Science category

Nuclear physics applied in smoke detectors

by robertgawron.blogspot.com:

Not many people know, but in some smoke detectors, radioactive materials play an essential role. Today I will present one of those devices, and my -successful- attempt to reverse engineer it and get the circuit diagram.

Nuclear physics applied in smoke detectors – [Link]

Human Motion Powered Nanotechnology Devices

Michigan State University researchers have came up with a new method for  harvesting energy from human motion using nanotechnology. They designed a low-cost film-like device, a nanogenerator, than can power a LCD display,  keyboard, and some LEDs without any source of electric power, by only using some human touching or pressing.

This device called FENG, biocompatible ferroelectret nanogenerator, consists of several thin layers of silicon wafer made of environmentally friendly substances like silver, polyimide, and polypropylene ferroelectret – which is introduced here as the active material of this device. To add the electrical powering feature, researchers added ions to each layer to make sure that each layer has its own charged particles. Finally the circuit works only once some pressure or mechanical energy is performed on the device. For example, by using this technology you will be able to power the LED lights with the pressure of your palm, while the pressure of your finger is enough to power the LCD screen.

In this video 20 LEDs are powered with hand pressing:

Researchers’ investigations had shown that the voltage and current generated by pressure can be doubled if the device is folded, means a high-frequency pressure is already demonstrated.

“Each time you fold it you are increasing exponentially the amount of voltage you are creating,” said Nelson Sepulveda, associate professor of electrical and computer engineering and lead investigator of the project. “You can start with a large device, but when you fold it once, and again, and again, it’s now much smaller and has more energy. Now it may be small enough to put in a specially made heel of your shoe so it creates power each time your heel strikes the ground.”

Sepulveda believes that implementing this technology in real life will shift wearables to be completely powered by human motion. He and his team are working now on transmitting the power generated from the heel strike to be used for powering other devices like a headset.

In this video you can take a look at the flexible keyboard they designed:

This research was funded by the National Science Foundation. You can learn more about this project by checking the scientific paper, and the university official website.

Supercapacitors Surpassing Conventional Batteries

Researchers at the University of Central Florida have been looking for alternatives for lithium rechargeable batteries which are largely used in every device.

Using two-dimensional (2D) transition-metal dichalcogenides (TMDs) capacitive materials, they are building a new supercapacitor that overcomes the performance of conventional lithium battery and replaces its efficiently.

Transition metal dichalcogenide monolayers (TMDs) are atomically thin semiconductors of the type MX₂, with M a transition metal atom and X a chalcogen atom. One layer of M atoms is sandwiched between two layers of X atoms.

TMDs are considered as promising capacitive materials for supercapacitor devices since they provide a suitable current conduction path and a robust large surface to increase the structure’s high energy and power density.

Researchers have developed “high-performance core/shell nanowire supercapacitors based on an array of one-dimensional (1D) nanowires seamlessly integrated with conformal 2D TMD layers. The 1D and 2D supercapacitor components possess “one-body” geometry with atomically sharp and structurally robust core/shell interfaces, as they were spontaneously converted from identical metal current collectors via sequential oxidation/sulfurization” according to the research paper.

The new prototype is said to be charged 30,000 times without any draining, 20 times the lifetime of an ordinary battery.

“You could charge your mobile phone in a few seconds and you wouldn’t need to charge it again for over a week,” says UCF postdoctoral associate Nitin Choudhary.

This research was published in the NANO science journal, you can check the scientific paper here.

New Thermoelectric Paint To Convert Heat Into Electricity

Scientists at the Ulsan National Institute of Science and Technology have developed a thermoelectric coating that can be directly painted onto any surface to turn it into thermal generator. This new technique can be used to convert waste heat into electricity from objects of almost any shape.

The team created an inorganic thermoelectric paint that possesses liquid-like properties using Bi2Te3 (bismuth telluride) and Sb2Te3 (antimony telluride) particles. These newly developed materials are both shape-engineerable and geometrically compatible so they can be directly brush-painted on almost any surface.

