Researchers in the US have developed heat-triggered self-destructing electronic devices as a step toward reducing waste and boosting sustainability in device manufacturing.
The goal is to find ways to disintegrate devices so that manufacturers can recycle costly materials from used or obsolete electronics or so that devices can break down in landfill.
Researchers at the University of Illinois have also developed a radio-controlled trigger that could remotely activate self-destruction on demand.
The team, led by aerospace engineering professor Scott R White, published their work in Advanced Materials.
“We have demonstrated electronics that are there when you need them and gone when you don’t need them anymore,” White said in a statement.
“This is a way of creating sustainability in the materials that are used in modern-day electronics. This was our first attempt to use an environmental stimulus to trigger destruction.”
White’s group teamed up with John A Rogers, a Swanlund chair in materials science and engineering and director of the Frederick Seitz Materials Laboratory at Illinois.
Rogers’ group pioneered transient devices that dissolve in water, with applications for biomedical implants.
Together, the two multi-disciplinary research groups tackled the problem of using other triggers to break down devices, including ultraviolet light, heat and mechanical stress.
The heat-triggered devices use magnesium circuits printed on very thin, flexible materials. The researchers trap microscopic droplets of a weak acid in wax, and coat the devices with the wax.
When the devices are heated the wax melts, releasing the acid, which dissolves the device completely.
To remotely trigger the reaction, researchers embedded a radio-frequency receiver and an inductive heating coil in the device.
The user can send a signal to cause the coil to heat up, which melts the wax and dissolves the device.
“This work demonstrates the extent to which clever chemistries can qualitatively expand the breadth of mechanisms in transience, and therefore the range of potential applications,” Rogers said.
The researchers can control how fast the device degrades by tuning the thickness of the wax, the concentration of the acid, and the temperature.
They can design a device to self-destruct within 20 seconds or in a couple of minutes after heat is applied.
The devices can be degraded in steps by encasing different parts in waxes with differing melting temperatures.
This gives more precise control over which parts of a device are operative, creating possibilities for sophisticated devices that can sense something in the environment and respond to it.
White’s group has long been concerned with device sustainability and pioneered methods of self-healing to extend the life of materials.
“We took our ideas in terms of materials regeneration and flipped it 180°,” White said.
“If you can’t keep using something, whether it’s obsolete or just doesn’t work anymore, we’d like to be able to bring it back to the building blocks of the material so you can recycle them when you’re done, or if you can’t recycle it, have it dissolve away and not sit around in landfills.”