Are you a cyborg?

Bioprinting a brain

Cryogenic 3D-printing soft hydrogels. Top: the bioprinting process. Bottom: SEM image of general microstructure (scale bar: 100 µm). (credit: Z. Tan/Scientific Reports)

A new bioprinting technique combines cryogenics (freezing) and 3D printing to create geometrical structures that are as soft (and complex) as the most delicate body tissues — mimicking the mechanical properties of organs such as the brain and lungs.

The idea: “Seed” porous scaffolds that can act as a template for tissue regeneration (from neuronal cells, for example), where damaged tissues are encouraged to regrow — allowing the body to heal without tissue rejection or other problems. Using “pluripotent” stem cells that can change into different types of cells is also a possibility.

Smoothy. Solid carbon dioxide (dry ice) in an isopropanol bath is used to rapidly cool hydrogel ink (a rapid liquid-to-solid phase change) as it’s extruded, yogurt-smoothy-style. Once thawed, the gel is as soft as body tissues, but doesn’t collapse under its own weight — a previous problem.

Current structures produced with this technique are “organoids” a few centimeters in size. But the researchers hope to create replicas of actual body parts with complex geometrical structures — even whole organs. That could allow scientists to carry out experiments not possible on live subjects, or for use in medical training, replacing animal bodies for surgical training and simulations. Then on to mechanobiology and tissue engineering.

Source: Imperial College London, Scientific Reports (open-access).

How to generate electricity with your body

Bending a finger generates electricity in this prototype device. (credit: Guofeng Song et al./Nano Energy)

A new triboelectric nanogenerator (TENG) design, using a gold tab attached to your skin, will convert mechanical energy into electrical energy for future wearables and self-powered electronics. Just bend your finger or take a step.

Triboelectric charging occurs when certain materials become electrically charged after coming into contact with a different material. In this new design by University of Buffalo and Chinese scientists, when a stretched layer of gold is released, it crumples, creating what looks like a miniature mountain range. An applied force leads to friction between the gold layers and an interior PDMS layer, causing electrons to flow between the gold layers.

More power to you. Previous TENG designs have been difficult to manufacture (requiring complex lithography) or too expensive. The new 1.5-centimeters-long prototype generates a maximum of 124 volts but at only 10 microamps. It has a power density of 0.22 millwatts per square centimeter. The team plans larger pieces of gold to deliver more electricity and a portable battery.

Source: Nano Energy. Support: U.S. National Science Foundation, the National Basic Research Program of China, National Natural Science Foundation of China, Beijing Science and Technology Projects, Key Research Projects of the Frontier Science of the Chinese Academy of Sciences ,and National Key Research and Development Plan.

This artificial electrical eel may power your implants

How the eel’s electrical organs generate electricity by moving sodium (Na) and potassium (K) ions across a selective membrane. (credit: Caitlin Monney)

Taking it a giant (and a bit scary) step further, an artificial electric organ, inspired by the electric eel, could one day power your implanted implantable sensors, prosthetic devices, medication dispensers, augmented-reality contact lenses, and countless other gadgets. Unlike typical toxic batteries that need to be recharged, these systems are soft, flexible, transparent, and potentially biocompatible.

Doubles as a defibrillator? The system mimicks eels’ electrical organs, which use thousands of alternating compartments with excess potassium or sodium ions, separated by selective membranes. To create a jolt of electricity (600 volts at 1 ampere), an eel’s membranes allow the ions to flow together. The researchers built a similar system, but using sodium and chloride ions dissolved in a water-based hydrogel. It generates more than 100 volts, but at safe low current — just enough to power a small medical device like a pacemaker.

The researchers say the technology could also lead to using naturally occurring processes inside the body to generate electricity, a truly radical step.

Source: Nature, University of Fribourg, University of Michigan, University of California-San Diego. Funding: Air Force Office of Scientific Research, National Institutes of Health.

E-skin for Terminator wannabes

A section of “e-skin” (credit: Jianliang Xiao / University of Colorado Boulder)

A new type of thin, self-healing, translucent “electronic skin” (“e-skin,” which mimicks the properties of natural skin) has applications ranging from robotics and prosthetic development to better biomedical devices and human-computer interfaces.

Ready for a Terminator-style robot baby nurse? What makes this e-skin different and interesting is its embedded sensors, which can measure pressure, temperature, humidity and air flow. That makes it sensitive enough to let a robot take care of a baby, the University of Colorado mechanical engineers and chemists assure us. The skin is also rapidly self-healing (by reheating), as in The Terminator, using a mix of three commercially available compounds in ethanol.

The secret ingredient: A novel network polymer known as polyimine, which is fully recyclable at room temperature. Laced with silver nanoparticles, it can provide better mechanical strength, chemical stability and electrical conductivity. It’s also malleable, so by applying moderate heat and pressure, it can be easily conformed to complex, curved surfaces like human arms and robotic hands.

Source: University of Colorado, Science Advances (open-access). Funded in part by the National Science Foundation.

