Ultrathin, Lightweight Solar Panels

A race is on in solar engineering to create almost impossibly-thin, flexible solar panels. Engineers imagine them used in mobile applications, from self-powered wearable devices and sensors to lightweight aircraft and electric vehicles. Against that backdrop, researchers at Stanford University have achieved record efficiencies in a promising group of photovoltaic materials. Chief among the benefits of these transition metal dichalcogenides – or TMDs – is that they absorb ultrahigh levels of the sunlight that strikes their surface compared to other solar materials.

Transition metal dichalcogenide solar cells on a flexible polyimide substrate

Imagine an autonomous drone that powers itself with a solar array atop its wing that is 15 times thinner than a piece of paper,” said Koosha Nassiri Nazif, a doctoral scholar in electrical engineering at Stanford and co-lead author of a study published in the Dec. 9 edition of Nature Communications. “That is the promise of TMDs.”

The search for new materials is necessary because the reigning king of solar materials, silicon, is much too heavy, bulky and rigid for applications where flexibility, lightweight and high power are preeminent, such as wearable devices and sensors or aerospace and electric vehicles.

Silicon makes up 95 percent of the solar market today, but it’s far from perfect. We need new materials that are light, bendable and, frankly, more eco-friendly,” said Krishna Saraswat, a professor of electrical engineering and senior author of the paper. While TMDs hold great promise, research experiments to date have struggled to turn more than 2 percent of the sunlight they absorb into electricity. For silicon solar panels, that number is closing in on 30 percent. To be used widely, TMDs will have to close that gap.

The new Stanford prototype achieves 5.1 percent power conversion efficiency, but the authors project they could practically reach 27 percent efficiency upon optical and electrical optimizations. That figure would be on par with the best solar panels on the market today, silicon included.

Moreover, the prototype realized a 100-times greater power-to-weight ratio of any TMDs yet developed. That ratio is important for mobile applications, like drones, electric vehicles and the ability to charge expeditionary equipment on the move. When looking at the specific power – a measure of electrical power output per unit weight of the solar cell – the prototype produced 4.4 watts per gram, a figure competitive with other current-day thin-film solar cells, including other experimental prototypes. “We think we can increase this crucial ratio another ten times through optimization,” Saraswat said, adding that they estimate the practical limit of their TMD cells to be a remarkable 46 watts per gram.”

Source: https://news.stanford.edu/

Sensitive Robotic Fingers

Although robotics has reshaped and even redefined many industrial sectors, there still exists a gap between machines and humans in fields such as health and elderly care. For robots to safely manipulate or interact with fragile objects and living organisms, new strategies to enhance their perception while making their parts softer are needed. In fact, building a safe and dexterous robotic gripper with human-like capabilities is currently one of the most important goals in robotics.

One of the main challenges in the design of soft robotic grippers is integrating traditional sensors onto the robot’s fingers. Ideally, a soft gripper should have what’s known as proprioception–a sense of its own movements and position–to be able to safely execute varied tasks. However, traditional sensors are rigid and compromise the mechanical characteristics of the soft parts. Moreover, existing soft grippers are usually designed with a single type of proprioceptive sensation; either pressure or finger curvature.

To overcome these limitations, scientists at Ritsumeikan University, Japan, have been working on novel soft gripper designs under the lead of Associate Professor Mengying Xie. In their latest study published in Nano Energy, they successfully used multimaterial 3D printing technology to fabricate soft robotic fingers with a built-in proprioception sensor. Their design strategy offers numerous advantages and represents a large step toward safer and more capable soft robots.

The use of multimaterial 3D printing, a simple and fast prototyping process, allowed the researchers to easily integrate the sensing and stiffness-tuning mechanisms into the design of the robotic finger itself.

Our work suggests a way of designing sensors that contribute not only as sensing elements for robotic applications, but also as active functional materials to provide better control of the whole system without compromising its dynamic behavior,” says Prof Xie. Another remarkable feature of their design is that the sensor is self-powered by the piezoelectric effect, meaning that it requires no energy supply–essential for low-power applications.

Source:  https://eurekalert.org/

Bionic Eye With Better Vision Than Humans

The world’s first 3D artificial eyeball — capable of outperforming the human eye in some ways — may help droves of people who are partially or fully blind in as little as five years, according to experts.

Researchers from Hong Kong University of Science and Technology have devised an electrochemical eye whose structure and performance mimic those of the ones humans are born with.

The device design has a high degree of structural similarity to a human eye with the potential to achieve high imaging resolution when individual nanowires are electrically addressed,” researchers of Hong Kong University of Science and Technology wrote in a paper published in the journal Nature.

