I mentioned in my first impressions of the t:slim that I was underwhelmed by the responsiveness of the touch screen. However, I want to add that I am thoroughly impressed that I can operate the pump while wearing gloves. And not those special conductive gloves you need to use your iPhone, but regular gloves that render my iPhone useless.
I’ve been attributing this (both traits actually) to there being a different touch mechanism in play with the pump verses the iphone. An iPhone is a multi touch system that uses a capacitive material to sense touch. This material is only activated by conductive materials (like your finger or a conductive glove) and most gloves (ie insulation) stop those signals from transmitting.
The t:slim seems to sense touch via pressure via a resistive screen. This means that it only registers a single touch at a time (which is all we need to operate a pump) and can be activated by anything capable of delivering pressure, be it conductive or insulating, thus there is no need for conductive gloves.
I haven’t taken the time to seek out Tandem’s patents or specs to know if I’m right (maybe someone else has this info?) so I certainly could be wrong. I’m just glad that I won’t have to purchase special gloves (!).
More info on how touch screens work, etc: http://electronics.howstuffworks.com/iphone.htm