The zinc-ion battery consists of a water-based electrolyte, a pillared vanadium oxide positive electrode (right), and an inexpensive metallic zinc negative electrode (left). The battery generates electricity through a reversible process called intercalation, where positively-charged zinc ions are oxidized from the zinc metal negative electrode, travel through the electrolyte and insert between the layers of vanadium oxide nanosheets in the positive electrode. This drives the flow of electrons in the external circuit, creating an electrical current. The reverse process occurs on charge. (credit: Dipan Kundu et al./Nature Energy)
University of Waterloo chemists have developed a long-lasting, safe, zinc-ion battery that costs half the price of current lithium-ion batteries. It could help communities shift from traditional power plants to renewable solar and wind energy production, where electricity storage overnight is needed.
The battery is water-based and uses cheap but safe, non-flammable, non-toxic materials, compared to expensive, flammable, organic electrolytes in lithium-ion batteries, which are used in the exploding Samsung Galaxy Note 7 smartphones reported last week and in previously reported exploding hoverboards.
Where cost, safety, and life cycle are vital, not size
Lithium-ion batteries have much higher energy density (energy that can be stored per unit volume) than water-based batteries (making lithium-ion batteries attractive for smartphones and other compact devices), but water-based zinc-ion batteries are more feasible for grid-scale applications, where cost, safety, and life cycle are important, not size.
The cell design satisfies four vital criteria: high reversibility, rate, capacity, and no zinc dendrite formation. It provides more than 1,000 cycles. Lithium-ion batteries also operate by intercalation (of lithium ions) but they typically use expensive, flammable, organic electrolytes.
The bonus for manufacturers is they can produce this zinc battery at low cost because its fabrication does not require special conditions, such as ultra-low humidity or the handling of flammable materials needed for lithium ion batteries, the chemists say.
“The focus used to be on minimizing size and weight for the portable electronics market and cars,” said Dipan Kundu, a University of Waterloo postdoctoral fellow and the paper’s first author. “Grid storage needs a different kind of battery and that’s given us license to look into different materials.”
Abstract of A high-capacity and long-life aqueous rechargeable zinc battery using a metal oxide intercalation cathode
Although non-aqueous Li-ion batteries possess significantly higher energy density than their aqueous counterparts, the latter can be more feasible for grid-scale applications when cost, safety and cycle life are taken into consideration. Moreover, aqueous Zn-ion batteries have an energy storage advantage over alkali-based batteries as they can employ Zn metal as the negative electrode, dramatically increasing energy density. However, their development is plagued by a limited choice of positive electrodes, which often show poor rate capability and inadequate cycle life. Here we report a vanadium oxide bronze pillared by interlayer Zn2+ ions and water (Zn0.25V2O5⋅nH2O), as the positive electrode for a Zn cell. A reversible Zn2+ ion (de)intercalation storage process at fast rates, with more than one Zn2+ per formula unit (a capacity up to 300 mAh g−1), is characterized. The Zn cell offers an energy density of ∼450 Wh l−1 and exhibits a capacity retention of more than 80% over 1,000 cycles, with no dendrite formation at the Zn electrode.
A nanocrystal-based material converts blue laser emission to white light for combined illumination and high-speed data communication. (credit: KAUST 2016)
Researchers at King Abdullah University of Science and Technology (KAUST) have developed a system that uses high-speed visible light communications (VLC) to replace slower Wi-Fi and Bluetooth, allowing ceiling lights, for example, to provide an internet connection to laptops.
“VLC has many advantages compared with lower frequency communications approaches (including Wi-Fi and Bluetooth), such as energy efficiency, an unregulated communication spectrum, environmental friendliness, greater security, and no RF interferences,” according to KAUST researchers.
However, VLC is currently limited to about 100 megabits/sec. (compared to a maximum speed for the current 802.11n Wi-Fi spec of about 600 megabits/sec.) because it requires light-emitting diodes (LEDs) that produce white light, according to KAUST Professor of Electrical Engineering Boon Ooi.
These are usually fabricated by combining a diode that emits blue light with phosphorous that turns some of this radiation into red and green light. However, this conversion process limits the switching speed.
To deal with that limitation, the researchers created nanocrystals based on cesium lead bromide perovskite combined with a conventional nitride red phosphor, which achieved a data rate of 2 gigabits/sec.* That’s comparable to the newest Wi-Fi spec, 802.11ac, which can deliver about 1.7Gbps to 2.5Gbps, as Extreme Techreports (but limited to the the 5 GHz Wi-Fi band, which has limited penetration).
