3 ms·
The 15-day limit is due to the enzyme degradation on the electrode. > While GOx maintains this level of activity in vitro, its stability in vivo is of the ord
by quanto 2y ago
The 15-day limit is due to the enzyme degradation on the electrode.
> While GOx maintains this level of activity in vitro, its stability in vivo is of the order of 10–14 days, necessitating novel immobilization and enzyme modification strategies to extend the functional lifetime of these oxygen-sensitive sensors.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3879770/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3879770/
Coincidentally, when I was doing this field of research, I wanted a hardware/software design that could algorithmically compensate for the sensor degradation. I even wanted to mathematically model the electrochemistry to find a clean solution. My electrode was nanoporous platinum, which then was considered more advanced/fashionable/versatile than glucose oxidase coating. In the end, I decided on reading off some cached table, not unlike a consumer electronics estimating remaining battery life.
On a separate note, you can design a fuel cell out of blood glucose. So, your body glucose generates electricity to fuel your electronics. The amount of electricity generated is not too off the target power for ultra-efficient circuits, and we even conducted in-vitro experiments as a proof of concept.
All of this was 20 years ago. I am glad that there are commercial solutions now but a bit saddened that the field hasn't progressed as fast as other areas of technology.
- MengerSponge 2y agoYou 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.
- walterbell 2y agoRecent discussion on optical glucose sensors, https://news.ycombinator.com/item?id=43124436 https://news.ycombinator.com/item?id=43124436
- MengerSponge 2y agoNeat. 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: https://www.diabetesincontrol.com/c8-medisensors/ https://www.diabetesincontrol.com/c8-medisensors/
- quanto 2y agoMy 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.
- djmips 2y agoI'm impressed! Anything else interesting that you worked on in the last 20 years?
- quanto 2y agoI worked on chemical reactivity prediction based on statistical methods. Back then, it was not clear whether stat/ML methods would be able to predict chemical reactions, thus aiding drug discovery. I would like to think that my simple project's success contributed to the ML revolution we now see in the field :) I also made another comment under this post about IR v Raman work I did. That work I have done is still relevant in the field, but I am hoping someone comes up with a better solution. Thanks for your kind words!
- djmips 2y agoVery cool! Thanks for sharing.