Wearable measurement device for measuring a physiological parameter of a user
FIELD OF THE INVENTION
The present invention relates to a wearable measurement device for measuring one or more physiological parameters of a user wearing said device. BACKGROUND OF THE INVENTION
Heart rate monitors have been used in the field of leisure and sport for some years already. There are many makes of these devices. Typical devices have the form of a (e.g. ECG) chestband or wristband, e.g. including a sensor or the optical type that measures on the arm.
US 2009/048526 discloses a monitoring apparatus for monitoring a user's heart, the apparatus comprising several sensors for measuring changes in an electrical parameter of a user's arm, from which changes in an electrocardiogram, heart rate and/or heart rate variation of the user's heart are determinable. The apparatus further comprises a data processor for determining the electrocardiogram, the heart rate and/or heart rate variation from the changes in the electrical parameter; and an output device for making knowable to the user the electrocardiogram, heart rate and/or heart rate variation. A basic idea of the present invention is, to use only a single wristband, particularly a wrist watch, having all the means to monitor the user's heart, without using for example a chest band. Herein, the single wristband is at least provided with the at least one sensor and particularly also comprises the data processor, and more particularly also comprises the output device.
Other wearable measurement devices use conductivity sensors for measuring the conductivity of the skin to make use of the known fact that skin conductance of a user is related with the level of arousal of the user.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a wearable measurement device for measuring one or more physiological parameters of a user wearing said device that provides a higher accuracy, performance and reliability. In a first aspect of the present invention a wearable measurement device for measuring one or more physiological parameters of a user wearing said device is presented comprising:
a sensor for measuring at least one physiological parameter of the user (1), - a case housing said sensor (),
a positioning unit coupled to said sensor enabling a change of the position of said sensor with respect to the case, and
a fixation for fixing the wearable measurement device to the user's body.
Known wearable measurement devices, e.g. optical heart rate monitors in the form of a wristwatch, have no built in possibility for sensor adjustments to have the best position for the optimal signal. The only adjustment possibilities are either to adjust the tightness of the band or physically rotate the watch to another position.
The present invention overcomes these disadvantages of the known devices and allows for easy and convenient positioning of the sensor. The device may have the form of an arm or wrist worn device. During operation the signal quality is fed back to the user, and by use of the positioning unit the sensor position can be adjusted to find the optimum measurement area. This has the benefit of accurate and convenient positioning and improved performance of the device.
Currently there is no real-time feedback to inform the user how good the signal measured is. This means that the adjustment possibilities provided in known devices are purely for comfort as without real-time feedback no information regarding signal quality can be given and adjusted for. Hence, in a preferred embodiment a signal indicator is provided for indicating the signal quality of a sensor signal of said sensor. Preferably, said signal indicator is configured for visually and/or audibly indicating the signal quality of said sensor signal, in particular on a display, a light bar or LED chain.
In another embodiment said sensor is positioned in or on a side face of the case facing the user's body and said positioning unit is positioned on a different side face, in particular on a side face of the case facing away from the user's body. This allows easy access of the positioning unit for the user.
In another embodiment said device comprises at least two sensors for commonly or separately measuring said at least one physiological parameter of the user, wherein said positioning unit is coupled to at least one of said sensors, in particular to all sensors. This allows to use only the best measurement signal or to commonly use some or all sensor signal, e.g. after averaging and/or weighting. In an alternative embodiment the device comprises at least two sensors for measuring different physiological parameters of the user, wherein said positioning unit is coupled to at least one of said sensors, in particular to all sensors. In an even more elaborate embodiment the position of some or all sensors can be individually changed by the positioning unit, and individual signal indicators for some or all sensors may be provided.
The present invention can be used with different types of sensors. In an embodiment said sensor is an optical sensor comprising a light emitting element for emitting light to the user's skin and a light receiving element for receiving light reflected from the user's skin, wherein at least one, in particular both, of the light emitting element and the light receiving element is coupled to the positioning unit for allowing a user to change the position of said at least one element with respect to the case. This embodiment may, for instance, be used for heart rate monitoring. In another embodiment said sensor is an electrical sensor comprising two skin conductance electrodes for contacting the user's skin and measuring conductivity the user's skin, wherein at least one electrode, in particular both electrodes (), is coupled to the positioning unit for allowing a user to change the position of said at least one electrode with respect to the case. This embodiment may, for instance, be used for stress monitoring.
