Computers Math

Engineers at UC Riverside have unveiled an air-powered computer memory that can be used to control soft robots. The innovation overcomes one of the biggest obstacles to advancing soft robotics: the fundamental mismatch between pneumatics and electronics. The work is published in the open-access journal, PLOS One.
Pneumatic soft robots use pressurized air to move soft, rubbery limbs and grippers and are superior to traditional rigid robots for performing delicate tasks. They are also safer for humans to be around. Baymax, the healthcare companion robot in the 2014 animated Disney film, Big Hero 6, is a pneumatic robot for good reason.
But existing systems for controlling pneumatic soft robots still use electronic valves and computers to maintain the position of the robot’s moving parts. These electronic parts add considerable cost, size, and power demands to soft robots, limiting their feasibility.
To advance soft robotics toward the future, a team led by bioengineering doctoral student Shane Hoang, his advisor, bioengineering professor William Grover, computer science professor Philip Brisk, and mechanical engineering professor Konstantinos Karydis, looked back to the past.
“Pneumatic logic” predates electronic computers and once provided advanced levels of control in a variety of products, from thermostats and other components of climate control systems to player pianos in the early 1900s. In pneumatic logic, air, not electricity, flows through circuits or channels and air pressure is used to represent on/off or true/false. In modern computers, these logical states are represented by 1 and 0 in code to trigger or end electrical charges.
Pneumatic soft robots need a way to remember and maintain the positions of their moving parts. The researchers realized that if they could create a pneumatic logic “memory” for a soft robot, they could eliminate the electronic memory currently used for that purpose.
The researchers made their pneumatic random-access memory, or RAM, chip using microfluidic valves instead of electronic transistors. The microfluidic valves were originally designed to control the flow of liquids on microfluidic chips, but they can also control the flow of air. The valves remain sealed against a pressure differential even when disconnected from an air supply line, creating trapped pressure differentials that function as memories and maintain the states of a robot’s actuators. Dense arrays of these valves can perform advanced operations and reduce the expensive, bulky, and power-consuming electronic hardware typically used to control pneumatic robots.
After modifying the microfluidic valves to handle larger air flow rates, the team produced an 8-bit pneumatic RAM chip able to control larger and faster-moving soft robots, and incorporated it into a pair of 3D-printed rubber hands. The pneumatic RAM uses atmospheric-pressure air to represent a “0” or FALSE value, and vacuum to represent a “1” or TRUE value. The soft robotic fingers are extended when connected to atmospheric pressure and contracted when connected to vacuum.
By varying the combinations of atmospheric pressure and vacuum within the channels on the RAM chip, the researchers were able to make the robot play notes, chords, and even a whole song — “Mary Had a Little Lamb” — on a piano. Click here to view a video of the robot playing piano.
In theory, this system could be used to operate other robots without any electronic hardware and only a battery-powered pump to create a vacuum. The researchers note that without positive pressure anywhere in the system — only normal atmospheric air pressure — there is no risk of accidental overpressurization and violent failure of the robot or its control system. Robots using this technology would be especially safe for delicate use on or around humans, such as wearable devices for infants with motor impairments.
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Materials provided by University of California – Riverside. Original written by Holly Ober. Note: Content may be edited for style and length. More

A team of researchers from the University of Maryland has 3D printed a soft robotic hand that is agile enough to play Nintendo’s Super Mario Bros. — and win!
The feat, highlighted on the front cover of the latest issue of Science Advances, demonstrates a promising innovation in the field of soft robotics, which centers on creating new types of flexible, inflatable robots that are powered using water or air rather than electricity. The inherent safety and adaptability of soft robots has sparked interest in their use for applications like prosthetics and biomedical devices. Unfortunately, controlling the fluids that make these soft robots bend and move has been especially difficult — until now.
The key breakthrough by the team, led by University of Maryland assistant professor of mechanical engineering Ryan D. Sochol, was the ability to 3D print fully assembled soft robots with integrated fluidic circuits in a single step.
“Previously, each finger of a soft robotic hand would typically need its own control line, which can limit portability and usefulness,” explains co-first author Joshua Hubbard, who performed the research during his time as an undergraduate researcher in Sochol’s Bioinspired Advanced Manufacturing (BAM) Laboratory at UMD. “But by 3D printing the soft robotic hand with our integrated fluidic transistors, it can play Nintendo based on just one pressure input.”
