I suppose I was one of the early pioneers in this field, I didn't know it had a name. A few years ago we published a paper on attaching three different olfactory receptors to carbon nanotube transistors and exposing the resulting devices to a half dozen or so chemicals while monitoring the responses. We were trying to produce something which was more usable (i.e. real-time) than the electrochemical methods described in TFA (to be clear, TFA describes very good work, we just had a different approach).
I wouldn't say this is a field which is taking off. It is significantly difficult to combine proteins with electronics. There are very, very few people/research groups who have the combination of abilities and experience to make these devices and properly interpret the results. More often than not, researchers perform laboratory, one-off measurements they can understand, but have no relevance to modern electronics or systems usable outside of the lab they were built in. Another common issue is performing measurements you don't understand, coming to conclusions that are wrong and sending the field off in a useless direction. It is very, very difficult to both build a good experiment AND properly interpret the results. The physics/chemistry guys don't understand the biology and the biologists don't understand the physics/chemistry. It can take many years to just learn to talk to eachother and stop assuming that "standard" processes, assumptions and statistics are applicable. Getting funding for this stuff can be a challenge, because no one really has claimed this field and none of the funding agencies (in the US, at least) seem to understand it. There are a handful of senior academics who can do this stuff, and a growing number of mid-career guys like me, but we're still a very small group.
If people are interested in what's going on with this field, I would recommend looking up the work of Phil Collins at UC Irvine, Ethan Minot at Oregon State and Charlie Johnson at University of Pennsylvania. I'm sure there are other good groups out there, but I know those guys are good.