To test the new materials results, the researchers painted alternate p-type and n-type layers of the thermoelectric semiconductor paint on a metal dome, which generates about 4 mW output power per square centimeter.

Compared with some flexible thermoelectric generators, such as KAIST’s wearable device and Northwestern University’s thermoelectric material, the generated power of UNIST materials is just 10% of others, but the most important advantage is that it can be applied on any surface with just a paintbrush.

“By developing integral thermoelectric modules through painting process, we have overcome limitations of flat thermoelectric modules and are able to collect heat energy more efficiently.” said Professor Son of UNIST. “Thermoelectric generation systems can be developed as whatever types user want and cost from manufacturing systems can also be greatly reduced by conserving materials and simplifying processes.”

The UNIST researchers aim to see their invention as a renewable energy source, which will be possible to convert heat and cold to electricity by simply painting the external surfaces of buildings, on roofs, and on the exterior of cars, and open the way to many other materials and devices easily transferred to many other voltage-generation applications.

Comparison of power generation between the conventional planar-structured TE generator and the painted TE generator on a curved heat source.

“Our thermoelectric material can be applied any heat source regardless of its shape, type and size.” said Professor Son. “It will place itself as a new type of new and renewable energy generating system.”

To know more about the results and other information of this research, read its paper in the journal Nature Communications.

Sources: New Atlas, UNIST

Supercapacitors made of 2D Materials Can End Battery Issues

These tiny batteries can be charged in seconds and last for a week

Battery anxiety is a modern day problem for many of us. Mobile phone and wearable technologies are getting developed rapidly, but battery issues seem to be neverending. As phones and wearables are getting thinner, there needs to be a trade-off between battery life and design. Scientists are searching for a way to make a battery that’s tiny yet capable of holding the charge for a long time. So, what’s the solution? Supercapacitor.

Flexible Laser Scribed Graphene Supercapacitor
Flexible Laser Scribed Graphene (LSG) Supercapacitor

Scientists have been researching on the use of nanomaterials to improve supercapacitors that could enhance or even replace batteries in electronic devices. But it’s not an easy task. Considering a typical supercapacitor, it must be a large one to store as much energy as a Li-ion battery holds.

To tackle the battery issue, a team of scientists at the University of Central Florida (UCF) has created a tiny supercapacitor battery applying newly discovered two-dimensional materials with only a few atoms thick layer. Surprisingly, the new process created at UCF yields a supercapacitor that doesn’t degrade even after it’s been recharged/discharged 30,000 times. Where a lithium-ion battery can be recharged less than 1,500 times without significant failure.

So, what else makes the supercapacitor special apart from their tiny size? Well, let’s hear it from Nitin Choudhary, a postdoctoral associate who conducted much of the research :

If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn’t need to charge it again for over a week.

Supercapacitors are not used in mobile devices for their large size. But the team at UCF has developed supercapacitors composed of millions of nanometer-thick wires coated with shells of two-dimensional materials. A highly conductive core helps fast electron transfer for fast charging and discharging. And uniformly coated shells of two-dimensional (2D) materials produce high energy and power densities.

Nanowire Supercapacitor Made of Capacitive 2D WS2 Layers
Nanowire Supercapacitor Made of Capacitive 2D WS2 Layers

Scientists already knew 2D materials held great promise for energy storage purpose. But until the UCF developed the process for integrating those materials, it was not possible to realize that potential. Nitin Choudhary said,

For small electronic devices, our materials are surpassing the conventional ones worldwide in terms of energy density, power density, and cyclic stability.

Supercapacitors that use the new materials could be used in phones, wearables, other electronic gadgets, and electric vehicles. Though it’s not ready for commercialization yet. But the research team at UCF hopes this technology will soon end the battery problem of smartphones and other devices. So let’s wait awhile, and at the end of this year maybe you’ll be using a new smartphone that can be charged in seconds and lasts for a week, who knows!

