Research

3D printing increases memory of flexible Silicon chips 7000 times

The U.S. Air Force Research Laboratory (AFRL) and American Semiconductor have combined traditional manufacturing techniques with 3D printed circuitry to produce a flexible Silicon-on-polymer chip.

Besides its material qualities, the new chip has a memory more than 7,000 times larger than any comparable commercially available devices, making it suitable as a micro-controller to be integrated into other objects.

The need for a flexible chip

Silicon chips, found in almost every electronic device today, are often rigid and brittle. While this usually not a problem for computers and smartphones, which house the chips within a protective shell, the advent of “the internet of things” necessitates more flexible Silicon chips, as more and more objects are integrated with computer technology.

“When we look at putting these type of devices into a flexible form factor, rigidness works against us,” explained Dr Dan Berrigan, a research scientist at the AFRL Materials and Manufacturing Directorate. Instead, a flexible chip could function as a microcontroller with an onboard memory for any number of objects, capable of system control and data gathering.

Dan Berrigan with flexible 3D printed second skin technology developed with the Harvard University. Photo via US AFRL.
Dan Berrigan with flexible 3D printed second skin technology developed with the Harvard University and other projects. Photo via US AFRL.

Slimming down the Silicon

“Working with American Semiconductor, we took Silicon integrated circuit chips and thinned them until they became flexible but were still able to maintain circuit functionality,” said Berrigan. “This now allows us to place the micro-controllers (essentially mini-computers) in places we couldn’t before.”

American Semiconductor’s FleX Silicon-on-Polymer process is capable of producing flexible wafers with a final Silicon thickness as thin as 2000 Ångstroms (0.0002mm), which can also conform to irregular surfaces.

This can then be combined with AFRL’s capabilities of 3D printing electronics. One such technology includes extruding a stretchable silver electronic ink across a substrate, and then digitally picking up small electronic components and placing them along the circuit.

The circuit with its components can then be placed on to a flexible mount capable of conducting electricity.

Malcolm J Thompson of American Semiconductor with a thin Silicon wafer. Photo via US Department of Commerce.

Putting flexible Silicon to good use

“It’s capable of turning a system on and off, and it can also collect data from a sensor and retain it in memory…” continued Berrigan. “We can wrap this type of chip around a fuel bladder sensor to detect leaks, use it to monitor munitions inventory and even augment cold-chain monitoring through temperature sensing.” 

According to the AFRL, further applications for wearable devices with microchips could include monitors for hydration and fatigue, and in soft robotics for wounded soldiers or the elderly.

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Flexible silicon-on-polymer. Photo via US AFRL.