As a demonstration, the team designed an integrated fluidic circuit that allowed the hand to operate in response to the strength of a single control pressure. For example, applying a low pressure caused only the first finger to press the Nintendo controller to make Mario walk, while a high pressure led to Mario jumping. Guided by a set program that autonomously switched between off, low, medium, and high pressures, the robotic hand was able to press the buttons on the controller to successfully complete the first level of Super Mario Bros. in less than 90 seconds.
“Recently, several groups have tried to harness fluidic circuits to enhance the autonomy of soft robots,” said recent Ph.D. graduate and co-first author of the study Ruben Acevedo, “but the methods for building and integrating those fluidic circuits with the robots can take days to weeks, with a high degree of manual labor and technical skill.”
To overcome these barriers, the team turned to “PolyJet 3D Printing,” which is like using a color printer, but with many layers of multi-material ‘inks’ stacked on top of one another in 3D. More

Measurements of biomechanical properties inside living cells require minimally invasive methods. Optical tweezers are particularly attractive as a tool. It uses the momentum of light to trap and manipulate micro- or nanoscale particles. A team of researchers led by Prof. Dr. Cornelia Denz from the University of Münster (Germany) has now developed a simplified method to perform the necessary calibration of the optical tweezers in the system under investigation. Scientists from the University of Pavia in Italy were also involved. The results of the study have been published in the journal Scientific Reports.
The calibration ensures that measurements of different samples and with different devices are comparable. One of the most promising techniques for calibrating optical tweezers in a viscoelastic medium is the so-called active-passive calibration. This involves determining the deformability of the sample under investigation and the force of the optical tweezers. The research team has now further improved this method so that the measurement time is reduced to just a few seconds. The optimized method thus offers the possibility of characterizing dynamic processes of living cells. These cannot be studied with longer measurements because the cells reorganize themselves during the measurement and change their properties. In addition, the shortening of the measurement time also helps to reduce the risk of damage to the biological samples due to light-induced heating.
In simplified terms, the underlying procedure to perform the calibration works as follows: The micro- or nanometer-sized particles are embedded in a viscoelastic sample held on the stage of a microscope. Rapid and precise nanometer-scale displacements of the specimen stage cause the optically trapped particle to oscillate. By measuring the refracted laser light, changes in the sample’s position can be recorded, and in this way, conclusions can be drawn about its properties, such as stiffness. This is usually done sequentially at different oscillation frequencies. The team led by Cornelia Denz and Randhir Kumar, a doctoral student in the Münster research group, now performed the measurement at several frequencies simultaneously for a wide frequency range. This multi-frequency method leads to a shortened measurement time of a few seconds. The scientists used solutions of methyl cellulose in water at different concentrations as samples. These have a similar viscoelasticity to living cells.
Background: Biomechanical properties such as stiffness, viscosity and viscoelasticity of living cells and tissues play a crucial role in many vital cellular functions such as cell division, cell migration, cell differentiation and tissue patterning. These properties of living cells could also serve as indicators of disease progression. For example, the onset and development of cancer is typically accompanied by changes in cell stiffness, viscosity, and viscoelasticity.
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The laws of quantum physics rule the microcosm. They determine, for example, how easily electrons move through a crystal and thus whether the material is a metal, a semiconductor or an insulator. Quantum physics may lead to exotic properties in certain materials: In so-called topological insulators, only the electrons that can occupy some specific quantum states are free to move like massless particles on the surface, while this mobility is completely absent for electrons in the bulk. What’s more, the conduction electrons in the “skin” of the material are necessarily spin polarized, and form robust, metallic surface states that could be utilized as channels in which to drive pure spin currents on femtosecond time scales (1 fs= 10-15 s).
These properties open up exciting opportunities to develop new information technologies based on topological materials, such as ultrafast spintronics, by exploiting the spin of the electrons on their surfaces rather than the charge. In particular, optical excitation by femtosecond laser pulses in these materials represents a promising alternative to realize highly efficient, lossless transfer of spin information. Spintronic devices utilizing these properties have the potential of a superior performance, as they would allow to increase the speed of information transport up to frequencies a thousand times faster than in modern electronics.
However, many questions still need to be answered before spintronic devices can be developed. For example, the details of exactly how the bulk and surface electrons from a topological material respond to the external stimulus i.e., the laser pulse, and the degree of overlap in their collective behaviors on ultrashort time scales.
A team led by HZB physicist Dr. Jaime Sánchez-Barriga has now brought new insights into such mechanisms. The team, which has also established a Helmholtz-RSF Joint Research Group in collaboration with colleagues from Lomonosov State University, Moscow, examined single crystals of elemental antimony (Sb), previously suggested to be a topological material. “It is a good strategy to study interesting physics in a simple system, because that’s where we can hope to understand the fundamental principles,” Sánchez-Barriga explains. “The experimental verification of the topological property of this material required us to directly observe its electronic structure in a highly excited state with time, spin, energy and momentum resolutions, and in this way we accessed an unusual electron dynamics,” adds Sánchez-Barriga.
