The “Watchsense” prototype uses a small depth camera attached to the arm, mimicking a depth camera on a smartwatch. It could make it easy to type, or in a music program, volume could be increased by simply raising a finger. (credit: Srinath Sridhar et al.)
If you wear a smartwatch, you know how limiting it is to type it on or otherwise operate it. Now European researchers have developed an input method that uses a depth camera (similar to the Kinect game controller) to track fingertip touch and location on the back of the hand or in mid-air, allowing for precision control.
The researchers have created a prototype called “WatchSense,” worn on the user’s arm. It captures the movements of the thumb and index finger on the back of the hand or in the space above it. It would also work with smartphones, smart TVs, and virtual-reality or augmented reality devices, explains Srinath Sridhar, a researcher in the Graphics, Vision and Video group at the Max Planck Institute for Informatics.
KurzweilAI has covered a variety of attempts to use depth cameras for controlling devices, but developers have been plagued with the lack of precise control with current camera devices and software.
The new software, based on machine learning, recognizes the exact positions of the thumb and index finger in the 3D image from the depth sensor, says Sridhar, identifying specific fingers and dealing with the unevenness of the back of the hand and the fact that fingers can occlude each other when they are moved.
A smartwatch (or other device) could have an embedded depth sensor on its side, aimed at the back of the hand and the space above it, allowing for easy typing and control. (credit: Srinath Sridhar et al.)
“The currently available depth sensors do not fit inside a smartwatch, but from the trend it’s clear that in the near future, smaller depth sensors will be integrated into smartwatches,” Sridhar says.
The researchers, which include Christian Theobalt, head of the Graphics, Vision and Video group at MPI, Anders Markussen and Sebastian Boring at the University of Copenhagen, and Antti Oulasvirta at Aalto University in Finland, will present WatchSense at the ACM CHI Conference on Human Factors in Computing Systems in Denver (May 6–11, 2017). Their open-access paper is also available.
Srinath Sridhar et al. | WatchSense: On- and Above-Skin Input Sensing through a Wearable Depth Sensor
Abstract of WatchSense: On- and Above-Skin Input Sensing through a Wearable Depth Sensor
This paper contributes a novel sensing approach to support on- and above-skin finger input for interaction on the move. WatchSense uses a depth sensor embedded in a wearable device to expand the input space to neighboring areas of skin and the space above it. Our approach addresses challenging camera-based tracking conditions, such as oblique viewing angles and occlusions. It can accurately detect fingertips, their locations, and whether they are touching the skin or hovering above it. It extends previous work that supported either mid-air or multitouch input by simultaneously supporting both. We demonstrate feasibility with a compact, wearable prototype attached to a user’s forearm (simulating an integrated depth sensor). Our prototype—which runs in real-time on consumer mobile devices—enables a 3D input space on the back of the hand. We evaluated the accuracy and robustness of the approach in a user study. We also show how WatchSense increases the expressiveness of input by interweaving mid-air and multitouch for several interactive applications.
Smart contact lens on mannequin eye (credit: UNIST)
Korean researchers have designed a “smart contact lens” that may one day allow patients with diabetes and glaucoma to self-monitor blood glucose levels and internal eye pressure.*
The study was conducted by researchers at Ulsan National Institute of Science and Technology (UNIST) and Kyungpook National University School of Medicine, both of South Korea.
Most previously reported contact lens sensors can only monitor a single analyte (such as glucose) at a time, and generally obstruct the field of vision of the subject.
The design is based on transparent, stretchable sensors that are deposited on commercially available soft-contact lenses.
Electrodes based on a hybrid graphene-silver nanowire material can measure glucose in tears. Internal eye pressure changes are measured by a sandwich structure whose electronic characteristics are modified by pressure.
Inductive coupling — batteries not required
Both of these readings are transmitted wirelessly using “inductive coupling” (similar to remote charging of batteries), so no connected power source, such as a battery, is required. This design also allows for 24-hour real-time monitoring by patients.
The researchers conducted in-vivo and in-vitro performance tests using a live rabbit and bovine eyeball.
The team expects that the research could also lead to developing biosensors capable of detecting and treating various other human diseases, or used as a component in other biomedical devices.
The study results were published in the March issue of the journal Nature Communications. The study was supported by the 2017 CooperVision Science and Technology (S&T) Awards Program.
* Diabetes is the most common cause of high blood sugar levels. Intraocular pressure is the largest risk factor for glaucoma, a leading cause of human blindness.
