The Kynix Blog

 A team of Harvard University researchers with expertise in 3D printing, mechanical engineering, and microfluidics has demonstrated the first autonomous, untethered, entirely soft robot. This small, 3D-printed robot—nicknamed the octobot—could pave the way for a new generation of completely soft, autonomous machines.Soft robotics could revolutionize how humans interact with machines. But researchers have struggled to build entirely compliant robots. Electric power and control systems—such as batteries and circuit boards—are rigid and until now soft-bodied robots have been either tethered to an off-board system or rigged with hard components.Robert Wood, the Charles River Professor of Engineering and Applied Sciences and Jennifer A. Lewis, the Hansjorg Wyss Professor of Biologically Inspired Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) led the research. Lewis and Wood are also core faculty members of the Wyss Institute for Biologically Inspired Engineering at Harvard University."One long-standing vision for the field of soft robotics has been to create robots that are entirely soft, but the struggle has always been in replacing rigid components like batteries and electronic controls with analogous soft systems and then putting it all together," said Wood. "This research demonstrates that we can easily manufacture the key components of a simple, entirely soft robot, which lays the foundation for more complex designs.""Through our hybrid assembly approach, we were able to 3D print each of the functional components required within the soft robot body, including the fuel storage, power and actuation, in a rapid manner," said Lewis. "The octobot is a simple embodiment designed to demonstrate our integrated design and additive fabrication strategy for embedding autonomous functionality."Octopuses have long been a source of inspiration in soft robotics. These curious creatures can perform incredible feats of strength and dexterity with no internal skeleton.Harvard's octobot is pneumatic-based, i.e., it is powered by gas under pressure. A reaction inside the bot transforms a small amount of liquid fuel into a large amount of gas, which flows into the octobot's arms and inflates them like a balloon."Fuel sources for soft robots have always relied on some type of rigid components," said Michael Wehner, a postdoctoral fellow in the Wood lab and co-first author of the paper. "The wonderful thing about hydrogen peroxide is that a simple reaction between the chemical and a catalyst—in this case platinum—allows us to replace rigid power sources."To control the reaction, the team used a microfluidic logic circuit based on pioneering work by co-author and chemist George Whitesides, the Woodford L. and Ann A. Flowers University Professor and core faculty member of the Wyss. The circuit, a soft analog of a simple electronic oscillator, controls when hydrogen peroxide decomposes to gas in the octobot."The entire system is simple to fabricate, by combining three fabrication methods—soft lithography, molding and 3D printing—we can quickly manufacture these devices," said Ryan Truby, a graduate student in the Lewis lab and co-first author of the paper.The simplicity of the assembly process paves the way for more complex designs. Next, the Harvard team hopes to design an octobot that can crawl, swim and interact with its environment."This research is a proof of concept," Truby said. "We hope that our approach for creating autonomous soft robots inspires roboticists, material scientists and researchers focused on advanced manufacturing."Reference:DS1260-50DS90340I-PCXM4Z28-BR00SH1 

Healthcare practitioners may one day be able to physically screen for breast cancer using pressure-sensitive rubber gloves to detect tumors, owing to a transparent, bendable and sensitive pressure sensor newly developed by Japanese and American teams.Conventional pressure sensors are flexible enough to fit to soft surfaces such as human skin, but they cannot measure pressure changes accurately once they are twisted or wrinkled, making them unsuitable for use on complex and moving surfaces. Additionally, it is difficult to reduce them below 100 micrometers thickness because of limitations in current production methods.To address these issues, an international team of researchers led by Dr. Sungwon Lee and Professor Takao Someya of the University of Tokyo's Graduate School of Engineering has developed a nanofiber-type pressure sensor that can measure pressure distribution of rounded surfaces such as an inflated balloon and maintain its sensing accuracy even when bent over a radius of 80 micrometers, equivalent to just twice the width of a human hair. The sensor is roughly 8 micrometers thick and can measure the pressure in 144 locations at once.The device demonstrated in this study consists of organic transistors, electronic switches made from carbon and oxygen based organic materials, and a pressure sensitive nanofiber structure. Carbon nanotubes and graphene were added to an elastic polymer to create nanofibers with a diameter of 300 to 700 nanometers, which were then entangled with each other to form a transparent, thin and light porous structure."We've also tested the performance of our pressure sensor with an artificial blood vessel and found that it could detect small pressure changes and speed of pressure propagation," says Lee. He continues, "Flexible electronics have great potential for implantable and wearable devices. I realized that many groups are developing flexible sensors that can measure pressure but none of them are suitable for measuring real objects since they are sensitive to distortion. That was my main motivation and I think we have proposed an effective solution to this problem."Reference:13C5000PA4K19C050PA4KMLH100PGM01B  