Importantly, the white light generated using their perovskite nanostructures was of a quality comparable to present LED technology.
The research is presented in an open-access paper in ACS Photonics.
* When illuminated by a blue laser light, the nanocrystals emitted green light while the nitride emitted red light. Together, these combined to create a warm white light. The researchers characterized the optical properties of their material using a technique known as femtosecond transient spectroscopy. They were able to show that the optical processes in cesium lead bromide nanocrystals occur on a time scale of roughly seven nanoseconds. This meant they could modulate the optical emission at a frequency of 491 Megahertz, 40 times faster than is possible using phosphorus, and transmit data at a rate of 2 gigabits/sec.
Interscatter communication
In interscatter communication, a backscattering device such as a smart contact lens converts Bluetooth transmissions from a device such as a smartwatch to generate Wi-Fi signals that can be read by a phone or tablet. (credit: University of Washington)
University of Washington researchers have introduced another variant on Wi-Fi called “interscatter communication” that may allow devices such as brain implants, contact lenses, credit cards and smaller wearable electronics to talk to everyday devices such as smartphones and watches (to report a medical condition, for example).
The interscatter communication method works by converting Bluetooth signals into Wi-Fi transmissions. Using only reflections, an interscatter device such as a smart contact lens converts Bluetooth signals from a smartwatch, for example, into Wi-Fi transmissions that can be picked up by a smartphone.
Due to their size and location within the body, these smart contact lenses are normally too constrained by power demands to send data using conventional wireless transmissions. That means they so far have not been able to send data using Wi-Fi to smartphones and other mobile devices. Those same requirements also limit emerging technologies such as brain implants that treat Parkinson’s disease, stimulate organs and may one day even reanimate limbs.
Smart contact lens (credit: University of Washington)
The team of UW electrical engineers and computer scientists has demonstrated for the first time that these types of power-limited devices can “talk” to others using standard Wi-Fi communication. Their system requires no specialized equipment, relying solely on mobile devices commonly found with users to generate Wi-Fi signals using 10,000 times less energy than conventional methods.
“Instead of generating Wi-Fi signals on your own, our technology creates Wi-Fi by using Bluetooth transmissions from nearby mobile devices such as smartwatches,” said co-author Vamsi Talla, a recent UW doctoral graduate in electrical engineering who is now a research associate in the Department of Computer Science & Engineering.
University of Washington Computer Science & Engineering | Interscatter
Backscatter communication: piggybacking on Bluetooth
The team’s process relies on a communication technique called backscatter, which allows devices to exchange information simply by reflecting existing signals. Because the new technique enables inter-technology communication by using Bluetooth signals to create Wi-Fi transmissions, the team calls it “interscattering.”
Interscatter communication uses the Bluetooth, Wi-Fi or ZigBee radios embedded in common mobile devices like smartphones, watches, laptops, tablets and headsets, to serve as both sources and receivers for these reflected signals.
In one example the team demonstrated, a smartwatch transmits a Bluetooth signal to a smart contact lens outfitted with an antenna. To create a blank slate on which new information can be written, the UW team developed an innovative way to transform the Bluetooth transmission into a “single tone” signal that can be further manipulated and transformed. By backscattering that single tone signal, the contact lens can encode data — such as health information it may be collecting — into a standard Wi-Fi packet that can then be read by a smartphone, tablet or laptop.
Examples of interscatter communication include a) a smart contact lens using Bluetooth signals from a watch to send data to a phone b) an implantable brain interface communicating via a Bluetooth headset and smartphone and c) credit cards communicating by backscattering Bluetooth transmissions from a phone. (credit: University of Washington)
The researchers built three proof-of-concept demonstrations for previously infeasible applications, including a smart contact lens and an implantable neural recording device that can communicate directly with smartphones and watches.
Consuming only tens of microwatts
“Preserving battery life is very important in implanted medical devices, since replacing the battery in a pacemaker or brain stimulator requires surgery and puts patients at potential risk from those complications,” said co-author Joshua Smith, associate professor of electrical engineering and of computer science and engineering. “Interscatter can enable Wi-Fi for these implanted devices while consuming only tens of microwatts of power.”
Beyond implanted devices, the researchers have also shown that their technology can apply to other applications, such as smart credit cards. The team built credit card prototypes that can communicate directly with each other by reflecting Bluetooth signals coming from a smartphone.
