and a corresponding pressure sensor for the measurement of the contact pressure can be applied. Depending on the arrangement and purpose of the individual sensors 5 they alternatively can have a single or partially common means for pressure regulation 7 as well as a single or partially common pressure sensor for measurement of the contact pressure.
[0106] It should be further noticed that the electronics which receive and process the measurement signals from the sensor 5 as well as the energy supply for the sensor 5 (e.g. battery, accumulator or energy harvester) are detached from it and arranged in the base body 2 in a manner that no force transfer occurs via the necessary connections to the sensor 5. In that way also the mass (and size) of the sensor 5 are especially low so that its weight has only a small influence e.g. on the contact pressure, and the sensor 5 can be moved by the means for pressure regulation 7 without big effort.
[0107] Moreover, it should be noted that the damped mounting of the sensor further effects that not only forces vertical to the skin surface but also shear forces are reduced and even eliminated. So, the at least one sensor is mounted in a way that shear forces acting on the base body are transferred only on a reduced extent to no extent to the sensorand thus to the skin. This is of significant importance because among other factors such as compressive forces shearing strain in the development of a decubitus leads to the shifting of skin layers. The top layer of skin shifts, the lower layers of skin do not shift.
[0108] Consequently, this leads to a disorder of the blood circulation and to injuries which are not immediately visible.
[0109] FIG. 9c shows a schematic longitudinal view of a further exemplary measurement device 1 for vital parameters according to the invention with an alternatively realized means for pressure regulation 7.sub.2. In the means for pressure regulation 7.sub.2 in FIG. 9c a piston 74 is connected with the sensor 5, wherein the piston 74 is moved in a cylinder 75. If the volumes V.sub.1 and V.sub.2 are changed the piston 74 moves in the cylinder 75 and thus changes the position of the sensor 5 in the recess 3, e.g. the distance H between the sensor 5 and the ceiling of the recess 3. Thus, in turn, the distance H can always be adjusted by a suitable regulator in dependence of the measured contact pressure, so that the contact pressure always corresponds to the desired nominal value. To move the piston for example air or another fluid can be pumped from the one cylinder chamber in the other, so that the two volumes V.sub.1 and V.sub.2 accordingly change in the opposite direction. In addition also (each) a spring could be arranged in the cylinder chamber(s)similar to the gas spring.
[0110] FIG. 9d shows a schematic longitudinal view of a further exemplary measurement device 1 for vital parameters according to the invention with a further alternatively realized means for pressure regulation 7.sub.3. In this case the means for pressure regulation is realized as air cushion. If the volume is reduced from V to V, the position of the sensor 5 in the recess 3 changes, that is the distance H between the sensor 5 and the ceiling of the recess 3 decreases because the sensor 5 is connected to the air cushion 7.sub.3. In this way, in turn, the distance H can always be adjusted by a suitable regulator in dependence of the measured contact pressure, so that the contact pressure always corresponds to the desired nominal value. To change the volume V e.g. air (or another fluid) is pumped in or out the air cushion.
[0111] FIG. 9e shows a schematic longitudinal view of a further exemplary measurement device 1 for vital parameters according to the invention with a further alternatively realized means for pressure regulation 7.sub.4. In this case the means for pressure regulation is realized as solenoid valve 7.sub.4 composed of an electric coil (solenoid) 76 and a plunger movably arranged in the coil. If the current through the coil 76 is changed, the plunger 77 accordingly moves in or out the latter and changes in this way the position of the sensor 5 in the recess 3, that is the distance H between the sensor 5 and the ceiling of the recess 3 because the sensor 5 is connected to the plunger 77. In this way, in turn, the distance H can always be adjusted by a suitable regulator in dependence of the measured contact pressure, so that the contact pressure always corresponds to the desired nominal value.
[0112] FIG. 9f shows a schematic longitudinal view of a further exemplary measurement device 1 for vital parameters according to the invention with a further alternatively realized means for pressure regulation 7.sub.5. In this case the means for pressure regulation is implemented as electrical capacitor 7.sub.3. It is composed of two parallel capacitor plates E.sub.1, E.sub.2 of which the one is connected with the sensor 5 and movable relative to the other capacitor plate arranged on the ceiling of the base body. If electrical charge is shifted by a current from the one capacitor plate E.sub.1 to the other capacitor plate E.sub.2, the electric field between the two capacitor plates E.sub.1, E.sub.2 changes, which then accordingly, more or less attract each other so whereby the capacitor plates E.sub.1 shift relative to capacitor plates E.sub.2 and the distance A between the two capacitor plates E.sub.1, E.sub.2 changes. Accordingly, the distance A can always be adjusted by a suitable regulator in dependence of the measured contact pressure, so that the contact pressure always corresponds to the desired nominal value.
[0113] FIG. 9g shows a schematic longitudinal view of a further exemplary measurement device 1 for vital parameters according to the invention with a further alternatively realized means for pressure regulation 7.sub.6. In this case the means for pressure regulation is formed as (spring) membrane 7.sub.6 made of an electroactive material of which the stiffness is modifiable by applying an electric voltage. If e.g. the voltage applied on the membrane 7.sub.6 is increased, the stiffness of the membrane increases thereby lifting the with it connected sensor 5, so that the distance H between the sensor 5 and the ceiling of the recess 3 is reduced. Accordingly, the distance H can always be adjusted by a suitable regulator in dependence of the measured contact pressure, so that the contact pressure always corresponds to the desired nominal value.