Altered Carbon

Vertebral cortical stack (credit: Netflix)

Altered Carbon takes place in the 25th century, when humankind has spread throughout the galaxy. After 250 years in cryonic suspension, a prisoner returns to life in a new body with one chance to win his freedom: by solving a mind-bending murder.

Resleeve your stack. Human consciousness can be digitized and downloaded into different bodies. A person’s memories have been encapsulated into “cortical stack” storage devices surgically inserted into the vertebrae at the back of the neck. Disposable physical bodies called “sleeves” can accept any stack.

But only the wealthy can acquire replacement bodies on a continual basis. The long-lived are called Meths, as in the Biblical figure Methuselah. The uber rich are also able to keep copies of their minds in remote storage, which they back up regularly, ensuring that even if their stack is destroyed, the stack can be resleeved (except for periods of time not backed up — as in the hack-murder).

Source: Netflix. Premiered on February 2, 2018. Based on the 2002 novel of the same title by Richard K. Morgan.






Penn researchers create first optical transistor comparable to an electronic transistor

By precisely controlling the mixing of optical signals, Ritesh Agarwal’s research team says they have taken an important step toward photonic (optical) computing. (credit: Sajal Dhara)

In an open-access paper published in Nature Communications, Ritesh Agarwal, a professor the University of Pennsylvania School of Engineering and Applied Science, and his colleagues say that they have made significant progress in photonic (optical) computing by creating a prototype of a working optical transistor with properties similar to those of a conventional electronic transistor.*

Optical transistors, using photons instead of electrons, promise to one day be more powerful than the electronic transistors currently used in computers.

Agarwal’s research on photonic computing has been focused on finding the right combination and physical configuration of nonlinear materials that can amplify and mix light waves in ways that are analogous to electronic transistors. “One of the hurdles in doing this with light is that materials that are able to mix optical signals also tend to have very strong background signals as well. That background signal would drastically reduce the contrast and on/off ratios leading to errors in the output,” Agarwal explained.

How the new optical transistor works

Schematic of a cadmium sulfide nanobelt device with source (S) and drain (D) electrodes. The fundamental wave at the frequency of ω, which is normally incident upon the belt, excites the second-harmonic (twice the frequency) wave at 2ω, which is back-scattered. (credit: Ming-Liang Ren et al./Nature Communications)

To address this issue, Agarwal’s research group started by creating a system with no disruptive optical background signal. To do that, they used a “nanobelt”* made out of cadmium sulfide. Then, by applying an electrical field across the nanobelt, the researchers were able to introduce optical nonlinearities (similar to the nonlinearities in electronic transistors), which enabled a signal mixing output that was otherwise zero.

“Our system turns on from zero to extremely large values,” Agarwal said.** “For the first time, we have an optical device with output that truly resembles an electronic transistor.”

The next steps toward a fully functioning photonic computer will involve integrating optical circuits with optical interconnects, modulators, and detectors to achieve actual on-chip integrated photonic computation.

The research was supported by the US Army Research Office and the National Science Foundation.

* “Made of semiconducting metal oxides, nanobelts are extremely thin and flat structures. They are chemically pure, structurally uniform, largely defect-free, with clean surfaces that do not require protection against oxidation. Each is made up of a single crystal with specific surface planes and shape.” — Reade International Corp.

** That is, the system was capable of precisely controlling the mixing of optical signals via controlled electric fields, with outputs with near-perfect contrast and extremely large on/off ratios. “Our study demonstrates a new way to dynamically control nonlinear optical signals in nanoscale materials with ultrahigh signal contrast and signal saturation, which can enable the development of nonlinear optical transistors and modulators for on-chip photonic devices with high-performance metrics and small-form factors, which can be further enhanced by integrating with nanoscale optical cavities,” the researchers note in the paper.

Abstract of Strong modulation of second-harmonic generation with very large contrast in semiconducting CdS via high-field domain

Dynamic control of nonlinear signals is critical for a wide variety of optoelectronic applications, such as signal processing for optical computing. However, controlling nonlinear optical signals with large modulation strengths and near-perfect contrast remains a challenging problem due to intrinsic second-order nonlinear coefficients via bulk or surface contributions. Here, via electrical control, we turn on and tune second-order nonlinear coefficients in semiconducting CdS nanobelts from zero to up to 151 pm V−1, a value higher than other intrinsic nonlinear coefficients in CdS. We also observe ultrahigh ON/OFF ratio of >104 and modulation strengths ~200% V−1 of the nonlinear signal. The unusual nonlinear behavior, including super-quadratic voltage and power dependence, is ascribed to the high-field domain, which can be further controlled by near-infrared optical excitation and electrical gating. The ability to electrically control nonlinear optical signals in nanostructures can enable optoelectronic devices such as optical transistors and modulators for on-chip integrated photonics.