How the smart contact lens works
Schematic of the top portion of the wearable contact-lens sensor. Left: antenna. Insert: Glucose sensor, based on a field-effect transistor (FET), which consists of a graphene channel and graphene/silver nanowire for source/drain. Not shown: chromium/gold interconnect, epoxy layer, and lens (below). (credit: UNIST)
Real-time glucose sensing with graphene/silver hybrid nanostructures. For selective and sensitive detection of glucose, glucose oxidase (GOD) catalyzes oxidation of glucose to gluconic acid and reduction of water to hydrogen peroxide, which produces oxygen, protons and electrons. The concentration of charge carriers in the FET channel, and thus the drain current, increases at higher concentration of glucose. (credit: UNIST)
The FET sensor (right) is modeled as an electrical RLC resonant circuit, comprised of the resistance (R) of the graphene channel, the inductance (L) of the antenna coil made of the graphene-AgNW hybrid, and the capacitance (C) of graphene-AgNW hybrid S/D electrodes. Wireless operation is achieved by mutually coupling the sensor antenna (center) with an external reader antenna (left) at a resonant frequency of 4.1 GHz. (credit: UNIST)
Schematic of intraocular pressure monitoring. A layer of silicone elastomer was placed between the two inductive spirals made of graphene-AgNW hybrid electrodes in a sandwich structure. The contact lens sensor responds to raised intraocular pressure (ocular hypertension), which increases the corneal radius of curvature, which in turn increases both the capacitance by thinning the dielectric and the inductance by bi-axial lateral expansion of the spiral coils. As a result, ocular hypertension shifts the reflection spectra of the spiral antenna to a lower frequency. (credit: UNIST)
Abstract of Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics
Wearable contact lenses which can monitor physiological parameters have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, previously reported contact lens sensors can only monitor a single analyte at a time. Furthermore, such ocular contact lenses generally obstruct the field of vision of the subject. Here, we developed a multifunctional contact lens sensor that alleviates some of these limitations since it was developed on an actual ocular contact lens. It was also designed to monitor glucose within tears, as well as intraocular pressure using the resistance and capacitance of the electronic device. Furthermore, in-vivo and in-vitro tests using a live rabbit and bovine eyeball demonstrated its reliable operation. Our developed contact lens sensor can measure the glucose level in tear fluid and intraocular pressure simultaneously but yet independently based on different electrical responses.
Elias Kristensson and Andreas Ehn (credit: Kennet Ruona)
A research group at Lund University in Sweden has developed a video camera* that can record at a rate equivalent to five trillion images per second, or events as short as 0.2 trillionths of a second. This is far faster than has previously been possible (100,000 images per second).
The new super-fast camera can capture rapid processes in chemistry, physics, biology and biomedicine that so far have not been caught on film.
To illustrate the technology, the researchers have successfully filmed how light travels a distance corresponding to the thickness of paper. In reality, it only takes a picosecond, but the process has been slowed down by a trillion times.
Currently, high-speed cameras capture images one by one in a sequence. The new technology is based on an innovative algorithm, and instead captures several coded images in one picture. It then sorts them into a video sequence afterwards.
The method involves exposing what you are recording (for example a chemical reaction) to light in the form of laser flashes, where each light pulse is given a unique code. The object reflects the light flashes, which merge into the single photograph. They are subsequently separated by detecting the keys.
The camera is initially intended to be used by researchers who literally want to gain better insight into many of the extremely rapid processes that occur in nature. Many take place on a picosecond and femtosecond scale.
“This does not apply to all processes in nature, but quite a few, for example, explosions, plasma flashes, turbulent combustion, brain activity in animals and chemical reactions. We are now able to ‘film’ such extremely short processes”, says professor Elias Kristensson. “In the long term, the technology can also be used by industry and others.”
“Today, the only way to visualize such rapid events is to photograph still images of the process. You then have to attempt to repeat identical experiments to provide several still images which can later be edited into a movie. The problem with this approach is that it is highly unlikely that a process will be identical if you repeat the experiment”, he says.
The researchers are currently conducting research on combustion — an area known to be difficult and complicated to study. The ultimate purpose of this basic research is to make next-generation car engines, gas turbines, and boilers cleaner and more fuel-efficient. Combustion is controlled by a number of ultra-fast processes at the molecular level, which can now be captured.
For example, the researchers will study the chemistry of plasma discharges, the lifetime of quantum states in combustion environments and in biological tissue, as well as how chemical reactions are initiated.
The research has been published in the journal Light: Science and Applications. A German company has already developed a prototype of the technology, which should be available commercially in two years.
* The technology, named FRAME (Frequency Recognition Algorithm for Multiple Exposures), uses a camera with a flash, using “coded” light flashes, as a form of encryption. Every time a coded light flash hits the object — for example, a chemical reaction in a burning flame — the object emits an image signal (response) with the exact same coding. The following light flashes all have different codes, and the image signals are captured in one single photograph. These coded image signals are subsequently separated using an encryption key on a computer.
