Researchers develop a recyclable wearable electronic device

06-09-2021 | By Sam Brown

Recently, researchers from China developed a fully functional smartwatch that can be easily dissolved to recycle and reuse the electronic components used. What challenges does e-waste present, what did the researchers achieve, and why could fully recyclable electronics be the key to the future of electronics?

The challenge with e-waste

It is no surprise that e-waste is a growing concern worldwide, with landfills quickly becoming full, contaminants leaking into the surrounding environment, and the often terrible conditions found around such sites. This matter is made worse when countries ship materials to be recycled to other nations who will usually burn the waste (thereby contributing to climate change) or dump the waste in toxic sites whose workers are exposed to severe compounds.

Electronic devices contain many valuable materials such as gold and platinum, but these are only worth extracting when the prices for such materials increase. Electronic devices can, in theory, be recycled for their electronic components, but this comes with a range of challenges.

The first challenge is that trying to reuse old electronic components can be extremely tricky. These recycled components are not on reels making them hard to use in any commercial application. The components will have solder and flux still on their contacts and body, and these components will be degraded compared to new parts.

The second challenge of reusing electronic components is that only a handful of components are worth salvaging. For example, it is cheaper to use brand new passives instead of reuse passives on an old electronics device as those older components require identification, cleaning, testing, and then re-reeling. In most cases, socketed components (i.e. ICs, CPUs, and RAM slots) are the only components worth recycling.

Researchers develop a fully dissolvable smartwatch

Recently, researchers from China have developed a smartwatch that is entirely recyclable whose performance is not far off from modern smartwatch designs. While the design itself is very bulky, it is designed to fall apart when submerged in water for over 40 hours yet is resistant to sweat.

The design utilises transient nanocomposite circuit boards, which use zinc nanoparticles and silver nanowires to connect various components. The board itself uses a water-soluble polymer so that it dissolves when in water.

The smartwatch case was also developed using a polyvinyl alcohol material to dissolve when submerged in water. This enables the entire design to be completely broken down while freeing all electronic components used. These components can be separated from the dissolved solution and then reused in other designs.

Could such electronics be the key to a sustainable future?

While the device developed by the team is far from being commercial, it perfectly demonstrates how future electronics could be designed to help tackle the e-waste problem. Most electronics are designed to last several years, meaning that what the team has designed would not be suitable. However, the disposable electronics market would highly benefit from such designs and recyclability.

Disposable electronics are typically programmed once, used for a short period, and then thrown away. One typical example of disposable electronics is RFID tags used to protect high-value items in shops. Once taken home, these devices are designed to be thrown away by the customer with no hope of being recycled.

If such devices were replaced with water-soluble devices, then such devices could not only be recycled but reassembled using older parts. This would reduce the amount of e-waste produced while decreasing the raw resources needed to make replacement parts.

By Sam Brown