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www.technology.org 2015 08521.txt.txt

#New Self-Destructing Devices to Lead the Way towards Sustainable Electronics Thanks to falling prices, increasing demand and short lifespans of most consumer appliances, electronic waste has become a growing problem worldwide. But what if all those devices, currently languishing in the landfill, could just dissolve away or break down to their molecular components, making them easy to recycle? With that goal in mind, a group of researchers from the University of Illinois teamed up with their colleagues from the Frederick Seitz Materials Laboratory, led by Professor John A. Rogers, a Swanlund Chair in Materials science and engineering, have developed a line of heat-triggered, self-destructing devices, a step toward greatly reducing electronic waste and boosting sustainability in device manufacturing. In announcing their new technology, which they detailed in the journal Advanced Materials, the researchers also demonstrated a radio-controlled trigger that could remotely activate self-destruction on demand. e have demonstrated electronics that are there when you need them and gone when you don need them anymore, said Aerospace engineer and team leader Professor Scott R. White. his 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. The new technique consists of coating magnesium resistors (or silicon diodes), printed on very thin and flexible materials, in wax that contains microscopic droplets of methanesulfonic acid. Whenever the device heats up, the wax melts and releases the acid which quickly and completely dissolves the device. his work demonstrates the extent to which clever chemistries can qualitatively expand the breadth of mechanisms in transience, and therefore the range of potential applications, said Rogers. By tuning the thickness of the wax layer, the concentration of the acid and the applied temperature, the researchers can control how fast the device dissolves from mere seconds to minutes. The devices can also be made to degrade in steps encasing individual components of the electric circuit in waxes with different melting temperatures could create possibilities for sophisticated devices that can sense something in the environment and respond to it in a timely manner. Triggering a device of this kind is achieved through a radio-frequency receiver which the end user manipulates to send a signal to an inductive heating coil within the device that melts the wax and releases the acid. If a cyclic polyphthalaldehyde (cppa) substrate is used to carry the electronic components, it can be depolymerized by the acid and the entire device is dissolved without leaving a trace. e took our ideas in terms of materials regeneration and flipped it 180 degrees, White said. f you can keep using something, whether it obsolete or just doesn work anymore, we like to be able to bring it back to the building blocks of the material so you can recycle them when youe done, or if you can recycle it, have it dissolve away and not sit around in landfills. The team work was supported by the National Science Foundation and DARPA whose Vanishing Programmable Resources (VAPR) program has been investigating the potential for transient electronics designed to self-destruct on command to prevent classified technology finding its way into enemy hands l

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