The world's smallest diode, the size of a single molecule, has been developed collaboratively by U.S. and Israeli researchers from the University of Georgia and Ben-Gurion University of the Negev (BGU).     "Creating and characterizing the world's smallest diode is a significant milestone in the development of molecular electronic devices," explains Dr. Yoni Dubi, a researcher in the BGU Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology. "It gives us new insights into the electronic transport mechanism." Continuous demand for more computing power is pushing the limitations of present day methods. This need is driving researchers to look for molecules with interesting properties and find ways to establish reliable contacts between molecular components and bulk materials in an electrode, in order to mimic conventional electronic elements at the molecular scale. An example for such an element is the nanoscale diode (or molecular rectifier), which operates like a valve to facilitate electronic current flow in one direction. A collection of these nanoscale diodes, or molecules, has properties that resemble traditional electronic components such as a wire, transistor or rectifier. The emerging field of single molecule electronics may provide a way to overcome Moore's Law— the observation that over the history of computing hardware the number of transistors in a dense integrated circuit has doubled approximately every two years - beyond the limits of conventional silicon integrated circuits. Prof. Bingqian Xu's group at the College of Engineering at the University of Georgia took a single DNA molecule constructed from 11 base pairs and connected it to an electronic circuit only a few nanometers in size. When they measured the current through the molecule, it did not show any special behavior. However, when layers of a molecule called "coralyne," were inserted (or intercalated) between layers of DNA, the behavior of the circuit changed drastically. The current jumped to 15 times larger negative vs. positive voltages—a necessary feature for a nano diode. "In summary, we have constructed a molecular rectifier by intercalating specific, small molecules into designed DNA strands," explains Prof. Xu. Dr. Dubi and his student, Elinor Zerah-Harush, constructed a theoretical model of the DNA molecule inside the electric circuit to better understand the results of the experiment. "The model allowed us to identify the source of the diode-like feature, which originates from breaking spatial symmetry inside the DNA molecule after coralyne is inserted." Reference: CLCS145V0-G PACDN004SR  SLVU2.8.TCT    

Disney Research has demonstrated that battery-free, radio frequency identification (RFID) tags can be used to cheaply and unobtrusively determine how people use and interact with daily objects, enabling new types of interactive play, smart homes and work environments, and new methods for studying consumer shopping habits.RFID tags are designed to simply report an identifying code when energized by an RFID reader, but a Disney Research team directed by Dr. Alanson Sample showed that the radio frequency signals transmitted by these tags provide a unique RF signature which can be used to determine whether a tagged item was being touched or moved.The researchers found that with their system, called IDSense, they could simultaneously track 20 objects in a room and infer four classes of movements with 93 percent accuracy. They will present their findings at CHI 2015, the Association for Computing Machinery's annual Conference on Human Factors in Computing Systems, April 18-23 in Seoul, South Korea."An effective means of identifying people's activities in their homes, schools and workplaces has the potential to enable a wide number of human-computer interaction applications," Sample said. "Whether it's reading a book to a child, cooking a meal or fixing a bicycle, the objects that we use both define and reflect the activities we do in our daily lives."One common approach has been to attach wireless sensors to objects, he noted, but the size of the sensors, their relatively high cost and the need for battery replacement has limited their applications. RFID tags, by contrast, are commercially available technology, cheap and easy to apply to a wide range of everyday objects.Sample, along with Disney Research's Can Ye and Hanchuan Li, a Ph.D. student in computer science and engineering at the University of Washington, employed ultra high frequency (UHF) RFID tags, which can return signals up to 10 meters. They found that by observing changes in the signals emitted by the tags - received signal strength indicator (RSSI), radio frequency (RF) phase and Doppler shift - they were able to make inferences about the object to which the tag was attached.RSSI is a measurement of signal power received at the receiver and is predominantly affected by the distance between the tag and the reader. RF phase - the angle between the carrier signal emitted by the RFID reader and the return signal from the tag - is sensitive to small changes in distance, while