Ultra-thin ‘atomistor’ synapse-like memory storage device paves way for faster, smaller, smarter computer chips

Illustration of single-atom-layer “atomristors” — the thinnest-ever memory-storage device (credit: Cockrell School of Engineering, The University of Texas at Austin)

A team of electrical engineers at The University of Texas at Austin and scientists at Peking University has developed a one-atom-thick 2D “atomristor” memory storage device that may lead to faster, smaller, smarter computer chips.

The atomristor (atomic memristor) improves upon memristor (memory resistor) memory storage technology by using atomically thin nanomaterials (atomic sheets). (Combining memory and logic functions, similar to the synapses of biological brains, memristors “remember” their previous state after being turned off.)

Schematic of atomristor memory sandwich based on molybdenum sulfide (MoS2) in a form of a single-layer atomic sheet grown on gold foil. (Blue: Mo; yellow: S) (credit: Ruijing Ge et al./Nano Letters)

Memory storage and transistors have, to date, been separate components on a microchip. Atomristors combine both functions on a single, more-efficient device. They use metallic atomic sheets (such as graphene or gold) as electrodes and semiconducting atomic sheets (such as molybdenum sulfide) as the active layer. The entire memory cell is a two-layer sandwich only ~1.5 nanometers thick.

“The sheer density of memory storage that can be made possible by layering these synthetic atomic sheets onto each other, coupled with integrated transistor design, means we can potentially make computers that learn and remember the same way our brains do,” said Deji Akinwande, associate professor in the Cockrell School of Engineering’s Department of Electrical and Computer Engineering.

“This discovery has real commercialization value, as it won’t disrupt existing technologies,” Akinwande said. “Rather, it has been designed to complement and integrate with the silicon chips already in use in modern tech devices.”

The research is described in an open-access paper in the January American Chemical Society journal Nano Letters.

Longer battery life in cell phones

For nonvolatile operation (preserving data after power is turned off), the new design also “offers a substantial advantage over conventional flash memory, which occupies far larger space. In addition, the thinness allows for faster and more efficient electric current flow,” the researchers note in the paper.

The research team also discovered another unique application for the atomristor technology: Atomristors are the smallest radio-frequency (RF) memory switches to be demonstrated, with no DC battery consumption, which could ultimately lead to longer battery life for cell phones and other battery-powered devices.*

Funding for the UT Austin team’s work was provided by the National Science Foundation and the Presidential Early Career Award for Scientists and Engineers, awarded to Akinwande in 2015.

* “Contemporary switches are realized with transistor or microelectromechanical devices, both of which are volatile, with the latter also requiring large switching voltages [which are not ideal] for mobile technologies,” the researchers note in the paper. Atomristors instead allow for nonvolatile low-power radio-frequency (RF) switches with “low voltage operation, small form-factor, fast switching speed, and low-temperature integration compatible with silicon or flexible substrates.”

Abstract of Atomristor: Nonvolatile Resistance Switching in Atomic Sheets of Transition Metal Dichalcogenides

Recently, two-dimensional (2D) atomic sheets have inspired new ideas in nanoscience including topologically protected charge transport,1,2 spatially separated excitons,3 and strongly anisotropic heat transport.4 Here, we report the intriguing observation of stable nonvolatile resistance switching (NVRS) in single-layer atomic sheets sandwiched between metal electrodes. NVRS is observed in the prototypical semiconducting (MX2, M = Mo, W; and X = S, Se) transitional metal dichalcogenides (TMDs),5 which alludes to the universality of this phenomenon in TMD monolayers and offers forming-free switching. This observation of NVRS phenomenon, widely attributed to ionic diffusion, filament, and interfacial redox in bulk oxides and electrolytes,6−9 inspires new studies on defects, ion transport, and energetics at the sharp interfaces between atomically thin sheets and conducting electrodes. Our findings overturn the contemporary thinking that nonvolatile switching is not scalable to subnanometre owing to leakage currents.10 Emerging device concepts in nonvolatile flexible memory fabrics, and brain-inspired (neuromorphic) computing could benefit substantially from the wide 2D materials design space. A new major application, zero-static power radio frequency (RF) switching, is demonstrated with a monolayer switch operating to 50 GHz.

An artificial synapse for future miniaturized portable ‘brain-on-a-chip’ devices

Biological synapse structure (credit: Thomas Splettstoesser/CC)

MIT engineers have designed a new artificial synapse made from silicon germanium that can precisely control the strength of an electric current flowing across it.

In simulations, the researchers found that the chip and its synapses could be used to recognize samples of handwriting with 95 percent accuracy. The engineers say the new design, published today (Jan. 22) in the journal Nature Materials, is a major step toward building portable, low-power neuromorphic chips for use in pattern recognition and other machine-learning tasks.

Controlling the flow of ions: the challenge

Researchers in the emerging field of “neuromorphic computing” have attempted to design computer chips that work like the human brain. The idea is to apply a voltage across layers that would cause ions (electrically charged atoms) to move in a switching medium (synapse-like space) to create conductive filaments in a manner that’s similar to how the “weight” (connection strength) of a synapse changes.