A high-resolution transmission electron microscope image of layered, crystalline tungsten oxide dihydrate, which acts as a better supercapacitor (similar to a battery) than plain tungsten oxide (without the water layer). The “stripes” are individual layers of atoms separated by atomically thin water layers; the gray area on the left is empty space. 6.9 Angstrom = 0.69 nanometer. (credit: James B. Mitchell et al./Chemistry of Materials)
Researchers at North Carolina State University have found that a material* that incorporates atomically thin layers of water can store more energy and deliver it much more quickly than the same material without the water.
The proof-of-concept finding could “ultimately lead to things like thinner batteries, faster storage for renewable-based power grids, or faster acceleration in electric vehicles,” according to Veronica Augustyn, an assistant professor of materials science and engineering at NC State and corresponding author of a paper in the journal Chemistry of Materials describing the work.
A basic goal of current energy-storage research is to combine the high energy-density (amount of energy stored) of batteries with the high power density (speed of charge/discharge) of capacitors. The new finding is a step in that direction — it could allow for an increased amount of energy to be stored per unit of volume, faster diffusion of ions through the material, and faster charge and discharge.
Crystallographic structures of tungsten oxide dihydrate (WO3.2H2O) and tungsten oxide (WO3). Dehydration of the layered hydrated phase (left) under heat treatment in air or in vacuum yields the anhydrous structure (right). (credit: James B. Mitchell et al./Chemistry of Materials)
In this research, the scientists compared two materials: a crystalline tungsten oxide and a layered, crystalline tungsten oxide dihydrate, which consists of crystalline tungsten oxide layers separated by atomically thin layers of water. When charging the two materials for 10 minutes, the researchers found that the regular tungsten oxide version stored more energy than the hydrate version. But when the charging period was only 12 seconds, the hydrate version surprisingly stored more energy than the regular material and stored energy more efficiently, wasting less energy as heat.
“Incorporating these solvent layers could be a new strategy for high-powered energy-storage devices that make use of layered materials,” Augustyn says. “We think the water layer acts as a pathway that facilitates the transfer of ions through the material. We are now moving forward with National Science Foundation-funded work on how to fine-tune this ‘interlayer,’ which will hopefully advance our understanding of these materials and get us closer to next-generation energy-storage devices.”
* The new material acts as a “pseudosupercapacitor” (between a battery and a supercapacitor, which is used in applications requiring many rapid charge/discharge cycles rather than long term compact energy storage, such as in cars, buses, and trains). The new material improves both energy density and power density.
Abstract of Transition from Battery to Pseudocapacitor Behavior via Structural Water in Tungsten Oxide
The kinetics of energy storage in transition metal oxides are usually limited by solid-state diffusion, and the strategy most often utilized to improve their rate capability is to reduce ion diffusion distances by utilizing nanostructured materials. Here, another strategy for improving the kinetics of layered transition metal oxides by the presence of structural water is proposed. To investigate this strategy, the electrochemical energy storage behavior of a model hydrated layered oxide, WO3·2H2O, is compared with that of anhydrous WO3 in an acidic electrolyte. It is found that the presence of structural water leads to a transition from battery-like behavior in the anhydrous WO3 to ideally pseudocapacitive behavior in WO3·2H2O. As a result, WO3·2H2O exhibits significantly improved capacity retention and energy efficiency for proton storage over WO3 at sweep rates as fast as 200 mV s–1, corresponding to charge/discharge times of just a few seconds. Importantly, the energy storage of WO3·2H2O at such rates is nearly 100% efficient, unlike in the case of anhydrous WO3. Pseudocapacitance in WO3·2H2O allows for high-mass loading electrodes (>3 mg cm–2) and high areal capacitances (>0.25 F cm–2 at 200 mV s–1) with simple slurry-cast electrodes. These results demonstrate a new approach for developing pseudocapacitance in layered transition metal oxides for high-power energy storage, as well as the importance of energy efficiency as a metric of performance of pseudocapacitive materials.
Bill Kochevar, who was paralyzed below his shoulders in a bicycling accident eight years ago, is the first person with quadriplegia to have arm and hand movements restored without robot help (credit: Case Western Reserve University/Cleveland FES Center)
A research team led by Case Western Reserve University has developed the first implanted brain-recording and muscle-stimulating system to restore arm and hand movements for quadriplegic patients.*
In a proof-of-concept experiment, the system included a brain-computer interface with recording electrodes implanted under his skull and a functional electrical stimulation (FES) system that activated his arm and hand — reconnecting his brain to paralyzed muscles.
The research was part of the ongoing BrainGate2 pilot clinical trial being conducted by a consortium of academic and other institutions to assess the safety and feasibility of the implanted brain-computer interface (BCI) system in people with paralysis. Previous Braingate designs required a robot arm.