Also the case may have different forms and may be configured for attachment to different parts of the user's body. In a preferred embodiment, said case is substantially disk-shaped, wherein said sensor is arranged off-centre of a rotation axis and is rotatable around said rotation axis by use of the positioning unit. Preferably, said case has substantially the form of a round disk having a central rotation axis wherein said sensor is arranged off- centre of said central rotation axis and is rotatable around said central rotation axis by use of the positioning unit. Still further, said positioning unit comprises a rotatable ring arranged in or on a flat surface of said disk-shaped case facing away from the user and a mechanical coupling to said sensor for rotating said sensor around said rotation axis. This allows for easy positioning of the sensor by the user.
In a practical embodiment said fixation is configured for fixing the device to a user's arm or leg, in particular in the form of a wristband or one or more straps. For instance, said case is the case of a wristwatch, multi-sport computer or heart-rate monitor.
As mentioned, said positioning unit is preferably configured for manually changing the position of said sensor with respect to the case by the user. However, it may also be provided in another embodiment that said positioning unit is configured to automatically change the position of said sensor with respect to the case based on the sensor signal. Thus, there is a feedback from the sensor to the positioning unit so that the positioning unit can change the position of the sensor unit the best signal quality or a signal quality above a desired level is obtained. BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. In the following drawings:
Fig. 1 shows a cross section through a first embodiment of a device according to the present invention,
Fig. 2 shows a cross section through a second embodiment of a device according to the present invention,
Fig. 3 shows a top view and a bottom view of a third embodiment of a device according to the present invention,
Fig. 4 shows a cross section through a fourth embodiment of a device according to the present invention, and
Fig. 5 shows a cross section through a fifth embodiment of a device according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 shows a cross section through a first embodiment of a wearable measurement device 10 for measuring one or more physiological parameters of user 1 wearing said device according to the present invention. It comprises a sensor 12 for measuring at least one physiological parameter of the user 1, a case 14 housing said sensor 12, a positioning unit 16 coupled to said sensor 12 enabling a change of the position of said sensor 12 with respect to the case, and a fixation 18 for fixing the wearable measurement device 10 to the user's body.
The sensor 12 may be a heart rate monitoring sensor for measuring the heart rate. But generally, the particular kind of sensor that measures one or more physiological parameters (e.g. heart rate, blood pressure, breathing rate, skin conductivity, skin humidity, etc.) is not essential for the present invention.
The case 14 may be a housing, e.g. of the type of a wristband, a wristwatch or monitoring device as used in sports. The particular kind and form of case 14 is also not essential for the present invention, but mainly serves to hold the sensor 12 at a desired position with respect to the user 1 and to optionally house further elements like a battery, a processing unit, a display, a user interface, etc.
In this embodiment the positioning unit 16 preferably comprises an interface element 161 and a coupling 162 between the interface element 161 and the sensor 12. By use of the interface element 161, e.g. by turning or moving a knob or a switch representing the interface element 161 as indicated by the arrows 163, the user can change the position of the sensor 12 as indicated by the arrows 164.
The fixation 18 comprises, in this embodiment, a strap for fixing the device 10 to an arm or leg of the user 1. Again, the particular form and arrangement of the fixation 18 is not essential for the present invention, as long as it is ensured that the case 14 can be attached to the desired part of the user's body. Hence, the particular design of the fixation 18 is generally correlated with the design and type of the sensor 12.
By changing the position of the sensor 12 the signal quality of the sensor signal can be changed and it can, for instance, be search for the position delivering the optimum signal quality.
Fig. 2 shows a cross section through a second embodiment of a device 20 according to the present invention. In this embodiment the optical sensor 22 is placed at the bottom of the case 24 and is configured for heart rate monitoring. The sensor 22 comprises a light emission device 221 (in particular an LED) for emitting light onto the user's skin and a light receiving device 222 (in particular a photo detector such as a photo diode) for receiving light reflected from the user 1. Similarly to the first embodiment the positioning unit 26 comprise one or more interface elements 261, 262 and one or more couplings 263, 264 to either the light emission device 261 and/or the light receiving device 262 for commonly or individually changing the position of the light emission device 263 and/or the light receiving device 264. Alternatively, a common coupling could be provided from a single interface element to the complete sensor 22, e.g. a sensor cover, to change the position of the whole sensor 22.
