Monthly Archives: May 2024

What are Artificial Muscles?

In the animal world, muscles are the basis of all movement. With commands from the brain, electrical pulses contract or release muscles, and this is how we can move our body parts. Now, researchers have created new types of actuators based on structures of multiple soft materials. Like regular actuators, these also convert electrical energy into force or motion. The advantage of these new actuators is they are lightweight, quiet in operation, and biodegradable. During the early stages of development, continuous electrical stimulation could only achieve short-term contraction of the actuators. However, new research has led to the development of a system that not only allows for longer-term contraction of the actuators but also enables accurate force measurements. These new actuators are the basis for artificial muscles.

With their ability to transform electrical energy into force or motion, the new actuators are serving an important role in everyday life. These are soft-material-based actuators, and because of their multiple functionality, have been attracting plenty of attention in the scientific community.

According to the researchers, making a soft actuator is rather simple. They use multi-material structures, in the form of pockets made of flexible films of plastic. They fill the pockets with oils and cover them with conductive plastics. Electrically activating the film results in the pocket contracting, similar to what happens in a biological muscle.

Using this technique, the researchers were able to create robotic muscles, tactile surfaces, and changeable optics. So far, using continual electrical stimulation has resulted in only short-term contractions, and this was a considerable practical barrier.

The researchers have published their findings in Nature Electronics. Researcher Ion-Dan Sirbu, at the Johannes Kepler University in Linz, along with an Austrian research group, developed a system enabling accurate measurement of force in the new actuators.

During their research on combining common materials, the researchers also experimented with plastic films that they were using for work on artificial muscles. They realized a specific combination of materials was able to sustain a constant force for long periods arbitrarily.

The team then constructed a theoretical model of the material for studying its characteristics in depth. They realized their simple model could accurately describe their experimental results. They claim their results with the simple but powerful tool will help in designing and investigating newer systems.

Their study has not only made this technology more functional, it additionally enables identifying material combinations that reduce energy consumption by a factor of thousands. With their material combinations, the researchers and other scientists have successfully investigated and developed various types of artificial muscles, tactile displays, and variable gradient optics.

The study has deepened our grasp of the basic workings of soft actuators. These advancements hold promise for significant strides in assistive devices, mobile robots, and automated machines, offering valuable contributions to marine, terrestrial, and space explorations. This is particularly crucial, given the ongoing quest in these sectors for cost-effective, high-performance solutions that prioritize low power consumption and sustainable environmental impact.

What is Magnetic Levitation?

Many systems such as flywheels, Maglev trains, and other high-speed machinery already use magnetic levitation. The Brookhaven National Laboratory had pioneered this technology in the late 1960s. Maglev trains use the magnetic levitation technology, where superconducting magnets keep a train car suspended above a U-shaped concrete guide-way. Like regular magnets, superconducting magnets repel one another when like poles face each other. Systematically electrifying propulsion loops in the system creates moving magnetic fields that pull the train car forward from the front and push it forward from the rear. As the train car is floating in a sea of interacting magnetic fields while moving, the trip is very smooth and very fast, reaching up to 375 miles per hour (ca. 604 km/h).

Now, at the Technical University of Denmark, latest research has given this old technology a new twist. They have shown it is possible to levitate a magnet simply by rotating another similar sized magnet near it. Hamdi Ucar, an electronics and software engineer, had first demonstrated this unusual effect in 2021. The team at TU Denmark is using this effect to exploit contactless object handling or for trapping and manipulating microplastics made of ferromagnetic materials.

Magnetic levitation can be of three types. The first of these is active magnetic stabilization. Here, a control system supplies the magnetic force that keeps the levitating object under balanced conditions. The second type is used by Maglev trains and is known as electrodynamic suspension. In this case, a moving magnet induces a current in a stationary conductor, which then produces a repulsive magnetic force. This force increases with the speed of the moving magnet. The third type is the spin-stabilized levitation. Here, a levitating magnet spins at about 500 RPM or revolutions per minute. Gyroscopic effect keeps the magnet stable.

The TU-Denmark type of levitation is a variation of the third type. It involves two magnets—a rotor, and a floater. The rotor magnet is mounted on a motor. It has its magnetic poles oriented perpendicular to its rotational axis. The motor makes it rotate at velocities of about 10,000 RPM. The TU-Denmark team used a spherical magnet, made from neodymium-iron-boron, and 19 mm in diameter.

The floater magnet, placed under the rotor, begins to automatically spin with the spinning rotor, moving upwards towards the rotor to hover in space a few centimeters below it. The frequency of precession of the floater is the same as that of the rotor and has its magnetization oriented near to the rotation axis, matching that of the like pole of the rotor. When disturbed, the interacting magnetic fields forces it back to its equilibrium position.

The team used computer simulations, taking into account the magneto-static interactions between the two magnets. They found the new type of levitation is caused by a combination of magnetic dipole to dipole coupling, and the gyroscopic effect. They explained it as a magneto-static force of one magnet exerting an attractive and repulsive force on the other.

Furthermore, they explained that the process goes on to create a midair energy minimum in the potential of interaction between the dipoles. The team’s computer modelling revealed this minimum, where the floater could stably levitate.