In 2012 research, Jan Scheuermann, who has quadriplegia, was able to feed herself using a brain-machine interface and a computer-driven robot arm (credit: UPMC)
Kochevar’s eight years of muscle atrophy first required rehabilitation. The researchers exercised Kochevar’s arm and hand with cyclical electrical stimulation patterns. Over 45 weeks, his strength, range of motion. and endurance improved. As he practiced movements, the researchers adjusted stimulation patterns to further his abilities.
To prepare him to use his arm again, Kochevar learned how to use his own brain signals to move a virtual-reality arm on a computer screen. The team then implanted the FES systems’ 36 electrodes that animate muscles in the upper and lower arm, allowing him to move the actual arm.
Kochevar can now make each joint in his right arm move individually. Or, just by thinking about a task such as feeding himself or getting a drink, the muscles are activated in a coordinated fashion.
Neural activity (generated when Kochevar imagines movement of his arm and hand) is recorded from two 96-channel microelectrode arrays implanted in the motor cortex, on the surface of the brain. The implanted brain-computer interface translates the recorded brain signals into specific command signals that determine the amount of stimulation to be applied to each functional electrical stimulation (FES) electrode in the hand, wrist, arm, elbow and shoulder, and to a mobile arm support. (credit: A Bolu Ajiboye et al./The Lancet)
“Our research is at an early stage, but we believe that this neuro-prosthesis could offer individuals with paralysis the possibility of regaining arm and hand functions to perform day-to-day activities, offering them greater independence,” said lead author Dr Bolu Ajiboye, Case Western Reserve University. “So far, it has helped a man with tetraplegia to reach and grasp, meaning he could feed himself and drink. With further development, we believe the technology could give more accurate control, allowing a wider range of actions, which could begin to transform the lives of people living with paralysis.”
Work is underway to make the brain implant wireless, and the investigators are improving decoding and stimulation patterns needed to make movements more precise. Fully implantable FES systems have already been developed and are also being tested in separate clinical research.
A study of the work was published in the The Lancet March 28, 2017.
Writing in a linked Comment to The Lancet, Steve Perlmutter, M.D., University of Washington, said: “The goal is futuristic: a paralysed individual thinks about moving her arm as if her brain and muscles were not disconnected, and implanted technology seamlessly executes the desired movement… This study is groundbreaking as the first report of a person executing functional, multi-joint movements of a paralysed limb with a motor neuro-prosthesis. However, this treatment is not nearly ready for use outside the lab. The movements were rough and slow and required continuous visual feedback, as is the case for most available brain-machine interfaces, and had restricted range due to the use of a motorised device to assist shoulder movements… Thus, the study is a proof-of-principle demonstration of what is possible, rather than a fundamental advance in neuro-prosthetic concepts or technology. But it is an exciting demonstration nonetheless, and the future of motor neuro-prosthetics to overcome paralysis is brighter.”
* The study was funded by the US National Institutes of Health and the US Department of Veterans Affairs. It was conducted by scientists from Case Western Reserve University, Department of Veterans Affairs Medical Center, University Hospitals Cleveland Medical Center, MetroHealth Medical Center, Brown University, Massachusetts General Hospital, Harvard Medical School, Wyss Center for Bio and Neuroengineering. The investigational BrainGate technology was initially developed in the Brown University laboratory of John Donoghue, now the founding director of the Wyss Center for Bio and Neuroengineering in Geneva, Switzerland. The implanted recording electrodes are known as the Utah array, originally designed by Richard Normann, Emeritus Distinguished Professor of Bioengineering at the University of Utah. The report in Lancet is the result of a long-running collaboration between Kirsch, Ajiboye and the multi-institutional BrainGate consortium. Leigh Hochberg, a neurologist and neuroengineer at Massachusetts General Hospital, Brown University and the VA RR&D Center for Neurorestoration and Neurotechnology in Providence, Rhode Island, directs the pilot clinical trial of the BrainGate system and is a study co-author.
Case | Man with quadriplegia employs injury bridging technologies to move again – just by thinking
Abstract of Restoration of reaching and grasping movements through brain-controlled muscle stimulation in a person with tetraplegia: a proof-of-concept demonstration
Background: People with chronic tetraplegia, due to high-cervical spinal cord injury, can regain limb movements through coordinated electrical stimulation of peripheral muscles and nerves, known as functional electrical stimulation (FES). Users typically command FES systems through other preserved, but unrelated and limited in number, volitional movements (eg, facial muscle activity, head movements, shoulder shrugs). We report the findings of an individual with traumatic high-cervical spinal cord injury who coordinated reaching and grasping movements using his own paralysed arm and hand, reanimated through implanted FES, and commanded using his own cortical signals through an intracortical brain–computer interface (iBCI).