The aim was to understand how fast excited electrons in the bulk and on the surface of Sb react to the external energy input, and to explore the mechanisms governing their response. “By controlling the time delay between the initial laser excitation and the second pulse that allows us to probe the electronic structure, we were able to build up a full time-resolved picture of how excited states leave and return to equilibrium on ultrafast time scales. The unique combination of time and spin-resolved capabilities also allowed us to directly probe the spin-polarization of excited states far out-of-equilibrium,” says Dr. Oliver J. Clark.
The data show a “kink” structure in transiently occupied energy-momentum dispersion of surface states, which can be interpreted as an increase in effective electron mass. The authors were able to show that this mass enhancement plays a decisive role in determining the complex interplay in the dynamical behaviors of electrons from the bulk and the surface, also depending on their spin, following the ultrafast optical excitation.
“Our research reveals which essential properties of this class of materials are the key to systematically control the relevant time scales in which lossless spin-polarised currents could be generated and manipulated,” explains Sánchez-Barriga. These are important steps on the way to spintronic devices which based on topological materials possess advanced functionalities for ultrafast information processing.
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A team of researchers from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), the University of Liège and the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy have developed a microswimmer that appears to defy the laws of fluid dynamics: their model, consisting of two beads that are connected by a linear spring, is propelled by completely symmetrical oscillations. The Scallop theorem states that this cannot be achieved in fluid microsystems. The findings have now been published in the academic journal Physical Review Letters.
Scallops can swim in water by quickly clapping their shells together. They are large enough to still be able to move forwards through the moment of inertia while the scallop is opening its shell for the next stroke. However, the Scallop theorem applies more or less depending on the density and viscosity of the fluid: A swimmer that makes symmetrical or reciprocal forward or backward motions similar to the opening and closing of the scallop shell will likely not move an inch. ‘Swimming through water is as tough for microscopic organisms as swimming through tar would be for humans,’ says Dr. Maxime Hubert. ‘This is why single-cell organisms have comparatively complex means of propulsion such as vibrating hairs or rotating flagella.’
Swimming at the mesoscale
Dr. Hubert is a postdoctoral researcher in Prof. Dr. Ana-Suncana Smith’s group at the Institute of Theoretical Physics at FAU. Together with researchers at the University of Liège and the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy, the FAU team has developed a swimmer which does not seem to be limited by the Scallop theorem: The simple model consists of a linear spring that connects two beads of different sizes. Although the spring expands and contracts symmetrically under time reversal, the microswimmer is still able to move through the fluid.
‘We originally tested this principle using computer simulations,’ says Maxime Hubert. ‘We then built a functioning model’. In the practical experiment, the scientists placed two steel beads measuring just a few hundred micrometres in diameter on the surface of water contained in a Petri dish. The surface tension of the water represented the contraction of the spring and expansion in the opposite direction was achieved with a magnetic field which caused the microbeads to periodically repel other.
Vision: Swimming robots for transporting drugs
The swimmer is able to propel itself because the beads are of different sizes. Maxime Hubert says, ‘The smaller bead reacts much faster to the spring force than the larger bead. This causes asymmetrical motion and the larger bead is pulled along with the smaller bead. We are therefore using the principle of inertia, with the difference that here we are concerned with the interaction between the bodies rather than the interaction between the bodies and water.’
Although the system won’t win any prizes for speed — it moves forwards about a thousandth of its body length during each oscillation cycle — the sheer simplicity of its construction and mechanism is an important development. ‘The principle that we have discovered could help us to construct tiny swimming robots,’ says Maxime Hubert. ‘One day they might be used to transport drugs through the blood to a precise location.’
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Scientists on the hunt for an unconventional kind of superconductor have produced the most compelling evidence to date that they’ve found one. In a pair of papers, researchers at the University of Maryland’s (UMD) Quantum Materials Center (QMC) and colleagues have shown that uranium ditelluride (or UTe2 for short) displays many of the hallmarks of a topological superconductor — a material that may unlock new ways to build quantum computers and other futuristic devices.
“Nature can be wicked,” says Johnpierre Paglione, a professor of physics at UMD, the director of QMC and senior author on one of the papers. “There could be other reasons we’re seeing all this wacky stuff, but honestly, in my career, I’ve never seen anything like it.”