There are more than 100 trillion synapses (in a typical human brain) that mediate neuron signaling in the brain, strengthening some neural connections while pruning (weakening) others — a process that enables the brain to recognize patterns, remember facts, and carry out other learning tasks, all at lightning speeds.

Instead of carrying out computations based on binary, on/off signaling, like current digital chips, the elements of a “brain on a chip” would work in an analog fashion, exchanging a gradient of signals, or “weights” — much like neurons that activate in various ways (depending on the type and number of ions that flow across a synapse).

But it’s been difficult to control the flow of ions in existing synapse designs. These have multiple paths that make it difficult to predict where ions will make it through, according to research team leader Jeehwan Kim, PhD, an assistant professor in the departments of Mechanical Engineering and Materials Science and Engineering, a principal investigator in MIT’s Research Laboratory of Electronics and Microsystems Technology Laboratories.

“Once you apply some voltage to represent some data with your artificial neuron, you have to erase and be able to write it again in the exact same way,” Kim says. “But in an amorphous solid, when you write again, the ions go in different directions because there are lots of defects. This stream is changing, and it’s hard to control. That’s the biggest problem — nonuniformity of the artificial synapse.”

Epitaxial random access memory (epiRAM)

(Left) Cross-sectional transmission electron microscope image of 60 nm silicon-germanium (SiGe) crystal grown on a silicon substrate (diagonal white lines represent candidate dislocations). Scale bar: 25 nm. (Right) Cross-sectional scanning electron microscope image of an epiRAM device with titanium (Ti)–gold (Au) and silver (Ag)–palladium (Pd) layers. Scale bar: 100 nm. (credit: Shinhyun Choi et al./Nature Materials)

So instead of using amorphous materials as an artificial synapse, Kim and his colleagues created an new “epitaxial random access memory” (epiRAM) design.

They started with a wafer of silicon. They then grew a similar pattern of silicon germanium — a material used commonly in transistors — on top of the silicon wafer. Silicon germanium’s lattice is slightly larger than that of silicon, and Kim found that together, the two perfectly mismatched materials could form a funnel-like dislocation, creating a single path through which ions can predictably flow.*

This is the most uniform device we could achieve, which is the key to demonstrating artificial neural networks,” Kim says.

Testing the ability to recognize samples of handwriting

As a test, Kim and his team explored how the epiRAM device would perform if it were to carry out an actual learning task: recognizing samples of handwriting — which researchers consider to be a practical test for neuromorphic chips. Such chips would consist of artificial “neurons” connected to other “neurons” via filament-based artificial “synapses.”

Image-recognition simulation. (Left) A 3-layer multilayer-perception neural network with black and white input signal for each layer in algorithm level. The inner product (summation) of input neuron signal vector and first synapse array vector is transferred after activation and binarization as input vectors of second synapse arrays. (Right) Circuit block diagram of hardware implementation showing a synapse layer composed of epiRAM crossbar arrays and the peripheral circuit. (credit: Shinhyun Choi et al./Nature Materials)

They ran a computer simulation of an artificial neural network consisting of three sheets of neural layers connected via two layers of artificial synapses, based on measurements from their actual neuromorphic chip. They fed into their simulation tens of thousands of samples from the MNIST handwritten recognition dataset**, commonly used by neuromorphic designers.

They found that their neural network device recognized handwritten samples 95.1 percent of the time — close to the 97 percent accuracy of existing software algorithms running on large computers.

A chip to replace a supercomputer

The team is now in the process of fabricating a real working neuromorphic chip that can carry out handwriting-recognition tasks. Looking beyond handwriting, Kim says the team’s artificial synapse design will enable much smaller, portable neural network devices that can perform complex computations that are currently only possible with large supercomputers.

“Ultimately, we want a chip as big as a fingernail to replace one big supercomputer,” Kim says. “This opens a stepping stone to produce real artificial intelligence hardware.”

This research was supported in part by the National Science Foundation. Co-authors included researchers at Arizona State University.

* They applied voltage to each synapse and found that all synapses exhibited about the same current, or flow of ions, with about a 4 percent variation between synapses — a much more uniform performance compared with synapses made from amorphous material. They also tested a single synapse over multiple trials, applying the same voltage over 700 cycles, and found the synapse exhibited the same current, with just 1 percent variation from cycle to cycle.

** The MNIST (Modified National Institute of Standards and Technology database) is a large database of handwritten digits that is commonly used for training various image processing systems and for training and testing in the field of machine learning. It contains 60,000 training images and 10,000 testing images. 

