DE102008022919A1 - Device for optimized pulse measurement of heart of person during e.g. medical diagnosis, has detector for detecting light reemitted from skin tissue, and emitter emitting light with wavelength in given range of specific Newton meter - Google Patents

Abstract

The device has optical sensors (S1-S3) consisting of emitters (E1-E3) e.g. LEDs, for emitting light on a skin tissue (HG), detectors (D1-D3) e.g. photodiodes, for detecting light reemitted from the skin tissue, and an evaluation unit (AW). The emitter emits light with a wavelength in a given range of 520 Newton meter (nm) to 600 nm. The sensors are arranged according to a criterion of highest probability for optimal readings. An acceleration sensor (BS) is provided for measurement of body movement.

Description

Technical area

The The invention generally relates to the technical field of signal processing. In particular, the subject invention relates to a device for optimized pulse measurement and an associated Method. The device comprises at least one optical Sensor consisting of an emitter for emitting light on a section a dermal tissue and a detector for receiving it Skin tissue remitted light and an evaluation unit. Further relates The invention relates to a method for optimized pulse measurement using the device according to the invention.

State of the art

to it is also medical diagnostics or sports diagnostics necessary to partially override the heart activities of a person to be able to control and interpret for a longer period of time.

heart activities such as the heartbeat are visible in the so-called pulse - a blood wave through the vascular system, which by a contraction of the heart muscle. The heart rate or heart rate is given in pulses per minute. The pulse measurement is next The frequency of the heartbeat also provides information about one Regularity of the heartbeat, about a pressure rise rate, above the absolute pressure as well as a filling volume of the vessels.

A Measurement of the pulse can z. B. done in different ways. The simplest method is, for example, a manual measurement, in which the pulse z. B. at the wrist thumb (radial pulse) or on the neck (carotid pulse) and then counted the pulse become. Apart from the fact that this method is very inaccurate and usually only in emergencies to determine, if at all a pulse is present, it is for one longer-term control and monitoring of the pulse not suitable.

in the Hospital area or in medical practices, the measurement of the pulse z. B. mostly performed in the context of the so-called electrocardiogram (ECG), from the signal not only the pulse rate, but a course a heartbeat can be read. To measure an ECG at least two electrodes are used, which are usually be attached to the arms or chest area and each on opposite Sides of the heart must lie. However, during an investigation in the hospital or at a doctor's heart or the pulse of a person neither controlled under everyday conditions nor sufficiently long and be monitored.

Around however, measurements and long-term controls outside of one Hospitals or a doctor's office, are portable and easy to use instruments for pulse detection - so called heart rate monitors or heart rate monitors - necessary. However, commonly available devices for Long-term monitoring of the pulse on the principle of the ECG and are therefore not only big and unwieldy, for example, but also complex and costly to use.

On the other hand, in the field of sports heart rate monitors - such as the heart rate monitors of the Finnish high-tech company Polar Elektro Oy ( http://www.polar.fi ) or the Finnish company Suunto Oy ( http://www.suunto.com ) - used, which are much more user-friendly, smaller and cheaper. Since these pulse measuring devices, which are primarily designed for use in athletes and in the fitness and endurance training area, are also based on the principle of the ECG, they are dependent on a sensor (eg chest strap) outside the actual instrument for pulse measurement. So z. As the pulse measuring devices of the company Polar from two components - a transmitter in the form of a chest belt and a receiver that is clock-like and is worn on the wrist.

at This type of pulse measurement is z. B. over two integrated skin electrodes of the heartbeat through a voltage measurement determined. Information about heartbeat times is called Radio signal with short range to an evaluation unit as Receiver sent, which z. B. in the form of a wristwatch executed or z. B. directly into an endurance sports device (eg ergometer, treadmill, etc.) is integrated. For the However, pulse measurement is a moisture film between skin and electrodes or chest belt necessary, which in sports activities quickly z. B. body sweats under the chest belt is formed. When used for longer-term pulse control z. B. in everyday life would therefore constantly moistening of the chest strap necessary for a pulse measurement. For this reason and because of the use of two components (eg, chest strap and Receiver) are these pulse measuring devices for a use in a long-term pulse monitoring In everyday life rather unsuitable and not very user-friendly.