30 Minutes HIV Detection Using USB Stick

In partnership with DNA Electronics,  Imperial College London researchers had developed a revolutionary USB stick that can detect HIV in the bloodstream.

In order to detect the virus, it’s enough to use a drop of blood. Then the USB stick generates an electrical signal that can be read by a computer, laptop or handheld device.

“We have taken the job done by equipment the size of a large photocopier, and shrunk it down to a USB chip” – Dr Graham Cooke, study author

This detection is useful for HIV patients for managing their treatment and to maintain their health. The longer the detection of HIV virus the harder to treat it, because antiretroviral treatment that is used for HIV may stop changing the status due to the resistance built by the virus to the medicine. This what the USB stick is working to solve, providing accurate results in a surprisingly short time.

To implement this, researcher had worked on “a novel complementary metal-oxide semiconductor (CMOS) chip based, pH-mediated, point-of-care HIV-1 viral load monitoring assay that simultaneously amplifies and detects HIV-1 RNA”.

Conventional ways to test HIV may take several days, but this device is promising to give results in less than 30 minutes! In addition, the detection can be done remotely, which allows faster detection for patients by themselves, and for some areas that don’t have advanced lab tests.

“This is a great example of how this new analysis technology has the potential to transform how patients with HIV are treated by providing a fast, accurate and portable solution. At DNAe we are already applying this highly adaptable technology to address significant global threats to health, where treatment is time-critical and needs to be right first time.” – Professor Chris Toumazou, DNAe’s Founder, Executive Chairman and Regius Professor at the Department of Electrical and Electronic Engineering at Imperial College London

Partnering with DNA Electronics was a great step for the researchers since this company is using similar technology to develop devices for detecting bacterial and fungal sepsis and antibiotic resistance. Right now, researchers are now looking for possibilities to advance their work and to check the ability that the device can detect other viruses such as hepatitis.

This research was funded by the National Institute for Health Research Imperial Biomedical Research Centre and it was published in Scientific Reports. You can learn more about it by checking the article “Novel pH sensing semiconductor for point-of-care detection of HIV-1 viremia” and the press release.

nano technology plus li-ion

Nanotechnoloy – Nano coating prevents exploding Li-ion batteries

Lithium-ion batteries are very popular as they’re lightweight and have high energy density. But at the same time, li-ion batteries are very sensitive to overcharge/over discharge. An internal short circuit can cause fire and it may even lead to a violent explosion. Fortunately, nanotechnology found a way to prevent this kind of nightmare. How? let’s discuss:

Why Does li-ion Battery Explode?

When a device draws too much power from a Li-Ion battery, it heats up and thus melts the internal separator between the two flammable electrolytes. This phenomenon ignites a chemical reaction between the electrolytes causing them to explode. Once their package ruptures, the oxygen in the surrounding air helps the flammable electrolytes to catch fire. The fire then spreads quickly to other cells and loads a thermal runaway.

Thermal runaway in Li-ion Battery
Thermal runaway in Li-ion Battery

During a thermal runaway, the high heat of the damaged or malfunctioning cell can propagate to the next cell, causing it to become completely thermally unstable as well. In some worse cases, a chain reaction occurs in which each cell disintegrates at its own timetable.

So, in a nutshell, Li-ion cells possess the potential of a thermal runaway. The temperature quickly rises to the melting point of the metallic lithium and cause a violent reaction, which finally causes an explosion.

How Can Nanotechnology Prevent This?

Recently conducted research shows that atomic layer deposition (ALD) of titania (TiO2) and alumina (Al2O3) on Ni-rich FCG NMC and NCA active material particles could substantially improve Li-ion battery’s performance and allow for increased upper cutoff voltage (UCV) during charging, which delivers significantly increased specific energy utilization.