Abstract of SiGe epitaxial memory for neuromorphic computing with reproducible high performance based on engineered dislocations

Although several types of architecture combining memory cells and transistors have been used to demonstrate artificial synaptic arrays, they usually present limited scalability and high power consumption. Transistor-free analog switching devices may overcome these limitations, yet the typical switching process they rely on—formation of filaments in an amorphous medium—is not easily controlled and hence hampers the spatial and temporal reproducibility of the performance. Here, we demonstrate analog resistive switching devices that possess desired characteristics for neuromorphic computing networks with minimal performance variations using a single-crystalline SiGe layer epitaxially grown on Si as a switching medium. Such epitaxial random access memories utilize threading dislocations in SiGe to confine metal filaments in a defined, one-dimensional channel. This confinement results in drastically enhanced switching uniformity and long retention/high endurance with a high analog on/off ratio. Simulations using the MNIST handwritten recognition data set prove that epitaxial random access memories can operate with an online learning accuracy of 95.1%.

Remote-controlled DNA nanorobots could lead to the first nanorobotic production factory

German researchers created a 55-nm-by-55-nm DNA-based molecular platform with a 25-nm-long robotic arm that can be actuated with externally applied electrical fields, under computer control. (credit: Enzo Kopperger et al./Science)

By powering a self-assembling DNA nanorobotic arm with electric fields, German scientists have achieved precise nanoscale movement that is at least five orders of magnitude (hundreds of thousands times) faster than previously reported DNA-driven robotic systems, they suggest today (Jan. 19) in the journal Science.

DNA origami has emerged as a powerful tool to build precise structures. But now, “Kopperger et al. make an impressive stride in this direction by creating a dynamic DNA origami structure that they can directly control from the macroscale with easily tunable electric fields—similar to a remote-controlled robot,” notes Björn Högberg of Karolinska Institutet in a related Perspective in Science, (p. 279).

The nanorobotic arm resembles the gearshift lever of a car. Controlled by an electric field (comparable to the car driver), short, single-stranded DNA serves as “latches” (yellow) to momentarily grab and lock the 25-nanometer-long arm into predefined “gear” positions. (credit: Enzo Kopperger et al./Science)

The new biohybrid nanorobotic systems could even act as a molecular mechanical memory (a sort of nanoscale version of the Babbage Analytical Engine), he notes. “With the capability to form long filaments with multiple DNA robot arms, the systems could also serve as a platform for new inventions in digital memory, nanoscale cargo transfer, and 3D printing of molecules.”

“The robot-arm system may be scaled up and integrated into larger hybrid systems by a combination of lithographic and self-assembly techniques,” according to the researchers. “Electrically clocked synthesis of molecules with a large number of robot arms in parallel could then be the first step toward the realization of a genuine nanorobotic production factory.”

Taking a different approach to a nanofactory, this “Productive Nanosystems: from Molecules to Superproducts” film — a collaborative project of animator and engineer John Burch and pioneer nanotechnologist K. Eric Drexler in 2005 — demonstrated key steps in a hypothetical process that converts simple molecules into a billion-CPU laptop computer. More here.

Abstract of A self-assembled nanoscale robotic arm controlled by electric fields

The use of dynamic, self-assembled DNA nanostructures in the context of nanorobotics requires fast and reliable actuation mechanisms. We therefore created a 55-nanometer–by–55-nanometer DNA-based molecular platform with an integrated robotic arm of length 25 nanometers, which can be extended to more than 400 nanometers and actuated with externally applied electrical fields. Precise, computer-controlled switching of the arm between arbitrary positions on the platform can be achieved within milliseconds, as demonstrated with single-pair Förster resonance energy transfer experiments and fluorescence microscopy. The arm can be used for electrically driven transport of molecules or nanoparticles over tens of nanometers, which is useful for the control of photonic and plasmonic processes. Application of piconewton forces by the robot arm is demonstrated in force-induced DNA duplex melting experiments.

A breakthrough low-light image sensor for photography, life sciences, security

A sample photo (right) taken with the one-megapixel low-light Quanta Image Sensor operating at 1,040 frames per second. It is a binary single-photon image, so if the pixel was hit by one or more photons, it is white; if not, it is black. The photo was created by summing up eight frames of binary images taken continuously. A de-noising algorithm was applied to the final image. (credit: Jiaju Ma, adapted by KurzweilAI)

Engineers from Dartmouth’s Thayer School of Engineering have created a radical new imaging technology called “Quanta Image Sensor” (QIS) that may revolutionize a wide variety of imaging applications that require high quality at low light.

These include security, photography, cinematography, and medical and life sciences research.

Low-light photography (at night with only moonlight, for example) currently requires photographers to use time exposure (keeping the shutter open for seconds or minutes), making it impossible to photograph moving images.

Capturing single photons at room temperature

The new QIS technology can capture or count at the lowest possible level of light (single photons) with a resolution as high as one megapixel* (one million pixels) — scalable for higher resolution up to hundreds of megapixels per chip** — and as fast as thousands of frames*** per second (required for “bullet time” cinematography in “The Matrix”).

The QIS works at room temperature, using existing mainstream CMOS image sensor technology. Current lab-research technology may require cooling to very low temperatures, such as 4 kelvin, and is limited to low pixel count.

