NT/ Researchers design new inks for 3D-printable wearable bioelectronics
Nanotechnology & nanomaterials biweekly vol.29, 12th August — 26th August
TL;DR
- A team of researchers has developed a new class of biomaterial inks that mimic native characteristics of highly conductive human tissue, much like skin, which is essential for the ink to be used in 3D printing.
- Researchers have created protonic programmable resistors — the building blocks of analog deep learning systems — that can process data 1 million times faster than the synapses in the human brain. These ultrafast, low-energy resistors could enable analog deep learning systems that can train new and more powerful neural networks rapidly, which could then be used for novel applications in areas like self-driving cars, fraud detection, and health care.
- Solar panels aren’t just for rooftops anymore — some buildings even have these power-generating structures all over their facades. But as more buildings and public spaces incorporate photovoltaic technologies, their monotonous black color could leave onlookers underwhelmed. Now, researchers have created solar panels that take on colorful hues while producing energy nearly as efficiently as traditional ones.
- A research team has developed an eco-friendly microplastic removal technology that can remove micro-to-nano-sized microplastics from water.
- Flexible implanted electronics are a step closer to clinical applications thanks to recent breakthrough technology. The work uses silicon carbide technology as a new platform for long-term electronic biotissue interfaces.
- Researchers have constructed the smallest flow-driven motors ever. Inspired by iconic Dutch windmills and biological motor proteins, they created a self-configuring flow-driven rotor from DNA that converts energy from an electrical or salt gradient into useful mechanical work. The results open new perspectives for engineering active robotics at the nanoscale.
- Engineers have developed an experimental strategy to control and observe the chemical reaction of a single nanocatalyst using an optical microscope — Expected to contribute to catalyst design based on an accurate understanding of the photocatalytic reaction through an analysis method that helps understand the electron excitation phenomenon and transition path.
- Researchers developed a piezoelectric polymer/ceramic composite fiber with a cross-sectional form that is uniformly controlled to allow the use of energy harvesting technologies that can recycle energy wasted or consumed in everyday life.
- Swarms of microrobots injected into the human body could unblock internal medical devices and avoid the need for further surgery, according to new research from the University of Essex. The study is the first-time scientists have developed magnetic microrobotics to remove deposits in shunts — common internal medical devices used to treat a variety of conditions by draining excess fluid from organs.
- Computer chip designers, materials scientists, biologists and other scientists now have an unprecedented level of access to the world of nanoscale materials thanks to 3D visualization software that connects directly to an electron microscope, enabling researchers to see and manipulate 3D visualizations of nanomaterials in real-time. Developed by a University of Michigan-led team of engineers and software developers, the capabilities are included in a new beta version of tomviz, an open-source 3D data visualization tool that’s already used by tens of thousands of researchers. The new version reinvents the visualization process, making it possible to go from microscope samples to 3D visualizations in minutes instead of days.
- And more!
Nanotech Market
Nanotechnology deals with the ability to see, understand, measure, predict, produce or control matter at the nanoscale (below 100 nanometers). The realm of nanotechnology lies between 0.1 and 100 nanometers, wherein a nanometer is defined as one-thousandth of a micron. As a versatile technology with widespread applications in a wide range of end-use sectors, nanotechnology is currently facing a mixed bag of challenges and opportunities as the COVID-19 pandemic continues to spread across the globe. With the world fighting its biggest public health crisis in history, nanotechnology healthcare applications are storming into the spotlight led by the focus on nano intervention in terms of designing effective ways to identify, diagnose, treat and eliminate the spread of COVID-19 infections. Their role as nanocarriers has the potential to design risk-free and effective immunization strategies. In the post-COVID-19 period, the use of nanotechnology solutions in the production of a multitude of devices & products will continue to grow.
Amid the COVID-19 crisis, the global market for Nanotechnology estimated at US$42.2 Billion in the year 2020, is projected to reach a revised size of US$70.7 Billion by 2026, growing at a CAGR of 9.2% over the analysis period. Nanocomposites, one of the segments analyzed in the report, is projected to record a 8.7% CAGR and reach US$35.4 Billion by the end of the analysis period. After a thorough analysis of the business implications of the pandemic and its induced economic crisis, growth in the Nanomaterials segment is readjusted to a revised 10.1% CAGR for the next 7-year period.
Global nanotechnology market to reach US $126.8 billion by the year 2027. Amid the COVID-19 crisis, the global market for Nanotechnology is estimated at US $54.2 billion in the year 2020, and is projected to reach a revised size of US $126 billion.
