University of California Merced Relies on Negative Stiffness Vibration Isolator from Minus K Technology For accurate research into microscale friction Case Study

Feb.2022 -- Elizabeth Valero, Editor CMM Msgazine: Welcome to the first issue of 2022, which, it goes without saying, we all hope will be a significantly more positive year than the previous two. CMM has got off to a good start, with articles expected from new as well as old faces in the coming months, and I like to think this Is a sign of our continuance on the road back to normality. First I thought I might highlight a case study on how a negative-stiffness vibration isolator from Minus-K Technology has enabled the School of Engineering at the University of California Merced (UC Merced) to isolate environmental vibrations and thus obtain precision microscale or, more specifically, micronewton friction measurements The school has been using a linear-reciprocating microtribometer to conduct valuable research into friction and wear on different material surfaces subjected to various loading and sliding speed conditions. In order to acquire measurements at (he micron level the microtribometer needs to be isolated from environmental vibrations, particularly very low hertz vibrations, these can be due to many factors from equipment and people inside the building to vehicles and construction noise outside of it. The negative-stiffness vibration isolator replaced the vibration isolator the school initially used for its research but that proved inadequate. This is because the microtribometer demanded greater vibration Isolation for the measurement of friction in micronewtons. The ability of the negative-stiffness vibration isolator 1o achieve a significantly higher level of vibration isolation means The researchers can be confident that the friction response measured is attributable to the microtribometer's sliding contact. Moreover, they are able to study materials that have much lower frictions.

Microtribometer on a Miinus K Negative Stiffness Vibration Isolator (Courtesy of the UC Merced)

The School of Engineering at the University of California Merced (UC Merced) has been engaged In research focusing on applications of microscale friction measurements to better understand fundamental mechanisms underlying tribological phenomena. A critical end fundamental component of the school's research Is the Isolation of environmental vibrations utilizing a negative-stiffness vibration isolator from Minus K Technology which has enabled precision measurements of friction at micronewton magnitudes.

Whenever two surfaces are moving in contact with each other their behavior is influenced by friction. Smooth surfaces, even those polished lo a mirror finish, are not truly smooth on scales. They are rough, with sharp or rugged projections referred to as asperities.

Initially, the surfaces only touch at a few of these asperity points which cover only a very small portion of the surface area. Friction and wear originate at these points, so understanding their behavior becomes important when studying materials in contact.

The measurement of this fractional force between two surfaces is undertaken using a microtriborneter This instrument measures quantities, such as coefficient of friction and friction force between the two surfaces that are in contact These measurements can relate to a number of types of important properties of mechanical components, including energy efficiency.

The basic operation of a microtribometer involves a flat of spherical surface that is moved repetitively across the face of another material. An exact load is applied to the moving part for the duration of the test. Equipment and methods used to examine the surfaces before and after sliding include optical microscopes, scanning electron microscopes, optical interferometers and mechanical roughness testers. The final measurements show the wear on the material end are often used to determine its strength and longevity.

The need for vibration isolation
Microtribometer measurements at the micron level require isolation from ambient environmental vibrations, particularly very low hertz vibrations. Isolating a laboratory s sensitive instrumentation against low-frequency vibrations has become increasingly more vital to maintaining imaging quality and data Integrity.

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Negative-Stiffness Vibration Isolation Aids Quantum Electronic Research Single-Atom Flakes & Quantum Electronics Vibration Isolation

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.

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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...

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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?

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Minus K Technology Opens

Minus K Technology opens for business in
February 1993

Minus K's original SM-1 patented Negative-Stiffness passive vibration isolator. This was the first commercialy available vibration isolator offering 0.5 Hz natural frequencies for both vertically and horizontally. This was accomplished without the use of air compressors, computer componets or electricity.

The isolator could be used alone, or in conjunction with other units, and could be engineered directly into a system.

Original SM-1 Vibration Isolator

Within Saint Louis University’s (SLU) Department of Physics, research has been ongoing in the development of novel techniques for synthesis, characterization and measurement of low dimensional (1D and 2D) systems. This is in hopes to better understand how size, geometry or interfacing various materials and nanostructures influences the properties of the resulting systems.