This opens up possibilities for smart credit cards that can communicate directly with other cards and enable applications where users can split the bill by just tapping their credit cards together.
The research was funded by the National Science Foundation and Google Faculty Research Awards.
Abstract of Perovskite Nanocrystals as a Color Converter for Visible Light Communication
Visible light communication (VLC) is an emerging technology that uses light-emitting diodes (LEDs) or laser diodes for simultaneous illumination and data communication. This technology is envisioned to be a major part of the solution to the current bottlenecks in data and wireless communication. However, the conventional lighting phosphors that are typically integrated with LEDs have limited modulation bandwidth and thus cannot provide the bandwidth required to realize the potential of VLC. In this work, we present a promising light converter for VLC by designing solution-processed CsPbBr3 perovskite nanocrystals (NCs) with a conventional red phosphor. The fabricated CsPbBr3 NC phosphor-based white light converter exhibits an unprecedented modulation bandwidth of 491 MHz, which is ∼40 times greater than that of conventional phosphors, and the capability to transmit a high data rate of up to 2 Gbit/s. Moreover, this perovskite-enhanced white light source combines ultrafast response characteristics with a high color rendering index of 89 and a correlated color temperature of 3236 K, thereby enabling dual VLC and solid-state lighting functionalities.
Abstract of Inter-Technology Backscatter: Towards Internet Connectivity for Implanted Devices
We introduce inter-technology backscatter, a novel approach that transforms wireless transmissions from one technology to another, on the air. Specifically, we show for the first time that Bluetooth transmissions can be used to create Wi-Fi and ZigBee-compatible signals using backscatter communication. Since Bluetooth, Wi-Fi and ZigBee radios are widely available, this approach enables a backscatter design that works using only commodity devices. We build prototype backscatter hardware using an FPGA and experiment with various Wi-Fi, Bluetooth and ZigBee devices. Our experiments show we can create 2–11 Mbps Wi-Fi standards-compliant signals by backscattering Bluetooth transmissions. To show the generality of our approach, we also demonstrate generation of standards-complaint ZigBee signals by backscattering Bluetooth transmissions. Finally, we build proof-of-concepts for previously infeasible applications including the first contact lens form-factor antenna prototype and an implantable neural recording interface that communicate directly with commodity devices such as smartphones and watches, thus enabling the vision of Internet connected implanted devices.
Artistic rendition of a metallic carbon nanotube being pulled into solution, in analogy to the work described by the Adronov group (credit: Alex Adronov, McMaster University)
Researchers at McMaster University in Canada have developed a radically improved way to purify single-wall carbon nanotubes (SWNTs) — flexible structures that are one nanometer in diameter and thousands of times longer, and that may revolutionize computers and electronics, replacing silicon.
To do that, we need to separate out semiconducting (sc-SWNTs) and metallic (m-SWNTs) nanotubes. That’s a challenging problem, because both are created simultaneously in the process* of producing carbon nanotubes.
“Once we have a reliable source of pure nanotubes that are not very expensive, a lot can happen very quickly,” says Alex Adronov, a professor of Chemistry at McMaster whose research team has developed a new and potentially cost-efficient way to purify carbon nanotubes.
Separating out semiconducting carbon nanotubes
Previous researchers have created polymers that could allow semiconducting carbon nanotubes to be dissolved and washed away, leaving metallic nanotubes behind, but there has not been such a process for doing the more-useful opposite: dispersing the metallic nanotubes and leaving behind the valuable semiconducting structures.
Single-wall carbon nanotube (credit: NASA)
Now, Adronov’s research group has reversed the electronic characteristics (from electron-rich to electron-poor) of a polymer known to disperse semiconducting nanotubes, while leaving the rest of the polymer’s structure intact. That is, they have reversed the purification process — leaving the semiconducting nanotubes behind while making it possible to disperse the metallic nanotubes.**
The next step, he explains, is for his team or other researchers to exploit the discovery by finding a way to develop even more efficient polymers and scale up the process for commercial production.
The unique properties of SWNTs — high tensile strength, the high aspect ratio, thermal and electrical conductivity, and extraordinary optical characteristics — could make carbon nanotubes potentially valuable as advanced materials in a variety of applications, including “field-effect transistors, photovoltaics, flexible electronics, sensors, touch screens, high-strength fibers, biotechnological constructs, and various other devices,” the researchers note in the current cover story of Chemistry – A European Journal.
Financial support for this work was provided by the Discovery and Strategic Grant programs of the Natural Science and Engineering Research Council (NSERC) of Canada.