A further possibility for measuring the pulse is the pulse measurement with the aid of light, in which for a user-friendly measurement not two components (eg chest belt and receiver) are necessary and a measurement at only one body site (eg wrist) is possible. This type of pulse measurement is based - such as in Gerber, M .; Schrag, D .: Wearable Heartbeat Logger, Institute of Electronics; Swiss Federal Institute of Technology Zurich, 2001 described on the so-called photoelectric plethysmography, which is used in medical diagnostics as a measuring method to measure volume fluctuations by means of remission, ie by reflection and / or backward scattering of light in vessels. In photoelectric plethysmography, it is believed that perfused tissue absorbs infrared or near-infrared light more than poorly perfused or perfused tissue, and therefore rejects a lesser portion of the light.

Cardiac actions also alter the circulation in the tissue (eg the capillaries of the skin). Ie. each heartbeat produces a pulse wave which changes the amount of blood in, for example, the capillaries of the skin. Therefore, the pulse rate can be derived from the remission of a light irradiated to a skin site, wherein in fonts such. In Gerber, M .; Schrag, D .: Wearable Heartbeat Logger or in the WO 2006/044677 Usually light in the infrared range or near infrared range is used.

In Scripture Gerber, M .; Schrag, D .: Wearable Heartbeat Logger a device and method for pulse measurement is described in which a plurality of sensors are used for measuring the pulse. These sensors consist of infrared transmitting diodes, from which infrared light is radiated to a skin site, and infrared photodetectors to detect the remission. The sensors are arranged as a so-called sensor array, each with at least one row of transmitting diodes and a number of photodetectors. A result of the sensors is evaluated with a processor card for signal processing. However, the described device has the disadvantage that disturbing influences (eg signal fluctuations, artifacts, etc.) due to mechanical influences, such as movements, can not be eliminated by an algorithm, or only by means of complex filter circuits or post-processing. The pulse measurement is therefore strongly influenced, since such disturbances are located in the same frequency range as the relatively small pulse signal.

In the WO 2006/044677 a pulse measuring device is also disclosed, of which a reflection of light in the infrared or near infrared range by skin tissue z. B. is evaluated on the wrist for a pulse measurement. When in the WO 2006/044677 In the case of a pulse measurement as disclosed, another sensor (for example an acceleration sensor) is used to detect periodic movements in order to compensate for the disturbances caused by these movements by means of an algorithm. However, it has proved to be disadvantageous that a relatively small measurement signal for the pulse measurement is achieved by using light in the infrared or near infrared range, in particular in pulse measurements on the wrist. This measurement signal is not only strongly influenced by interfering signals (eg scattered light, movements, etc.), but also depends on the sensor position and irradiated skin area (eg sensor position above an artery, skin area with many or few capillaries, etc.). ). Therefore, due to the relatively small measurement signal, a rather unreliable and inaccurate pulse measurement is achieved.

Presentation of the invention

Of the Invention is therefore based on the object, a device for To provide pulse measurement, with which in a simple way a reliable and accurate pulse measurement with light without complicated post-processing can be carried out.

The Solution to this problem is achieved by a device of eingang indicated type, wherein of an emitter of the optical Sensors light of any wavelength from one predetermined range of 520 nm to 600 nm is emitted.

Of the The main aspect of the invention is that when using a any wavelength from the range of 520 nm to 600 nm - ie from the range of green to yellow Light - in a simple and advantageous way to one Many times larger quantity is achieved for the pulse measurement than when using Light from the infrared or near infrared range. The measured quantity is the change of a remission degree (ie the change of a Proportion of the remitted light at the incident light). By calculation and in the experiment it was found that at a given pulse-related fluctuation the percentage of blood in the dermis changes the remission rate using the range of 520 nm to 600 nm about 10 times as is great as in already known approaches with Infrared light. This can easily on body parts (eg, wrist) to which the dermis is very weak and / or from skin to skin site is very different blood supply.

