Patent Publication Number: US-2009227853-A1

Title: Wearable optical pulse plethysmography sensors or pulse oximetry sensors based wearable heart rate monitoring systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of provisional patent application Ser. No. 61/033,244, filed Mar. 3, 2008 by the present inventor. 
    
    
     FEDERALLY SPONSORED RESEARCH  
     Not Applicable 
     SEQUENCE LISTING OR PROGRAM  
     Not Applicable 
     BACKGROUND-FIELD 
     This application relates to wearable pulse plethysmography (PPG) sensors or pulse oximetry (SpO 2 ) sensors based heart rate monitoring systems. 
     BACKGROUND-PRIOR ART 
     Wearable optical pulse plethysmography (PPG)/SpO 2  sensors are used to measure heart rate information. These (PPG)/SpO 2  sensors based heart rate monitoring systems can be divided into several categories depending on the orientation and the location of the sensor. The following categories including ear pinna wearable, in ear wearable, finger wearable, body surface wearable and head wearable can be identified. The heart rate monitoring and the display systems based on these sensors are either worn by the wearer or placed on table top. The present optical PPG/SpO 2  sensor based heart rate monitors are uncomfortable to wear, poor in signal quality, poor in signal accuracy and poor in reliability due to the motion artifacts produced during the motion of the wearer. 
     The present invention includes a new wearable PPG/SpO 2  senor arrangement and a wearable heart rate monitoring device that can be used to measure and monitor the heart rate reliably and accurately with less motion artifact having better signal to noise ratio. 
     SUMMERY OF THE PRESENT INVENTION 
     An ear wearable hook with a PPG/SpO 2  sensor, the sensor is attached to the skin on the head in the region of superficial artery and vein near the ear ( 010 ). In a second approach to increase the signal quality an ear hook is invented with multiple PPG/SpO 2  sensors. The sensors are attached to the skin of the head in the regions of superficial artery and vein ( 010 ) and posterior auricular artery and vein around the ear ( 011  of  FIG. 1C ). The PPG/SpO 2  sensors are attached to the skin with adhesives. The PPG signal picked up by these sensors are due to the fluctuations of the blood flow in these regions. These sensor units are shown in the  FIG. 1A  and  FIG. 1B . A person wearing the sensor unit is shown in the  FIG. 1D . The sensor unit is connected to the signal conditioning device via the conductive cable ( 004 ). 
     In addition an ear wearable heart rate monitoring device is monitored with the PPG/SpO 2  sensor are picking up the fluctuation of the blood flow from the region marked on the  FIG. 1C  ( 010 , 011 ). The sensory unit is constructed according to the previous chapter and this sensor unit is connected to the ear wearable heart rate monitoring unit ( FIG. 2A ). A person wearing the unit is shown in the  FIG. 2C . In addition PPG/SpO 2  sensors can be connected to the ear wearable heart rate monitoring via a cable. The PPG/SpO 2  sensor is attached to the skin by using adhesives. The ear wearable heart rate monitoring unit has speaker that is capable of audio feed back. The switches ( 007 ) on the device are used for controlling the device. This device is capable of wireless PPG signal transmitting and control signals or audio feedback physiological information receiving. 
    
    
     
       DRAWING—Figures 
       FIG.  1 A—Shows the ear hook with PPG/SpO 2  sensor located on the hook such that it sets on either the regions  010  or  011 . 
       FIG.  1 B—Shows the ear hook with multiple PPG/SpO 2  sensors located on the hook such that they set on the regions  010  and  011 . 
       FIG.  1 C—Shows the regions of superficial artery and vein ( 010 ) and posterior auricular artery and vein around the ear ( 011 ). 
       FIG.  1 D—A person wearing the ear hook PPG/SpO 2  sensor unit. 
       FIG.  2 A—An ear wearable wireless heart rate monitoring unit with ear hook PPG/SpO 2  sensor the unit hook. 
       FIG.  2 B—An ear wearable wireless heart rate monitoring unit with PPG/SpO 2  sensor connected via cable. 
       FIG.  2 C—A person wearing a device described in  FIG. 2A . 
       FIG.  2 D—A person wearing a device described in  FIG. 2B . 
       FIG.  3 B—PPG signal form a ear pinna connected PPG/SpO 2  sensor when the wearer in moving. 
       FIG.  3 A—PPG signal form the new PPG/SpO 2  sensor hook when the wearer in moving. 
     
    
    
     DRAWINGS—Reference Numerals 
     
         
           001 —The ear hook 
           002 —PPG/SpO 2  sensor 
           003 —Ear plug of the sensor hook 
           004 —PPG/SpO 2  Sensor/s power and signal pathways. 
           010 —Region of superficial artery and vein near the ear. 
           011 —Region of posterior auricular artery and vein around the ear. 
           003 —Ear plug of the ear wearable heart rate monitor. 
           005 —The housing of the ear wearable heart rate monitor. 
           006 —The connector cable that connects the PPG/SpO 2  sensor/s to the ear wearable heart rate monitor. 
           007 —The switches of the ear wearable heart rate monitor. 
       
    
     DETAILED DESCRIPTION of FIG.  1 A, FIG.  1 B, FIG.  2 A, FIG.  2 B 
       FIG. 1A  shows the ear hook with PPG/SpO 2  sensor located on the hook such that it sets on either the regions  010  or  011 . The ear hook is designed to set around the ear. The PPG/SpO 2  sensor is connected to the ear hook. The signal and power conductive pathways are embedded inside the ear hook. The ear hook with the PPG/SpO 2  sensor consists of an ear plug. This ear plug is made with softer and flexible materials. The signal and power lines of the sensor are connect to the signal conditioning unit via the conduction pathways ( 004 ). 
       FIG. 1B  shows the ear hook with multiple PPG/SpO 2  sensors located on the hook such that they set on the regions  010  and  011 . This is to increase the reliability and the accuracy of the heart rate information. Two or more PPG/SpO 2  sensors may used for the signal pickup. 
       FIG. 2A  shows an ear wearable wireless heart rate monitoring unit with ear hook PPG/SpO 2  sensor the unit hook . The hook ( 001 ) connected to the Housing ( 005 ) and housing has an ear plug ( 003 ). This unit may contain an audio feedback unit. The unit is capable of wireless information transmission. 
       FIG. 2B  shows an ear wearable wireless heart rate monitoring unit with PPG/SpO 2  sensor connected via a cable. In this arrangement the stress on the ear is lower while one wearing the device. 
     Operation of the System  
     Upon wearing the ear hook sensor with single or multiple PPG/SpO 2  sensors, the PPG/SpO 2  sensors sticks to the skin via adhesives. Since the pulse is stronger in the area of the sensors low power is required to detect the pulse. The PPG signals are picked up by the sensors and sent to the monitoring unit via the wireless link. This new innovative system is tested against the ear wearable PPG/SpO 2  sensors based heart rate monitoring unit where the PPG/SpO 2  sensors are connect to the ear pinna. The results are shown in the  FIG. 3A  and  FIG. 3B .  FIG. 3A  shows the PPG signal of the present invention and  FIG. 3B  shows the PPG signal pick up by the PPG/SpO 2  sensors based heart rate monitoring unit where the PPG/SpO 2  sensors are connect to the ear pinna. These test results were recorded under the same motion level while the wearer was running at 5 mph. It is clear from these results that the present invention is much better under motion conditions than the existing PPG/SpO 2  sensors based heart rate monitoring unit where the PPG/SpO 2  sensors are connect to the ear pinna.