Mindey, 
Life-Saving Oximeter Handbands
Just like smoke alarms, but for human bodies.
Fire alarms work sensing alarming levels of fumes, and oximeters work by measuring how red light and infra-red light is absorbed by the blood, which can be done by really small light-powered diodes and photo sensors, connected via bluetooth to phone.
The advantage of oximeter, is in lower false positives rates. When measuring just pulse (heart-rate), the reasons of absence of pulse could be numerous, such as removal of the handband. However, the absence of measurement of oxygen would not raise the alarm. Only the measurement of oxygen level that is dangerously low, would, and automatically summon help.
(via "Reverse engineering a bluetooth low energy oximeter)
Bluetooth scanner, github/apk. In my case, for YWK-J1 oximeter, github.com/PolyU-IC/oxiMeter code was useful, though, I bumped into this bleak.exc.BleakError issue. There is though interesting Android Flutter project apparently successfully connecting to it, that I didn't try yet.
There are other BLE oximeters, and another approach described in this video alongside this code in Adafruit.
血中酸素濃度を測定します。この考えを自然界に具体化する実験があります https://www.nature.com/articles/d41586-019-03483-7
测量血氧水平，Nature上有具体化这个想法的实验 https://www.nature.com/articles/d41586-019-03483-7
[Transiency @ 0D38482D]、[] :)
[Transiency@0D38482D], [+] :)
「ウェアラブルグラフェンセンサーは周囲光を使用して健康状態を監視します」 周囲光を使用する————まったく同じアイデア、それらとcooprerateできるmabe
“Wearable graphene sensors use ambient light to monitor health” use ambient light———— Exactly same idea, mabe you can cooprerate with them
死亡のほとんどは酸素不足によるものであり、非常に広範囲の問題の場合の指標となります。
Most of deaths are because of lack of oxygen, so, an indicator in the case of very large spectrum of issues.
[Nimb]（https://nimb.com）リングは、使いやすさの観点から非常に近いようです。[Beurer PO60]（https://www.oxigo.co/en/beurer-po60-pulse-oximeter。 html）は、機能の観点から非常に近く見えます。集合的に何が達成できるかを見て興味深いでしょう。
It looks like the Nimb rings are very close from usability standpoint, and Beurer PO60 looks very close from functionality point of view. Would be interesting to see, what could be achieved collectively.