The device converts images through tiny sensors that mirror the lightdetecting photoreceptor cells in a human eyeThe Sun reported. Those sensors reside within a membrane made of aluminum and tungsten which is shaped into a half sphere for the purpose of mimicking a human retina.

Source:  https://www.nature.com/
AND
https://www.foxbusiness.com/

On Mars or Earth, biohybrid can turn CO2 into new products

If humans ever hope to colonize Mars, the settlers will need to manufacture on-planet a huge range of organic compounds, from fuels to drugs, that are too expensive to ship from Earth. University of California, Berkeley, and Lawrence Berkeley National Laboratory (Berkeley Lab) chemists have a plan for that.

For the past eight years, the researchers have been working on a hybrid system combining bacteria and nanowires that can capture the energy of sunlight to convert carbon dioxide and water into building blocks for organic molecules. Nanowires are thin silicon wires about one-hundredth the width of a human hair, used as electronic components, and also as sensors and solar cells.

A device to capture carbon dioxide from the air and convert it to useful organic products. On left is the chamber containing the nanowire/bacteria hybrid that reduces CO2 to form acetate. On the right is the chamber where oxygen is produced

On Mars, about 96% of the atmosphere is CO2. Basically, all you need is these silicon semiconductor nanowires to take in the solar energy and pass it on to these bugs to do the chemistry for you,” said project leader Peidong Yang, professor of chemistry and Energy at UC Berkeley. “For a deep space mission, you care about the payload weight, and biological systems have the advantage that they self-reproduce: You don’t need to send a lot. That’s why our biohybrid version is highly attractive.”

The only other requirement, besides sunlight, is water, which on Mars is relatively abundant in the polar ice caps and likely lies frozen underground over most of the planet, said Yang, who is a senior faculty scientist at Berkeley Lab and director of the Kavli Energy Nanoscience Institute.

The biohybrid can also pull carbon dioxide from the air on Earth to make organic compounds and simultaneously address climate change, which is caused by an excess of human-produced CO2 in the atmosphere.

In a new paper published in the journal Joule, the researchers report a milestone in packing these bacteria (Sporomusa ovata) into a “forest of nanowires” to achieve a record efficiency: 3.6% of the incoming solar energy is converted and stored in carbon bonds, in the form of a two-carbon molecule called acetate: essentially acetic acid, or vinegar.

Source: https://news.berkeley.edu/

How To Take Delivery Door To Door By Droid

As an automotive supplier specialized in developing electric, autonomous and connected vehicle technologies, Valeo is presenting its autonomous, electric delivery droid prototype, Valeo eDeliver4U, at CES 2020 in Las Vegas. Valeo developed the technology in partnership with Meituan Dianping, China’s leading e-commerce platform for services, which operates popular food delivery service Meituan Waimai. The two groups signed a strategic cooperation agreement at last year’s CES to develop a last-mile autonomous delivery solution.

At 2.80m long, 1.20m wide and 1.70m tall, the droid can deliver up to 17 meals per trip, autonomously negotiating dense and complex urban environments at about 12 km/h without generating any pollutant emissions. With a range of around 100km, this prototype gives us a glimpse of what home delivery could look like in the near future, especially in the ever‑growing number of zero-emissions zones that are being created around the world. Meituan Dianping’s connected delivery locker allows for safe delivery to the end customer, who can book through a smartphone application.

The droid’s autonomy and electric power are delivered by Valeo technologies that are already series produced and aligned with automotive industry standards, thereby guaranteeing a high-level of safety. The droid operates autonomously using perception systems including algorithms and sensors. It is equipped with four Valeo SCALA® laser scanners (the only automotive LiDAR already fitted to vehicles in series production), a front camera, four fisheye cameras, four radar devices and twelve ultrasonic sensors, coupled with software and artificial intelligence. The electrified chassis features a Valeo 48V motor and a Valeo 48V inverter, which acts as the system’s “brain” and controls the power, a speed reducer, a 48V battery, a DC/DC converter and a Valeo 48V battery charger, as well as electric power steering and braking systems.

CLICK ON THE IMAGE TO ENJOY THE VIDEO

“This delivery droid illustrates Valeo’s ability to embrace new forms of mobility using its technological platforms. The modularity of the platforms means our technologies can just as easily be fitted to cars, autonomous shuttles, robotaxis and even droids,” said Jacques Aschenbroich, Chairman and Chief Executive Officer of Valeo. “These new markets will allow us to further consolidate our leadership around the world in vehicle electrification, driver assistance systems and autonomous driving.”

