Measuring user respiration at extremities

Abstract

Systems and methods measure impedance across a user's chest during respiration to determine a rate of respiration. With AC-modulation contacts separated from impedance-measuring contacts, analog filtering to remove EMI, a bridging capacitor to remove DC noise, and digital filtering to further remove EMI, a user's respiration may be measured with the AC-modulation contacts and the impedance-measuring contacts placed at user extremities.

1 .- 10 . (canceled) 
     
     
         11 . A wrist-mountable device including:
 electronics including a processor with memory and instructions;   a first user contact disposed on a first side of the device;   a second user contact disposed on a second side of the device;   a third user contact disposed on the first side of the device; and   a fourth user contact disposed on the second side of the device or a third side of the device,   wherein:
 when the device is mounted on the user, and the first side of the device is positioned against a first arm of the user, the first user contact and the third user contact make contact with the first arm of the user and are not accessible by a second arm of the user, and the second user contact and fourth user contact are accessible by the second arm; and 
 the instructions, when executed by the processor with the first and third user contacts in contact with the first arm and the second and fourth user contacts in contact with the second arm, cause the electronics to:
 provide an AC current between the first and second user contacts, the AC current causing an impedance to develop between the third and the fourth user contacts; 
 detect the impedance between the third and the fourth user contacts, the impedance changing with time; and 
 based on the detected change of the impedance with time, create a signal indicating a respiration rate of the user. 
 
   
     
     
         12 . The device of  claim 11 , wherein the instructions further cause the electronics to:
 create an impedance signal from the detected impedance between the third and the fourth user contacts;   filter the impedance signal to remove a DC component; and   filter the impedance signal through a low-pass filter.   
     
     
         13 . The device of  claim 12 , wherein the low-pass filter has a cut-off frequency of two hertz and the attenuation is minus forty decibels per decade above three hertz. 
     
     
         14 .- 19 . (canceled) 
     
     
         20 . The device of  claim 11 , wherein the electronics includes a Texas Instruments ADS1292R analog-to-digital converter and an Arm Cortex M4 processor and first through fourth electronics contacts are on the Texas Instruments ADS1292R analog-to-digital converter. 
     
     
         21 . A method comprising:
 providing a user with a wrist-mountable device including:
 electronics including a processor with memory and instructions; 
 a first user contact disposed on a first side of the device; 
 a second user contact disposed on a second side of the device; 
 a third user contact disposed on the first side of the device; and 
 a fourth user contact disposed on the second side of the device or a third side of the device, 
 wherein:
 when the device is mounted on the user, and the first side of the device is positioned against a first arm of the user, the first user contact and the third user contact make contact with the first arm of the user and are not accessible by a second arm of the user, and the second user contact and fourth user contact are accessible by the second arm; 
 
   bringing the first and third user contacts in contact with the first arm and the second and fourth user contacts in contact with the second arm:   providing, by the wrist-mountable device, an AC current between the first and second user contacts, the AC current causing an impedance to develop between the third and the fourth user contacts;   detecting, by the wrist-mountable device, the impedance between the third and the fourth user contacts, the impedance changing with time; and   based on the detected change of the impedance with time, creating, by the wrist-mountable device, a signal indicating a respiration rate of the user.   
     
     
         22 . The method of  claim 21 , further including:
 creating, by the wrist-mountable device, an impedance signal from the detected impedance between the third and the fourth user contacts;   filtering, by the wrist-mountable device, the impedance signal to remove a DC component; and   filtering, by the wrist-mountable device, the impedance signal through a low-pass filter.   
     
     
         23 . The method of  claim 22 , wherein the low-pass filter has a cut-off frequency of two hertz and the attenuation is minus forty decibels per decade above three hertz. 
     
     
         24 . The method of  claim 21 , wherein the electronics includes a Texas Instruments ADS1292R analog-to-digital converter and an Arm Cortex M4 processor and first through fourth electronics contacts are on the Texas Instruments ADS1292R analog-to-digital converter. 
     
     
         25 . A non-transitory computer-readable medium encoded with a plurality of instructions which, when executed by a processor of a wrist-mounted device including:
 electronics including the processor and memory;   a first user contact disposed on a first side of the device;   a second user contact disposed on a second side of the device;   a third user contact disposed on the first side of the device; and   a fourth user contact disposed on the second side of the device or a third side of the device, wherein:
 when the device is mounted on the user, and the first side of the device is positioned against a first arm of the user, the first user contact and the third user contact make contact with the first arm of the user and are not accessible by a second arm of the user, and the second user contact and fourth user contact are accessible by the second arm; and 
   with the first and third user contacts in contact with the first arm and the second and fourth user contacts in contact with the second arm, cause the wrist-mounted device to:   provide an AC current between the first and second user contacts, the AC current causing an impedance to develop between the third and the fourth user contacts;   detect the impedance between the third and the fourth user contacts, the impedance changing with time; and   based on the detected change of the impedance with time, create a signal indicating a respiration rate of the user.   
     
     
         26 . The computer-readable medium of  claim 25 , the instructions further causing the wrist-mounted device to:
 create an impedance signal from the detected impedance between the third and the fourth user contacts;   filter the impedance signal to remove a DC component; and   filter the impedance signal through a low-pass filter.   
     
     
         27 . The computer-readable medium of  claim 26 , wherein the low-pass filter has a cut-off frequency of two hertz and the attenuation is minus forty decibels per decade above three hertz. 
     
     
         28 . The computer-readable medium of  claim 25 , wherein the electronics includes a Texas Instruments ADS1292R analog-to-digital converter and an Arm Cortex M4 processor and first through fourth electronics contacts are on the Texas Instruments ADS1292R analog-to-digital converter. 
     
     
         29 . The device of  claim 11 , wherein the second user contact and fourth user contact being accessible by the second arm includes the second user contact and fourth user contact being accessible by one or more fingers on a hand of the second arm. 
     
     
         30 . The method of  claim 21 , wherein the second user contact and fourth user contact being accessible by the second arm includes the second user contact and fourth user contact being accessible by one or more fingers on a hand of the second arm. 
     
     
         31 . The computer-readable medium of  claim 25 , wherein the second user contact and fourth user contact being accessible by the second arm includes the second user contact and fourth user contact being accessible by one or more fingers on a hand of the second arm.