If you have diabetes, you’re likely familiar with finger pricks and glucose meters. Good news! These meters are getting better. They now require less blood, making it easier on your fingertips. Still, checking your blood multiple times a day can be a hassle. Continuous glucose monitoring (CGM) is an option, but it used to need a prescription and could be pricey. Recently, though, there’s a new affordable option available over-the-counter: the Stelo CGM. Curious about its insides? [Andy] explored this and shared his findings.
For those who haven’t tried a CGM, there’s still an initial prick. You’ll feel it about every two weeks on the back of your arm. A special needle quickly punctures the skin and then retracts, leaving a small tube called a catheter behind. This catheter connects to a module that sticks to your skin. It might sound a bit uncomfortable, but most people barely notice it. It’s definitely a better option than multiple finger pricks every day.
So, what’s inside this module? Quite a bit! It contains a coin cell battery and an nRF52832 microcontroller. This tiny chip checks the sensor every 30 seconds and sends readings to your phone every 5 minutes via Bluetooth. There are antennas for both Bluetooth and NFC, which helps pair the module with your phone. A few custom chips are included, but their functions are still a mystery.
[Andy] mentions that the battery could last longer than the two weeks the device is designed for. Factors like the chemicals used, adhesive strength, and site cleanliness probably limit its lifespan. Still, two weeks seems reasonable.
It’s fascinating to think we’re in an age where such advanced technology can be so easily disposable. Creating a CGM is no small feat. What we really hope for is a fully functional artificial pancreas someday.
