You know better than almost anybody just how hard it is to insert sensors in the body. Optical techniques let you bypass that degradation, and a company actually shipped a portable raman-based glucometer something like a decade ago. Its battery life wasn't good enough, but making a wearable, miniaturized Raman spectrometer was crazy impressive.
Neat. Too bad nobody remembers C8 Medisensors! They went under more than a decade ago, and it's too bad that they didn't leave a lasting cultural or digital footprint. They did ship a raman-based CGM:
My take is that Raman spectroscopy is not getting the love it deserves purely due to the hardware cost and difficulty, which has come down a lot but still high. IR spectroscopy has been quite popular due to its cheap hardware and its amenability towards ML.
My (weakly held) hypothesis is that ML stack on IR already maxed out, and there is no more signal we can get out of. H20 interference is still difficult to work with. Raman is the way to go for those cases. An affordable, portable (true) Raman could change how we do medical and chemical sensing in aqueous solutions, anywhere from medicine to food production.
I actually spent a full year outside academia doing IR v Raman work. I ended up deciding on industrial IR with a sophisticated signal processing & ML stack, but at some point, I was planning to build a Raman from scratch because I was so tired of compensating for O-H bonds.
