Better understanding the character and properties of graphene, and similar two-dimensional materials, will advance their integration into improvements for semiconductors, electronics, photovoltaics, battery energy storage and many other applications.

One university laboratory that has been conducting research with graphene and other atomically-thin materials for some years is the Henriksen Research Group at Washington University in St. Louis, Missouri.

Our experiments entail the careful measurement of the electronic properties of thinly-layered materials, including both electronic transport and thermodynamic quantities, such as the magnetization and compressibility of electron gas, says Professor Erik Henriksen Ph.D., leading professor of the Henriksen Research Group. We also conduct measurements of the infrared absorption spectrum to probe the electronic structure directly.

The group searches for unusual and unexpected properties of low-dimensional materials, utilizing a combination of electronic, optical and thermodynamic measurement approaches to understand the novel quantum electronic phases that arise. The experiments are generally conducted at very low temperatures, fractions of a degree Kelvin above absolute zero, and in high magnetic fields, employing custom devices made of graphene or related crystals.

Single-Atom Flakes
We look at the physics of the layered graphene, where the layers are weakly bound, so they can be pulled apart, explains Henriksen. We isolate these very thin layers down to a single atom. Then, lift the graphene flakes from bulk graphite with adhesive tape, transferring them very carefully onto silicon wafers.

Full article...

In its continuing efforts to revolutionize discovery-based research into complex biological systems, Pacific Biosciences has released its next generation of automated, long-read genomic sequencer with single molecule, real-time (SMRT) sequencing technology – the Sequel System.

In its continuing efforts to revolutionize discovery-based research into complex biological systems, Pacific Biosciences has released its next generation of automated, long-read genomic sequencer with single molecule, real-time (SMRT) sequencing technology – the Sequel System.

The Sequel System is very multifaceted in operation, says Kevin Lin, mechanical engineer at Pacific Biosciences. It encompasses robotics, chemical and biological processing, and photonics. Because its intended to be used in diverse settings within research and laboratory environments, excessive ambient vibrations could negatively influence the data sets. So, we needed to implement a vibration isolation component that not only isolated the sensitive components from vibrations, but also was sufficiently small, compact, and integrative.

Internal and external factors can create vibration issues from buildings housing the system including heating and ventilation systems, fans, pumps, elevators, adjacent road traffic, nearby construction, loud noise from aircraft, and weather conditions. These influences cause vibrations as low as 2Hz that can create strong disturbances in sensitive equipment.

With our earlier sequencer model, we used air tables for vibration isolation, which, for the most part, performed adequately, Lin says. But use of the Sequel System in more diverse locations, where low-frequency vibrations may be present to a greater or lesser degree, necessitated a vibration isolator that was compact enough to fit into our much smaller Sequel System and could effectively cancel out these low-frequency vibrations.

Negative-stiffness vibration isolation
Pacific Biosciences ultimately decided on negative-stiffness isolation to address their needs. Developed by Minus K Technology, negative-stiffness isolators use completely passive mechanical technology for low-frequency vibration isolation without using motors, pumps, or chambers, making them zero maintenance. Because of their very high vibration isolation efficiencies, particularly in the low frequencies, negative-stiffness vibration isolation systems enable vibration- sensitive instruments, such as the Sequel System, to operate in severe low-vibration environments that wouldnt be practical with top-performance air tables and other vibration-mitigation technologies...

Full article...

All of the JWST systems-level cryogenic vacuum tests were performed at the NASA Johnson Space Center’s (JSC) Chamber-A. It is now the largest high-vacuum, cryogenic-optical test chamber in the world, and made famous for testing the space capsules for NASA's Apollo mission, with and without the mission crew. It is 55 feet (16.8 meters) in diameter by 90 feet (27.4 meters) tall. The door weighs 40 tons and is opened and closed hydraulically. The air in the chamber weighs 25 tons, when all the air is removed the mass left inside will be the equivalent of half of a staple.

Diagram of the Cyrogenic Chamber in which the JWST was tested for space.

For three years, NASA JSC engineers built and remodeled the chambers interior for the temperature needed to test the James Webb Space Telescope. Chamber A was retrofitted with the helium shroud, inboard of the existing liquid-nitrogen shroud and is capable of dropping the chambers temperature farther down than ever, which is 11 degrees above absolute zero (11 Kelvin, -439.9 Fahrenheit or -262.1 Celsius).

A key addition to Chamber A was the addition of a set of six custom Minus K negative-stiffness vibration isolators. The Minus K passive isolators do not require air and offer better isolation than air and active isolation systems. A major factor in the selection of the of the vibration isolators was that they not only isolate vibration vertically, but also horizontally at less than 1 Hz.

JWST was designed to work in space where the disturbances are highly controlled and only come from the spacecraft, while on Earth with all the ground-based disturbances, such as the pumps and motors, and even traffic driving by can affect the testing. The Minus K vibration isolators provided dynamic isolation from external vibration sources to create a near flight-like disturbance environment.

The isolators utilize Minus K's patented Thermal Responsive Element (TRE) compensator device, a passive mechanical device, requiring no air or electricity just like the isolators. The TRE compensator adjusted the isolators as the temperature changes throughout the testing at JSC, keeping the JWST in the proper position.

The Critical Design Review for Spacecraft-to-Optical Telescope Element vibration isolation system was completed one month earlier than scheduled at the end of 2011. The six Minus K negative-stiffness vibration isolators were installed on top of Johnson Space Centers Thermal Vacuum Chamber A in March 2014.

JWST needed a support structure inside the vacuum chamber to hold equipment for the testing. Engineers installed a massive steel platform suspended from the six vibration isolators via steel rods about 60 feet long (18.2 meters) each and about 1.5 inches (or 38.1 mm) in diameter, to hold the telescope and key pieces of test equipment. The sophisticated optical telescope test equipment included an interferometer, auto-collimating flat mirrors, and a system of photogrammetry precision surveying cameras in precise relative alignment inside the chamber while isolated from any sources of vibration, such as the flow of nitrogen and helium inside the shroud plumbing and the rhythmic pulsing of vacuum pumps.

Minus K's Involvement continued...

-How much farther can JWST see than the Hubble?
-Why was it launched from near the equator?
-How cold does the JWST get in space?
-How did origami play into the trip?
-Why 24-karat gold on the mirrors?

Full article...