The tomato thing has been done by SCIO: https://www.youtube.com/watch?v=s_5Al294Nak https://www.youtube.com/watch?v=s_5Al294Nak which apparently is now availab

The tomato thing has been done by SCIO: https://www.youtube.com/watch?v=s_5Al294Nak https://www.youtube.com/watch?v=s_5Al294Nak which apparently is now available as an extra sensor small enough to build into ordinary phones, with just one obscure Chinese manufacturer showing a prototype (at $299 for the handheld, it's probably too expensive for now).