Methods: We recruited a participant into the BrainGate2 clinical trial, an ongoing study that obtains safety information regarding an intracortical neural interface device, and investigates the feasibility of people with tetraplegia controlling assistive devices using their cortical signals. Surgical procedures were performed at University Hospitals Cleveland Medical Center (Cleveland, OH, USA). Study procedures and data analyses were performed at Case Western Reserve University (Cleveland, OH, USA) and the US Department of Veterans Affairs, Louis Stokes Cleveland Veterans Affairs Medical Center (Cleveland, OH, USA). The study participant was a 53-year-old man with a spinal cord injury (cervical level 4, American Spinal Injury Association Impairment Scale category A). He received two intracortical microelectrode arrays in the hand area of his motor cortex, and 4 months and 9 months later received a total of 36 implanted percutaneous electrodes in his right upper and lower arm to electrically stimulate his hand, elbow, and shoulder muscles. The participant used a motorised mobile arm support for gravitational assistance and to provide humeral abduction and adduction under cortical control. We assessed the participant’s ability to cortically command his paralysed arm to perform simple single-joint arm and hand movements and functionally meaningful multi-joint movements. We compared iBCI control of his paralysed arm with that of a virtual three-dimensional arm. This study is registered with ClinicalTrials.gov, number NCT00912041.
Findings: The intracortical implant occurred on Dec 1, 2014, and we are continuing to study the participant. The last session included in this report was Nov 7, 2016. The point-to-point target acquisition sessions began on Oct 8, 2015 (311 days after implant). The participant successfully cortically commanded single-joint and coordinated multi-joint arm movements for point-to-point target acquisitions (80–100% accuracy), using first a virtual arm and second his own arm animated by FES. Using his paralysed arm, the participant volitionally performed self-paced reaches to drink a mug of coffee (successfully completing 11 of 12 attempts within a single session 463 days after implant) and feed himself (717 days after implant).
Interpretation: To our knowledge, this is the first report of a combined implanted FES+iBCI neuroprosthesis for restoring both reaching and grasping movements to people with chronic tetraplegia due to spinal cord injury, and represents a major advance, with a clear translational path, for clinically viable neuroprostheses for restoration of reaching and grasping after paralysis.
Funding: National Institutes of Health, Department of Veterans Affairs.
Overview of the entire chip. AC = Accumulator, internal buffer; PC = Program Counter, points at the next instruction to be executed; IR = Instruction Register, used to buffer data- and instruction-bits received from the external memory; CU = Control Unit, orchestrates the other units according to the instruction to be executed; OR = Output Register, memory used to buffer output-data; ALU = Arithmetic Logic Unit, does the actual calculations. (credit: TU Wien)
Researchers at Vienna University of Technology (known as TU Wien) in Vienna, Austria, have developed the world’s first two-dimensional microprocessor — the most complex 2D circuitry so far. Microprocessors based on atomically thin 2D materials promise to one day replace traditional microprocessors as well as open up new applications in flexible electronics.
Consisting of 115 transistors, the microprocessor can run, simple user-defined programs stored in an external memory, perform logical operations, and communicate with peripheral devices. The microprocessor is based on molybdenum disulphide (MoS2), a three-atoms-thick 2D semiconductor transistor layer consisting of molybdenum and sulphur atoms, with a surface area of around 0.6 square millimeters.
Schematic drawing of an inverter (“NOT” logic) circuit (top) and an individual MoS2 transistor (bottom) (credit: Stefan Wachter et al./Nature Communications)
For demonstration purposes, the microprocessor is currently a 1-bit design, but it’s scalable to a multi-bit design using industrial fabrication methods, says Thomas Mueller, PhD., team leader and senior author of an open-access paper on the research published in Nature Communications.*
New sensors and flexible displays
Two-dimensional materials are flexible, making future 2D microprocessors and other integrated circuits ideal for uses such as medical sensors and flexible displays. They promise to extend computing to the atomic level, as silicon reaches its physical limits.
However, to date, it has only been possible to produce individual 2D digital components using a few transistors. The first 2D MoS2 transistor with a working 1-nanometer (nm) gate was created in October 2016 by a team led by Lawrence Berkeley National Laboratory (Berkeley Lab) scientists, as KurzweilAI reported.
Mueller said much more powerful and complex circuits with thousands or even millions of transistors will be required for this technology to have practical applications. Reproducibility continues to be one of the biggest challenges currently being faced within this field of research, along with the yield in the production of the transistors used, he explained.
