SparkFun Forums

[Thiran]

Dear Sparkfun community,

I am currently undertaking a project where I am trying to derive the respiratory rate of a subject. One of the ways to do this is by monitoring the expansion and contraction of the chest during breathing. I'm thinking of approaching this by using a sensor to monitor the changes in distance of the chest wall. What I'm unsure about is the sensor to use.

I've come across a number of proximity sensors on Sparkfun and elsewhere but am unsure of their capability. Could anyone advise me on which might be best to use out sensors listed below:

• Infrared Proximity Sensor
  Ultrasonic Range Finder
  Laser-Based Optical Ranging Sensor

What concerns me is their sensitivity. During respiration the chest wall expands by roughly 2cm-4cm. Would the listed sensors be capable of picking up changes of this size?

Thanks in advance!