Latest News & Research
Nanoengineered Ink for Designing 3D Printable Flexible Bioelectronics
by Kaivalya A. Deo, Manish K. Jaiswal, Sara Abasi, Giriraj Lokhande, Sukanya Bhunia, Thuy-Uyen Nguyen, Myeong Namkoong, Kamran Darvesh, Anthony Guiseppi-Elie, Limei Tian, Akhilesh K. Gaharwar in ACS Nano
Flexible electronics have enabled the design of sensors, actuators, microfluidics and electronics on flexible, conformal and/or stretchable sublayers for wearable, implantable or ingestible applications. However, these devices have very different mechanical and biological properties when compared to human tissue and thus cannot be integrated with the human body.
A team of researchers atTexas A&M University has developed a new class of biomaterial inks that mimic native characteristics of highly conductive human tissue, much like skin, which are essential for the ink to be used in 3D printing.
This biomaterial ink leverages a new class of 2D nanomaterials known as molybdenum disulfide (MoS2). The thin-layered structure of MoS2 contains defect centers to make it chemically active and, combined with modified gelatin to obtain a flexible hydrogel, comparable to the structure of Jell-O.
“The impact of this work is far-reaching in 3D printing,” said Dr. Akhilesh Gaharwar, associate professor in the Department of Biomedical Engineering and Presidential Impact Fellow. “This newly designed hydrogel ink is highly biocompatible and electrically conductive, paving the way for the next generation of wearable and implantable bioelectronics.”
The ink has shear-thinning properties that decrease in viscosity as force increases, so it is solid inside the tube but flows more like a liquid when squeezed, similar to ketchup or toothpaste. The team incorporated these electrically conductive nanomaterials within a modified gelatin to make a hydrogel ink with characteristics that are essential for designing ink conducive to 3D printing.
“These 3D-printed devices are extremely elastomeric and can be compressed, bent or twisted without breaking,” said Kaivalya Deo, graduate student in the biomedical engineering department and lead author of the paper. “In addition, these devices are electronically active, enabling them to monitor dynamic human motion and paving the way for continuous motion monitoring.”
In order to 3D print the ink, researchers in the Gaharwar Laboratory designed a cost-effective, open-source, multi-head 3D bioprinter that is fully functional and customizable, running on open-source tools and freeware. This also allows any researcher to build 3D bioprinters tailored to fit their own research needs.
The electrically conductive 3D-printed hydrogel ink can create complex 3D circuits and is not limited to planar designs, allowing researchers to make customizable bioelectronics tailored to patient-specific requirements.
In utilizing these 3D printers, Deo was able to print electrically active and stretchable electronic devices. These devices demonstrate extraordinary strain-sensing capabilities and can be used for engineering customizable monitoring systems. This also opens up new possibilities for designing stretchable sensors with integrated microelectronic components.
One of the potential applications of the new ink is in 3D printing electronic tattoos for patients with Parkinson’s disease. Researchers envision that this printed e-tattoo can monitor a patient’s movement, including tremors.
Nanosecond protonic programmable resistors for analog deep learning
by Murat Onen, Nicolas Emond, Baoming Wang, Difei Zhang, Frances M. Ross, Ju Li, Bilge Yildiz, Jesús A. del Alamo in Science
As scientists push the boundaries of machine learning, the amount of time, energy, and money required to train increasingly complex neural network models is skyrocketing. A new area of artificial intelligence called analog deep learning promises faster computation with a fraction of the energy usage.
Programmable resistors are the key building blocks in analog deep learning, just like transistors are the core elements for digital processors. By repeating arrays of programmable resistors in complex layers, researchers can create a network of analog artificial “neurons” and “synapses” that execute computations just like a digital neural network. This network can then be trained to achieve complex AI tasks like image recognition and natural language processing.
A multidisciplinary team of MIT researchers set out to push the speed limits of a type of human-made analog synapse that they had previously developed. They utilized a practical inorganic material in the fabrication process that enables their devices to run 1 million times faster than previous versions, which is also about 1 million times faster than the synapses in the human brain.
Moreover, this inorganic material also makes the resistor extremely energy-efficient. Unlike materials used in the earlier version of their device, the new material is compatible with silicon fabrication techniques. This change has enabled fabricating devices at the nanometer scale and could pave the way for integration into commercial computing hardware for deep-learning applications.
“With that key insight, and the very powerful nanofabrication techniques we have at MIT.nano, we have been able to put these pieces together and demonstrate that these devices are intrinsically very fast and operate with reasonable voltages,” says senior author Jesús A. del Alamo, the Donner Professor in MIT’s Department of Electrical Engineering and Computer Science (EECS). “This work has really put these devices at a point where they now look really promising for future applications.”
“The working mechanism of the device is electrochemical insertion of the smallest ion, the proton, into an insulating oxide to modulate its electronic conductivity. Because we are working with very thin devices, we could accelerate the motion of this ion by using a strong electric field, and push these ionic devices to the nanosecond operation regime,” explains senior author Bilge Yildiz, the Breene M. Kerr Professor in the departments of Nuclear Science and Engineering and Materials Science and Engineering.
