Lots of folks joke about smelling things through the internet… I just saw this one a few minutes ago. Technically, if the range of potential smells is limited, its not that hard to do. It only gets crazy, if one wants true smell, or hundreds of variations, and there in lies the difficulty.
A cursory view of patents, and applications shows everything from scented ink, to heated capilaries, to pressure, venturi, or heat based atomizing systems. Its not rocket science to add ethernet connectivity to such, but physical size and space constraints make variations a challenge. Otoh, such systems provide for the possibility of scenting an entire room, which most times is overkill.
An alternative solution might be a specialized scent printer, where in an array of scents are preprinted on paper sheets, but are only activated upon being mixed with printer ink. Mechanically, such a solution is exceedingly simple. COTS printers could be used, albeit significant resources would likely be needed in the paper, and ink chemistry domain. The end product could provide for hundreds of scents on a page, and being the amount of material used is miniscule, the time duration of a scent would be automatically limited. It is possible, the scent paper could even be reused.
Another possibility is a scribing type device, ie scratch and sniff, where in an internet controlled syllus surrounded by a gasket of some nature, and a fan to disperse the scent could be used. Such an approach would reduce the need for substantial chemistry resources, being it is riding upon well developed prior art. The scribing method could be implemented similar to the pen plotters of old, another well developed technology. The only real challenge is the gasketing to prevent cross contamination of the scratch and snift zones. Scribe cleaning between scent product may also prove a challenge, but less so than the gasket aspect.
ut may pose significant chemical challenges. The scribe method, sort of