I haven't enjoyed a teardown as much iFixit's Apple Watch teardown in a long time. Here are some things that I found particularly interesting:
- The heart rate monitor is actually a plethysmograph capable of measuring blood oxygen level. Sadly, that feature isn't enabled.
- The ambient light sensor is behind the display panel as opposed to surface-mounted like on most smartphones.
- It appears upgrading the internals is unlikely, as some had speculated. iFixit states "the difficulty of removing the S1 alone casts serious doubt on the idea of simply swapping out the internals."
- Everything is tiny. Really tiny. Including the tiniest tri-wing screws iFixit has ever seen. Apple Watch is truly an engineering marvel.
Related: Chipworks technical teardown which includes X-ray shots. Chipworks