“The action potential in biological cells rises and falls with a timescale of milliseconds, since the voltage difference of about 0.1 volt is constrained by the stability of water,” says senior author Ju Li, the Battelle Energy Alliance Professor of Nuclear Science and Engineering and professor of materials science and engineering, “Here we apply up to 10 volts across a special solid glass film of nanoscale thickness that conducts protons, without permanently damaging it. And the stronger the field, the faster the ionic devices.”
These programmable resistors vastly increase the speed at which a neural network is trained, while drastically reducing the cost and energy to perform that training. This could help scientists develop deep learning models much more quickly, which could then be applied in uses like self-driving cars, fraud detection, or medical image analysis.
“Once you have an analog processor, you will no longer be training networks everyone else is working on. You will be training networks with unprecedented complexities that no one else can afford to, and therefore vastly outperform them all. In other words, this is not a faster car, this is a spacecraft,” adds lead author and MIT postdoc Murat Onen.
Analog deep learning is faster and more energy-efficient than its digital counterpart for two main reasons. “First, computation is performed in memory, so enormous loads of data are not transferred back and forth from memory to a processor.” Analog processors also conduct operations in parallel. If the matrix size expands, an analog processor doesn’t need more time to complete new operations because all computation occurs simultaneously.
The key element of MIT’s new analog processor technology is known as a protonic programmable resistor. These resistors, which are measured in nanometers (one nanometer is one billionth of a meter), are arranged in an array, like a chess board.
In the human brain, learning happens due to the strengthening and weakening of connections between neurons, called synapses. Deep neural networks have long adopted this strategy, where the network weights are programmed through training algorithms. In the case of this new processor, increasing and decreasing the electrical conductance of protonic resistors enables analog machine learning.
The conductance is controlled by the movement of protons. To increase the conductance, more protons are pushed into a channel in the resistor, while to decrease conductance protons are taken out. This is accomplished using an electrolyte (similar to that of a battery) that conducts protons but blocks electrons.
To develop a super-fast and highly energy efficient programmable protonic resistor, the researchers looked to different materials for the electrolyte. While other devices used organic compounds, Onen focused on inorganic phosphosilicate glass (PSG).
PSG is basically silicon dioxide, which is the powdery desiccant material found in tiny bags that come in the box with new furniture to remove moisture. It is also the most well-known oxide used in silicon processing. To make PSG, a tiny bit of phosphorus is added to the silicon to give it special characteristics for proton conduction.
Onen hypothesized that an optimized PSG could have a high proton conductivity at room temperature without the need for water, which would make it an ideal solid electrolyte for this application. He was right.
PSG enables ultrafast proton movement because it contains a multitude of nanometer-sized pores whose surfaces provide paths for proton diffusion. It can also withstand very strong, pulsed electric fields. This is critical, Onen explains, because applying more voltage to the device enables protons to move at blinding speeds.
“The speed certainly was surprising. Normally, we would not apply such extreme fields across devices, in order to not turn them into ash. But instead, protons ended up shuttling at immense speeds across the device stack, specifically a million times faster compared to what we had before. And this movement doesn’t damage anything, thanks to the small size and low mass of protons. It is almost like teleporting,” he says.
“The nanosecond timescale means we are close to the ballistic or even quantum tunneling regime for the proton, under such an extreme field,” adds Li.
Because the protons don’t damage the material, the resistor can run for millions of cycles without breaking down. This new electrolyte enabled a programmable protonic resistor that is a million times faster than their previous device and can operate effectively at room temperature, which is important for incorporating it into computing hardware.
Thanks to the insulating properties of PSG, almost no electric current passes through the material as protons move. This makes the device extremely energy efficient, Onen adds.
Now that they have demonstrated the effectiveness of these programmable resistors, the researchers plan to reengineer them for high-volume manufacturing, says del Alamo. Then they can study the properties of resistor arrays and scale them up so they can be embedded into systems.
At the same time, they plan to study the materials to remove bottlenecks that limit the voltage that is required to efficiently transfer the protons to, through, and from the electrolyte.
“Another exciting direction that these ionic devices can enable is energy efficient hardware to emulate the neural circuits and synaptic plasticity rules that are deduced in neuroscience, beyond analog deep neural networks,” adds Yildiz.
“The collaboration that we have is going to be essential to innovate in the future. The path forward is still going to be very challenging, but at the same time it is very exciting,” del Alamo says.
