Most people I know who work in the field of physiological computing purchase off-the-shelf sensors for their research. There’s nothing specifically wrong with this, most of us are not engineers and nor do we have the time to become one as our interests lie elsewhere. At LJMU all our equipment is off-the-shelf and we have some damn fine devices which we’ve used in our work (e.g. see my review of the BM CS-5 cheststrap). However I’ve noticed we place a lot of faith (and money) in these devices to do what they say on the tin (e.g. see the issue I raised last year about the software bundled with BioHarness). Personally I like to know the limitations of any equipment I’m using, and if I find anything outside the spec I’ll try to figure out why (sometimes to my detriment as you’ll see below). Its not that I’m particularly troubled if a sensor has any defects as I don’t expect them to be perfect, the problem I have is with defects I don’t know about as they can make things, problematic to say the least. For example the first off-the-shelf sensor I ever worked with was the WaveRider Pro a 4 channel biofeedback device which had a slight problem with counting time.