A mathematical relationship between the wavelength of light and a change in the degree of remission when changing the blood content in the dermis are known from literature such. B. Kubelka, P .; Munk, F .: A Contribution to the Optics of Coloring, Journal of Technical Physics 1931 , and Rahman, AA; Chen, M .: Spectral Volume Rendering based on the Kubelka-Munk Theory, EUROGRA PHICS 2005 , known from which a remission behavior of multilayer media such. B. skin tissue has been examined. With optical properties of skin have also been busy: Jacques, SL: Skin Optics, Oregon Medical Laser Center News 1998 , and Osterholz, J .: Frequency domain spectroscopy and dynamic scattered light spectroscopy on biological tissues, Heinrich-Heine-University Düsseldorf 2002 ,

Biological parameters on which a relationship between the wavelength of the light and the change in the remission degree upon change in the blood component of the dermis depends, for example, the thicknesses of epidermis, dermis and muscle tissue, the melanin content of the epidermis, the oxygen content of the blood, the blood content of the Dermis, the reduced scattering coefficients of blood and muscle tissue and the absorption coefficient of muscle tissue. Values for these parameters are, for example, in Cheong, WF; Prahl, SA; Welch, AJ: A Review of the Optical Properties of Biological Tissue, IEEE Journal at Quantum Electronics 1990 and 1993 , or in Prahl, SA: Tabulated Molar Extinction Coefficient for Hemoglobin at Water, Oregon Medical Laser Center, 1999 , cited.

Become the findings of all these sources mentioned in one Computed, it follows that that wavelength, at which of the absolute value of the change of the remission degree when changing the proportion of blood in the dermis a maximum is assumed to be 577 nm, and that the given Range between 520 nm to 600 nm as for the pulse measurement is to look favorably. The results of this calculation were confirmed by experiments.

In a preferred embodiment of the invention Device are when using multiple optical sensors the sensors according to a criterion of highest probability arranged for optimal readings. For example of sensors attached via veins, none particularly good and unreliable measured values. Through this optimization, a sensor arrangement is achieved in a simple manner, at the possibly unfavorably placed sensors other sensors are likely to be cheap Placement for the pulse measurement have.

• • von jedem Sensor aufgrund seiner Platzierung mit einer Wahrscheinlichkeit p gute Messwerte geliefert werden und
• • dass in jedem Paar von Sensoren von einem zweiten Sensor mit einer Wahrscheinlichkeit q gute Messwerte geliefert werden, wobei vorausgesetzt wird, dass auch die Messwerte eines ersten Sensors des Paars gut sind, und
• • in jedem Paar von Sensoren vom zweiten Sensor mit einer Wahrscheinlichkeit r gute Messwerte geliefert werden, wobei allerdings vom ersten Sensor des Paars schlechte Messwerte geliefert werden.

The starting point for a determination of an optimal sensor arrangement is that:

• • from each sensor due to its placement with a probability p good readings are delivered and
• • that in each pair of sensors from a second sensor with a probability q good readings are provided, assuming that the readings of a first sensor of the pair are also good, and
• • good readings are provided in each pair of sensors from the second sensor with a probability r, but poor readings are provided by the first sensor of the pair.

wobei i eine laufende Variable ist, von der ganzzahlige Werte von k bis N angenommen werden.Then there is a probability p _kN that at least k sensors of a total of N sensors provide good measured values, given by

where i is a running variable from which integer values from k to N are assumed.