Source: https://www.valeo.com/

Walking Again With Robot Exoskeleton Steered By The Brain

The French tetraplegic man who has been able to walk again using a pioneering four-limb robotic system, or exoskeleton, said walking was a major feat for him after being immobile for years. The French scientists behind the system, which was publicly unveiled last week, use a system of sensors implanted near the brain which send signals to the robotic system, moving the patient’s legs and arms. Speaking to media in the French city of Grenoble, the 30-year-old patient, who was identified only by his first name, Thibault, said he had to re-educate to use his brain when he started to try the whole-body exoskeleton.

CLICK ON THE IMAGE TO ENJOY THE VIDEO

  • As I hadn’t moved for two years I had to re-learn to use my brain,” he said. “At the beginning, walking was very difficult. Now I can stand up for two hours in the exoskeleton and I can do walking cycles for a very long time”, he also said. “This is a feat for me.”

In a two-year-long trial, two recording devices were implanted, one either side of Thibault’s head between the brain and the skin, spanning the region of the brain that controls sensation and motor function. Each recorder contained 64 electrodes which collected brain signals and transmitted them to a decoding algorithm. The system translated the brain signals into the movements the patient thought about, and sent his commands to the exoskeleton. Over 24 months, the patient carried out various mental tasks to train the algorithm to understand his thoughts and to progressively increase the number of movements he could make. For now the exoskeleton is purely an experimental prototype.

Source: https://www.reuters.com/

How To Improve Your Body Movement

Massachusetts Institute of Technology engineer Nan-Wei Gong went from designing sensors to search the universe for dark matter, to designing sensors to track the movement of the human body.

It’s a particle that’s really hard to find, and I didn’t find it,” Gong said of dark matter.

She’s had better luck with the human body, attracting $7.5 million to launch Figur8 at the end of August 2019. Figur8 is a startup that boasts of having the world’s most cost-effective and portable system for “accurately assessing quality of movement.”

That’s exciting news for trainers, physical therapists and physicians, all of whom have an interest in being able to quantify and assess the quality of human movement. Previously that took expensive equipment, including cumbersome cameras, to do it accurately.

But with Gong’s sensors strapped to the body, feeding data to a cloud-based mobile app, movement measurements and analytics can be taken anywhere, quickly and easily.

 

Gong developed Figur8 in conjunction with Massachusetts General Hospital as well as MIT’s Media Lab. The strap-on sensors produced by Figur8 do the job of much more expensive systems that were generally unavailable to anyone other than elite athletes.

 

Source: https://www.forbes.com/

How To Make Solar Panels More Sustainable And Cheaper

An innovative way to pattern metals has been discovered by scientists in the Department of Chemistry at the University of Warwick in UK, which could make the next generation of  solar panels more sustainable and cheaperSilver and copper are the most widely used electrical conductors in modern electronics and solar cells. However, conventional methods of patterning these metals to make the desired pattern of conducting lines are based on selectively removing metal from a film by etching using harmful chemicals or printing from costly metal inks.

Scientists from the Department of Chemistry at the University of Warwick, have developed a way of patterning these metals that is likely to prove much more sustainable and cheaper for large scale production, because there is no metal waste or use of toxic chemicals, and the fabrication method is compatible with continuous roll-to-roll processing. Dr Ross Hatton and Dr Silvia Varagnolo have discovered that silver and copper do not condense onto extremely thin films of certain highly fluorinated organic compounds when the metal is deposited by simple thermal evaporation.

Thermal evaporation is already widely used on a large scale to make the thin metal film on the inside of crisp packets, and organofluorine compounds are already common place as the basis of non-stick cooking pans. The researchers have shown that the organofluorine layer need only be 10 billionths of a metre thick to be effective, and so only tiny amounts are needed. This unconventional approach also leaves the metal surface uncontaminated, which Hatton believes will be particularly important for the next generation sensors, which often require uncontaminated patterned films of these metals as platforms onto which sensing molecules can be attached.

To help address the challenges posed by climate change, there is a need for colour tuneable, flexible and light weight solar cells that can be produced at low cost, particularly for applications where conventional rigid silicon solar cells are unsuitable such as in electric cars and semi-transparent solar cells for buildings. Solar cells based on thin films of organic, perovskite or nano-crystal semiconductors all have potential to meet this need, although they all require a low cost, flexible transparent electrode. Hatton and his team have used their method to fabricate semi-transparent organic solar cells in which the top silver electrode is patterned with millions of tiny apertures per square centimetre, which cannot be achieved by any other scalable means directly on top of an organic electronic device.

This innovation enables us to realise the dream of truly flexible, transparent electrodes matched to needs of the emerging generation of thin film solar cells, as well as having numerous other potential applications ranging from sensors to low-emissivity glass” explains Dr Hatton from the Department of Chemistry at the University of Warwick.

