There seems to be one aspect in this entire discussion that no one has touched on. (Or at least all the posts that I have seen so far.)
Other than the issue of producing sparks or electrical impulses. What about the M’lacha (Work/Task) of Koseiv Sh’tei Osiyos. ????? ??? ?????? ???? ????. But, on a practical level. This phenomenon of some youths (Mainly in the MO community) who are texting on Shabbos has Two root causes. 1) Some, in the MO community are hugging the line of what is permitted (on shabbos). And when you are that close to the line, it is very easy to push the envelope, metaphorically; 2) some individuals feel disconnected. And to them observing Shabbos is a restriction or sacrifice. Others, then, are not willing to sacrifice.