On the basis of this approach, an optimal arrangement for the sensors of the device according to the invention for pulse measurement can then be determined in a simple manner, since for a given number of sensors N with decreasing value of p, increasing number k and increasing correlation between the measurement results of the sensors, the determined probability p _kN drops sharply for at least k sensors with good readings.

by virtue of the determination of the probability of optimal measurements has proven to be advantageous that a number of optical Sensors is used, which is divisible by four. Ideally should the sensors be arranged such that each of four Sensors on against a longitudinal axis of the forearm to approximately 30 ° inclined square is formed. That has the advantage on, in particular, such a placement insensitive against a displacement of the device according to the invention for pulse measurement is. It does not have to be that way from the user a certain positioning to be respected.

at a preferred embodiment of the invention is additional an acceleration sensor for measuring body movements intended. This allows easy measurements due to Body movements are avoided, as the pulse only measured at rest. The acceleration sensor is ideal designed as a three-dimensional acceleration sensor, to detect movements in all three directions.

Expediently, in the device according to the invention, the emitter is referred to as a light-emitting diode, also referred to as LED, for any dominant wavelength from the predetermined range of 520 nm to 600 nm and the detector as photodetek tor, in particular as a photodiode or phototransistor executed.

It is also advantageous if for the inventive Device an integration into a bracelet, especially a band Wristwatch, especially on the inside is, as an application and removal of the device according to the invention for pulse measurement can be done easily and the user by a longer-term monitoring of the pulse, even in everyday life, is not disturbed.

It is favorable when an insert of the invention Device for pulse measurement is provided in an emergency system. By such integration into an emergency system can for example, at measured, critical pulse values (eg no pulse, weak pulse, irregular pulse, etc.) emergencies recognized and z. B. be dropped off an emergency call.

The The task is solved further by a procedure for optimized pulse measurement using the invention Device, wherein from an emitter light of any wavelength from a predetermined range of 520 nm to 600 nm on a section a skin tissue is sent out. From a detector is the received from the skin tissue remitted light and then based on the received, remitted light from an evaluation unit a value the pulse rate determined.

Of the Main aspect of the method lies in the use of light of any wavelength the predetermined range of 520 nm to 600 nm. In this area in a simple and advantageous way a much larger Measured variable for a pulse measurement achieved as when using light from the infrared or near-infrared range. This allows a more accurate and reliable pulse measurement be performed with light, in particular z. B. at a Wavelength of about 577 nm, at which the remission of light through skin tissue has an optimum.

Ideally a measurement of the pulse rate is performed only if no body movement is detected by the acceleration sensor, because in this way disturbances, adulterations and Incorrect measurements can be excluded and avoided.

A further, expedient embodiment of the invention Method provides that based on the determined pulse rate - for example if missing, irregular or excessive Pulse - an emergency signal is sent. With that you can Easily emergency situations - especially in older ones or cardiac patients - be recognized.

Brief description of the drawing

The Invention will be described below by way of example with reference to the attached Figures explained. Show it:

1 schematically and by way of example a structure of the device according to the invention for optimized pulse measurement and a sequence of the method according to the invention

2 an exemplary variant of an optimal arrangement of optical sensors of the device according to the invention.

Embodiment of the invention

In 1 The inventive device PM for optimized pulse measurement is shown in a schematic and exemplary manner. The device PM includes exemplary, optical sensors S1, S2, S3, wherein for the optimized pulse measurement a larger number z. B. eight or more optical sensors S1, S2, S3 can be used for a measurement.

The optical sensors S1, S2, S3 each comprise an emitter E1, E2, E3, from which on a section of a skin tissue HG light with any wavelength from a given range 520 nm to 600 nm - ie from one area green until yellow light - is sent out. As emitter E1, E2, E3, for example, light-emitting diodes, which also referred to as LED be used. Of the light emitting diodes used as emitter E1, E2, E3 becomes with any dominant wavelength from the Area irradiated from 520 nm to 600 nm. Ideal for use as an emitter therefore z. B. green or yellow LEDs.

Furthermore, The optical sensors S1, S2, S3 each comprise a detector D1, D2, D3, from which the light remitted by the skin tissue HG is received becomes. As a detector D1, D2, D3, for example, a photodetector (For example, photodiode, phototransistor) are used.

