I recently opined that natural telepathy is a trope and not speculative science, for lack of evidence or reasonable theory.
Technological telepathy is, IMO, another story (heh). EEGs already pick up something from neural activity. More sensitive electronics will, presumably, discern more. More advanced computers will, presumably, separate more (and lower amplitude) signals from the overall noise. Thereafter, the signal(s) can be sent anywhere using garden-variety comm technology. Somewhat more speculatively, the process can be reversed -- electrical fields impinging on synapses to influence the state of neurons.
And the reading and writing electrodes need not operate at a distance, separated from the brain by skull, scalp, and hair. There has already been experimentation with electrodes surgically inserted into the brain of a monkey. The SFnal next step is nanotech forming finer -- and many more -- electrodes in situ within the brain.
But will machine-aided telepathy "read minds" or "project thoughts"? Not any time soon, I suspect. Raw sensations, perhaps. Emotional states, maybe. The more complex the information one seeks to transfer, the more challenging. And might individuality bollix up the works? We're all wired slightly differently, for reasons genetic, environmental, and learned.
So technological telepathy? Not easy -- and for hard SF, still a bit of a stretch -- but by all means, fair game for the genre.