Get your first month of KiwiCo free: https://kiwico.com/stevemould Smart watches use a flashing green light to measure your heart rate and a red and infarred light to measure your oxygen saturation. The way it works is really clever. Check out Andrew Steele's video here: https://www.youtube.com/watch?v=fDj2kYIF-sE Check out the python code he used to analyse my face: https://github.com/ajsteele/faceHR Check out my Motion Amplification video here: https://www.youtube.com/watch?v=rEoc0YoALt0 You can buy my books here: https://stevemould.com/books You can support me on Patreon and get access to the exclusive Discord: https://www.patreon.com/stevemould just like these amazing people: Brendan Williams Edward Unthank Frank Hereford Jeremy Buchanan Tj Steyn Jeremy Cole Matthew Cocke Pavel Dubov Alan Wilderland Alnitak DamTheGreat David Whitesell Grant Hay Heather Liu John Doe John Zelinka Lukas Biewald Marshall Fitzpatrick Matt Nathan Blubaugh Paul Warelis Tim S Root Alnitak Damien Szerszinski Lizzy and Jack Twitter: http://twitter.com/moulds Instagram: https://www.instagram.com/stevemouldscience/ Facebook: https://www.facebook.com/stevemouldscience/ Buy nerdy maths things: http://mathsgear.co.uk/