the Doppler shift is a radio frequency shift caused by the speed of a moving object."The key insight is that these low-level channel parameters represent a snap shot of the RF environment that is unique to each tag," Sample said. "By measuring changes in these signals over time we can infer how someone is interacting with the object."By using machine learning algorithms, which identify patterns in data, the researchers were able to associate changes in these communication parameters with certain states of the object, such as whether the object was still, whether the object was being rotated or moved, or whether the tag was covered, such as when the object was being held.The Disney team demonstrated how IDSense could be used by applying RFID tags to stuffed toys, enabling an interactive storytelling game in which rocking or petting a toy lion triggered actions by digital characters. In another demonstration, they used IDSense to monitor 10 commonly used items, such as a drinking glass, a milk container and a cereal box, to show how information about daily living activities could be gathered, and they showed that the tags could be used for studying the browsing behavior of consumers in a retail store.Reference:PCF7935AARI-TRP-IR2B-30RI-TRP-WR2B-30 

Use of copper as a fluorescent material allows for the manufacture of inexpensive and environmentally compatible organic light-emitting diodes (OLEDs). Thermally activated delayed fuorescence (TADF) ensures high light yield. Scientists of Karlsruhe Institute of Technology (KIT), CYNORA, and the University of St Andrews have now measured the underlying quantum mechanics phenomenon of intersystem crossing in a copper complex. The results of this fundamental work are reported in the Science Advances journal and contribute to enhancing the energy efficiency of OLEDs.  Organic light-emitting diodes are deemed tomorrow's source of light. They homogeneously emit light in all observation directions and produce brilliant colors and high contrasts. As it is also possible to manufacture transparent and flexible OLEDs, new application and design options result, such as flat light sources on window panes or displays that can be rolled up. OLEDs consist of ultra-thin layers of organic materials, which serve as emitter and are located between two electrodes. When voltage is applied, electrons from the cathode and holes (positive charges) from the anode are injected into the emitter, where they form electron-hole pairs. These so-called excitons are quasiparticles in the excited state. When they decay into their initial state again, they release energy.Excitons may assume two different states: Singlet excitons decay immediately and emit light, whereas triplet excitons release their energy in the form of heat. Usually, 25 percent singlets and 75 percent triplets are encountered in OLEDs. To enhance energy efficiency of an OLED, also triplet excitons have to be used to generate light. In conventional light-emitting diodes heavy metals, such as iridium and platinum, are added for this purpose. But these materials are expensive, have a limited availability, and require complex OLED production methods.It is cheaper and environmentally more compatible to use copper complexes as emitter materials. Thermally activated delayed fluorescence (TADF) ensures high light yields and, hence, high efficiency: Triplet excitons are transformed into singlet excitons which then emit photons. TADF is based on the quantum mechanics phenomenon of intersystem crossing (ISC), a transition from one electronic excitation state to another one of changed multiplicity, i.e. from singlet to triplet or vice versa. In organic molecules, this process is determined by spin-orbit coupling. This is the interaction of the orbital angular momentum of an electron in an atom with the spin of the electron. In this way, all excitons, triplets and singlets, can be used for the generation of light. With TADF, copper luminescent material reaches an efficiency of 100 percent.Stefan Bräse and Larissa Bergmann of KIT's Institute of Organic Chemistry (IOC), in cooperation with researchers of the OLED technology company CYNORA and the University of St Andrews, United Kingdom, for the first time measured the speed of intersystem crossing in a highly luminescent, thermally activated delayed fluorescence copper(I) complex in the solid state. The results are reported in the Science Advances journal. The scientists determined a time constant of intersystem crossing from singlet to triplet of 27 picoseconds (27 trillionths of a second). The reverse process – reverse intersystem crossing – from triplet to singlet is slower and leads to a TADF lasting for an average of 11.5 microseconds. These measurements improve the understanding of mechanisms leading to TADF and facilitate the specific development of TADF materials for energy-efficient OLEDs.Reference:KY59-0202NYKY59-S101D2LCD-S301C31TR 

