Researchers realized a dissolvable smartwatch which can be easily recycled.
Small electronic products such as smartwatches and fitness trackers cannot be easily recycled once they end up in a landfill. And with all the fast paced innovations happening, older versions of products are being replaced by newer, which generates millions of tons of electronic waste per year. Recycling is therefore mandatory to reduce these wastes. However, it often isn’t worth the effort to recycle small consumer electronics because their parts must be salvaged by hand, and some processing steps, such as open burning and acid leaching, can cause health issues and environmental pollution.
To simplify recycling of such small electronics, researchers, in ACS Applied Materials and Interfaces, have reported development of two-metal nanocomposite for circuits that disintegrates when submerged in water. They demonstrated the circuits in a prototype transient device that dissolved within 40 hours.
Previously, Xian Huang and colleagues developed a zinc-based nanocomposite that dissolved in water, but it wasn’t conductive enough for consumer electronics. Now, scientists have improved their dissolvable nanocomposite’s electrical properties while also creating circuits robust enough to withstand everyday use. They added silver nanowires to zinc-based nanocomposite to make it highly conductive.
The smartwatch had sensors that accurately measured a person’s heart rate, blood oxygen levels and step count, and sent the information to a cellphone app via a Bluetooth connection. All that is left behind after dissolving is OLED display, the microcontroller, resistors, and capacitors that have been integrated on circuits.
The researchers say the two-metal nanocomposite can be used to produce transient devices with performance matching that of commercial models, which could go a long way toward solving the challenges of small electronics waste.