One aspect coming back often in those installations is the use of objects, technologies we are often in contact without thinking of them. By that I mean we are not seing them anymore as what they are at first (e.g. paper bags used as lungs). For the video surveillance camera it's different, I guess people still see them but don't realize what we are trying to make the algorithms say automatically about what they see.
Another aspect is to push the spectator out of his/her coordinate system to see differently, to change his/her view point. For example how to illustrate a sound with a 3D shape or population with speakers playing national anthems simultasneously: so using real form to illustrate air vibrations and using air vibrations to illustrate real alive people, from non visible to tactile and vice versa.
Last one, from physiological to digital. The two installations, one which records you heartbeat to control the pulse of a tree made of lamps where each lamp is one person recorded pulsation and the second recording your voice to then play it together with many others previously recorded, only a light per recording with its intensity varying accordingly. It can sound or look very noisy at first, but there is some harmony appearing from this chaos.