How to use the Blood Oxygen app on Apple Watch - Apple Support
Smart Fingertip Pulse Oximeter with iPhone App
Amazon.com: iHealth AIR Rechargeable Fingertip Pulse Oximeter, Blood Oxygen Saturation Monitor with App, SpO2, Pulse Rate, Plethysmograph, and Perfusion Index : Health & Household
Amazon.com: iHealth AIR Rechargeable Fingertip Pulse Oximeter, Blood Oxygen Saturation Monitor with App, SpO2, Pulse Rate, Plethysmograph, and Perfusion Index : Health & Household
Sensors | Free Full-Text | Design and Evaluation of a Low-Cost Smartphone Pulse Oximeter