continuous blood glucose monitor are nothing short of a true wonder. for people with diabetic it is a enormous help in keeping their health. the continues knowledge of your blood sugar level is overwhelming even to those who’ve been constantly fighting the disease, and makes it easy to check trends and influences on your body.
Current devices takes a measurement every 15 minutes and store all that information. Then with a scan of the reader (or even your cellphone, if you’re willing to void warranty) it’s all downloaded and displayed.
Unfortunately, my wife got Type I diabetes, so she’s using the Freestyle Libre sensor. Each sensor works for 2 weeks and then disables itself, so it needs to be replaced.
One day, I took one unit and dismantled it into pieces.
The design is very minimal: A battery, one chip, the sensor and an antenna.
What surprised me is the battery. It is a simple coin battery, and it’s not even soldered to the pcb. I thought it might be because of a tab, like the one used in toys to save battery until the device is unboxed. But I could not find nothing like that.
The chip is labeled RF430FRL152H, and a short googling finds out it is an “(ACTIVE) NFC ISO15693 Sensor Transponder With SPI/I2C Interface and 14-Bit Sigma-Delta ADC”.
That also explains the small antenna.
The sensor itself is where the magic happens. It is located in a white housing with rubber contacts that connects it to the pcb.
ny the way, contrary to popular belief, the constant pricking while being a nuisance, is definitely not the worst part of the the treatment. you get used to it quite quickly. But not having to do it is a joy.