* “We also gave careful consideration to the dimensions of the individual transistors,” explains Mueller. “The exact relationships between the transistor geometries within a basic circuit component are a critical factor in being able to create and cascade more complex units. … the major challenge that we faced during device fabrication is yield. Although the yield for subunits was high (for example, ∼80% of ALUs were fully functional), the sheer complexity of the full system, together with the non-fault tolerant design, resulted in an overall yield of only a few per cent of fully functional devices. Imperfections of the MoS2 film, mainly caused by the transfer from the growth to the target substrate, were identified as main source for device failure. However, as no metal catalyst is required for the synthesis of TMD films, direct growth on the target substrate is a promising route to improve yield.
Abstract of A microprocessor based on a two-dimensional semiconductor
The advent of microcomputers in the 1970s has dramatically changed our society. Since then, microprocessors have been made almost exclusively from silicon, but the ever-increasing demand for higher integration density and speed, lower power consumption and better integrability with everyday goods has prompted the search for alternatives. Germanium and III–V compound semiconductors are being considered promising candidates for future high-performance processor generations and chips based on thin-film plastic technology or carbon nanotubes could allow for embedding electronic intelligence into arbitrary objects for the Internet-of-Things. Here, we present a 1-bit implementation of a microprocessor using a two-dimensional semiconductor—molybdenum disulfide. The device can execute user-defined programs stored in an external memory, perform logical operations and communicate with its periphery. Our 1-bit design is readily scalable to multi-bit data. The device consists of 115 transistors and constitutes the most complex circuitry so far made from a two-dimensional material.
Regina Dugan, PhD, Facebook VP of Engineering, Building8, revealed today (April 19, 2017) at Facebook F8 conference 2017 a plan to develop a non-invasive brain-computer interface that will let you type at 100 wpm — by decoding neural activity devoted to speech.
Dugan previously headed Google’s Advanced Technology and Projects Group, and before that, was Director of the Defense Advanced Research Projects Agency (DARPA).
She explained in a Facebook post that over the next two years, her team will be building systems that demonstrate “a non-invasive system that could one day become a speech prosthetic for people with communication disorders or a new means for input to AR [augmented reality].”
Dugan said that “even something as simple as a ‘yes/no’ brain click … would be transformative.” That simple level has been achieved by using functional near-infrared spectroscopy (fNIRS) to measure changes in blood oxygen levels in the frontal lobes of the brain, as KurzweilAI recently reported. (Near-infrared light can penetrate the skull and partially into the brain.)
Dugan agrees that optical imaging is the best place to start, but her Building8 team team plans to go way beyond that research — sampling hundreds of times per second and precise to millimeters. The research team began working on the brain-typing project six months ago and she now has a team of more than 60 researchers who specialize in optical neural imaging systems that push the limits of spatial resolution and machine-learning methods for decoding speech and language.
The research is headed by Mark Chevillet, previously an adjunct professor of neuroscience at Johns Hopkins University.
Besides replacing smartphones, the system would be a powerful speech prosthetic, she noted — allowing paralyzed patients to “speak” at normal speed.
Dugan revealed one specific method the researchers are currently working on to achieve that: a ballistic filter for creating quasi ballistic photons (avoiding diffusion) — creating a narrow beam for precise targeting — combined with a new method of detecting blood-oxygen levels.
Neural activity (in green) and associated blood oxygenation level dependent (BOLD) waveform (credit: Facebook)
Dugan also described a system that may one day allow hearing-impaired people to hear directly via vibrotactile sensors embedded in the skin. “In the 19th century, Braille taught us that we could interpret small bumps on a surface as language,” she said. “Since then, many techniques have emerged that illustrate our brain’s ability to reconstruct language from components.” Today, she demonstrated “an artificial cochlea of sorts and the beginnings of a new a ‘haptic vocabulary’.”
A Facebook engineer with acoustic sensors implanted in her arm has learned to feel the acoustic shapes corresponding to words (credit: Facebook)
To detect DNA methylation changes (for cancer early warning), researchers punched a tiny hole (pore) in a flat sheet of graphene (or other 2D material). They then submerged the material in a salt solution and applied an electrical voltage to force the DNA molecule through the pore. A dip in the ionic current (black A) identified a methyl group (green) is passing through, but a dip in the electrical current (blue A) could detect smaller DNA changes. (credit: Beckman Institute Nanoelectronics and Nanomaterials Group)
University of Illinois researchers have designed a high-resolution method to detect, count, and map tiny additions to DNA called methylations*, which can be a early-warning sign of cancer.
The method threads DNA strands through a tiny hole, called a nanopore, in an atomically thin sheet of graphene or other 2D material** with an electrical current running through it.
There have been previous attempts to use nanopores to detect methylation (by measuring ionic changes), which have been limited in resolution (how precise the measurement is). The Illinois group instead applied a current directly to the conductive sheet surrounding the pore. Working with Klaus Schulten, a professor of physics at Illinois, Leburton’s group at Illinois’ Beckman Institute for Advanced Science and Technology, they used advanced computer simulations to test applying current to different flat materials, such as graphene and molybdenum disulfide, while methylated DNA was threaded through.