Atomic Layer Deposition in li-ion CellsAtomic Layer Deposition in li-ion Cells
Atomic Layer Deposition in li-ion Cells

 

A company called Forge Nano claims to prevent this thermal runaway situation by never letting it get started even if the battery electrodes are shorted out. Forge Nano’s precision coatings on cathode and anode powders protect against the most common degradation mechanisms found in Li-ion batteries.

The benefits of Forge Nano precision coatings include extended battery life and greater safety, especially in extreme situations such as high-temperature operation, fast cycling rates, and overvoltage conditions.

By implementing lithium-based ALD films in nanostructured 3D lithium-ion batteries, significant gains in power density, cycling performances during charge/discharge, and safety is noticed.

What’s the Result?

Some of Forge Nano’s accomplishments in the Li-ion battery space includes:

  • Increased lifetime of commercial cathode material by as much as 250%
  • 15% higher energy density in large format pouch cells (40 Ah) that pass nail penetration testing
  • 60% reduced gas generation in cathode material
  • A low-cost high-voltage cathode powder with exceptional performance
  • Increased rate capability of conventional materials for enhanced fast charge acceptance using Forge Nano’s proprietary solid electrolyte coatings

    ForgeNano Claims Their Technology as Best Solution
    ForgeNano Claims Their Technology as Best Solution

Since the solution found by the research, Forge Nano has been working on a commercial version of the product that they finally believe they can place in the market very soon.

Conductive Plastic Holes For Wearables

The National Institute of Standards and Technology (NIST) research team has just debuted a new way of building flexible nontoxic golden film out of golden wires. They predict it will be a major step in wearable sensor research since it is comfortable and convenient for health usage, especially that it won’t be harmful to the human body causing any extra chemicals to do its function.

Wearable electronics - Source: NIST
Wearable electronics – Source: NIST

With one of his attempt in separating microfluidics, Reyes Hernandez NIST biomedical engineer found out that flexible plastic membranes can help conducting electricity. While twisting golden films on this membrane, that is similar to warp, the film kept connected even though all the twists and bends.

“Apparently the pores keep the gold from cracking as dramatically as usual,” Hernandez said. “The cracks are so tiny that the gold still conducts well after bending.”

forwearablee

“This thin membrane could fit into very small places,” he said, “and its flexibility and high conductivity make it a very special material, almost one of a kind.”

Hopefully, this discovery will lead Hernandez and his team to a new level of integrating small and convenient healthcare sensors in our body. The fact that the gold is non toxic and the superconductivity of the porous plastic membrane makes it a great deal to combine them in future researches and applications.

More information about the golden-membrane conductivity you can check NIST official page.

For detailed description and technical information, check this paper by NIST research group: Flexible Thin-Film Electrodes on Porous Polyester Membranes for Wearable Sensors.

Chemical Wireless Communication Without Electronics

Researchers at Stanford University have just invented a revolutionary way of communication. They are replacing the conventional way of wiring, wireless, radio and Bluetooth connectivity using chemicals that can be found in every house.

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Nariman Farsad, now a postdoctoral fellow at Stanford, had built the first ever experimental chemical texting system in York University, which used vodka to send its messages.

While making research in the lab of Andrea Goldsmith, professor of electrical engineering, he and his fellow researchers have built a machine that sends messages using common chemicals. With the use of vinegar and glass cleaner, Farsad overcomes some hurdles he faced while sending data using vodka. In his vodka messaging machine, the signal would build up to the point that the receiving end was too saturated with vodka to receive more messages. Instead, easy to obtain chemicals like vinegar and glass cleaner could do better and plus these two specific liquids can cancel each other out at the receiving end of the system.

This system is extracting one and zero bits out of liquid since it sends pulses of acid (vinegar) or base (glass cleaner). After typing the message in a small computer, it will be send to a machine that pumps out the corresponding “bits” of chemicals, which travel through plastic tubes to a small container with a pH sensor. Changes in pH are then transmitted to a computer that deciphers the encoded message.