What are Thermal Transistors?

Modern electronic devices depend on electronic transistors. Although transistors control the flow of electricity precisely, in the process, they also generate heat. So far, there was not much control over the amount of heat transistors generated during operation—it depended on the efficiency of the device—devices with higher efficiency generated lower amounts of heat. Now, using a solid-state thermal transistor, it is possible to use an electric field to control the flow of heat through electronic devices.

The new device, the thermal transistor, was developed by researchers at the University of California, Los Angeles. They published their study in Science, demonstrating the capabilities of the new technology. The lead author of the study explained the process as very challenging, as, for a long time, scientists and engineers wanted to control heat transfer as easily as they could control current flow.

So far, engineers cooled electronics with heat sinks. They used passive heat sinks to draw excess heat away from the electronic device to keep it cool. Although many have tried active approaches to thermal management, these mostly rely on moving parts or fluids. They can take typically from minutes to hours to ramp up or down, depending on the thermal conductivity of the material. On the other hand, using thermal transistors, the researchers were able to actively modulate the heat flow with higher precision and speed. The higher rate of cooling or heating makes thermal transistors a promising option for thermal management in electronic devices.

Similar to the working of an electronic transistor, the thermal transistor uses electric fields to modulate its channel conductance. However, in this case, the conductance is thermal, rather than electrical. Researchers engineered a thin film of molecules in the form of a cage to act as the transistor’s channel. They then applied an electric field, making the molecular bonds stronger within the film. This, in turn, increased its thermal conductance.

As the film was only a single molecule thick, the researchers could attain maximum change in conductivity. The most astonishing feature of this technology was the speed at which the change in conductivity occurred. The researchers were able to go up to a frequency of 1 MHz and above—this was several times faster than that achieved by other heat management systems.

Other types of thermal switches typically control heat flow through molecular motion. However, compared to the motion of electrons, molecular motion is far slower. The use of electrical fields allowed the researchers to increase the speed of electrons in the switch from mHz to MHz frequencies.

Another difference between molecular and electron motion is that the former cannot create a large enough difference in thermal conduction between the on and off states of the transistor. However, with electron motion, the difference achieved can be as high as 13 times, an enormous figure, both in speed and magnitude.

Because of this improvement, the device assumes an important status for cooling processors. Being small, the transistors use only a tiny amount of power to control the heat flow. Another advantage is that it is possible to integrate many thermal transistors on the same chip.

What is a CPU?

We use computers every day, and most users are aware of the one indispensable hardware component in it—the CPU or the Central Processing Unit. However, contrary to popular belief, the entire desktop computer or the router is not the CPU, as the actual CPU is small enough to fit in the palm of your hand. Small as it is, the CPU is the most important component inside any computer.

That is because the central processing unit is the main driving force or the brain of the computer and is the only component that does the actual thinking and decision-making. To do that, CPUs typically contain one or more cores that break up the workload and handle individual tasks. As each task requires data handling, a CPU must have access to the memory where such data actually resides. To enable fast computing, the memory speed must be high. This is generally RAM or Random Access Memory, and together with a great amount of cache memory, which is part of the CPU, helps the central processing unit to complete tasks at high speed. However, the RAM and cache can only store a small amount of data, and the CPU must periodically transfer the required data from external disk drives, as these can hold much more of it.

Being processors, CPUs are available in large varieties of ISAs or Instruction-Set Architectures. ISAs can be highly distinct, making them so extreme that software running on one ISA may not run on others. Even within CPUs using the same ISA, there may be differences in microarchitecture, specifically related to the actual design of the CPU. Manufacturers use different microarchitectures to offer CPUs with various levels of performance, features, and efficiency.

A CPU with a single core is highly efficient in accomplishing tasks that require a serial, sequential order of execution. To improve the performance even further, CPUs with multiple cores are available. Where consumer chips typically offer up to eight cores, bigger server CPUs may offer anywhere from 32 to 128 cores. CPU designers target improving per-core performance by increasing the clock speed, thereby increasing the number of instructions per second that the core handles. This is again dependent on the microarchitecture.

Crafting CPUs is an incredibly intricate endeavor, navigated by only a select few experts worldwide. Noteworthy contributors to this field include industry giants like Intel, AMD, ARM, and RISC-V International. Intel and AMD, the pioneers in this arena, consistently engage in fierce competition, each striving to outdo the other in various CPU categories.

ARM, on the other hand, distinguishes itself by offering its proprietary ARM ISA, a technology it licenses to prominent entities such as Apple, Qualcomm, and Samsung. These licensees then leverage the ARM ISA to fashion bespoke CPUs, often surpassing the performance of the standard ARM cores developed by the parent company.

In a departure from the proprietary norm, RISC-V International promotes an open-standard approach with its RISC-V ISA. This innovative model allows anyone to freely adopt and modify the ISA, fostering a collaborative environment that encourages diverse contributions to CPU design.

To truly grasp how well a CPU performs, your best bet is to dive into reviews penned by fellow users and stack their experiences against your specific needs. This usually involves delving into numerous graphs and navigating through tables brimming with numbers. Simply relying on the CPU specification sheet frequently falls short of providing a comprehensive understanding.