“Our simulations indicate that measuring the current through the membrane instead of just the solution around it is much more precise,” Leburton said. “If you have two methylations close together, even only 10 base pairs away, you continue to see two dips and no overlapping. We also can map where they are on the strand, so we can see how many there are and where they are.”
Leburton’s group is now working with collaborators to improve DNA threading, to cut down on noise in the electrical signal, and to perform experiments to verify their simulations.
The study was published in 2D Materials and Applications, a new open-access journal from Nature Press. Grants from Oxford Nanopore Technology, the Beckman Institute, the National Institutes of Health, and the National Science Foundation supported this work.
* Methylation refers to the addition of a methyl group, which contains one carbon atom bonded to three hydrogen atoms, with the formula CH3.
** Such as graphene and molybdenum disulfide (MoS2).
NewsIllinois | Nanopore detection of DNA methylation
Colorized scanning electron microscopy (SEM) image of a neuron (orange) interfaced with the nanowire array (green). (credit: Integrated Electronics and Biointerfaces Laboratory, UC San Diego)
A research team* led by engineers at the University of California San Diego has developed nanowire technology that can non-destructively record the electrical activity of neurons in fine detail.
The new technology, published April 10, 2017 in Nano Letters, could one day serve as a platform to screen drugs for neurological diseases and help researchers better understand how single cells communicate in large neuronal networks.
A brain implant
The researchers currently create the neurons in vitro (in the lab) from human induced pluripotent stem cells. But the ultimate goal is to “translate this technology to a device that can be implanted in the brain,” said Shadi Dayeh, PhD, an electrical engineering professor at the UC San Diego Jacobs School of Engineering and the team’s lead investigator.
The technology can uncover details about a neuron’s health, activity, and response to drugs by measuring ion channel currents and changes in the neuron’s intracellular voltage (generated by the difference in ion concentration between the inside and outside of the cell).
The researchers cite five key innovations of this new nanowire-to-neuron technology:
It’s nondestructive (unlike current methods, which can break the cell membrane and eventually kill the cell).
It can simultaneously measure voltage changes in multiple neurons and in the future could bridge or repair neurons.**
It can isolate the electrical signal measured by each individual nanowire, with high sensitivity and high signal-to-noise ratios. Existing techniques are not scalable to 2D and 3D tissue-like structures cultured in vitro, according to Dayeh.
It can also be used for heart-on-chip drug screening for cardiac diseases.
The nanowires can integrate with CMOS (computer chip) electronics.***
A colorized scanning electron microscopy (SEM) image of the silicon-nickel-titanium nanowire array. The nanowires are densely packed on a small chip that is compatible with CMOS chips. The nanowires poke inside cells without damaging them, and are sensitive enough to measure small voltage changes (millivolt or less). (credit: Integrated Electronics and Biointerfaces Laboratory, UC San Diego)
* The project was a collaborative effort between researchers at UC San Diego, the Conrad Prebys Center for Chemical Genomics at the Sanford Burnham Medical Research Institute, Nanyang Technological University in Singapore, and Sandia National Laboratories. This work was supported by the National Science Foundation, the Center for Brain Activity Mapping at UC San Diego, Qualcomm Institute at UC San Diego, Los Alamos National Laboratory, the National Institutes of Health, the March of Dimes, and UC San Diego Frontiers of Innovation Scholar Program. Dayeh’s laboratory holds several pending patent applications for this technology.
** “Highly parallel in vitro drug screening experiments can be performed using the human-relevant iPSC cell line and without the need of the laborious patch-clamp … which is destructive and unscalable to large neuronal densities and to long recording times, or planar multielectrode arrays that enable long-term recordings but can just measure extracellular potentials and lack the sensitivity to subthreshold potentials. … In vivo targeted modulation of individual neural circuits or even single cells within a network becomes possible, and implications for bridging or repairing networks in neurologically affected regions become within reach.” — Ren Liu et al./Nanoletters
*** The researchers invented a new wafer bonding approach to fuse the silicon nanowires to the nickel electrodes. Their approach involved a process called silicidation, which is a reaction that binds two solids (silicon and another metal) together without melting either material. This process prevents the nickel electrodes from liquidizing, spreading out and shorting adjacent electrode leads. Silicidation is usually used to make contacts to transistors, but this is the first time it is being used to do patterned wafer bonding, Dayeh said. “And since this process is used in semiconductor device fabrication, we can integrate versions of these nanowires with CMOS electronics, but it still needs further optimization for brain-on-chip drug screening.”