Furthermore, the device PM according to the invention has an evaluation unit AW for optimized pulse measurement, from which a pulse frequency is determined on the basis of measured values of the optical sensors S1, S2, S3, and an acceleration sensor BS, which is designed as a two- or three-dimensional acceleration sensor BS, for example from which body movements can be determined. In addition, the device PM according to the invention is suitable for optimized pulse measurement net, with appropriate pulse values (eg no pulse, excessive pulse, irregular pulse, etc.) to send an emergency call signal NS.

The Device PM for optimized pulse measurement can, for example, on an inside of a band can be arranged. Through this band is the device PM for optimized pulse measurement on the skin tissue HG positioned.

The Band can z. B. be a bracelet or watchband, whereby the pulse measurement Can be done easily on the wrist. The Band further has the purpose of the sensors S1, S2, S3 or in particular the detectors D1, D2, D3 as possible before parasitics protected by stray light.

1 further shows, by way of example, the schematic sequence of the method according to the invention for optimized pulse measurement using the device PM according to the invention for optimized pulse measurement. In a first process step 1 is determined by means of the acceleration sensor BS, whether there are body movements or the user is at rest. The process step 1 is used to avoid incorrect measurements during body movements, which superimpose the measurement signals for the pulse measurement. However, the first process step 1 in the process for optimized pulse measurement also be omitted when z. B. in the device PM no acceleration sensor BS is provided.

Will in the first step 1 determined that there is no body movement, the actual pulse measurement is started. In a second process step 2 is then by the emitters E1, E2, E3 (eg light-emitting diodes) of the sensors S1, S2, S3, which are on the skin tissue HG - for example by means of a band on which the device PM is arranged for optimized pulse measurement, are mounted , Light emitted with any wavelength from a predetermined range of 520 nm to 600 nm, thereby illuminating the skin tissue HG. Depending on the capillary perfusion of the dermis - the second uppermost layer of the skin tissue HG - the incident light is reflected and scattered backwards, that is, remitted. Capillary blood flow to the dermis is subject to pulse-related fluctuations. As a result of these fluctuations, the remission of the incident light is also subject to changes. These changes are greatest, and therefore best measurable, at light wavelengths between 520 nm and 600 nm, given a fluctuation of the blood level in the dermis.

In a third process step 3 Therefore, the detectors D1, D2, D3 (eg photodiode, phototransistor) of the sensors S1, S2, S3 will receive the reflected and backscattered light. Each detector D1, D2, D3 then provides a voltage which is approximately proportional to an intensity of the reflected and backscattered light. For the pulse measurement, the respective detectors D1, D2, D3 are mounted close to the respective emitters E1, E2, E3.

In a fourth process step 4 Then, the voltage values, which have been converted, for example, into digital signals, are forwarded by the detectors D1, D2, D3 or the respective sensors S1, S2, S3 to the evaluation unit AW. On the basis of these voltage values or digital signals, and thus on the basis of the received, remitted light, a value for a pulse frequency is determined by the evaluation unit.

In a fifth process step 5 can - when integrating the device PM for optimized pulse measurement - be provided that depending on the evaluation of the value of the pulse rate, an emergency call signal NS is issued. An emergency call signal can be sent, for example, in the event of a missing, elevated or irregular pulse. Particularly when integrating the device PM for optimized pulse measurement in a wristband or watchband, the pulse can be monitored reliably and with little annoyance for endangered persons (eg the elderly, people with heart problems).

2 shows an example of a possible arrangement for eight sensors S1 to S8 of a device PM for optimized pulse measurement. The sensors S1 to S8 are arranged on the inside of a bracelet AB, to a pulse measurement in a skin tissue HG of a forearm, which schematically in 2 is shown to perform. The pulse measurement takes place, for example, the palm side - ie on an inner side of the forearm in the vicinity of the wrist, as on skin sites with weak pigmentation such. B. the inside of the forearm, the remission of light is better measurable than heavily pigmented skin.