Quanta Image Sensor applications (credit: Gigajot)

For astrophysicists, the QIS will allow for detecting and capturing signals from distant objects in space at higher quality. For life-science researchers, it will provide improved visualization of cells under a microscope, which is critical for determining the effectiveness of therapies.

The QIS technology is commercially accessible, inexpensive, and compatible with mass-production manufacturing, according to inventor Eric R. Fossum, professor of engineering at Dartmouth. Fossum is senior author of an open-access paper on QIS in the Dec. 20 issue of The Optical Society’s (OSA) Optica. He invented the CMOS image sensor found in nearly all smartphones and cameras in the world today.

The research was performed in cooperation with Rambus, Inc. and the Taiwan Semiconductor Manufacturing Corporation and was funded by Rambus and the Defense Advanced Research Projects Agency (DARPA). The low-light capability promises to allow for improved security uses. Fossum and associates have co-founded the startup company Gigajot Technology to further develop and apply the technology to promising applications.

* By comparison, the iPhone 8 can capture 12 megapixels (but is not usable in low light).

** The technology is based on what the researchers call “jots,” which function like miniature pixels. Each jot can collect one photon, enabling the extreme low-light capability and high resolution.

*** By comparison, the iPhone 8 can record 24 to 60 frames per second.

Abstract of Photon-number-resolving megapixel image sensor at room temperature without avalanche gain

In several emerging fields of study such as encryption in optical communications, determination of the number of photons in an optical pulse is of great importance. Typically, such photon-number-resolving sensors require operation at very low temperature (e.g., 4 K for superconducting-based detectors) and are limited to low pixel count (e.g., hundreds). In this paper, a CMOS-based photon-counting image sensor is presented with photon-number-resolving capability that operates at room temperature with resolution of 1 megapixel. Termed a quanta image sensor, the device is implemented in a commercial stacked (3D) backside-illuminated CMOS image sensor process. Without the use of avalanche multiplication, the 1.1 μm pixel-pitch device achieves 0.21e−  rms0.21e−  rms average read noise with average dark count rate per pixel less than 0.2e−/s0.2e−/s, and 1040 fps readout rate. This novel platform technology fits the needs of high-speed, high-resolution, and accurate photon-counting imaging for scientific, space, security, and low-light imaging as well as a broader range of other applications.

A new low-cost, simple way to measure medical vital signs with radio waves

A radio-frequency identification (RFID) tag, used to monitor vital signs, can go into your pocket or be woven into a shirt (credit: Cornell)

Replacing devices based on 19th-century technology* and still in use, Cornell University engineers have developed a simple method for gathering blood pressure, heart rate, and breath rate from multiple patients simultaneously. It uses low-power radio-frequency signals and low-cost microchip radio-frequency identification (RFID) “tags” — similar to the ubiquitous anti-theft tags used in department stores.

The RFID tags measure internal body motion, such as a heart as it beats or blood as it pulses under skin. Powered remotely by electromagnetic energy supplied by a central reader, the tags use a new concept called “near-field coherent sensing.” Mechanical motions (heartbeat, etc.) in the body modulate (modify) radio waves that are bounced off the body and internal organs by passive (no battery required) RFID tags.

The modulated signals detected by the tag then bounce back to an electronic reader, located elsewhere in the room, that gathers the data. Each tag has a unique identification code that it transmits with its signal, allowing up to 200 people to be monitored simultaneously.

Electromagnetic simulations of monitoring vital signs via radio transmission, showing heartbeat sensing (left) and pulse sensing (right) (credit: Xiaonan Hui and Edwin C. Kan/Nature Electronics)

“If this is an emergency room, everybody that comes in can wear these tags or can simply put tags in their front pockets, and everybody’s vital signs can be monitored at the same time. I’ll know exactly which person each of the vital signs belongs to,” said Edwin Kan, a Cornell professor of electrical and computer engineering.

The signal is as accurate as an electrocardiogram or a blood-pressure cuff, according to Kan, who believes the technology could also be used to measure bowel movement, eye movement, and many other internal mechanical motions produced by the body.

The researchers envision embedding the RFID chips in clothing to monitor health in real time, with little or no effort required by the user. They have also developed a method for embroidering the tags directly onto clothing using fibers coated with nanoparticles. A cellphone could read (and display) your vital signs and also transmit them for remote medical monitoring.

The system is detailed in the open-access paper “Monitoring Vital Signs Over Multiplexed Radio by Near-Field Coherent Sensing,” published online Nov. 27 in the journal Nature Electronics. “Current approaches to monitoring vital signs are based on body electrodes, optical absorption, pressure or strain gauges, stethoscope, and ultrasound or radiofrequency (RF) backscattering, each of which suffers particular drawbacks during application,” the paper notes.