Nanolithography Research
Nanolithography in general terms is concerned with the study and application of fabricating nanometer-scale structures, meaning patterns with at least one lateral dimension between 1 and 100 nm. A prime focus is very largescale integration (VLSI) and ultralarge-scale integration (ULSI) technology of nanoelectromechanical (NEMS) systems, and the need for better atomic-scale understanding of issues arising from the miniaturization of silicon devices. Under the direction of Dr. Irma Kuljanishvili, who heads up SLUs nanomaterials and nanofabrication research lab, the groups focus is on This approach is similar to a technique known as dip pen nanolithography.

In this technique, AFM tips or sharp needles can be employed to transfer small, femtoliter volumes of molecular solutions, or other liquid-based ink, to predefined locations on the surface of samples.

Carbon nanotubes, grapheme and other atomically monolayered materials are being considered as prime candidates for nanoscale science and technology applications, due to their unique and superior combination of electrical, thermal, optical and mechanical properties, says Kuljanishvili.

SLU's Negative-Stiffness Vibration Isolation System

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Notice that between points A and B, displacement is increasing while force is decreasing. Thus, the structure’s stiffness is negative in that region.

Negative-stiffness vibration isolators consist of a horizontal isolator and a vertical isolator connected in series. To counter motions that involve rotation (pitch and roll), a tilt motion pad can also be connected in series with the horizontal and vertical isolators.

The horizontal isolator consists of two fixed-free vertical beams (columns) supporting a weight. The weight imparts both eccentric (off-axis) axial compressive load and a transverse bending load. This phenomenon is referred to as the beam-column effect and causes the lateral bending stiffness of the beams to decrease. In effect, the isolator is acting as a horizontal spring with a negative-stiffness mechanism.

The horizontal isolator is designed to take advantage of the beam-column effect, allowing it to act like a negative-stiffness mechanism.

Vertical motion is addressed using two horizontal flexures loaded in compression, which form a negative-stiffness mechanism. The flexures are supported at their outer ends and connected to a stiff spring at their inner ends. The stiffness of the isolator is determined by the design of the flexures and by their compressive load.

Two flexures, fixed at their outer ends and connected to a spring at their inner ends, form a negative-stiffness mechanism that isolates equipment from vertical motion due to vibrations.

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Close-up of a stylus and LP record vinyl grooves

"Vinyl remains unsurpassed for reproducing music,” said Mark Döhmann, Founder of Döhmann Audio. To convey vinyls rich, nuanced potential a turntable must have precise speed control and operate without producing mechanical or electronic noise. The goal is an uncompromised signal emerging from a silent background, resulting from precisely designed construction that eliminates noise and gives precision speed control for ideal playback.

This goal has been very closely approximated with the release of the Helix One and Helix Two turntables, representing a breakthrough in analog playback design and execution. These turntables are a showcase for micro-signal architecture, a new way of thinking borne from the world of ultra-precision sub-atomic research, where the removal of unwanted vibration is critical to achieving precision results.

The Helix One and Helix Two turntables reward the listener with the closest facsimile to master tape yet realized. Their specifications demand the ultimate in noise suppression and vibration isolation systems, allowing the turntables and pick-up arms to deliver the micro-signals buried in the vinyl grooves of LPs.

Every aspect of the turntables' design requires the preservation of the micro-signals found in the grooves of the LP to be retrieved with as little modification and distortion as physically and electronically possible, added Döhmann. The turntables incorporate a number of engineering advances to deliver the lowest resonance profile for any pickup arm and LP combination.

These engineering advances include: a) mechanical crossover technology; b) a tri-modal platter system; c) an edge-damping ring; d) a tone arm damping system; e) resonance-tuned suspension; f) a diamond-like coating, amorphous material-bearing friction modifier; g) high-torque, adjustable-drive speed selections; and h) a velocity adjustment lock.

But what contributes to making the Helix One and Helix Two turntables truly unique is their highly precise, fully-integrated vibration isolation system.