* These processes include high-pressure carbon monoxide disproportionation (HiPCO),carbon vapor deposition (CVD),arc discharge,laser ablation, and plasma torch growth.
** “We expect that relatively electron-poor conjugated polymers should disperse m-SWNTs to a greater extent when compared to structurally similar electron-rich conjugated polymers. Here, we demonstrate this concept through the comparison of a poly(fluorene-co-pyridine) conjugated polymer before and after post-polymerization functionalization. By partially methylating the pyridine units, cationic charges are introduced onto the conjugated backbone, which convert the polymer from being electron-rich to electron-poor. This enables the comparison of two polymers that are identical in length and polydispersity, and differ primarily in their electronic characteristics. We show that the electron-poor conjugated polymer results in dispersions that are enriched in m-SWNTs, while the electron-rich counterpart solely selects for sc-SWNTs, thus providing evidence that the electronic structure of a conjugated polymer plays an important role in determining its selectivity for different SWNT types.” — Darryl Fong et al./Chemistry – A European Journal.
Abstract of Influence of Polymer Electronics on Selective Dispersion of Single-Walled Carbon Nanotubes
In the pursuit of next-generation polymers for the selective dispersion and purification of single-walled carbon nanotubes (SWNTs), understanding the key parameters dictating polymer selectivity is imperative. Simple modification of a poly(fluorene-co-pyridine) backbone, such that it is transformed from being electron-rich to -poor, has a significant impact on the electronic nature of the SWNTs dispersed. The unmodified copolymer bearing an electron-rich fluorene co-monomer preferentially forms stable colloids with sc-SWNTs, while the methylated copolymer bearing electron-withdrawing cationic charges produces dispersions that are more enriched with m-SWNTs.
Liquid metal material with metallic core and semiconducting skin (credit: RMIT University)
Imagine a soft liquid-metal material right out of the T-1000 Terminator movie character. One that can morph itself into different self-propelling soft electronic circuits that act like live cells, communicating with each other.
Using a liquid metallic core* and semiconducting skin, such a soft material might be used to make instant flexible 3D electronic displays. Or morph into self-propelled biomedical diagnostic sensors, for example, reconfiguring themselves on demand, say RMIT University researchers.
Diagram of ionic-imbalance-induced self-propulsion of liquid metals. (a) Schematic of the droplet and arrangement of ions, forming the EDL. (b) Schematic of the experimental setup showing two U-shaped open-top (see inset) inlet channels, which extend in parallel and join at an outlet. Two channels carry different types of electrolytes (acidic in yellow and basic in blue). Two parallel flows come in contact with the Galinstan droplet (3 mm diameter) residing in a recess. (credit: Ali Zavabeti et al./Nature Communications)
Morphing metal — more like live cells
To achieve that magic, Professor Kourosh Kalantar-zadeh and his group first immersed liquid-metal droplets in water. The droplets were able to move about freely in three dimensions, driven by pH (acid or base) or ionic (electric charge) concentration gradients across a liquid metal droplet, which induced deformation and surface flow.
“We adjusted the concentrations of acid, base, and salt components in the water and investigated the effect. Simply tweaking the water’s chemistry made the liquid metal droplets move and change shape, without any need for external mechanical, electronic, or optical stimulants.”
No, these are not lollipops. These devices demonstrate continuous motion of a self-propelling liquid metal droplet under a pH gradient, shown at different time intervals (left to right). The droplet is placed in a fluidic channel, midway between two reservoirs filled with different acid and base electrolytes. (credit: RMIT University)
The elastic electronic soft circuit systems act more like live cells, moving around autonomously and communicating with each other to form new circuits, rather than being stuck in one configuration.
“Using this discovery, we were able to create moving objects, switches, and pumps that could operate autonomously — self-propelling liquid metals driven by the composition of the surrounding fluid,” Kalantar-zadeh said. “Eventually, using the fundamentals of this discovery, it may be possible to build a 3D liquid metal humanoid on demand.”
The research was published August 4 in open-access Nature Communications.
* Galinstan, an alloy of of 68.5% gallium, 21.5% indium, and 10% tin, is used as the model liquid metal. Galinstan’s melting point can be lowered to below 0 °C (32 °F).
RMIT University | Liquid metals propel future electronics | RMIT University
Abstract of Ionic imbalance induced self-propulsion of liquid metals
Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems.
