19 November 2015 Last updated at 01:07 GMT
The Blocks project had hoped to raise $250,000 (Â£164,000) but backers pledged six times that amount.
The creators say the modular design, which lets wearers choose which sensors they want on their wrist, makes the device future-proof and upgradeable.
Co-founders Serge Didenko and Ali Tahmaseb showed a prototype to BBC technology reporter Chris Foxx.
A customisable smartwatch with removable sensors has smashed through its crowdfunding target.