Abstract of High Density Individually Addressable Nanowire Arrays Record Intracellular Activity from Primary Rodent and Human Stem Cell Derived Neurons
We report a new hybrid integration scheme that offers for the first time a nanowire-on-lead approach, which enables independent electrical addressability, is scalable, and has superior spatial resolution in vertical nanowire arrays. The fabrication of these nanowire arrays is demonstrated to be scalable down to submicrometer site-to-site spacing and can be combined with standard integrated circuit fabrication technologies. We utilize these arrays to perform electrophysiological recordings from mouse and rat primary neurons and human induced pluripotent stem cell (hiPSC)-derived neurons, which revealed high signal-to-noise ratios and sensitivity to subthreshold postsynaptic potentials (PSPs). We measured electrical activity from rodent neurons from 8 days in vitro (DIV) to 14 DIV and from hiPSC-derived neurons at 6 weeks in vitro post culture with signal amplitudes up to 99 mV. Overall, our platform paves the way for longitudinal electrophysiological experiments on synaptic activity in human iPSC based disease models of neuronal networks, critical for understanding the mechanisms of neurological diseases and for developing drugs to treat them.
(a) High-resolution, high-speed quantum-dot shortwave infrared imaging was used to image the blood-vessel network of a mouse glioblastoma brain tumor (b) at 60 frames per second and to compare it to the blood-vessel network (c) in the opposite (healthy) brain hemisphere. (credit: Oliver T. Bruns et al./ Nature Biomedical Engineering)
A team of researchers has created bright, glowing nanoparticles called quantum dots that can be injected into the body, where they emit light at shortwave infrared (SWIR) wavelengths that pass through the skin — allowing internal body structures such as fine networks of blood vessels to be imaged in vivo (in live animals) on high-speed video cameras for the first time.
The new findings are described in an open-access paper in the journal Nature Biomedical Engineering by Moungi Bawendi, MIT Lester Wolf Professor of Chemistry, and 22 other researchers.*
Near-infrared imaging for research on biological tissues, with wavelengths between 700 and 900 nanometers (billionths of a meter), is widely used because these wavelengths can shine through tissues. But wavelengths of around 1,000 to 2,000 nanometers have the potential to provide even better results, because body tissues are more transparent at that longer light-wavelength range.
The problem in doing that has been the lack of light-emitting materials that could work at those longer wavelengths and that were bright enough to be easily detected through the surrounding skin and muscle tissues.
Live internal images of awake, moving mice
Contact-free video monitoring of heart and respiratory rate in mice using quantum dots covered with biocompatible lipid molecules and injected into mice. A newly developed camera is highly sensitive to shortwave infrared light. (credit: Oliver T. Bruns et al./ Nature Biomedical Engineering)
Now the team has succeeded in making particles that are “orders of magnitude better than previous materials, and that allow unprecedented detail in biological imaging,” says lead author Oliver T. Bruns, an MIT research scientist. The synthesis of these new particles was initially described in an open-access paper by researchers from the Bawendi group in Nature Communications last year.
These new light-emitting nanoparticles are the first that are bright enough to allow imaging of internal organs in mice that are awake and moving, as opposed to previous methods that required them to be anesthetized, Bruns says. Initial applications would be for preclinical research in animals, as the compounds contain some materials, such as indium arsenide, that are unlikely to be approved for use in humans. The researchers are also working on developing versions that would be safer for humans.
Quantum dots, made of semiconductor materials, emit light whose frequency can be precisely tuned by controlling the exact size and composition of the particles. These were functionalized via three distinct surface coatings that tailor the physiological properties for specific shortwave infrared imaging applications. The quantum dots are so bright, their emissions can be captured with very short exposure times. That makes it possible to produce not just single images but video that captures details of motion, such as the flow of blood — making it possible to distinguish between veins and arteries. (credit: Oliver T. Bruns et al./ Nature Biomedical Engineering)
Not only can the new method determine the direction of blood flow, Bruns says, it is detailed enough to track individual blood cells within that flow. “We can track the flow in each and every capillary, at super-high speed,” he says. “We can get a quantitative measure of flow, and we can do such flow measurements at very high resolution, over large areas.”
Such imaging could potentially be used, for example, to study how the blood flow pattern in a tumor changes as the tumor develops, which might lead to new ways of monitoring disease progression or responsiveness to a drug treatment. “This could give a good indication of how treatments are working that was not possible before,” he says.
* The team included members from Harvard Medical School, the Harvard T.H. Chan School of Public Health, Raytheon Vision Systems, and University Medical Center in Hamburg, Germany. The work was supported by the National Institutes of Health, the National Cancer Institute, the National Foundation for Cancer Research, the Warshaw Institute for Pancreatic Cancer Research, the Massachusetts General Hospital Executive Committee on Research, the Army Research Office through the Institute for Soldier Nanotechnologies at MIT, the U.S. Department of Defense, and the National Science Foundation.