Prototype wireless battery-less “neural dust” mote (3 x 1 x 1 millimeters) with electrodes attached to a nerve fiber in a rat. The mote contains a piezoelectric crystal (silver cube) that converts ultrasonic signals to electrical current, powering a simple electronic circuit containing a transistor (black square) that responds to the voltage generated by a nerve firing and triggers the piezoelectric crystal to create ultrasonic backscatter, which indicates detection of a neural signal. (photo credit: Ryan Neely/UC Berkeley)
University of California, Berkeley engineers have designed and built millimeter-scale device wireless, batteryless “neural dust” sensors and implanted them in muscles and peripheral nerves of rats to make in vivo electrophysiological recordings.
The new technology opens the door to “electroceuticals” — bioelectronic methods to monitor and record wireless electromyogram (EMG) signals from muscle membranes and electroneurogram (ENG) signals from local neuron electrical activity, and to stimulate the immune system, reduce inflammation, and treat disorders such as epilepsy.
The technology could also improve neural control of prosthetics (allowing a paraplegic to control a computer or a robotic arm, for example) by stimulating nerves and muscles directly, instead of requiring implanted wires.
The neural-dust sensors use ultrasound technology to both power the sensors and read out measurements. Ultrasound is already well-developed for hospital use and can penetrate nearly anywhere in the body, unlike radio waves.
The researchers reported their findings August 3 in an open-access paper in the journal Neuron.
How a neural dust “mote” sensor monitors neural and muscle signals
Diagram showing the components of the neural-dust mote (sensor). The entire device is covered in a biocompatible gel. (credit: Dongjin Seo et al./Neuron)
1. A team implants the neural dust mote. In the reported study, the mote was implanted in the rat sciatic nerve to do ENG recordings and in the gastrocnemius muscle to do EMG recordings. The tether-less connection also avoids potential infections and adverse biological responses due to micro-motion of the implant within the tissue.
2. An external ultrasonic generator sends a ultrasound signal to a piezoelectric crystal, which converts the sound energy into an electrical voltage, used to power a transistor circuit — no battery required.
3. When neurons or muscle fibers fire, they generate a tiny voltage (action potential) that the two electrodes pick up and send to the transistor.
4. The transistor amplifies the signal and drives the piezoelectric crystal to vibrate at an ultrasonic rate.
5. That vibration interferes with the transmitted ultrasonic signal, causing a modified “backscatter” signal that communicates information about the voltage across the sensor’s two electrodes.
In vivo experimental setup for a tether-less neural dust electromyography (EMG) recording from the gastrocnemius muscle in rats. The neural dust mote was placed on the exposed muscle surface, and the wound was closed with surgical suture. The ASIC chip switches between ultrasound transmit and receive modules.Triggered by the FPGA chip, the external transducer sends ultrasound (TX, green) to the mote. The backscatter received signal (RX, red) carries information about the EMG voltage that is decoded and recorded/displayed on a computer. The dust mote was pinged every 100 microseconds with six 540-nanosecond ultrasound pulses. (credit: Dongjin Seo et al./Neuron)
6. The backscatter ultrasound signal is decoded to extract EMG or ENG data.
7. A computer displays and records the information.
Microscale motes: future research
The experiments so far have involved the peripheral nervous system and muscles, using an external ultrasonic patch over the implanted site to acquire information from the motes for the desired diagnosis or therapy.
But according to the researchers, neural dust motes can be implanted anywhere in the body, including the central nervous system and brain to control prosthetics. This would be an alternative to today’s implantable electrodes (for Parkinson’s disease, for example), which require wires that pass through holes in the skull and degrade within one to two years.
The researchers are now building motes from biocompatible thin films, which would potentially last in the body without degradation for a decade or more. Up to hundreds of wireless sensors could be sealed in, avoiding infection and unwanted movement of the electrodes, and could last a timeline, according to the researchers.
The team is also now working to miniaturize the device further and they plan to use beam-steering technology to focus the ultrasonic signals on individual motes. The team is also building little backpacks for rats to hold the ultrasound transceiver that will record data from implanted motes. And the researchers are working to expand the motes’ ability to detect non-electrical signals, such as oxygen or hormone levels.
The researchers estimate that they could eventually shrink the sensors down to a cube 50 micrometers on a side. At that size, the motes could monitor a few specific nerve axons and continually record their electrical activity.