High-Efficiency, Mass-Producible, and Colored Solar Photovoltaics Enabled by Self-Assembled Photonic Glass
by Zhenpeng Li, Tao Ma, Senji Li, Wenbo Gu, Lin Lu, Hongxing Yang, Yanjun Dai, Ruzhu Wang in ACS Nano
Solar panels aren’t just for rooftops anymore — some buildings even have these power-generating structures all over their facades. But as more buildings and public spaces incorporate photovoltaic technologies, their monotonous black color could leave onlookers underwhelmed. Now, researchers reporting in ACS Nano have created solar panels that take on colorful hues while producing energy nearly as efficiently as traditional ones.
Solar panels are typically a deep black color because their job is to absorb light, whereas a red car looks red because the finish reflects red light instead of absorbing it. Most attempts to give these devices color, then, will decrease their ability to absorb light and generate power. One alternative is to use structural sources of color that take advantage of microscopic shapes to only reflect a very narrow, selective portion of light, like the scales on butterfly wings. However, previous technologies attempting to incorporate structural color gave panels an undesirable iridescence or were expensive to implement at a large scale. So, Tao Ma, Ruzhu Wang, and colleagues wanted to develop a way of giving solar panels color using a structural material that would be easy and inexpensive to apply, and that would maintain their ability to produce energy efficiently.
The team sprayed a thin layer of a material called a photonic glass onto the surfaces of solar cells. The glass was made of a thin, disorderly layer of dielectric microscopic zinc sulfide spheres. Although most light could pass through the photonic glass, selective colors were reflected back based on the sizes of the spheres. Using this approach, the researchers created solar panels that took on blue, green and purple hues while only dropping the efficiency of power generation from 22.6% to 21.5%. They also found that solar panels manufactured with this photonic glass layer maintained their color and performance during standard durability tests, and that the fabrication could be scaled up. The researchers plan to explore ways to make the colors more saturated, as well as methods to achieve a wider range of colors.
Wide bandgap semiconductor nanomembranes as a long-term biointerface for flexible, implanted neuromodulator
by Tuan-Khoa Nguyen, Matthew Barton, Aditya Ashok, Thanh-An Truong, Sharda Yadav, Michael Leitch, Thanh-Vinh Nguyen, Navid Kashaninejad, Toan Dinh, Leonie Hold, Yusuke Yamauchi, Nam-Trung Nguyen, Hoang-Phuong Phan in Proceedings of the National Academy of Sciences
Flexible implanted electronics are a step closer toward clinical applications thanks to a recent breakthrough technology developed by a research team from Griffith University and UNSW Sydney.
The work was pioneered by Dr Tuan-Khoa Nguyen, Professor Nam-Trung Nguyen and Dr Hoang-Phuong Phan (currently a senior lecturer at the University of New South Wales) from Griffith University’s Queensland Micro and Nanotechnology Centre (QMNC) using in-house silicon carbide technology as a new platform for long-term electronic biotissue interfaces.
The project was hosted by the QMNC, which houses a part of the Queensland node of the Australian National Nanofabrication Facility (ANFF-Q).
ANFF-Q is a company established under the National Collaborative Research Infrastructure Strategy to provide nano- and microfabrication facilities for Australia’s researchers.
The QMNC offers unique capabilities for the development and characterisation of wide band gap material, a class of semiconductors that have electronic properties lying between non-conducing materials such as glass and semi-conducting materials such as silicon used for computer chips.
These properties allow devices made of these materials to operate at extreme conditions such as high voltage, high temperature, and corrosive environments.
The QMNC and ANFF-Q provided this project with silicon carbide materials, the scalable manufacturing capability, and advanced characterisation facilities for robust micro/nanobioelectronic devices.
“Implantable and flexible devices have enormous potential to treat chronic diseases such as Parkinson’s disease and injuries to the spinal cord,” Dr Tuan-Khoa Nguyen said. “These devices allow for direct diagnosis of disorders in internal organs and provide suitable therapies and treatments. For instance, such devices can offer electrical stimulations to targeted nerves to regulate abnormal impulses and restore body functions.”
Because of the direct contact requirement with biofluids, maintaining their long-term operation when implanted is a daunting challenge.
The research team developed a robust and functional material system that could break through this bottleneck.
“The system consists of silicon carbide nanomembranes as the contact surface and silicon dioxide as the protective encapsulation, showing unrivalled stability and maintaining its functionality in biofluids,” Professor Nam-Trung Nguyen said. “For the first time, our team has successfully developed a robust implantable electronic system with an expected duration of a few decades.”
The researchers demonstrated multiple modalities of impedance and temperature sensors, and neural stimulators together with effective peripheral nerve stimulation in animal models.
Corresponding author Dr Phan said implanted devices such as cardiac pace markers and deep brain stimulators had powerful capabilities for timely treatment of several chronical diseases.
“Traditional implants are bulky and have a different mechanical stiffness from human tissues that poses potential risks to patients. The development of mechanically soft but chemically strong electronic devices is the key solution to this long-standing problem,” Dr Phan said.
