Scientists made the first dissolvable smartwatch. While it’s not as slim as current devices, it has similar performance and capabilities. The watch is sweat resistant, but disintegrates within 40 hours if submerged in water.
Electronic waste is difficult and dangerous to recycle and is therefore often not worthwhile for small electronic devices. To reduce this waste, scientists in China made a temporary nanocomposite circuit board. Transient materials are not designed to last – in this case the material dissolves in water into environmentally friendly compounds.
The composite consists of zinc nanoparticles with silver nanowires, which improves the electrical properties of the device. This bimetallic nanocomposite is screen-printed onto a water-soluble polymer, polyvinyl alcohol. Drops of water then trigger chemical reactions to solidify the material – a technique known as water sintering.
The circuit boards are enclosed in a soluble 3D-printed housing, also made of polyvinyl alcohol, which can dissolve in water and remains intact when welded. Any non-dissolvable components, such as the screen and transistors, can be collected and recycled after the rest of the watch crumbles.
This resolvable smartwatch can perform many of the same functions as current non-resolvable devices: monitor heart rate and step count, and display messages from Bluetooth-connected phones.
Printable and volatile electronic devices like this watch could offer a solution to the increasing electronic waste – as soon as they become more visually appealing.