* The sphygmomanometer was invented by Samuel Siegfried Karl Ritter von Basch in 1881. Devices based on its basic pressure principle are still in use. (credit: Wellcome Trustees)

Abstract of Monitoring vital signs over multiplexed radio by near-field coherent sensing

Monitoring the heart rate, blood pressure, respiration rate and breath effort of a patient is critical to managing their care, but current approaches are limited in terms of sensing capabilities and sampling rates. The measurement process can also be uncomfortable due to the need for direct skin contact, which can disrupt the circadian rhythm and restrict the motion of the patient. Here we show that the external and internal mechanical motion of a person can be directly modulated onto multiplexed radiofrequency signals integrated with unique digital identification using near-field coherent sensing. The approach, which does not require direct skin contact, offers two possible implementations: passive and active radiofrequency identification tags. To minimize deployment and maintenance cost, passive tags can be integrated into garments at the chest and wrist areas, where the two multiplexed far-field backscattering waveforms are collected at the reader to retrieve the heart rate, blood pressure, respiration rate and breath effort. To maximize reading range and immunity to multipath interference caused by indoor occupant motion, active tags could be placed in the front pocket and in the wrist cuff to measure the antenna reflection due to near-field coherent sensing and then the vital signals sampled and transmitted entirely in digital format. Our system is capable of monitoring multiple people simultaneously and could lead to the cost-effective automation of vital sign monitoring in care facilities.

Using light instead of electrons promises faster, smaller, more-efficient computers and smartphones

Trapped light for optical computation (credit: Imperial College London)

By forcing light to go through a smaller gap than ever before, a research team at Imperial College London has taken a step toward computers based on light instead of electrons.

Light would be preferable for computing because it can carry much-higher-density information, it’s much faster, and more efficient (generates little to no heat). But light beams don’t easily interact with one other. So information on high-speed fiber-optic cables (provided by your cable TV company, for example) currently has to be converted (via a modem or other device) into slower signals (electrons on wires or wireless signals) to allow for processing the data on devices such as computers and smartphones.

Electron-microscope image of an optical-computing nanofocusing device that is 25 nanometers wide and 2 micrometers long, using grating couplers (vertical lines) to interface with fiber-optic cables. (credit: Nielsen et al., 2017/Imperial College London)

To overcome that limitation, the researchers used metamaterials to squeeze light into a metal channel only 25 nanometers (billionths of a meter) wide, increasing its intensity and allowing photons to interact over the range of micrometers (millionths of meters) instead of centimeters.*

That means optical computation that previously required a centimeters-size device can now be realized on the micrometer (one millionth of a meter) scale, bringing optical processing into the size range of electronic transistors.

The results were published Thursday Nov. 30, 2017 in the journal Science.

* Normally, when two light beams cross each other, the individual photons do not interact or alter each other, as two electrons do when they meet. That means a long span of material is needed to gradually accumulate the effect and make it useful. Here, a “plasmonic nanofocusing” waveguide is used, strongly confining light within a nonlinear organic polymer.

Abstract of Giant nonlinear response at a plasmonic nanofocus drives efficient four-wave mixing

Efficient optical frequency mixing typically must accumulate over large interaction lengths because nonlinear responses in natural materials are inherently weak. This limits the efficiency of mixing processes owing to the requirement of phase matching. Here, we report efficient four-wave mixing (FWM) over micrometer-scale interaction lengths at telecommunications wavelengths on silicon. We used an integrated plasmonic gap waveguide that strongly confines light within a nonlinear organic polymer. The gap waveguide intensifies light by nanofocusing it to a mode cross-section of a few tens of nanometers, thus generating a nonlinear response so strong that efficient FWM accumulates over wavelength-scale distances. This technique opens up nonlinear optics to a regime of relaxed phase matching, with the possibility of compact, broadband, and efficient frequency mixing integrated with silicon photonics.

How to open the blood-brain-barrier with precision for safer drug delivery

Schematic representation of the feedback-controlled focused ultrasound drug delivery system. Serving as the acoustic indicator of drug-delivery dosage, the microbubble emission signal was sensed and compared with the expected value. The difference was used as feedback to the ultrasound transducer for controlling the level of the ultrasound transmission. The ultrasound transducer and sensor were located outside the rat skull. The microbubbles were generated in the bloodstream at the target location in the brain. (credit: Tao Sun/Brigham and Women’s Hospital; adapted by KurzweilAI)

Researchers at Brigham and Women’s Hospital have developed a safer way to use focused ultrasound to temporarily open the blood-brain barrier* to allow for delivering vital drugs for treating glioma brain tumors — an alternative to invasive incision or radiation.

Focused ultrasound drug delivery to the brain uses “cavitation” — creating microbubbles — to temporarily open the blood-brain barrier. The problem with this method has been that if these bubbles destabilize and collapse, they could damage the critical vasculature in the brain.

To create a finer degree of control over the microbubbles and improve safety, the researchers placed a sensor outside of the rat brain to listen to ultrasound echoes bouncing off the microbubbles, as an indication of how stable the bubbles were.** That data was used to modify the ultrasound intensity, stabilizing the microbubbles to maintain safe ultrasound exposure.