The concept of the silicon carbide flexible electronics provides promising avenues for neuroscience and neural stimulation therapies, which could offer live-saving treatments for chronic neurological diseases and stimulate patient recovery.
“To make this platform a reality, we are fortunate to have a strong multidisciplinary research team from Griffith University, UNSW, University of Queensland, Japan Science and Technology Agency (JST) — ERATO, with each bringing their expertise in material science, mechanical/electrical engineering, and biomedical engineering,” said Dr Phan.
Toxic micro/nano particles removal in water via triboelectric nanogenerator
by Byung-Geon Park, Cheoljae Lee, Young-Jun Kim, Jinhyoung Park, Hyeok Kim, Young Jung, Jong Soo Ko, Sang-Woo Kim, Ju-Hyuck Lee, Hanchul Cho in Nano Energy
A research team led by Professor Lee Ju-hyuck of the Department of Energy Science and Engineering of DGIST, collaborating with the research team of Korea Institute of Industrial Technology (President Lee Nak-gyu) led by Dr. Cho Han-cheol, developed an eco-friendly microplastic removal technology that can remove micro-to-nano-sized microplastics in the water.
Microplastics are very small plastics (usually less than 5mm) that accumulate in the body and become a threat to humans by disturbing biological functions and so forth. These microplastics are mainly introduced into the ocean and eventually affect humans on the top of the food chain by disrupting the endocrine system of the marine life system. A technology to filter microplastics is needed to minimize the harm.
However, it is difficult to separate or dispose of microplastics in the water using filters due to their small sizes. In particular, nano-particles, smaller than microns, entail problems that are difficult to overcome, such as filter clogging and environmental pollution by the filter itself when we try to physically remove them using a filter. For this, there is a need for a new and eco-friendly method to overcome these limitations.
Prof. Lee Ju-hyuck’s research team in joint research with Dr. Cho Han-cheol’s team at the Korea Institute of Industrial Technology developed the world’s first eco-friendly power generation device that removes fine particles in the water. It is a collaboration between the triboelectric nagogenerator (TENG) of Professor Lee Ju-hyuck’s research team and the particle removal technology using electrophoresis of Dr. Cho Han-cheol’s team.
As TENG generates electrical energy through physical energy, we can manufacture eco-friendly microplastic filters. In addition, since it utilizes the high voltage characteristic of triboelectric energy, it does not require a special external power source, which gives it the advantage that it can be operated without being restricted by location. The new porous microstructure-based TENG developed through this study showed more than threefold higher output than the existing TENG. The test of the new TENG showed that the removal rate of micro-sized microplastic particles was 21.4%, about 5.6 times higher than that of the existing TENG, which was recorded at 3.8%. In addition, it was confirmed that this technology can remove micro-sized microplastics and various micro-toxic particles such as nano-sized zinc oxides and silicon dioxide.
Combinatorial selective synthesis and excitation experiments for quantitative analysis of effects of Au on a semiconductor photocatalyst
by Yongdeok Ahn, Jiseong Park, Minsoo Park, Siwoo Jin, Woohyun Jo, Jeongho Kim, Seung Hwan Cho, Daeha Seo in Chem
A research team led by Professor Seo Dae-ha of the Department of Physics and Chemistry at DGIST (President Kuk Yang) developed an optical microscopy that can control and observe electron transfer and transfer in complex chemical reactions occurring in nano-catalysts. This technology is expected to provide an experiment strategy based on system chemistry, a new experiment strategy for precisely studying photocatalysts at the single particle level.
Plasmonic metals at the nanometer level, such as gold, exhibit high light absorption rate in a wide place within the range of visible light. They are combined with semiconductor photocatalysts to act as a medium to increase light absorption. Excitation occurs in which electrons gain energy and move as a reaction to light absorption, and it appears through various paths depending on the size of the metal and the wavelength of the light. There are various hypotheses on the effect of this electron movement as a catalyst. The research team was able to test the hypotheses and reveal how electrons transfer by developing a new microscope that is experimentally simpler and more sophisticated than the conventional method of observing chemical reactions.
Professor Seo Dae-ha’s research team developed hybrid nanoparticles (for example, ‘gold/copper oxides’, a combination of gold and copper oxides), and lasers of different wavelengths (colors) (i.e., lasers A, B, and C are A+B, A+C … A+B+C) were combined into a new form, respectively, to investigate the reaction between them to test various hypotheses on the electron excitation phenomenon through experiments and verify them one by one. Through this process, the team was able to selectively induce electron excitation in gold nanoparticles, and quantitatively analyze their contributions by evaluating the increase in the reactivity of the catalyst. In addition, the team confirmed that these excited electrons were transferred to the semiconductor to increase stability and reactivity at the same time.
