Build log
Why our first ring has no health sensors, yet.
Most smart rings are health rings. Ours starts as a ring you talk to. That was a trade-off, and there is one health claim we will not make at all.
In short. Heart and temperature sensors would take room from the battery and wake through the night; in our design model that shortens a typical charge by roughly a quarter to two-fifths. The first Lychnos Ring keeps its whole battery for conversation; health comes with the second model, as wellness rather than medicine. And we will not claim to read blood sugar from a ring.
The trade-off
A ring has room for one small battery, and in ours the radio already takes most of the day’s energy. Adding a heart-rate and temperature sensor means a smaller cell and a sensor that wakes through the night. In our design model, that shortens a typical charge by roughly a quarter to two-fifths. For a ring whose job is to answer you all day, that is too much to give up in the first model.
Every number here is an estimate from the design files. We will measure the real ones on a prototype, and publish them.
What the second model adds Planned
- Heart rate and heart rate variability, the signals behind recovery and stress.
- Skin temperature, for trends from night to night.
- Sleep: when you slept and how well, from heart, temperature and movement together.
- Stress, as a trend over the day.
- Blood oxygen, as a trend through the night.
- Blood pressure trends: changes in your blood pressure, set against a cuff once a month. A trend, not a reading: a ring is no substitute for a blood pressure monitor.
These are wellness insights, the kind that help you notice patterns and ask better questions. They are not medical measurements and they do not diagnose anything. Health data stays in our EU cloud with your explicit consent, and Lychnos, the assistant, sees it only if you allow it.
The claim we will not make
Blood sugar from a ring, without a needle, would be extraordinary. No ring or watch does it reliably today. In February 2024 the US Food and Drug Administration warned people not to use smartwatches or smart rings that claim to measure blood glucose without piercing the skin: it has authorized none, and a wrong number can lead to a wrong insulin dose. Since January 2026 its wellness guidance leaves room for non-invasive glucose estimates meant only for wellness, which it does not review. We still will not make that claim: a number that looks like blood sugar invites decisions it cannot carry.
What we plan instead is simpler and useful: if you already wear an approved glucose monitor, Lychnos can read its numbers out to you and show them on the ring.
Further out: tests with a needle Research
A painless micro-needle that tests a drop of blood is a research idea for us, not a product. It would be a medical device and a diagnostic test in Europe and the US, with clinical studies before anything else. If we get there, you will read about the studies here first.
Why this order
We would rather ship a ring that does one thing well, a conversation from your finger without your phone, and add health properly, than promise everything on day one. You can see what the first ring does on the ring’s page, and how it compares with health rings in AI rings, compared.
What a ring can and cannot read through the skin, and what the FDA changed in 2026: can a smart ring replace a blood test?