System Bits: Dec. 30

3D printing merges plastics, active electronics
Princeton researchers have embedded tiny light-emitting diodes into a standard contact lens, allowing the device to project beams of colored light as part of a project demonstrating 3-D printing techniques.

And while the lens is not designed for actual use — it requires an external power supply — the device was created to demonstrate the ability to 3D print electronics into complex shapes and materials, and shows 3D printing can be used to create complex electronics including semiconductors. In this case, the researchers 3D printed an entire LED.

In this project, the hard contact lens is made of plastic. The researchers used tiny quantum dot crystals as the ink to create the LEDs that generated the colored light. Different size dots can be used to generate various colors.

Instant-start computers
A research team at Cornell University has reported a breakthrough in the direction of instant-on computing with a room-temperature magnetoelectric memory device. Equivalent to one computer bit, they believe this exhibits the holy grail of next-generation nonvolatile memory: magnetic switchability, in two steps, with nothing but an electric field.

The device requires a low voltage, without current, to switch it. Devices that use currents consume more energy and dissipate a significant amount of that energy in the form of heat, which is what heats up computers and drains batteries, they reminded.

The Cornell team made their device out of a compound called bismuth ferrite due to its rare trait of being both both magnetic and ferroelectric. This means it’s always electrically polarized, and that polarization can be switched by applying an electric field. Such so-called ferroic materials are typically one or the other, rarely both, as the mechanisms that drive the two phenomena usually fight each other.

This combination makes it a “multiferroic” material, which means it can be used for nonvolatile memory devices with relatively simple geometries — as well as working at room temperature.