Could vampires use a touchscreen device, or would they have to spend a blood point to generate the electricity required to operate a conductive touchscreen?
While I'm not a NWoD player -- the simulationist answer is "no, it will work without it" because you do not need to generate a whit of electricity in order to use either of the two common touchscreen technologies.
These use two layers of flexible material separated by an airgap and with conductive rows and columns printed onto them. Pressure from a small object (stylus, finger, etal) pushes the rows and columns at the pressure point together, creating an electrical row-to-column connection that is then detected by the control circuits -- which provide all the electricity needed (not much!) for the touch screen to function. So, you need to do nothing there -- you could poke it with a bone, pencil, stick, piece of wire, hot dog, or whatever, and it will still work.
These use one or two grids of conductive material that are capacitively coupled. Introducing a correctly sized conductive object into the field (live finger, hot dog, capacitive stylus) causes changes in the capacitance between the two grids or grid sections, which are then picked up by the circuitry. Again, the actual electricity needed to run this comes from the control circuits, not the operator, and this means that the notion of your character having to spend something to generate electricity simply to run a touchscreen is mildly absurd; they simply need to maintain an adequate water content in their fingers (shouldn't be hard!), or whip out an appropriate instrument whenever they use their touchscreen device.
Footnote: there are optical touchscreens as well, used sometimes for kiosks and larger form factors -- obviously, they will work with anything non-transparent, which in practice includes just about everything I listed above for resistive touchscreens.
Vampires should have no problem using touchscreen devices, though they may not be used to them. Think how long it took your parents, or possibly grandparents, to start using computers. Multiply that by several generations.
Resistive touchscreens work on mechanical pressure, and capacitive touchscreens work by detecting changes in local capacitance.
You can tell capacitive and resistive screens apart by seeing if you can do two finger gestures. Resistive screens (generally) can't handle multitouch gestures. Most modern devices use capacitive touchscreens for that reason.
Creatures that might have problems with capacitive screens would include:
- Mummies, liches and animated skeletons (no water in their fingers = nonconductive fingers)
- Robots, or cyborgs with metal fingers - some capacitive touchscreens reject metal objects due to their design parameters, others do not though and will function when touched by a metal finger of appropriate size
- Dresden File wizards (their magic shorts out technology)
- Some kinds of Laundry Files fey (because it is theorized that they dislike iron because of changes in ambient electrical fields and capacitance that they need to manifest in this reality)
- Laundry Files zombies (because they are actually entities that are composed of strong electrical fields that take over bodies)
- Gauru form werewolves (because their fingers are too big, the claws get in the way, and CRUSH NATURE DESTROYING TECHNOLOGY)
In short, you need creatures that have fingers that are much less conductive than human fingers, that generate strong electrical fields of their own, or that have fingers that are too big.
Creatures with non-conductive fingers could work around that limitation by using a sausage stylus, the nearest metal object of an appropriate diameter (about 6.3mm) in most cases, or since this is WOD, someone else's fingers.
Vampires have standard fingers, as far as conductivity goes.
Of course, all of this is predicated on the GM using the same assumptions. If they rule that touchscreens work off detecting the electric field of a human body, and that vampires don't have this electric field, then I guess that modern-inclined vampires will have to do with a nice techno-geek ghoul as a personal assistant.
You will be able to use an iPhone or similar touch screen device without spending a blood point, as long as the Vampire's finger is moist, not completely dried out. The technology used by iPhones and other more recent touch screen devices is Capacitive sensing. In a nutshell, in order to create the electrical impulse needed to register, there needs to be some level of moisture in the tool used. A live finger is ideal, a regular stylus will not work (only a specially-designed capacitive stylus), and some Googling suggests even a hot dog will do the trick. Your Vampire would have more problems with the iPhone's fingerprint identification though, as that has been specially designed only to accept living fingers, not dead / bloodless ones. See for example here though it's all over the web.
My vote is no vampires can not use touch screens, at least not the style that Apple technology uses.
What is the basis for my opinion?
In the dead of winter time when it stays well below freezing, if you allow your fingers to get cold they no longer activate the touch screen. A vampire's fingers are a lot colder than a humans winter chilled fingers.
Yes, but only if they're not hollow!
Not because fully hollowed vampires don't have capacitance but because they don't have a reflection which means they can't:
- Use touch screens
- Interact with automatic grocery store sliding doors
- Have their fingerprints scanned
- Use Siri
- Use a retina scanner