The Need For Vibration Isolation
Vibration isolation in the playback process of high-end audio systems is crucial. Any external vibration, no matter how slight, even someone walking near the turntable or vibration from floor-mounted speakers, is sensed by the turntables stylus and affects the sound being played back from the record. Capacitors, resistors, transistors, tube amplifiers and other electronic components are likewise sensitive to vibration.

Analog audio is a very detailed and information rich storage and retrieval mechanism, continued Döhmann. The enemy of retrieval information is vibration, which can modulate with the needle as it works its way through the groove. If you can remove exterior vibration and allow the needle to operate in an optimally quiet method or platform, then you will get more information out because your noise is much lower.

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More at our Audio & Turntable Vibration Isolation Applications page...

(2016 Legacy Article) The tunable microwave-frequency alternating current scanning tunneling microscope (ACSTM) has opened the possibility of recording local spectra and local chemical information on insulator surfaces, much like the conventional scanning tunneling microscope (STM) has done for metals and semiconductors..

Spectroscopy in the microwave frequency range enables unrealizable measurements on conducting substrates, such as the rotational spectroscopy of a single adsorbed molecule. Developed in the early 1990s by Professor Paul Weiss, the nano-pioneering Director of the Weiss Group, a nanotechnology research unit of UCLAs California NanoSystems Institute, the ACSTMs single-molecule measurement techniques have illuminated unprecedented details of chemical behavior, including observations of the motion of a single molecule on a surface, and even the vibration of a single bond within a molecule. Such measurements are critical to understanding entities ranging from single atoms to the most complex protein assemblies.We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules, said David McMillan, Lead Technician at the Weiss Group.

Critical to understanding these variations has been developing the means to make tens- to hundreds-of-thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements.

Vibration isolation
To achieve these nano-level chemical and spectroscopic data sets, the ACSTM must be positioned in an ultra-stable operating environment, one free of low-frequency vibrations.The lab was using almost exclusively optical tables on pneumatic isolation, said McMillan.One of our big problems has been space constraint. We needed smaller pneumatic optical tables to fit. But as the air tables get smaller, their vibration isolation performance diminishes.

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The compound microscope has evolved from an instrument providing simple contrast viewing, into super-resolution systems capable of sub-diffraction accuracy. Its two platforms, upright and inverted, can be found in most laboratories doing cellular research, such as in biotech and pharmaceutical. Upright microscopes are used for viewing glass slides, and inverted for viewing live cells in Petri dishes. Despite its imaging advances, the basic architecture of the compound microscope has not substantially been modified in centuries.

This has now changed, with the recent release of the Revolve hybrid compound microscope, developed by Echo Laboratories (Echo), which has set a new precedent in microscope usability and design. The Revolve combines the full functionality of both upright and inverted microscopes in one instrument, and can switch between the two imaging modes relatively swiftly and easily. This gives the flexibility to view many types of samples with one microscope to a level of 300 350 nanometers resolution.

“More than 70 percent of labs end up having both inverted and upright microscopes,” said Jeff Huber, Director of Sales for Echo Laboratories. “But both uprights and inverts use similar objectives, illuminators, position systems and cameras. Why duplicate all of these expensive components? And why take up valuable lab space with two instruments? So, Echo Laboratories engineered a way to merge these two systems into one unified instrument, which is the Revolve microscope.”

Brightfield, Phase Contrast and Epifluorescence Imaging with iPad and Wireless Upload
his is a compound, infinity-path microscope, with applications for brightfield, phase contrast, and epi-fluorescence imaging. Current glass selection includes the entire line of Olympus objectives. Due to the unique nature of the upright/inverted combination, both a high-NA and long-working-distance transmitted-light condensers are available to support phase and brightfield. A high-accuracy locking mechanism is used to securely hold the condenser assembly in place, while still allowing for easy removal by a single lever.

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Press Release:
New Ultra-Thin CT-2 Low-Frequency Vibration Isolation Platform Adapts
to Space Constraints in Critical Micro- and Nano-Microscopy
(replaces the CT-1)

Full release...