Towards Transient Electronics And The Need For It

Dr S.S. Verma is a professor at Department of Physics, Sant Longowal Institute of Engineering and Technology, Sangrur, Punjab

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Electronic waste can also be controlled by designing integrated circuits out of materials that are biodegradable. Transient electronics, the new class of silk-silicon devices, promises a generation of medical implants that would never need surgical removal, as well as environmental monitors and consumer electronics that can become compost rather than trash.

Developmental status

Transient electronics can go as far and as complex as the demand and applications allow. Development of self-destructing devices came from a broad multi-disciplinary collaboration uniting researchers from all fields of science and technology. Multi-disciplinary research groups have tackled the problem of using other triggers to break down devices, including ultraviolet light, heat and mechanical stress. The goal is to find ways to disintegrate the devices so that manufacturers can recycle costly materials from used or obsolete devices, or so that devices could break down in a landfill.

Previous research in the area has explored the use of transient materials to create dissolvable devices such as transistors, resistors and diodes. Describing the research, researchers have mentioned that polymer composites consist of different ratios of gelatin or sucrose integrated with poly (vinyl alcohol) matrices. They have also demonstrated that dissolution and transiency of polymer composites could be retarded or enhanced by addition of gelatin or sucrose at different ratios, respectively.

Researchers are experimenting with a blend of programmable biodegradable and transient insulating polymer films. They have found that, by adding gelatin to the mix, dissolution can be slowed, while addition of sucrose speeds up the rate of transiency.

Using these special polymers, researchers were able to build and test an antenna that was capable of sending data and then completely dissolving when a trigger was activated. One constant in this experimentation with different composite structures is that the material maintains the appropriate physical properties to function as a substrate for electronics.

Scientists have tested several biodegradable materials including DNA, proteins and metals for making transient electronics. Tiny electronic sensors and devices that can be implanted in the body and then dissolve almost without a trace are getting closer to reality.

Efforts are on to develop a transient memory resistor with dissolvable components. This electronic component, also called a memristor, is a new type of resistor that regulates the flow of electric current and also remembers charges.

A flock of small, single-use drones capable of making precise deliveries or completing other military missions and then vapourising into thin air sounds suspiciously like science fiction, but such devices have already been developed and are being brought into the realm of reality. One intriguing example of these ephemeral materials is small polymer panels that sublimate directly from solid to gas.

So far, the disappearing antenna is the most impressive application of this technology. One minute, it is an antenna broadcasting important coordinates or whatever. Drop in a solution, though, and the next minute it is gone—nothing but a few flecks of metal remain.

Another device is a blue LED. It is bright and shiny, and then it is gone, almost without any trace.

Researchers hope to develop more sophisticated devices like a credit card that could dissolve when lost by just sending a signal from a smartphone to start the process.

A new technology can make computer chips self-destruct when remotely triggered. The new method uses silicon computer wafers attached to a piece of tempered glass that shatters into smithereens when heated in one spot. Heat can be turned on via a remote, which, in the future, could conceivably be triggered by anything using Wi-Fi to a radio frequency signal.

Methodology

Researchers have created electronics that will self-destruct on command, and the technology uses radio frequency, acid and a layer of wax on the circuit to let the devices melt with an application of heat or on receiving a signal from a remote device.

They have dissolved electronics in water, which could be used for biomedical implants using heat as the trigger. Heat-triggered devices use magnesium circuits printed on very thin, flexible materials. They have embedded a weak acid in a bit of wax on the circuit. When wax is heated, acid is released and dissolves the components. To remotely trigger the reaction, researchers have installed a heating coil that the radio signal turns on. That, in turn, melts the wax.

Researchers can control how fast the device degrades by tuning the thickness of wax, concentration of acid and temperature. They can now design a device to self-destruct within 20 seconds to a couple of minutes after heat is applied. Devices can also degrade in steps by encasing different parts in waxes with different melting temperatures.

This gives precise control over parts of a device that are operative, creating possibilities for sophisticated devices that can sense something in the environment and respond to it. To remotely trigger the reaction, researchers have embedded a radio frequency receiver and an inductive heating coil in the device. You can send a signal to cause the coil to heat up, which melts the wax and dissolves the device.

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