The researchers conceived of the idea of neural dust about five years ago, but initial attempts to power an implantable device and read out the data using radio waves were disappointing. Radio attenuates very quickly with distance in tissue, so communicating with devices deep in the body would be difficult without using potentially damaging high-intensity radiation. In 2013, the researchers published an open-access arXivpaper that described how a neural-dust system with ultrasonic signals might work.
The ongoing research is supported by the U.S. Defense Advanced Research Projects Agency as part of DARPA’s Electrical Prescriptions (ElectRx) program, which is focused in part on developing interface technologies that are suitable for chronic use for biosensing and neuromodulation of specific peripheral nerves.
UC Berkeley | “Neural dust” sensor
Abstract of Wireless Recording in the Peripheral Nervous System with Ultrasonic Neural Dust
The emerging field of bioelectronic medicine seeks methods for deciphering and modulating electrophysiological activity in the body to attain therapeutic effects at target organs. Current approaches to interfacing with peripheral nerves and muscles rely heavily on wires, creating problems for chronic use, while emerging wireless approaches lack the size scalability necessary to interrogate small-diameter nerves. Furthermore, conventional electrode-based technologies lack the capability to record from nerves with high spatial resolution or to record independently from many discrete sites within a nerve bundle. Here, we demonstrate neural dust, a wireless and scalable ultrasonic backscatter system for powering and communicating with implanted bioelectronics. We show that ultrasound is effective at delivering power to mm-scale devices in tissue; likewise, passive, battery-less communication using backscatter enables high-fidelity transmission of electromyogram (EMG) and electroneurogram (ENG) signals from anesthetized rats. These results highlight the potential for an ultrasound-based neural interface system for advancing future bioelectronics-based therapies.
A prototype chip with large arrays of phase-change devices that store the state of artificial neuronal populations in their atomic configuration. The devices are accessed via an array of probes in this prototype to allow for characterization and testing. The tiny squares are contact pads used to access the nanometer-scale phase-change cells (inset). Each set of probes can access a population of 100 cells. There are thousands to millions of these cells on one chip and IBM accesses them (in this particular photograph) by means of the sharp needles (probe card). (credit: IBM Research)
Scientists at IBM Research in Zurich have developed artificial neurons that emulate how neurons spike (fire). The goal is to create energy-efficient, high-speed, ultra-dense integrated neuromorphic (brain-like) technologies for applications in cognitive computing, such as unsupervised learning for detecting and analyzing patterns.
Applications could include internet of things sensors that collect and analyze volumes of weather data for faster forecasts and detecting patterns in financial transactions, for example.
The results of this research appeared today (Aug. 3) as a cover story in the journal Nature Nanotechnology.
Emulating neuron spiking
General pattern of a neural spike (action potential). A neuron fires (generates a rapid action potential, or voltage, when triggered by a stimulus) a signal from a synapse (credit: Chris 73/Diberri CC)
IBM’s new neuron-like spiking mechanism is based on a recent IBM breakthrough in phase-change materials. Phase-change materials are used for storing and processing digital data in re-writable Blu-ray discs, for example. The new phase-change materials developed by IBM recently are used instead for storing and processing analog data — like the synapses and neurons in our biological brains.
The new phase-change materials also overcome problems in conventional computing, where there’s a separate memory and logic unit, slowing down computation. These functions are combined in the new artificial neurons, just as they are in a biological neuron.
In biological neurons, a thin lipid-bilayer membrane separates the electrical charges inside the cell from those outside it. The membrane potential is altered by the arrival of excitatory and inhibitory postsynaptic potentials through the dendrites of the neuron, and upon sufficient excitation of the neuron (a phase change), an action potential, or spike, is generated. IBM’s new germanium-antimony-tellurium (GeSbTe or GST) phase-change material emulates this process. It has two stable states: an amorphous one (without a clearly defined structure) and a crystalline one (with a structure). (credit: Tomas Tuma et al./Nature Nanotechnology)
Alternative to von-Neumann-based algorithms
In addition, previous attempts to build artificial neurons are built using CMOS-based circuits, the standard transistor technology we have in our computers. The new phase-change technology can reproduce similar functionality at reduced power consumption. The artificial neurons are also superior in functioning at nanometer-length-scale dimensions and feature native stochasticity (based on random variables, simulating neurons).
“Populations of stochastic phase-change neurons, combined with other nanoscale computational elements such as artificial synapses, could be a key enabler for the creation of a new generation of extremely dense neuromorphic computing systems,” said Tomas Tuma, a co-author of the paper.
