My initial research into odour simulations reveals a sad story. Artificial noses are big business; simulated scents are not.
The first artificial nose was apparently developed by Persaud and Dodd in 1982. See this biography of Mr Dodd and his life as a perfume expert. According to Wired, "There are about 1,000 odor-matching proteins, each with a slightly different configuration, scattered across a human's 10 million odor-detecting neurons. (By comparison, a mouse has about 1 million neurons of this type, while a pig boasts 100 million.) When the shape of an odor molecule matches the shape of a protein, the molecules lock together, triggering the neuron, which sends a signal that the brain recognizes as a smell."
There now seems to be a whole industry in artificial noses, which have uses or potential uses in the food and beverage industries, in medical diagnosis, in sensing the escape of chemicals, for military purposes, detecting explosives, etc. They don't seem to be as sensitive as human noses yet, but they don't tire or get head colds, and you can put them in dangerous places. There's even an academic website on electronic noses, listing 16 academic institutes and 20 commercial organisations involved in research in the field.
But these are detecting smells, not making them. The story of simulated smells is sadder.
According to Retrofuture, there were two attempts to simulate smells in the cinema.
(a) Smell-O-Vision, introduced in the 1960 film "Scent of Mystery", used plastic hidden tubes under the seats to pump out selected smells. Bottles of scent were held on a rotating drum and the process was triggered by a signal on the film itself. (This process, it was claimed, would do for the movies what the talkies did in the 20s - introduce a whole new dimension.)
(d) In 1981, scratch-and-sniff "Odorama" cards were issued for the film "Polyester".
Neither attempt was a commercial or artistic success. Neither was repeated on a second film.
Wired in 1999 had an article about Digiscents, a product which Wired claimed would 'launch the next web revolution'. This was a box that sat by your PC and used tiny vials of oils, heated selectively in response to signals from the computer, and blown out by a fan. By blending different proportions of just 100 to 200 "scent primaries" the makers claimed to be able to generate billions of smells, just as colours are generated by blending three primary colours.
Alas, by 2005, the digiscents website is little more than a would-be portal advertising perfumes etc. There are quite a few references to the company in 2000, eg when it launched the iSmell. (I'm not making this up...). But then in 2001 the company failed to find second round VC financing to follow the $20 million it reportedly got from angel investors and Pacific Century CyberWorks. (PCCW embarked on a programme of acquisitions at this time which now meakes it the largest telecoms company in Hong Kong, at least according to Wikipedia.. But no mention of smells any more.)
It's a puzzle. Here are three attempts to do the technology, all practical up to a point. (Certainly no less practical than the early sound simulators, ie gramophones.) We could doubtless do it even better today. But no-one wants it.
Interesting entry. The old appliance manufacturer for whom I designed products had a digiscent-style system on a Chinese product around 2000. It used small bead-things though. I might still have the unit, but I never tried the scent beads and might have tossed those - they had a "Spencer's gift store" look to them; very low-brow (fortunately the unit was a giveaway).
In 1981, scratch-and-sniff "Odorama" cards were issued for the film "Polyester".
wrt "Polyester", I have to say that I saw it back in the Spring of '82 as part of a campus event. Quality control for the little cards they handed out may have been an issue. I've sometimes wondered if some mismatches weren't intentional in order to play the audience. In other words, 90% of the crowd would gag at the smell (the screen would flash a number first and then the scene would show the source of the smell) of, for example, manure while a few others in the crowd would indicate that the smell was pleasing. It happened to me as well. Everyone would gag and I was busy enjoying the scent! People would then look at you as if you were disturbed... of course anyone there to see "Polyester" didn't have a finger to point. That almost sounds like something John Waters might do intentionally.