Systems and methods for acquiring ppg signals for measuring blood pressure

Abstract

Systems and methods for acquiring photoplethysmographic (PPG) signals for measuring blood pressure can include a computing device acquiring a sequence of images representing transdermal optical data of a subject, and generating a corresponding sequence of downsampled color frames. The computing device can identify, in each downsampled color frame, a respective central image block representing a central image region of the downsampled color frame and having a first size smaller than a second size of the downsampled color frame. The computing device can generate, for each downsampled color frame, a corresponding color intensity value based on the respective central image block. The computing device can generate, using color intensity values corresponding to the sequence of downsampled color frames, a PPG signal to determine a blood pressure value of the subject.

What is claimed is: 
     
         1 . A device for measuring blood pressure comprising:
 a housing including a curved top portion and a flat base portion, the curved top portion including at least one visual output device including a plurality of light emitting diodes (LEDs), the curved top portion including a groove to receive a finger of a user, the groove having a curved end towards a center of the housing, the groove partially defined by a bottom surface;   a light source disposed within the housing and positioned beneath the bottom surface of the groove and configured to emit light in the groove;   a photodetector disposed within the housing and positioned beneath the bottom surface of the groove and configured to capture a sequence of image frames while the light is emitted;   one or more tactile surface features extending from the bottom surface of the groove and defining a first portion of the bottom surface of the groove to aid the user in positioning a pulp region of the finger above the photodetector, wherein the photodetector is positioned within the first portion and configured to capture images of the pulp region of the finger of the user; and   a processor configured to generate a photoplethysmographic (PPG) signal of a user using the sequence of image frames to determine a blood pressure of the user, and wherein the processor is configured to control the plurality of LEDs to i) provide a first indication indicating that a finger of the user has been detected; and ii) provide a second indication indicating a quality of the PPG signal.   
     
     
         2 . The device of  claim 1 , wherein the groove extends from an edge of the housing towards a center of the device. 
     
     
         3 . The device of  claim 1 , wherein the one or more tactile surface features include a protrusion at the bottom surface and forming a closed loop to accommodate the pulp region of the finger of the user. 
     
     
         4 . The device of  claim 3 , wherein the thickness of the protrusion is less than 1 mm. 
     
     
         5 . The device of  claim 1 , wherein the first portion of the bottom surface has a first dimension between 2 mm and 10 mm and a second dimension between 5 mm and 20 mm. 
     
     
         6 . The device of  claim 1 , wherein the first portion of the bottom surface of the groove is less than 15 mm and greater than 2 mm from a center of the curved end. 
     
     
         7 . The device of  claim 1 , wherein the photodetector includes at least one of:
 a red-green-blue (RGB) photodetector;   a full light spectrum photodetector; or   a combination of a RGB photodetector and an infrared photodetector.   
     
     
         8 . The device of  claim 1 , further comprising a communications interface configured to communicate with a remote device. 
     
     
         9 . The device of  claim 8 , wherein the processor is configured to:
 cause the communication interface to transmit the PPG signal to the remote device, the remote device configured to:
 determine a blood pressure measurement of the user using the PPG signal; and 
 display the blood pressure measurement on a display device. 
   
     
     
         10 . The device of  claim 1 , further comprising a display device disposed within the housing, the processor is configured to:
 determine a blood pressure measurement of the user using the PPG signal; and   display the blood pressure measurement on a display device.   
     
     
         11 . The device of  claim 1 , further comprising at least one of:
 a pressure sensor to measure pressure applied by the finger to a first portion of the bottom region of the groove;   a thermometer to measure a temperature of the finger; or   an oximeter to measure oxygen level in blood flowing through the finger.   
     
     
         12 . The device of  claim 1 , wherein the processor is configured to:
 assess a quality of the sequence of image frames or a quality of the PPG signal;   select, based on the quality of the sequence of image frames or the quality of the PPG signal, from the plurality of LEDs, a subset of the plurality of LEDs; and   cause the subset of the plurality of LEDs to emit a light output.   
     
     
         13 . The device of  claim 1 , further comprising a light pipe disposed within the housing at an upper edge of the groove, the processor configured to cause the light pipe to be illuminated to prompt the user to take a measurement of the one or more vital signs. 
     
     
         14 . A method of measuring vital signs of a user, comprising:
 receiving a finger within a groove of a housing of a device, the groove partially defined by a bottom surface, the device including:
 a curved top portion and a flat base portion, the curved top portion including at least one visual output device including a plurality of light emitting diodes (LEDs), the curved top portion including the groove; 
 a processor; 
 a light source disposed within the housing and positioned beneath the bottom surface of the groove; 
 a photodetector disposed within the housing and positioned beneath the bottom surface of the groove; and 
 one or more tactile surface features extending from the bottom surface of the groove and defining a first portion of the bottom surface of the groove to aid the user in positioning a pulp region of the finger above the photodetector, wherein the photodetector is positioned within the first portion and configured to capture images of the pulp region of the finger of the user; 
   emitting, by the light source, light in the groove;   capturing, by the photodetector, a sequence of images of the finger while the light is emitted; and   generating, by the processor, a photoplethysmographic (PPG) signal using the sequence of images to determine one or more vital signs of the user, and wherein the processor is configured to control the plurality of LEDs to i) provide a first indication indicating that a finger of the user has been detected; and ii) provide a second indication indicating a quality of the PPG signal.   
     
     
         15 . The method of  claim 14 , further comprising:
 determining a measurement of the one or more vital signs using the PPG signal; and   displaying the measurement of the one or more vital signs on a display device.   
     
     
         16 . The method of  claim 14 , further comprising:
 transmitting the PPG signal to a remote device, the remote device determining a measurement of the one or more vital signs using the PPG signal and displaying the measurement of the one or more vital signs on a display device.   
     
     
         17 . The method of  claim 14 , further comprising:
 assessing, by the processor, a quality of the sequence of image frames or a quality of the PPG signal; and   providing, via the plurality of LEDs, a light signal indicative of the quality of the sequence of image frames or the quality of the PPG signal.   
     
     
         18 . The method of  claim 17 , further comprising:
 instructing the user to adjust placement of the finger within the groove, responsive to determining a poor quality of the sequence of image frames or a poor quality of the PPG signal.   
     
     
         19 . The method of  claim 14 , further comprising providing, via a finger groove light pipe located at an upper edge of the groove, a light signal to prompt the user to take a measurement of the one or more vital signs. 
     
     
         20 . The method of  claim 14 , wherein the one or more tactile surface features include a protrusion at the bottom surface and forming a closed loop to accommodate the pulp region of the finger of the user.