I very much doubt this equipment is designed to detect electrical charge. My understanding of the technology is that it uses a form of image sensing and looks at the fingerprint pattern. Responsibility2nd's point about a pulse being required is within the capability of an image sensor, so I believe that requirement is plausible, and indeed, an obviously good idea to prevent people from faking it.
On some fictional tv cop drama, they used a defibrillator to overcome the electrical check...
The touch screen itself is looking for electrical charges - that’s how it perceives the world. The screen can neither see optically, nor feel the touch - it looks for patterns in the charges.