The team tested the approach in both healthy rats and in an animal model of glioma brain cancer. Further research will be needed to adapt the technique for humans, but the approach could offer improved safety and efficacy control for human clinical trials, which are now underway in Canada.

The research, published this week in the journal Proceedings of the National Academy of Sciences, was supported by the National Institutes of Health in Canada.

* The blood brain barrier is an impassable obstacle for 98% of drugs, which it treats as pathogens and blocks them from passing from patients’ bloodstream into the brain. Using focused ultrasound, drugs can administered using an intravenous injection of innocuous lipid-coated gas microbubbles.

** For the ultrasound transducer, the researchers combined two spherically curved transducers (operating at a resonant frequency at 274.3 kHz) to double the effective aperture size and provide significantly improved focusing in the axial direction.

Abstract of Closed-loop control of targeted ultrasound drug delivery across the blood–brain/tumor barriers in a rat glioma model

Cavitation-facilitated microbubble-mediated focused ultrasound therapy is a promising method of drug delivery across the blood–brain barrier (BBB) for treating many neurological disorders. Unlike ultrasound thermal therapies, during which magnetic resonance thermometry can serve as a reliable treatment control modality, real-time control of modulated BBB disruption with undetectable vascular damage remains a challenge. Here a closed-loop cavitation controlling paradigm that sustains stable cavitation while suppressing inertial cavitation behavior was designed and validated using a dual-transducer system operating at the clinically relevant ultrasound frequency of 274.3 kHz. Tests in the normal brain and in the F98 glioma model in vivo demonstrated that this controller enables reliable and damage-free delivery of a predetermined amount of the chemotherapeutic drug (liposomal doxorubicin) into the brain. The maximum concentration level of delivered doxorubicin exceeded levels previously shown (using uncontrolled sonication) to induce tumor regression and improve survival in rat glioma. These results confirmed the ability of the controller to modulate the drug delivery dosage within a therapeutically effective range, while improving safety control. It can be readily implemented clinically and potentially applied to other cavitation-enhanced ultrasound therapies.

Consumer Technology Association inducts Ray Kurzweil, 11 other visionaries into the 2017 Consumer Technology Hall of Fame

Gary Shapiro (left) and Ray Kurzweil (right) (credit: CTA)

The Consumer Technology Association (CTA) inducted Ray Kurzweil and 11 other industry leaders into the Consumer Technology (CT) Hall of Fame at its 19th annual awards dinner, held Nov. 7, 2017 at the Rainbow Room, atop 30 Rockefeller Center in Manhattan.

CTA, formerly Consumer Electronics Association (CEA), created the Hall of Fame in 2000 to honor industry visionaries and pioneers.

A noted inventor, author, and futurist, Ray Kurzweil was the principal inventor of the first CCD flatbed scanner, the first omni-font optical character recognition, the first print-to-speech reading machine for the blind, the first text-to-speech synthesizer, the first music synthesizer capable of recreating the grand piano and other orchestral instruments, and the first commercially marketed large-vocabulary speech recognition. He has written five national best-selling books, including New York Times best sellers The Singularity Is Near (2005) and How to Create a Mind (2012).

This year’s honorees also include Mike Lazaridis, founder of BlackBerry, which created the first smartphone; Mitch Mohr, founder of Celluphone; and Charles Tandy, legendary retailer. Also honored: the team that developed the MPEG video-file-compression technique — Leonardo Chiariglione, PhD, and Hiroshi Yasuda, PhD; and the team responsible for developing a breakthrough circuit that enabled high-power sound amplification with low distortion — McIntosh Labs founder Frank McIntosh and McIntosh president Gordon Gow.

Gary Shapiro, president and CEO of CTA, praised the inductees for their contributions to the growth of the $321 billion U.S. consumer technology industry.

Kurzweil: “A bright future”

Concluding the evening, Kurzweil gave a few predictions on where he sees the industry heading: “Technology is accelerating, it’s growing exponentially. Technology is also miniaturizing. We will have devices that are as powerful as our cell phones today that are the size of blood cells in the 2030s, and they will go through our bloodstream, keeping us healthy.

“Technology has been making life better. Over the next decade with biotechnology, we will get little devices that are robotic, intelligent and can augment our immune system. I think the future is going to be dramatically better.

“Despite the progress that I’ve alluded to — there’s still a lot of human suffering — it is the advance of these exponential technologies that is going to help us overcome age-old afflictions like disease, poverty, and environmental degradation. If we keep our focus on both the promise and the peril, we’ll have a very bright future.”

With the 2017 class, the CT Hall of Fame grows to 246 inventors, engineers, retailers, journalists, and entrepreneurs who conceived, promoted, and/or wrote about the innovative technologies, products and services that connect and improve the lives of consumers around the world. The Hall of Fame inductees have been selected by a group of media and industry professionals, who judge the nominations submitted by manufacturers, retailers and industry journalists.

Complete profiles of the honorees will be included in the forthcoming November issue of It Is Innovation (i3) magazine.