The work is published in the journal Materials Horizons.

Source: https://warwick.ac.uk/

3D Printed Metamaterials With Super Optical Properties

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is possible using conventional optical or electronic materials. The fabrication methods developed by the researchers demonstrate the potential, both present and future, of 3D printing to expand the range of geometric designs and material composites that lead to devices with novel optical properties. In one case, the researchers drew inspiration from the compound eye of a moth to create a hemispherical device that can absorb electromagnetic signals from any direction at selected wavelengths.

The geometry of a moth’s eye provides inspiration for a 3D printed antenna that absorbs specific microwave frequencies from any direction

Metamaterials extend the capabilities of conventional materials in devices by making use of geometric features arranged in repeating patterns at scales smaller than the wavelengths of energy being detected or influenced. New developments in 3D printing technology are making it possible to create many more shapes and patterns of metamaterials, and at ever smaller scales. In the study, researchers at the Nano Lab at Tufts describe a hybrid fabrication approach using 3D printing, metal coating and etching to create metamaterials with complex geometries and novel functionalities for wavelengths in the microwave range. For example, they created an array of tiny mushroom shaped structures, each holding a small patterned metal resonator at the top of a stalk. This particular arrangement permits microwaves of specific frequencies to be absorbed, depending on the chosen geometry of the “mushrooms” and their spacing. Use of such metamaterials could be valuable in applications such as sensors in medical diagnosis and as antennas in telecommunications or detectors in imaging applications.

The research has been published in the journal Microsystems & Nanoengineering (Springer Nature).

Source: https://now.tufts.edu/

Tiny 4-Inch Wafer Holds One Million NanoRobots

Researchers have harnessed the latest nanofabrication techniques to create bug-shaped robots that are wirelessly powered, able to walk, able to survive harsh environments and tiny enough to be injected through an ordinary hypodermic needle.

When I was a kid, I remember looking in a microscope, and seeing all this crazy stuff going on. Now we’re building stuff that’s active at that size. We don’t just have to watch this world. You can actually play in it,” said Marc Miskin, who developed the nanofabrication techniques with his colleagues professors Itai Cohen and Paul McEuen and researcher Alejandro Cortese at Cornell University while Miskin was a postdoc in the laboratory for atomic and solid state physics there. In January, he became an assistant professor of electrical and systems engineering at the University of Pennsylvania.

Miskin will present his microscopic robot research on this week at the American Physical Society March Meeting in Boston. He will also participate in a press conference describing the work. Information for logging on to watch and ask questions remotely is included at the end of this news release.

Over the course of the past several years, Miskin and research colleagues developed a multistep nanofabrication technique that turns a 4-inch specialized silicon wafer into a million microscopic robots in just weeks. Each 70 micron long (about the width of a very thin human hair), the robots’ bodies are formed from a superthin rectangular skeleton of glass topped with a thin layer of silicon into which the researchers etch its electronics control components and either two or four silicon solar cells — the rudimentary equivalent of a brain and organs.

Robots are built massively in parallel using nanofabrication technology: each wafer holds 1 million machines

The really high-level explanation of how we make them is we’re taking technology developed by the semiconductor industry and using it to make tiny robots,” said Miskin.

Each of a robot’s four legs is formed from a bilayer of platinum and titanium (or alternately, graphene). The platinum is applied using atomic layer deposition. “It’s like painting with atoms,” said Miskin. The platinum-titanium layer is then cut into each robot’s four 100-atom-thick legs. “The legs are super strong,” he said. “Each robot carries a body that’s 1,000 times thicker and weighs roughly 8,000 times more than each leg.”

The researchers shine a laser on one of a robot’s solar cells to power it. This causes the platinum in the leg to expand, while the titanium remains rigid in turn, causing the limb to bend. The robot’s gait is generated because each solar cell causes the alternate contraction or relaxing of the front or back legs. The researchers first saw a robot’s leg move several days before Christmas 2017. “The leg just twitched a bit,” recalled Miskin. “But it was the first proof of concept — this is going to work!

Teams at Cornell and Pennsylvania are now at work on smart versions of the robots with on-board sensors, clocks and controllers. The current laser power source would limit the robot’s control to a fingernail-width into tissue. So Miskin is thinking about new energy sources, including ultrasound and magnetic fields, that would enable these robots to make incredible journeys in the human body for missions such as drug delivery or mapping the brain.

We found out you can inject them using a syringe and they survive — they’re still intact and functional — which is pretty cool,” he said.

Source: https://eurekalert.org/