“The relatively complex computational tasks, such as Bayesian inference, that stochastic neuronal populations can perform with collocated processing and storage render them attractive as a possible alternative to von-Neumann-based algorithms in future cognitive computers,” the IBM scientists state in the paper.
IBM scientists have organized hundreds of these artificial neurons into populations and used them to represent fast and complex signals. These artificial neurons have been shown to sustain billions of switching cycles, which would correspond to multiple years of operation at an update frequency of 100 Hz. The energy required for each neuron update was less than five picojoule and the average power less than 120 microwatts — for comparison, 60 million microwatts power a 60 watt lightbulb.
IBM Research | All-memristive neuromorphic computing with level-tuned neurons
Abstract of Stochastic phase-change neurons
Artificial neuromorphic systems based on populations of spiking neurons are an indispensable tool in understanding the human brain and in constructing neuromimetic computational systems. To reach areal and power efficiencies comparable to those seen in biological systems, electroionics-based and phase-change-based memristive devices have been explored as nanoscale counterparts of synapses. However, progress on scalable realizations of neurons has so far been limited. Here, we show that chalcogenide-based phase-change materials can be used to create an artificial neuron in which the membrane potential is represented by the phase configuration of the nanoscale phase-change device. By exploiting the physics of reversible amorphous-to-crystal phase transitions, we show that the temporal integration of postsynaptic potentials can be achieved on a nanosecond timescale. Moreover, we show that this is inherently stochastic because of the melt-quench-induced reconfiguration of the atomic structure occurring when the neuron is reset. We demonstrate the use of these phase-change neurons, and their populations, in the detection of temporal correlations in parallel data streams and in sub-Nyquist representation of high-bandwidth signals.
“Do-it-yourself” users of transcranial direct current stimulation (tDCS) seeking cognitive enhancement are exposing themselves to hidden risks, neuroscientists warn in an open-access Open Letter in the journal Annals of Neurology.
tDCS devices are made up of a band that wraps around one’s head with electrodes placed at specific scalp locations to target specific brain regions. The devices transmit varying levels of electrical current to the brain to achieve the desired result, such as an enhanced state of relaxation, energy, focus, creativity, or a variety of other goals.
Cognitive neuroscience research suggests that tDCS can enhance cognition, and relieve symptoms of anxiety, depression, and other conditions. “Published results of these studies might lead DIY tDCS users to believe that they can achieve the same results if they mimic the way stimulation is delivered in research studies. However, there are many reasons why this simply isn’t true,” said first author, Rachel Wurzman, PhD, a postdoctoral research fellow in the Laboratory for Cognition and Neural Stimulation at Perelman School of Medicine at the University of Pennsylvania.
“It is important for people to understand why outcomes of tDCS can be unpredictable, because we know that in some cases, the benefits that are seen after tDCS in certain mental abilities may come at the expense of others.”
The “Open Letter” is signed by 39 researchers who share this sentiment, representing an unprecedented consensus among tDCS experts. “Given the possibility that the improper use of our articles might cause harm, as a community we felt it necessary — an ethical obligation — to explain in a peer-reviewed journal why it is that we generally do not encourage do-it-yourself use of tDCS,” she said.
tDCS risks
Among the concerns explained in the paper:
It is not yet known whether stimulation extends beyond the specific brain regions targeted. These indirect effects may alter unintended brain functions. Stimulating one region could improve one’s ability to perform one task but hurt the ability to perform another.
What a person is doing during tDCS — reading a book, watching TV, sleeping — can change its effects. Which activity is best to achieve a certain change in brain function is not yet known.
The researchers have never performed tDCS at the frequency levels some home users experiment with, such as stimulating daily for months or longer. “We know that stimulation from a few sessions can be quite lasting, but we do not yet know the possible risks of a larger cumulative dose over several years or a lifetime,” they wrote.
Small changes in tDCS settings, including the current’s amplitude, stimulation duration and electrode placement, can have large and unexpected effects; more stimulation is not necessarily better.
The effects of tDCS vary across different people. Up to 30 percent of experimental subjects respond with changes in brain excitability in the opposite direction from other subjects using identical tDCS settings. Factors such as gender, handedness, hormones, medication, etc. could impact and potentially reverse a given tDCS effect.
Most research is conducted for the purpose of treating disease, with the goal of alleviating symptoms, with a detailed disclosure or risks as required of studies of human research subjects. The level of risk is quite different for healthy subjects performing tDCS at home.
The two companies plan to expand drone delivery tests in Reno and expect drone packages to include “everyday essentials” such as batteries and sunscreen in the future, according to 7‑Eleven EVP Jesus H. Delgado-Jenkins.
