System Bits: March 24

A better band-aid
UC Berkeley engineers are working on a bandage that can detect bedsores before they are visible – while recovery from them is still possible.

Leveraging flexible electronics advancements, the researchers collaborated with colleagues at UC San Francisco to create their “smart bandage” that uses electrical currents to detect early tissue damage from pressure ulcers as they are forming, before the damage reaches the surface of the skin by using the electrical changes that occur when a healthy cell starts dying.

The smart bandage is fabricated by printing gold electrodes onto a thin piece of plastic. This flexible sensor uses impedance spectroscopy to detect bedsores that are invisible to the naked eye. (Source: UC Berkeley)

The idea is that this bandage could be carried by a nurse for spot-checking target areas on a patient, or incorporated into a wound dressing to regularly monitor how it’s healing.

A cool process for making better graphene
Caltech researchers have created a way to make graphene at room temperature which could pave the way for commercially feasible graphene-based solar cells and light-emitting diodes, large-panel displays, and flexible electronics.

With this new technique, large sheets of electronic-grade graphene can be grown in much less time and at much lower temperatures.

Graphene is expected to revolutionize a variety of engineering and scientific fields due to its unique properties, which include a tensile strength 200 times stronger than steel and an electrical mobility that is two to three orders of magnitude better than silicon. The electrical mobility of a material is a measure of how easily electrons can travel across its surface, the team explained.

Achieving these properties on an industrially relevant scale has proven to be complicated as existing techniques require temperatures that are much too hot—1,800 degrees Fahrenheit, or 1,000 degrees Celsius—for incorporating graphene fabrication with current electronic manufacturing. Also, high-temperature growth of graphene tends to induce large, uncontrollably distributed strain in the material, which severely compromises its intrinsic properties.

However, the Caltech method promises the production of high-mobility and nearly strain-free graphene in a single step in just a few minutes without high temperature.

Images of early-stage growth of graphene on copper. The lines of hexagons are graphene nuclei, with increasing magnification from left to right, where the scale bars from left to right correspond to 10 μm, 1 μm, and 200 nm, respectively. The hexagons grow together into a seamless sheet of graphene. (Source: Caltech)

The ability to produce graphene without the need for active heating not only reduces manufacturing costs, but also results in a better product because fewer defects—introduced as a result of thermal expansion and contraction processes—are generated. This in turn eliminates the need for multiple postproduction steps.

Quantum device detects, corrects its own errors
Researchers at UC Santa Barbara reminded that when scientists finally develop a full quantum computer, the world of computing will undergo a revolution of sophistication, speed and energy efficiency. Until then, quantum physicists like the ones in UC Santa Barbara’s physics professor John Martinis’ lab will have to create circuitry that takes advantage of the marvelous computing prowess promised by the quantum bit (“qubit”), while compensating for its high vulnerability to environmentally-induced error.

In what they are calling a major milestone, the researchers in the Martinis Lab are reporting their development of quantum circuitry that self-checks for errors and suppresses them, preserving the qubits’ state(s) and imbuing the system with the highly sought-after reliability that will prove foundational for the building of large-scale superconducting quantum computers.

It turns out keeping qubits error-free, or stable enough to reproduce the same result time and time again, is one of the major hurdles scientists on the forefront of quantum computing face, the researchers said.

The error detection process involves creating a scheme in which several qubits work together to preserve the information, whereby information is stored across several qubits.

The idea is that a system of nine qubits is built, which can then look for errors. Qubits in the grid are responsible for safeguarding the information contained in their neighbors in a repetitive error detection and correction system that can protect the appropriate information and store it longer than any individual qubit can.

A photograph of the nine qubit device. The device consists of nine superconducting ‘Xmon’ transmon in a row. Qubits interact with their nearest neighbors to detect and correct errors. (Source: UCSB)