Communications of the ACM

The Cornell group, in conjunction with Honeywell Aerospace, has explored self-destructing technology by experimenting with a number of different approaches, including systems that use liquids and signals to trigger the disintegration process. In one instance, they created a circuit with microscopic cavities of novel polymers containing sodium bifluoride and rubidium. Exposing the shell to radio waves of a specific frequency triggers graphene-on-nitride micro-valves in the shell to open, allowing the alkali metals to oxidize and produce a thermal reaction that causes an already thinned-out chip to disintegrate and vaporize rapidly. “The technique uses the metals in the chips as an energy source. They are attached to a special polymer that reacts to the heat,” Lal explains.

The disintegration process is triggered by a tiny block that measures 0.04 inches wide. After the electronics disintegrate, the result is a fine powder consisting of cesium and rubidium oxides, sand-like particles from the silicon chip, and tiny flakes of carbon from the graphene, along with the remaining battery (the research team is also working on a way to make the battery vaporizable, too). “The project requires ongoing research into polymers and how to optimize both mechanical and materials functions,” Intel’s Gund says. One area of particular interest is how to use flexible layers of a material substrate to produce a circuit that operates like conventional silicon electronics, while using plastics and other materials that can also be broken down or recycled using the vaporization process.

Meanwhile, Rogers and his research
group have focused on engineering
a system that could wirelessly deliver
programmable drug doses to a specific
part of the body, then naturally degrade
and disappear. This technology might
be used to deliver medication post-
surgery, for example. The challenge of
this approach, Rogers says, “is that we
have to build a device that is very stable
over a relevant time period but then is
ultimately completely unstable, in the
sense that it eventually vanishes with-
out a trace.” The team is working to per-
fect a silicon, magnesium, magnesium
oxide, and silk circuit that dissolves in
the body in much the same way that
absorbable sutures vanish after minor
surgeries. This involves using mixtures
of chemicals and polymers that cause
disintegration and packing them into
layers with electrodes that will trigger
the destruction process.

Materially There

Developing new types of circuits and electronics that self-destruct requires rethinking and redesigning semiconductors that have never been engineered for anything other than maximum performance over a desired lifespan, Gund says. Adding to the task: the design and engineering process can vary greatly, depending on the desired performance and results. A biomedical device may require 10 weeks of high-performance operation before it is made to degrade and dissolve into the body, while a military device might be required to disintegrate in a matter of seconds. What’s more, depending on the device and how it used, the trigger mechanism might vary.

Researchers continue to explore how different combinations of chemicals and substances interact to produce a desired result, and how they can get to the point where there is little or no trace of the circuit or electronic component. So, far, most of the research has been conducted through trial and error and testing different combinations of materials together. In the future, Yu says, machine learning might also serve as a valuable tool for sorting through growing mountains of data and discovering combinations that can be used for different types of circuits and in different situations.

“These projects require an interdisci-
plinary approach and experimentation
with a lot of different chemicals and
materials,” Yu explains. “We are only
beginning to understand how to build
these self-destructive electronics and
engineer the desired systems.”
Says Rogers: “Transient electronics
are beginning to take shape in a tan-
gible way. The technology will almost
certainly impact a wide range of areas
in the years to come.”