Device and system for monitoring of pulse-related information of a subject

Abstract

The present invention relates to a wearable device for obtaining signals from a subject for use in the monitoring of pulse-related information of the subject. To enable the use of such a device in the monitoring of pulse-related information of the subject, which provides for unobtrusive, reproducible, easy to use, and simple measurements, the device comprises a device body (20), a PPG signal sensing unit (21) for acquiring a first photoplethysmography, PPG, signal from a first body location of the subject's body, and an imaging unit (22) for acquiring a sequence of images from a second body location of the subject's body different from the first body location, said sequence of images being configured for deriving a second PPG signal for the second body location of the subject's body. Said PPG signal sensing unit and said imaging unit are mounted in or at the device body and are configured to simultaneously acquire the first PPG signal and the sequence of images.

1 . Wearable device for obtaining signals from a subject for use in the monitoring of pulse transit time and/or pulse arrival time, said device comprising:
 a device body ( 20 ),   a PPG signal sensing unit ( 21 ) for acquiring a first photoplethysmography, (PPG), signal from a first body location of the subject's body, wherein the first PPG signal sensing unit is in contact with the first location, and   an imaging unit ( 22 ) for acquiring a sequence of images from a second body location of the subject's body different from the first body location, said sequence of images being configured for deriving a second PPG signal for the second body location of the subject's body, wherein said PPG signal sensing unit and said imaging unit are mounted in or at the device body and are configured to simultaneously acquire the first PPG signal and the sequence of images, and   a processing unit ( 27 ) for deriving the second PPG signal from said sequence of images, wherein the processing unit ( 27 ) is configured to determine the pulse transit time and/or pulse arrival time based on the first PPG signal and the second PPG signal.   
     
     
         2 . Wearable device as claimed in  claim 1 , wherein the processing unit determines the pulse transit time and/or pulse arrival time based on time delay between the peaks of the first PPG signal and the second PPG signal. 
     
     
         3 . Wearable device as claimed in  claim 1 ,
 wherein said PPG signal sensing unit comprises an optical sensing unit ( 21   a ), in particular a contact sensor.   
     
     
         4 . Wearable device as claimed in  claim 1 ,
 wherein said PPG signal sensing unit comprises another imaging unit ( 21   b,    21   c ).   
     
     
         5 . Wearable device as claimed in  claim 1 ,
 further comprising a distance unit ( 29 ) for obtaining the distance between said first and second body locations and/or the distances between the first body location and the second body location, respectively, and the heart, wherein said processing unit ( 27 ) is configured to use the obtained distance or distances in determining the pulse-related information.   
     
     
         6 . Wearable device as claimed in  claim 5 ,
 wherein said distance unit ( 29 ) is configured to obtain the distance or distances through measurement, in particular from an image of the sequence of images acquired by the imaging unit, or through input.   
     
     
         7 . Wearable device as claimed in  claim 1 ,
 further comprising an illumination unit ( 40 ) mounted in or at the device body for illuminating said first and/or second body location.   
     
     
         8 . Wearable device as claimed in  claim 1 , further comprising
 an image recognition unit ( 41 ) for detecting when said second body part is shown in the images of the acquired sequence of images and a control unit ( 42 ) for controlling the PPG signal sensing unit to start acquiring the first PPG signal if it is detected that the second body part is shown in an image.   
     
     
         9 . Wearable device as claimed in  claim 1 ,
 further comprising mounting equipment ( 26 ) for mounting the device body at the subject's body.   
     
     
         10 . Wearable device as claimed in  claim 1 ,
 wherein said wearable device is a wrist worn device, in particular a watch or heart rate monitor, glasses, camera, multimedia player, mobile phone or smart phone.   
     
     
         11 . Wearable device as claimed in  claim 1 ,
 wherein said wearable device is a wrist worn device ( 2   a ), wherein said PPG signal sensing unit is arranged at the bottom of the device body and the imaging unit is arranged at the front or a side surface of the device body.   
     
     
         12 . Wearable device as claimed in  claim 1 ,
 wherein said PPG signal sensing unit ( 21 ) is mounted at a first position in or at the device body facing said first body location when the wearable device is worn by the subject and   wherein said imaging unit ( 22 ) is mounted at a second position in or at the device body facing said second body location when the wearable device is worn by the subject.   
     
     
         13 . Wearable device as claimed in  claim 1 ,
 wherein said processing unit ( 27 ) is further configured to determine pulse wave velocity, hemodynamic information and/or blood pressure changes of the subject.   
     
     
         14 . System ( 1 ) for monitoring of pulse transit time and/or pulse arrival time, said system comprising:
 a wearable device ( 2 ,  2   b,    2   c,    2   d ) comprising:   a PPG signal sensing unit ( 21 ) for acquiring a first photoplethysmography, (PPG), signal from a first body location of the subject's body, wherein the first PPG signal sensing unit is in contact with the first location;   an imaging unit ( 22 ) for acquiring a sequence of images from a second body location of the subject's body different from the first body location, said sequence of images being configured for deriving a second PPG signal for the second body location of the subject's body; and   an output unit ( 23 ) for outputting said first PPG signal and said sequence of images, wherein the said outputted first PPG signal and sequence of images are sent to another entity ( 5 ) for processing via a communication network ( 30 ),   wherein the another entity ( 5 ) comprising: an input unit ( 3 ) for obtaining the first PPG signal and the sequence of images acquired by the wearable device via the communication network, and   a processor ( 4 ) for deriving a second PPG signal from said sequence of images and for determining the pulse transit time and/or the pulse arrival time from said first and second PPG signals.   
     
     
         15 . The system according to  claim 14 , wherein the another entity ( 5 ) is at least one of a remote server, a wireless communication device, and a computer.