As we push the limits of agriculture to feed more people in a warmer world, we do not understand how plants sense temperature.In a surprising turn of events scientists have just learned that plant light sensors also respond to temperature.Plants contain specialized light-sensitive proteins that change shape when they absorb light, much as do the photopigments in the human eye. All plants have three main red-light photoreceptors, called phytochrome A, B and C.As part of an effort to create plants that can tolerate different growth conditions, Richard Vierstra the George and Charmaine Mallinckrodt Professor in Arts & Sciences at Washington University in St. Louis has been developing a library of phytochrome B mutants, including ones that are much more or less sensitive to light than the wild type plant.To better understand their mutant plants, the Vierstra lab shared them with Jorge J. Casal lab in Argentina where doctoral student Martina Legris grew them under a wide variety of carefully controlled conditions."We got 'weird' results that couldn't be explained unless the phytochrome we were working with was sensitive to temperature as well as light," Vierstra said.As the temperature rose, some plants exposed to constant sunlight generate less of the biologically active form of phytochrome B—not more, as you'd expect.At summer temperatures, these plants behave as though they're in dim light even though they're in bright sun.The findings will be published in the Oct. 27 issue of Science, together with a companion paper also on plant temperature sensors by a lab at the University of Cambridge in England.A switch with the jittersVierstra explains that phytochrome proteins work by switching between two forms, called Pr and Pfr.The Pr form is best at absorbing red light, which is plentiful in full sun. When it absorbs red light, phytochrome converts to the Pfr state, which is better at absorbing far-red light that dominates in shade. When the Pfr absorbs far-red light, it switches back to the Pr form.This clever little system is able to detect many different qualities of light, including the light intensity (encoded in the speed at which the molecule bounces from one form to another), and the color of the light (encoded by the ratio of the Pfr form to the Pr form). Intensity tells a seed when to emerge from the soil and color tells the seeding when to grow tall to avoid shade."The beauty of this is you can purify the phytochromes, put them in a test tube and watch them switch forms simply by shining red or far-red light on the solutions," Vierstra said. "So they're not figments of our imagination."An hour glass that runs too fastBut this description leaves out one conversion. Pfr can convert to Pr by absorbing far-red light but also by a process called thermal reversion, which occurs without light.People thought thermal reversion worked like an hour glass, Vierstra said. As soon as the sun set, the hour glass started running, and Pfr started trickling back to the Pr form. The amount of Pfr at the end of the night then told the plant how long the night was.This is important because the length of night varies with the season, especially away from the Equator. So changes in day (and night) length helps plants to tell where they are in the seasonal cycle, which in turn helps them to flower in the right season.Nobody had been able to test the idea that thermal reversion was an hourglass, or timer, however. But as they were tinkering with phytochrome B, the Vierstra lab made phytochrome mutants that were fast reverters and ones that were slow reverters. And these mutants were among those that traveled to Argentina.When they grew the plants, the Casals lab got strange results they could understand only if thermal reversion is much faster than anyone realized; and only if the rate of reversion is very sensitive to temperature. In other words, the only possible interpretationwas that phytochrome B in the wild type (unmodified) plant is a temperature as well as light sensor."The plant is looking for Pfr, which tells it the light is on," said Vierstra. "In sunlight a plant slowly makes more and more Pfr until the reaction that converts Pr to Pfr saturates. But as the temperature rises, the thermal reversion starts running so fast, the plants accumulate relatively little Pfr."You would expect that at higher temperatures the Pr -> Pfr reaction would go faster," Vierstra said, "and it probably does, but thermal reversion goes even faster. It erases the light signal because the reversion reaction is more sensitive to temperature than the one creating the light signal."You can predict what this will do as temperature rises," Vierstra said. "Plants that make lots of Pfr are short, intensely green and happy. But thermal reversion will draw down the Pfr at higher temperatures, so that plants will respond as if they are in the dark (even though they are in the light) and grow tall and leggy.""We don't yet know right now whether it's just phytochrome B that's a temperature sensor," Vierstra said. So right now members of his team, including Research Scientist Sethe Burgie, are trying to get accurate measurement on the other phytochromes. "Once we have this figured out, we could make mutants that are less or more sensitive to temperature by modifying thermal reversion."Coming in from the cold"Phytochromes are the worst to work on," Vierstra said. "You have to spend four days in the dark to purify them. They are incredibly unstable, they are present at very low levels, and they have got all kinds of variants. And unlike most other proteins, their amino-acid sequences also don't tell us how phytochromes work."So when people purify phytochromes, they want to keep the proteins as happy as possible and that means keeping them as cold as possible. All the experiments are done on ice!"And that's why we didn't realize until now that phytochromes could act as temperature sensors!"Reference:LM50BIM3/NOPBLM61CIM3XTMP03FT9Z