“The observational technology reported here is a technology that observes chemical reactions with high precision, efficiency, and low cost,” said Professor Seo Dae-ha of the Department of Physics and Chemistry at DGIST, while adding, “It is expected that it will contribute to the sophisticated design of catalysts and will be applied as a sophisticated evaluation and control technology using nanoparticles for pharmaceuticals.”
Effects of biomimetic cross-sectional morphology on the piezoelectric properties of BaTiO3 nanorods-contained PVDF fibers
by Young Kwang Kim, Sung-Ho Hwang, Hye-Jin Seo, Soon Moon Jeong, Sang Kyoo Lim in Nano Energy
A research team led by Lim Sang-kyoo, senior researcher of the Division of Energy Technology at DGIST (President Kuk Yang) developed a piezoelectric polymer/ceramic composite fiber with a cross-sectional form that is uniformly controlled to allow the use of energy harvesting technologies that can recycle energy wasted or consumed in everyday life.
Piezoelectric fiber can produce electrical energy through the piezoelectric effect of the material and drive wearable electronic devices through the movement of the wearer. However, most of the piezoelectric fibers developed so far are made of nanofibers, meaning that it is difficult to control the shape of the fibers, and that the fibers are weak, thus hindering its commercialization. In addition, there are very few studies on the relationship between the shape of the fiber material and the piezoelectric performance.
A research team led by Lim Sang-kyoo, senior researcher of Division of Energy Technology, produced PVDF (Polyvinylidene fluoride) fiber that contains barium titanate in a nano stick form by taking the shape of flowers and stems (daffodils, radish blossoms, papyrus stems, and sedge stems) using melt spinning technology and controlling their cross-sectional shapes uniformly. The team confirmed that it improved the piezoelectric performance by increasing the surface area of the fiber while simultaneously increasing the crystallinity of the fiber, which is advantageous for generating electricity.
Also, the team confirmed the correlation between the specific surface area and the piezoelectric effect according to the shape of the fiber using a high-speed camera. The piezoceramic PVDF composite fiber generates an electrical signal according to the deformation by an external force. PVDF fibers containing barium titanate nanostructures in different shapes (spherical and stick shapes) were produced to investigate the difference in piezoelectric performance depending on the shape of piezoelectric ceramics. The team confirmed that it maximizes the dielectric polarization and contributes to the improvement of the piezoelectric performance favorable to the arrangement.
Senior Researcher Lim Sang-kyoo said, “It is expected that high-performance fiber-type energy harvesting materials with enhanced fiber strength can be commercialized through this research in the future.”
Sustained unidirectional rotation of a self-organized DNA rotor on a nanopore
by Xin Shi, Anna-Katharina Pumm, Jonas Isensee, Wenxuan Zhao, Daniel Verschueren, Alejandro Martin-Gonzalez, Ramin Golestanian, Hendrik Dietz, Cees Dekker in Nature Physics
Researchers from TU Delft have constructed the smallest flow-driven motors in the world. Inspired by iconic Dutch windmills and biological motor proteins, they created a self-configuring flow-driven rotor from DNA that converts energy from an electrical or salt gradient into useful mechanical work. The results open new perspectives for engineering active robotics at the nanoscale.
Rotary motors have been the powerhouses of human societies for millennia: from the windmills and waterwheels across the Netherlands and the world to today’s most advanced off-shore wind turbines that drive our green-energy future.
“These rotary motors, driven by a flow, also feature prominently in biological cells. An example is the FoF1-ATP synthase, which produces the fuel that cells need to operate. But the synthetic construction at the nanoscale has thus far remained elusive,” says Dr. Xin Shi, postdoc in the lab of prof. Cees Dekker in the department of Bionanoscience at TU Delft.
“Our flow-driven motor is made from DNA material. This structure is docked onto a nanopore, a tiny opening, in a thin membrane. The DNA bundle of only 7 nanometer thickness self-organizes under an electric field into a rotor-like configuration, that subsequently is set into a sustained rotary motion of more than 10 revolutions per second,” says Shi, first author of the publication in Nature Physics.
“For already 7 years, we have been trying to build such rotary nanomotors synthetically from the bottom up. We use a technique called DNA origami, in collaboration with Hendrik Dietz’s lab from the Technical University of Munich,” adds Cees Dekker, who supervised the research.
This technique uses the specific interactions between complementary DNA base pairs to build 2D and 3D nano-objects. The rotors harness energy from a water and ion flow that is established through an applied voltage or even simpler: by having different salt concentrations on the two sides of the membrane. The latter is one of the most abundant energy sources in biology that powers various critical processes, like cellular fuel synthesis and cell propulsion.