If now the inside of the forearm near the wrist is considered, then a middle area MB in the y-direction is dominated by tendons over which the pulse can not be measured. This results in a range B1 and a range B2 as interesting for the pulse measurement. The sensors S1 to S8 are therefore - as in 2 represented - arranged on the bracelet AB, that the sensors S1 to S4 in the area B1 and the sensors S5 to S8 are positioned in the area B2.

The probability p _kN that good readings are provided by at least k sensors of N sensors can, for example, be based on calculated according to the following formula:

• – p eine Wahrscheinlichkeit dafür, dass von einem Sensor aufgrund seiner Platzierung gute Messwerte geliefert werden,
• – q eine Wahrscheinlichkeit dafür, dass in einem Paar von Sensoren von einem zweiten Sensor des Paars gute Messwerte geliefert werden, vorausgesetzt, dass auch ein erste Sensor des Paars gute Messwerte ergibt, und
• – r eine Wahrscheinlichkeit dafür, dass in einem Paar von Sensoren vom zweiten Sensor des Paars gute Messwerte geliefert werden, vorausgesetzt, dass vom ersten Sensor des Paars schlechte Messwerte geliefert werden.

The quantities p, q and r mean

• P a probability of good readings being given by a sensor because of its placement,
• Q a probability of providing good readings in a pair of sensors from a second sensor of the pair, provided that also a first sensor of the pair gives good readings, and
• A probability that good readings will be provided in a pair of sensors from the second sensor of the pair, provided that bad readings are provided by the first sensor of the pair.

The Variable i is a running variable, of which integer Values from k to N are assumed. N is the number of sensors used S1 to S8 and k a minimum number of sensors S1 to S8 with good Readings.

On the basis of a criterion of highest probability for optimum measured values, a placement of four sensors S1 to S4 and S5 to S8 in the form of a square was determined as an optimal arrangement. In each case four sensors S1 to S8 are arranged at coordinates _x.sub.j and _y.sub.j , the values of _j being assumed to be from 1 to 4. x and y indicate the horizontal or vertical dimension.

• – min{|x_i – x_j|} ist zu maximieren, damit Korrelationen der Messwerte aufgrund vertikaler Strukturen (z. B. Muskeln, Sehnen, Blutgefäße) gering sind,
• – min{|y_i – y_j|} ist zu maximieren, damit Korrelationen der Messwerte aufgrund horizontaler Strukturen (z. B. quer verlaufende Hautfalten) gering sind,
• – und das Minimum der euklidischen Distanz ist zu maximieren, damit Korrelationen aufgrund räumlicher Nähe minimiert werden.

Thus, if one sensor S1 to S8 is poorly placed, the other sensors S1 to S8 are well placed with high probability, four sensors S1 to S4 and S5 to S8 are arranged in a square and thereby the following requirements for the arrangement for all pairs (Si, Sj), where i and j pass through values from 1 to 4) of sensors S1 to S4 and S5 to S8 in this square:

• - min {| x _i - x _j |} is to be maximized so that correlations of the measured values due to vertical structures (eg muscles, tendons, blood vessels) are low,
• - min {| y _i - y _j |} is to be maximized so that correlations of the measured values due to horizontal structures (eg transverse skin folds) are small,
• - and to maximize the minimum of Euclidean distance so that correlations due to spatial proximity are minimized.

From these requirements, a positioning of the sensors S1 to S8 in 2 Grid grid shown schematically, wherein grid lines in the x direction a distance .DELTA.x and grid lines in the y direction have a distance .DELTA.y. For .DELTA.x and .DELTA.y, advantageously results in a length of 5 mm. The arrangement of the sensors S1 to S8 or the respective squares within the grid network is derived from the requirement to minimize the correlations between the measured values due to the sensor placement.