While working in Wireless Systems Laboratory, Goldsmith had faced a lot of challenges in her career in wireless communication and worked hard to overcome them, but now dealing with chemicals will be a new adventure for her and her research group without any previous best practices.

“Every problem that we’ve addressed in traditional wireless communications over the last three or four decades is really different now because it’s a different mode of communicating,” Goldsmith said. “As so, it opens up all of these new ways of thinking about the optimal way to design this type of communication system.”

Most of nanotechnology solutions that are out there are small in size, need power plus some wiring for connectivity, or depend on high frequency signals to operate, what would be harmful for body functions. This new chemical technology can be widely used in body-related sensors since chemical-based data exchange could be self-powered, traveling throughout the body harmlessly and can not be detected by outside devices.

Goldsmith and Farsad are now working in two directions, improving the current chemical texting system, and collaborating with two bioengineering groups at Stanford to make human body-friendly chemical messaging a reality.

This technology can open up new avenues in communication protocols replacing the base unit, the electricity, with chemicals.

You can read more about this brand-new way of communication at Stanford University website, and you can learn more in this video

This work is funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship and by the National Science Foundation Center for the Science of Information.

Ultralow Power Transistors Function for Years Without Batteries

Researchers at Cambridge University have just achieved a spectacular breakthrough in electronics design. They have developed new ultralow power transistors that could function for months or even years without a battery. These transistors look for energy from the environment around, thus reducing the amount of power used.

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Dr Sungsik Lee, one of the researchers at the Department of Engineering says, “if we were to draw energy from a typical AA battery based on this design, it would last for a billion years.” The new design could be produced in low temperatures and they are versatile enough to be printed on materials like glass, paper, and plastic.

Basically, transistors are semiconductor devices that function like a faucet. Turn a transistor on and the electricity flows,  turn it off and the flow stops. When a transistor is off however, some electric current could still flow through, just like a leaky faucet. This current, which is called a near-off-state, was exploited by the engineers to power the new transistors.

power-consumption

schematicThe researchers developed a thin-film transistor (TFT) from In-Ga-Zn-O (indium-gallium-zinc-oxide) thin films. To make the material less conductive, the films were fabricated to avoid oxygen vacancies. Eventually, they achieved a new design that operates in near the OFF state at low supply voltages (<1 volt) and ultralow power (<1 nanowatt).

The transistor’s design also utilizes a ‘non-desirable’ characteristic, namely the ‘Schottky barrier’ to create smaller transistors. Transistors today cannot be manufactured into smaller sizes since the smaller a transistor gets, the more its electrodes influence each other, causing a non-functioning transistor.The use of the Schottky barrier in the new design creates seal between the electrodes that make them work independently from each other.

“We’re challenging conventional perception of how a transistor should be,” said Professor Arokia Nathan of Cambridge’s Department of Engineering, the paper’s co-author. “We’ve found that these Schottky barriers, which most engineers try to avoid, actually have the ideal characteristics for the type of ultralow power applications we’re looking at, such as wearable or implantable electronics for health monitoring.”

According to Arokia Nathan of Cambridge’s Department of Engineering, the second author of the paper, this new design can see use in various sensor interfaces and wearable devices that require only a low amount of power to run. Professor Gehan Amaratunga, Head of the Electronics, Power and Energy Conversion Group at Cambridge’s Engineering Department sees its use in more autonomous electronics that can harness energy from their environments similar to a bacteria.

As electronic devices become more compact and powerful, conventional methods for manufacturing electrical components simply won’t do. This unconventional way will not only consume minimum power but it also will open up new avenues for system design for the Internet of Things and ultralow power applications.

This research was introduced as a research paper in Science magazine on October 2016. More details are available here  “Subthreshold Schottky-barrier thin-film transistors with ultralow power and high intrinsic gain”.