Where do electronics go when they die? Most devices are laid to eternal rest in landfills. But what if they just dissolved away, or broke down to their molecular components so that the material could be recycled?
Expanding on previous research into electronic devices that dissolve in water once they have reached the end of their useful life, researchers at the University of Illinois have developed a new type of “transient” electronic device that self-destructs in response to heat exposure. The work is aimed at making it easy for materials from devices that usually end up in landfill to be recycled or dissolved completely.
Using heat as a trigger has now enabled the creation of electronic devices that can be prompted to self-destruct on demand.
The technology involves first printing magnesium circuits on thin, flexible materials. Microscopic droplets of a weak acid are then trapped in wax, which is coated onto the devices. When exposed to heat, the wax melts and releases the acid, which completely dissolves the device. The researchers were also able to create devices that can be remotely triggered to self-destruct by embedding a radio-frequency receiver and inductive heating coil. In response to a radio signal, the coil heats up and melts the wax, leading to the destruction of the device.
Similar to the devices that dissolve in water, the time it takes for the heat-triggered devices to dissolve can be controlled by tuning the thickness of the wax, the concentration of the acid, and the temperature. The researchers say it is possible to create a device that dissolves in as little as 20 seconds or up to a couple of minutes after the heat is applied.
Additionally, by encasing different parts in waxes with different melting temperatures, it is possible to create devices that degrade in a series of predefined steps. This gives control over which parts of the device are operative at what time, thereby providing the potential for devices that can sense and respond to conditions in their environment. The team is also exploring the potential for other triggers, such as ultraviolet light and mechanical stress.
The researchers, led by aerospace engineering professor Scott R. White, published their work in the journal Advanced Material.
More information: “Thermally triggered degredation of transient electronic devices,”