[0114] At this point it should be noticed that the means for pressure regulation 7 can reduce/compensate not only external forces F.sub.a in the vertical direction to the skin surface (as shown in the FIGS. 9b-g) but also that according to the invention, the means for pressure regulation 7 can work in all three dimensions/spatial directions (and thus compensate). In this way it is also possible to (partially) compensate or reduce external forces such as the gravity or forces which act on the sensor due to movements and due to the position of the wearer of the measurement device, and in particular to keep the sensor in a desired measuring position (while sitting, lyingindependent from the position or orientation direction of the sensorand running, where ever-changing (external) movement forces act on the sensor).
[0115] FIG. 10 shows a comparison of measurements of oxygen saturation in the blood taken with a measurement device 100 known from the state of the art and a measurement device 1 according to the invention. The male patient on whom the test measurements were taken was 69 years old at the time of measurement and smoker, however not an excessive drinker and no pre-existing conditions such as e.g. COPD or asthma were known. His skin can be described as older and therefor saggy, and damaged from the sun. His fitness level was passable even if not well to very well trained. Nevertheless, his pulse normalizes comparably fast after a physical effort because he was very active in sports in his younger years (skiing, jogging, cycling and body building). The graphic compares the oxygen saturation in [%] which was recorded on one day from 9.55 o'clock to 14.40 o'clock with a conventional measurement device 100 (thick solid line) and a measurement device 1 according to the invention (thick dashed line). The measurement devices were arranged on the upper arm of the patient. During the measurement time, strictly speaking between 12.20 o'clock and 13.20 o'clock, the patient was not resting and instead, he was physically active by cycling. It is clearly visible that the oxygen saturation measured by the conventional measurement device 100 greatly fluctuates (between 88% and 95%), whereas the values measured by the measurement device 1 according to the invention at a contact pressure of ca. 13 mmHg were quasi constant and above 96%. The difference of the values between 95% and 96%, in particular in the rest phase, can happen due to the measurement with two different measurement devices 1, 100 and these have a certain tolerance. However, it also becomes apparent that the conventional measurement device 100 determines in the rest phase an oxygen saturation which tends to be too low. Reason for this would be that the blood flow below the sensor is already affected by the too high contact pressure. The difference becomes seriously and definitively evident in the phases in which the body of the patient comes to rest again after the activity (cool down phase still while sitting on the bicycle and first rest phase while sitting). Although the actual oxygen saturation practically does not change in this phase, the conventional measurement device 100 indicated, misdirected by the changing venous pressure of the patient, a great fluctuation of the oxygen saturation. In particular, in this example the deviation during the physical activity is evident only towards the end because:
[0116] A) the contact pressure is relatively low but still above 11 mmHg. The patient is 69 years old.
[0117] B) in the beginning different internal venous pressures predominate. The upper arm moves during the exertion (cycling) which supports the blood circulation plus the muscles in the veins. Under physical exertion the pressure of the sensor can be significantly increased because of the movement, the increased pulse, and the blood pressure without any change of the measurement values because the blood flow under the sensor is still guaranteedalso by movement.
[0118] C) at the end of the exertion (cycling) there is the cool down phase. The pulse drops from about 145 to 90, then the patient moves, moves his position on the sofa. Finally, when the patient recovered, the values are identical to the initial values, the internal venous pressure stabilized.
[0119] D) the adjusted pressure of the sensor compensates these fluctuations in the course of the day.
[0120] E) the sensor of the measurement device 100 according to the state of the art has a contact pressure of about 25-30 mmHg (the exact value is difficult to determine because the upper arm has different diameters and the sensor does not always lie the same thereon).
LIST OF REFERENCE SIGNS
[0121] 1 measurement device for vital parameters [0122] 2 base body [0123] 3 recess [0124] 5 sensor [0125] 6 spring element [0126] 7 means for pressure regulation: [0127] 7.sub.1 means for pressure regulation with servomotor and trapezoidal construction (scissor jack) [0128] 7.sub.2 means for pressure regulation with piston [0129] 7.sub.3 means for pressure regulation with air cushion [0130] 7.sub.4 means for pressure regulation with magnet valve [0131] 7.sub.5 means for pressure regulation with capacitor (plates) [0132] 7.sub.6 means for pressure regulation with electroactive membrane [0133] 71 trapezoidal construction [0134] 72 servomotor [0135] 73 spindle [0136] 74 piston [0137] 75 cylinder [0138] 76 coil/solenoid [0139] 77 plunger [0140] 8 skin surface [0141] 9 vein [0142] 10 fixing means [0143] 20 closure [0144] 21 first part of the closure [0145] 22 second part of the closure [0146] 50 measurement system [0147] 51 computer [0148] 100 measurement device according to the state of the art [0149] A distance of the capacitor plates [0150] d.sub.1 distance between the ceiling of the recess and the skin surface without external force on the base body [0151] d.sub.2 distance between the ceiling of the recess and the skin surface with external force on the base body (<d.sub.1) [0152] E.sub.1 movable capacitor plate [0153] E.sub.2 fixed capacitor plate [0154] F force [0155] F.sub.s force sensor [0156] F.sub.a external force [0157] F.sub.a external force transferred to the skin surface [0158] H distance of the sensor to the ceiling of the recess [0159] V, V volume of the air cushion [0160] V.sub.1 first cylinder volume [0161] V.sub.2 second cylinder volume
