This image represents my breathing pattern for seven minutes. By reading the motion sensor in my laptop, I was able to plot the rise and fall of my chest. Each circle represents five seconds of data. This was an experiment to see whether the sensor was sensitive enough to detect respiration.
If you would like to experiment with using the sudden motion sensor (SMS) in an Apple MacBook (or MacBook Pro), my Processing source code is provided here. Please note that you must download the sms library, available from the Processing website. Commented out is code to turn the laptop into an etch-a-sketch, where you draw by tilting the laptop in various directions.