Additionally, in this embodiment a signal indicator 23 is provided for indicating the signal quality of a sensor signal of said sensor. For this purpose the signal indicator 26 is coupled to the sensor 22. Preferably, said signal indicator 23 is configured for visually and/or audibly (e.g. on a small loud speaker) indicating the signal quality of said sensor signal, in particular on a display, a light bar or LED chain.
A top view (Fig. 3A) and a bottom view (Fig. 3B) of a practical implementation of the device 30 are shown in Fig. 3. The case 34 of the device 30 is implemented as a kind of watch or is implemented in a real watch having a wristband 38. The positioning unit 36 comprises an adjustment ring 361 representing common positioning elements 261, 262 on top (in this example) of the device 20 (see Fig. 2). The user can rotate the ring 361, which in turn rotates the sensor 32 (as indicated by the arrow 362 in Fig. 3B) located underneath the watch in or on the bottom side of the watch facing the user's skin.
In this implementation the sensor 32 (comprising, in this embodiment, a single photo detector 321 and two LEDs 322) is mounted off centre, so to allow for it to travel over the top of wrist, i.e. rotate about a central axis 35, to a position where the blood flow can be better measured and gives a better signal for heart rate detection. The off centre mounting enables the search for areas where the blood flow would give a better signal. A real-time feedback displayed on the display 33 tells the user when the optimum position has been found.
It shall be noted that the rotation axis of the sensor 32 must not coincide with the central axis 35 of the device 30, but the sensor 32 can also be rotated about a rotation axis of the sensor, i.e. a central axis of the sensor 32, about which part of or the total sensor 22 can be rotated.
As mentioned, in this embodiment the adjustment ring 361 on the watch face 37 is mechanically coupled to the sensor 32 at the bottom side 39 of the watch 30. The sensor 22is mounted off centre to enable the sensor to move to another position. The sensor position selector of the positioning unit can, however, also be arranged at another position on the watch and / or designed differently. In this example it is placed on top of the watch as it allows the user to see the rotation angle easily.
Still another embodiment of a device 40 according to the present invention, which is partly identical to the device 10 shown in Fig. 1, is depicted in Fig. 4. In this embodiment the sensor signal of the sensor 42 is fed back to the positioning unit 46 which is configured for automatically changing the position of the sensor 42 unit an optimal position is found delivering an optimum signal quality or until a certain condition is met, e.g. if a threshold for the signal level or another signal- related parameter (e.g. signal amplitude, signal-to-noise ratio, etc) is achieved. The positioning unit 42 can thus be arranged completely within the case 44. In addition, optionally in certain embodiments, a manual positioning interface, as shown in Fig. 1, could be provided.
In other embodiments the device may be designed as a stand-alone device of a new type, e.g. having a case of a slice-shaped form. Still another embodiment of a device 50 according to the present invention is shown in Fig. 5. In this embodiment in the case 54 at least two sensors 521, 522 are provided for measuring different physiological parameters of the user 1. For instance, one sensor 521 is an optical sensor and the other sensor 522 is an electrical sensor. The sensor 522 comprises two skin conductance electrodes 523, 524 for contacting the user's skin and measuring conductivity the user's skin, wherein at least one electrode, in particular both electrodes 523, 524, is coupled to the positioning unit 562 for allowing a user to change the position of said at least one electrode with respect to the case 54.
Generally, the positioning elements 561, 562 are coupled separately to a respective sensor 521, 522, but one common positioning element would also be possible.
In quite a similar embodiment (which is not shown) the two sensors 521, 522 are provided for commonly or separately measuring said at least one physiological parameter of the user 1. In this embodiment the sensor signals could be evaluated so that only the sensor signal with the highest quality is used, or the sensor signal are averaged or weighted.
The present invention allows for a simple, convenient and yet effective way for the user to find the optimal position for measuring a physiological parameter such as the heart rate. Further benefits include improved robustness for the signal processing and reduced errors in the system.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.
In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
Any reference signs in the claims should not be construed as limiting the scope.