In order to a placement of the sensors S1 to S8 z. B. when applying the bracelet AB in the areas of interest for a pulse measurement B1 and B2 of the forearm are done, the two sensor squares arranged symmetrically to the y-axis. In this way, the device can PM for optimized pulse measurement of both left-handers also be worn by right-handers.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - WO 2006/044677 [0010, 0012, 0012]

Cited non-patent literature

• - http://www.polar.fi [0007]
• - http://www.suunto.com [0007]
• - Gerber, M .; Schrag, D .: Wearable Heartbeat Logger, Institute of Electronics; Swiss Federal Institute of Technology Zurich, 2001 [0009]
• - Gerber, M .; Schrag, D .: Wearable Heartbeat Logger [0010]
• - Gerber, M .; Schrag, D .: Wearable Heartbeat Logger [0011]
• - Kubelka, P .; Munk, F .: A Contribution to the Optics of Coatings, Zeitschrift für Technische Physik 1931 [0016]
• - Rahman, AA; Chen, M .: Spectral Volume Rendering based on the Kubelka-Munk Theory, EUROGRAPHICS 2005 [0016]
• - Jacques, SL: Skin Optics, Oregon Medical Laser Center News 1998 [0016]
• - Osterholz, J .: Frequency domain spectroscopy and dynamic scattered light spectroscopy on biological tissues, Heinrich-Heine-Universität Düsseldorf 2002 [0016]
• - Cheong, WF; Prahl, SA; Welch, AJ: A Review of the Optical Properties of Biological Tissue, IEEE Journal to Quantum Electronics 1990 and 1993 [0017]
• - Prahl, SA: Tabulated Molar Extinction Coefficient for Hemoglobin in Water, Ore. Medical Laser Center, 1999. [0017]

Claims (13)

Device for optimized pulse measurement, comprising at least one optical sensor (S1, S2, S3) consisting of an emitter (E1, E2, E3) for emitting light to a skin tissue (HG) and a detector (D1, D2, D3) for receiving of the skin tissue (HG) remitted light and an evaluation unit (AW), characterized in that from the emitter (E1, E2, E3) of the respective optical sensor (S1, S2, S3) light of any wavelength from a predetermined range of 520 nm to 600 nm is emitted. Device according to claim 1, characterized in that when using several optical sensors (S1, S2, S3) these sensors (S1, S2, S3) according to a criterion highest Probability for optimal measurements are arranged. Device according to one of claims 1 to 2, characterized in that a number of the optical Sensors (S1, S2, S3) is divisible by four. Device according to claim 3, characterized in that that in each case four optical sensors (S1, S2, S3) in the form of a square are arranged. Device according to one of claims 1 to 4, characterized in that in addition an acceleration sensor (BS) is provided for measuring body movements. Device according to claim 5, characterized in that that the acceleration sensor (BS) as a three-dimensional acceleration sensor is executed. Device according to one of claims 1 to 6, characterized in that the emitter (E1, E2, E3) as a light emitting diode for any dominant wavelength the predetermined range of 520 nm to 600 nm executed is. Device according to one of claims 1 to 7, characterized in that the detector (D1, D2, D3) as a photodetector, in particular as a photodiode or phototransistor is. Device according to one of claims 1 to 8, characterized in that an integration in a bracelet (AB), especially volume of a wristwatch, excellent on an inside, is provided. Device according to one of claims 1 to 9, characterized in that an insert in an emergency call system is provided. Method for optimized pulse measurement using a device (PM) according to any one of claims 1 to 10, characterized in that - of an emitter (E1, E2, E3) light of any wavelength from the predetermined range of 520 nm to 600 nm a section of skin tissue (HG) is emitted ( 2 ), That from a detector (D1, D2, D3) the light reflected from the skin tissue (HG) is received ( 3 ), And that a value of the pulse rate is then determined by an evaluation unit (AW) on the basis of the received, remitted light ( 4 ). A method according to claim 11, characterized in that a measurement of the pulse rate is only performed when no body movement is detected by an acceleration sensor (BS) ( 1 ). Method according to one of Claims 11 to 12, characterized in that an emergency signal (NS) is sent on the basis of the determined pulse frequency ( 5 ).