This achievement is a milestone, as it is the first-ever experimental realization of flow-driven active rotors at the nanoscale. When the researchers first observed the rotations, however, they were puzzled: how could such simple DNA rods exhibit these nice, sustained rotations? The puzzle was solved in discussions with theorist Ramin Golestanian and his team at the Max Planck Institute for Dynamics and Self-Organization in Göttingen. They modeled the system and revealed the fascinating self-organization process where the bundles spontaneously deform into chiral rotors that then couple to the flow from the nanopores.
“This self-organization process truly shows the beauty of simplicity,” says Shi. But the importance of this work does not stop at this simple rotor itself. The technique and physical mechanism behind it establish an entirely new direction of building synthetic nanomotors: flow-driven nanoturbines, which is, a surprisingly unexplored field by scientists and engineers. “You would be surprised how little we knew and achieved on building such flow-driven nanoturbines, especially given the millennia-old knowledge we have on building their macroscale counterparts, and the critical roles they fulfill in the life itself,” says Shi.
In a further step (which is in preprint) the group has used the knowledge they learnt from building this self-organized rotor to make a next important advance: the first rationally designed nanoscale turbine.
“Like how science and technologies always work, we started from a simple pinwheel, now are able to recreate the beautiful Dutch windmills, but this time with a size of only 25 nm, the size of one single protein in your body,” says Shi, “and we demonstrated their ability to carry loads.” “And now, the rotation direction was set by the designed chirality,” Dekker adds. “Left-handed turbines rotated clockwise; right-handed ones rotated anticlockwise.”
Next to better understanding and mimicking motor proteins such as FoF1-ATP synthase, the results open new perspectives for engineering active robotics at the nanoscale.
Shi: “What we have demonstrated here is a nanoscale engine that is truly able to transduce energy and do work. You could draw an analogy with the first invention of the steam engine in the 18th century. Who could have predicted then how it fundamentally changed our societies? We might be in a similar phase now with these molecular nanomotors. The potential is unlimited, but there is still a lot of work to do.”
A novel non-invasive intervention for removing occlusions from shunts using an abrading magnetic microswarm
by A. Moghanizadeh et al in IEEE Transactions on Biomedical Engineering
Swarms of microrobots injected into the human body could unblock internal medical devices and avoid the need for further surgery, according to new research from the University of Essex. The study is the first-time scientists have developed magnetic microrobotics to remove deposits in shunts — common internal medical devices used to treat a variety of conditions by draining excess fluid from organs.
Shunts are prone to malfunctioning, often caused by blockages due to a build-up of sediment. The sediment not only narrows and obstructs liquid passing through the shunt, but it also affects the shunt’s flexibility. This leads to patients needing repeated, invasive surgeries throughout their lives either to replace the shunt or use a catheter to remove the blockage.
However, this new research, led by microrobotics expert Dr. Ali Hoshiar, from Essex’s School of Computer Science and Electronic Engineering, has shown there could be a wireless, non-invasive alternative to clearing the blockage in a shunt.
Published in the IEEE Transactions on Biomedical Engineering journal, Dr. Hoshiar and his team have shown that a swarm of hundreds of microrobots — made of nano size magnetic nanoparticles — injected into the shunt could remove the sediment instead.
“Once the magnetic microrobots are injected into the shunt they can be moved along the tube to the affected area using a magnetic field, generated by a powerful magnet on the body’s surface,” explained Dr. Hoshiar. “The swarm of microrobots can then be moved so they scrape away the sediment, clearing the tube.
“The non-invasive nature of this method is a considerable advantage to existing methods as it will potentially eliminate the risk of surgery and a surgery-related infection, thereby decreasing recovery time.”
With each microrobot smaller than the width of a human hair, once the swarm has done its job, it can either be guided to the stomach via a magnetic field or bodily fluid, so they leave the body naturally. Because the microrobots have very high biocompatibility they will not cause toxicity.
The research also found a direct relation between the strength of the magnetic field and the success of scraping away the sediment in the shunt.
This is the first proof-of-concept experiment using microswarms for opening a blockage in a shunt. The next stage of this research is to work with clinicians to carry out trials. The researchers are also looking at how the concept can be used to other applications.
Real-time 3D analysis during electron tomography using tomviz
by Jonathan Schwartz et al in Nature Communications
Computer chip designers, materials scientists, biologists and other scientists now have an unprecedented level of access to the world of nanoscale materials thanks to 3D visualization software that connects directly to an electron microscope, enabling researchers to see and manipulate 3D visualizations of nanomaterials in real time. Developed by a University of Michigan-led team of engineers and software developers, the capabilities are included in a new beta version of tomviz, an open-source 3D data visualization tool that’s already used by tens of thousands of researchers. The new version reinvents the visualization process, making it possible to go from microscope samples to 3D visualizations in minutes instead of days.
