While 2015 ended on a high note with the late-November announcement of Ali Javey’s team’s creation of the first optoelectronically perfect monolayer semiconductor, that was just a taste of things to come.  Research conducted in the EECS department in 2016 would go on to produce no fewer than four new firsts in a variety of arenas: magnetic chips, sensors, transistors, and robotics.

March: The first time magnetic chips shown able to operate at lowest energy dissipation rate theoretically possible

Magnetic microscope image of three nanomagnetic computer bits. Each bit is a tiny bar magnet only 90 nanometers long. The microscope shows a bright spot at the “North” end and a dark spot at the “South” end of the magnet. The “H” arrow shows the direction of magnetic field applied to switch the direction of the magnets. (Image by Jeongmin Hong and Jeffrey Bokor)

This successful experiment by Prof. Jeffrey Bokor’s team, published in Science Advances, demonstrates that magnetic chips can dramatically reduce power consumption — down to as little as one-millionth the amount of energy per operation used by transistors in modern computers.

The team employed an innovative technique to measure the tiny amount of energy dissipation that resulted when they flipped a nanomagnetic bit: they used a laser probe to follow the direction that a magnet was pointing as an external magnetic field was used to rotate the magnet from “up” to “down” or vice versa (see photo caption).  They determined that it only took 15 millielectron volts of energy (the equivalent of 3 zeptojoules) to flip a magnetic bit at room temperature, effectively demonstrating the Landauer limit–a formula, based on the second law of thermodynamics, which calculates the lowest limit of energy required for a computer operation.  This was the first time that a practical memory bit could be manipulated and observed under conditions that allowed the Landauer limit to be reached.

Reducing power consumption is critical for both mobile devices, which demand powerful processors that can run for a day or more on small batteries, and large-scale cloud computing, which is progressively increasing the load on the world’s power grids.

Full story at: Berkeley News  Experiments show magnetic chips could dramatically increase computing’s energy efficiency

August: The first implantable dust-sized wireless sensor

Wireless, batteryless implantable sensors could improve brain control of prosthetics, avoiding wires that go through the skull. (UC Berkeley video by Roxanne Makasdjian and Stephen McNally)

“Neural dust,” created by a team led by Associate Prof. Michel Maharbiz and Prof. Jose Carmena, uses the novel approach of converting ultrasound vibrations into electricity to power and read out measurements when implanted in the muscles and peripheral nerves of rats. Their findings were reported in the August 3 issue of the journal Neuron.

“I think the long-term prospects for neural dust are not only within nerves and the brain, but much broader,“ said Maharbiz, “Having access to in-body telemetry has never been possible because there has been no way to put something supertiny superdeep. But now I can take a speck of nothing and park it next to a nerve or organ, your GI tract or a muscle, and read out the data.“

“The beauty is that now, the sensors are small enough to have a good application in the peripheral nervous system, for bladder control or appetite suppression, for example,“ Carmena said. “The technology is not really there yet to get to the 50-micron target size, which we would need for the brain and central nervous system. Once it’s clinically proven, however, neural dust will just replace wire electrodes. This time, once you close up the brain, you’re done.“

Full story at: Berkeley News Sprinkling of neural dust opens door to electroceuticals

October: The smallest transistor ever built

Schematic of a transistor with a molybdenum disulfide channel and 1-nanometer carbon nanotube gate. (Credit: Sujay Desai/UC Berkeley)

“We made the smallest transistor reported to date,” said Prof. Ali Javey. “The gate length is considered a defining dimension of the transistor. We demonstrated a 1-nanometer-gate transistor, showing that with the choice of proper materials, there is a lot more room to shrink our electronics.”

The research team led by Javey, Prof. Jeffrey Bokor and Prof. Chenming Hu, is part of the Electronic Materials program in Berkeley Lab’s Materials Science Division.   A transistor with a working 1-nanometer gate is comparatively tiny–a strand of human hair is about 50,000 nanometers thick.  Most transistors now on the market have between 14- and  20-nanometer gates.

The materials chosen were carbon nanotubes and molybdenum disulfide (MoS₂), an engine lubricant commonly sold in auto parts shops. MoS₂ is part of a family of materials with immense potential for applications in LEDs, lasers, nanoscale transistors, solar cells, and more.  Javey cautions, “It’s a proof of concept. We have not yet packed these transistors onto a chip, and we haven’t done this billions of times over. We also have not developed self-aligned fabrication schemes for reducing parasitic resistances in the device. But this work is important to show that we are no longer limited to a 5-nanometer gate for our transistors.”

Full story at: Berkeley Lab Smallest. Transistor. Ever.

December: The most vertically agile robot ever created

Salto, for saltatorial locomotion on terrain obstacles (Photo by Stephen McNally)

Prof. Ronald Fearing,  PhD student Justin Yim, post doc Mark Plecnik, and ME PhD student Duncan Haldane designed a small robot that can leap into the air and then spring off a wall, or perform multiple vertical jumps in a row, resulting in the highest robotic vertical jumping agility ever recorded.

Salto (for SAltatorial Locomotion on Terrain Obstacles) weighs 100 grams (3.5 ounces), is 26 centimeters (10.2 inches) tall when fully extended, has a vertical jumping agility of 1.75 meters per second and can jump to a maximum height of roughly 1.008 meters (3.3 ft). For the wall jump, Salto attained an average height gain of approximately 1.21 meters (3.97 ft).  Other robots can jump higher than Salto in a single leap, but by using power modulation, Salto doesn’t need to wind up before a subsequent leap. As soon as it jumps, Salto is ready to jump again.

The design for the robot was inspired by the physiology of the galago, also known as a bushbaby, which can jump five times in just four seconds to gain a combined height of 8.5 meters (27.9 feet). The galago has a special ability to store energy in its tendons, so that it can jump to heights not achievable by its muscles alone.

Salto’s agility opens new pathways of locomotion that were previously unattainable. The researchers hope that one day this robot and other vertically agile robots can be used to jump around rubble in search and rescue missions.

Full story at: Berkeley News Wall-jumping robot is most vertically agile ever built