Flirtey previously conducted the first FAA-approved drone delivery last July, a series of urgent medical deliveries to a rural healthcare clinic. The company also completed the first fully autonomous, FAA-approved urban drone delivery in the U.S. on March 25 to an uninhabited residential setting in Hawthorne, Nevada. The package included bottled water, emergency food, and a first aid kit.
And in June, Flirtey performed the first drone delivery of stool, blood, and urine samples from land to a medical testing facility on a barge in New Jersey’s Delaware Bay. Johns Hopkins University researchers on the barge sent back water purification tablets, insulin and a First Aid kit back to shore.
Amazon Prime Air testing moves to the UK
Amazon Prime Air’s new drone design, now being tested in the UK (credit: Amazon)
Meanwhile, hampered by the FAA’s strict new requirement* that commercially operated drones must fly within the operator’s line of sight at all times, on Monday July 25, Amazon.com Inc. announced plans for a partnership with the UK Government to make the delivery of parcels (up to 5 pounds to customers in 30 minutes or less) by Amazon’s planned Prime Air delivery service a reality.
Supported by the UK Civil Aviation Authority (CAA), Amazon now has UK permissions to “explore beyond line of sight operations in rural and suburban areas, test sensor performance to make sure the drones can identify and avoid obstacles, and [for] flights where one person operates multiple highly-automated drones.”
* According to an FAA announcement June 21 of the first operational rules for “unmanned aircraft drones weighing less than 55 pounds that are conducting non-hobbyist operations … pilots must “keep an unmanned aircraft within visual line of sight. Operations are allowed during daylight and during twilight if the drone has anti-collision lights. The new regulations also address height and speed restrictions and other operational limits, such as prohibiting flights over unprotected people on the ground who aren’t directly participating in the UAS operation.”
The FAA notes that “according to industry estimates, the [new] rule could generate more than $82 billion for the U.S. economy and create more than 100,000 new jobs over the next 10 years.”
Flirity | Flirtey making history with the first U.S. drone delivery (demo)
Elon Musk revealed his new master plan for Tesla today (July 20) in a blog post published on Tesla’s website:
Create stunning solar roofs with seamlessly integrated battery storage.
Expand the electric vehicle product line to address all major segments.
Develop a self-driving capability that is 10X safer than manual via massive fleet learning.
Enable your car to make money for you when you aren’t using it.
Increasing safety: “morally reprehensible to delay”
In the context of the recent Autopilot problem, Musk clarified why Tesla is deploying partial autonomy now, rather than waiting until some point in the future: “When used correctly, it is already significantly safer than a person driving by themselves and it would therefore be morally reprehensible to delay release simply for fear of bad press or some mercantile calculation of legal liability.
“According to the recently released 2015 NHTSA report, automotive fatalities increased by 8% to one death every 89 million miles. Autopilot miles will soon exceed twice that number and the system gets better every day. It would no more make sense to disable Tesla’s Autopilot, as some have called for, than it would to disable autopilot in aircraft, after which our system is named.”
Another way to increase safety, he says, is new heavy-duty trucks and high passenger-density urban transport, both planned for unveiling next year. “With the advent of autonomy, it will probably make sense to shrink the size of buses and transition the role of bus driver to that of fleet manager. … Traffic congestion would improve due to increased passenger areal density by eliminating the center aisle and putting seats where there are currently entryways, and matching acceleration and braking to other vehicles, thus avoiding the inertial impedance to smooth traffic flow of traditional heavy buses. It would also take people all the way to their destination.”
Lowering the cost of an autonomous car
Musk said that when true self-driving is approved by regulators, “it will mean that you will be able to summon your Tesla from pretty much anywhere. Once it picks you up, you will be able to sleep, read, or do anything else enroute to your destination.
“You will also be able to add your car to the Tesla shared fleet just by tapping a button on the Tesla phone app and have it generate income for you while you’re at work or on vacation, significantly offsetting and at times potentially exceeding the monthly loan or lease cost. This dramatically lowers the true cost of ownership to the point where almost anyone could own a Tesla. Since most cars are only in use by their owner for 5% to 10% of the day, the fundamental economic utility of a true self-driving car is likely to be several times that of a car which is not.”
Musk said that in cities where demand exceeds the supply of customer-owned cars, “Tesla will operate its own fleet, ensuring you can always hail a ride from us no matter where you are.”