In addition to generating results more quickly, the new capabilities enable researchers to see and manipulate 3D visualizations during an ongoing experiment. That could dramatically speed research in fields like microprocessors, electric vehicle batteries, lightweight materials and many others.
“It has been a longstanding dream of the semiconductor industry, for example, to be able to do tomography in a day, and here we’ve cut it to less than an hour,” said Robert Hovden, an assistant professor of materials science and engineering at U-M and corresponding author on the paper, published in Nature Communications. “You can start interpreting and doing science before you’re even done with an experiment.”
Hovden explains that the new software pulls data directly from an electron microscope as it’s created and displays results immediately, a fundamental change from previous versions of tomviz. In the past, researchers gathered data from the electron microscope, which takes hundreds of two-dimensional projection images of a nanomaterial from several different angles. Next, they took the projections back to the lab to interpret and prepare them before feeding them to tomviz, which would take several hours to generate a 3D visualization of an object. The entire process took days to a week, and a problem with one step of the process often meant starting over.
The new version of tomviz does all the interpretation and processing on the spot. Researchers get a shadowy but useful 3D render within a few minutes, which gradually improves into a detailed visualization.
“When you’re working in an invisible world like nanomaterials, you never really know what you’re going to find until you start seeing it,” Hovden said. “So the ability to begin interpreting and making adjustments while you’re still on the microscope makes a huge difference in the research process.”
The sheer speed of the new process could also be useful in industry — semiconductor chip makers, for example, could use tomography to run tests on new chip designs, looking for failures in three-dimensional nanoscale circuitry far too small to see. In the past, the tomography process was too slow to run the hundreds of tests required in a commercial facility, but Hovden believes tomviz could change that.
Hovden emphasizes that tomviz can be run on a standard consumer-grade laptop. It can connect to newer or older models of electron microscopes. And because it’s open-source, the software itself is accessible to everyone.
“Open-source software is a great tool for empowering science globally. We made the connection between tomviz and the microscope agnostic to the microscope manufacturer,” Hovden said. “And because the software only looks at the data from the microscope, it doesn’t care whether that microscope is the latest model at U-M or a twenty-year-old machine.”
To develop the new capabilities, the U-M team drew on its longstanding partnership with software developer Kitware and also brought on a team of scientists who work at the intersection of data science, materials science and microscopy.
At the start of the process, Hovden worked with Marcus Hanwell of Kitware and Brookhaven National Laboratory to hone the idea of a version of tomviz that would enable real-time visualization and experimentation. Next, Hovden and Kitware’s developers collaborated with U-M materials science and engineering graduate researcher Jonathan Schwartz, microscopy researcher Yi Jiang and machine learning and materials science expert Huihuo Zheng, both of Argonne National Laboratory, to build algorithms that could quickly and accurately turn electron microscopy images into 3D visualizations.
Once the algorithms were complete, Cornell professor of applied and engineering physics David Muller and Peter Ericus, a staff scientist at the Berkeley Lab’s Molecular Foundry, worked with Hovden to design a user interface that would support the new capabilities.
Finally, Hovden teamed up with materials science and engineering professor Nicholas Kotov, undergraduate data scientist Jacob Pietryga, biointerfaces research fellow Anastasiia Visheratina and chemical engineering research fellow Prashant Kumar, all at U-M, to synthesize a nanoparticle that could be used for real-world testing of the new capabilities, to both ensure their accuracy and show off their capabilities. They settled on a nanoparticle shaped like a helix, about 100 nanometers wide and 500 nanometers long. The new version of tomviz worked as planned; within minutes, it generated an image that was shadowy but detailed enough for the researchers to make out key details like the way the nanoparticle twists, known as chirality. About 30 minutes later, the shadows resolved into a detailed, three-dimensional visualization.
The source code for the new beta version of tomviz is freely available for download at GitHub. Hovden believes it will open new possibilities to fields beyond materials-related research; fields like biology are also poised to benefit from access to real-time electron tomography. He also hopes the project’s “software as science” approach will spur new innovation across the fields of science and software development.
“We really have an interdisciplinary approach to research at the intersections of computer science, material science, physics, chemistry,” Hovden said. “It’s one thing to create really cool algorithms that only you and your graduate students know how to use. It’s another thing if you can enable labs across the world to do these state-of-the-art things.”
Kitware collaborators on the project were Chris Harris, Brainna Major, Patrick Avery, Utkarsh Ayachit, Berk Geveci, Alessandro Genova and Hanwell. Kotov is also the Irving Langmuir Distinguished University Professor of Chemical Sciences and Engineering, Joseph B. and Florence V. Cejka Professor of Engineering, and a professor of chemical engineering and macromolecular science and engineering.
“I’m excited for all the new science discoveries and 3D visualizations that will come out of the material science and microscopy community with our new real-time tomography framework,” Schwartz said.
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