All superconductors carry electrical currents without any resistance. It’s kind of their thing. The wiring behind your walls can’t rival this feat, which is one of many reasons that large coils of superconducting wires and not normal copper wires have been used in MRI machines and other scientific equipment for decades.
But superconductors achieve their super-conductance in different ways. Since the early 2000s, scientists have been looking for a special kind of superconductor, one that relies on an intricate choreography of the subatomic particles that actually carry its current.
This choreography has a surprising director: a branch of mathematics called topology. Topology is a way of grouping together shapes that can be gently transformed into one another through pushing and pulling. For example, a ball of dough can be shaped into a loaf of bread or a pizza pie, but you can’t make it into a donut without poking a hole in it. The upshot is that, topologically speaking, a loaf and a pie are identical, while a donut is different. In a topological superconductor, electrons perform a dance around each other while circling something akin to the hole in the center of a donut.
Unfortunately, there’s no good way to slice a superconductor open and zoom in on these electronic dance moves. At the moment, the best way to tell whether or not electrons are boogieing on an abstract donut is to observe how a material behaves in experiments. Until now, no superconductor has been conclusively shown to be topological, but the new papers show that UTe2 looks, swims and quacks like the right kind of topological duck. More

Electronic circuits that compute and store information contain millions of tiny switches that control the flow of electric current. A deeper understanding of how these tiny switches work could help researchers push the frontiers of modern computing.
Now scientists have made the first snapshots of atoms moving inside one of those switches as it turns on and off. Among other things, they discovered a short-lived state within the switch that might someday be exploited for faster and more energy-efficient computing devices.
The research team from the Department of Energy’s SLAC National Accelerator Laboratory, Stanford University, Hewlett Packard Labs, Penn State University and Purdue University described their work in a paper published in Science today.
“This research is a breakthrough in ultrafast technology and science,” says SLAC scientist and collaborator Xijie Wang. “It marks the first time that researchers used ultrafast electron diffraction, which can detect tiny atomic movements in a material by scattering a powerful beam of electrons off a sample, to observe an electronic device as it operates.”
Capturing the cycle
For this experiment, the team custom-designed miniature electronic switches made of vanadium dioxide, a prototypical quantum material whose ability to change back and forth between insulating and electrically conducting states near room temperature could be harnessed as a switch for future computing. The material also has applications in brain-inspired computing because of its ability to create electronic pulses that mimic the neural impulses fired in the human brain. More

By combining oil drops with water containing a detergent-like substance, the scientists found they could produce artificial swimmers that are able to swim independently and even harvest energy to recharge.
The oil droplets use fluctuating temperature changes in their surrounding environment to store energy and to swim. When cooled, the droplets release thin ‘tail-like’ threads into the environment. The friction generated between the tails and surrounding fluid, pushes the droplet causing them to move. On heating, the droplets then retract their tails returning to their original state, and harness the heat from their environment to recharge.
The researchers show that the droplets recharge multiple times and are able to swim for periods of up to 12 minutes at a time.
Dr Stoyan Smoukov, Reader in Chemical Engineering at Queen Mary University of London and author of the study, said: “In biology, research shows that to create even the simplest artificial cells we need over 470 genes. However, through this international collaboration, we show that just by using a few simple and inexpensive components we can create a new type of active matter that can change shape and move just like a living thing.”
“We hope that this study will open up the opportunity for people to engage in cutting-edge science. As the only equipment needed is a simple optical microscope, people could create these microswimmers with the most basic laboratory set-ups, or even at home. With thousands of swimmers per drop of water, it’s a world in a drop situation. And when it costs 7p per teaspoon, there’s plenty for everyone.”
Other types of artificial swimmers exist however their movements are either driven by chemical reactions, which create bubbles that propel the swimmers through fluids, or by physical forces such as magnetic or electric fields. Instead, this new class of swimmers, which are around the size of a red blood cell, are able to spontaneously assemble and move without using external forces.
As the swimmers are not harmful to other living things, the scientists hope they could be used to study the basic interactions between living organisms such as bacteria and algae.
“In nature we often see large numbers of organisms such as bacteria, grouping together but our understanding of how these organisms interact with each other is incomplete. By mixing our simple artificial swimmers with groups of living organisms we could develop a clearer picture of how biological microswimmers communicate with each other. For example, do they only communicate due to the physical act of ‘bumping’ into each other, or are there other chemicals or signals released into the environment essential for their interaction.”
Video: https://www.youtube.com/watch?v=OKe54UucXD8
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