Researchers from the Georgia Institute of Technology (Atlanta) and two other institutions have developed a new 3D printing method to create objects that can permanently transform into a range of different shapes in response to heat. The team, including researchers from the Singapore University of Technology and Design (SUTD) and Xi’an Jiaotong University in China, created the objects by printing layers of shape memory polymers with each layer designed to respond differently when exposed to heat.
“This new approach significantly simplifies and increases the potential of 4D printing by incorporating the mechanical programming postprocessing step directly into the 3D printing process,” said Jerry Qi, a professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech. “This allows high-resolution 3D printed components to be designed by computer simulation, 3D printed, and then directly and rapidly transformed into new permanent configurations by simply heating.”
The scientists reported their research April 12 in an article entitled “Direct 4D printing via active composite materials,” in the journal Science Advances, a publication of the American Association for the Advancement of Science. A copy of the research can be downloaded at http://dx.doi.org/10.1126/sciadv.1602890.
The work is funded by the US Air Force Office of Scientific Research, the US National Science Foundation and the Singapore National Research Foundation through the SUTD DManD Centre.
Their development of the new 3D printed objects follows earlier work the team had done using smart shape memory polymers (SMPs), which have the ability to remember one shape and change to another programmed shape when uniform heat is applied, to make objects that could fold themselves along hinges. “The approach can achieve printing time and material savings up to 90%, while completely eliminating time-consuming mechanical programming from the design and manufacturing workflow,” Qi said.
To demonstrate the capabilities of the new process, the team fabricated several objects that could bend or expand quickly when immersed in hot water—including a model of a flower whose petals bend like a real daisy responding to sunlight and a lattice-shaped object that could expand by nearly eight times its original size.
“Our composite materials at room temperature have one material that is soft but can be programmed to contain internal stress, while the other material is stiff,” said Zhen Ding, a postdoctoral researcher at SUTD. “We use computational simulations to design composite components where the stiff material has a shape and size that prevents the release of the programmed internal stress from the soft material after 3D printing. Upon heating the stiff material softens and allows the soft material to release its stress and this results in a change—often dramatic—in the product shape.”
The researchers said the new 4D objects could enable a range of new product features, such as allowing products that could be stacked flat or rolled for shipping and then expanded once in use. Eventually, the technology could enable components that could respond to stimuli such as temperature, moisture or light in a way that is precisely timed to create space structures, deployable medical devices, robots, toys, and range of other structures.
“The key advance of this work is a 4D printing method that is dramatically simplified and allows the creation of high-resolution complex 3D reprogrammable products,” said Martin L. Dunn a professor at SUTD who is also the director of the SUTD Digital Manufacturing and Design Centre. “It promises to enable myriad applications across biomedical devices, 3D electronics, and consumer products. It even opens the door to a new paradigm in product design, where components are designed from the onset to inhabit multiple configurations during service.”
This research was supported by the Air Force Office of Scientific Research, the National Science Foundation, and by the SUTD Digital Manufacturing and Design Centre, supported by the Singapore National Research Foundation.
A team led by engineers at the University of California San Diego (UCSD; San Diego) has developed nanowires that can record the electrical activity of neurons in fine detail. The new nanowire technology potentially could serve as a future platform to screen drugs for neurological diseases and could enable researchers to better understand how single cells communicate in large neuronal networks.
“We’re developing tools that will allow us to dig deeper into the science of how the brain works,” said Shadi Dayeh, an electrical engineering professor at the UC San Diego Jacobs School of Engineering and the team’s lead investigator.
“We envision that this nanowire technology could be used on stem-cell-derived brain models to identify the most effective drugs for neurological diseases,” said Anne Bang, director of cell biology at the Conrad Prebys Center for Chemical Genomics at the Sanford Burnham Medical Research Institute.
The project was a collaborative effort between the Dayeh and Bang labs, neurobiologists at UC San Diego, and researchers at Nanyang Technological University in Singapore and Sandia National Laboratories. The research team published its work April 10 in the journal Nano Letters.
Researchers can uncover details about a neuron’s health, activity and response to drugs by measuring ion channel currents and changes in its intracellular potential, which is due to the difference in ion concentration between the inside and outside of the cell. The state-of-the-art measurement technique is sensitive to small potential changes and provides readings with high signal-to-noise ratios.
“Existing high sensitivity measurement techniques are not scalable to 2D and 3D tissue-like structures cultured in vitro,” Dayeh said. “The development of a nanoscale technology that can measure rapid and minute potential changes in neuronal cellular networks could accelerate drug development for diseases of the central and peripheral nervous systems.” The nanowire technology developed in Dayeh’s laboratory is nondestructive and can simultaneously measure potential changes in multiple neurons—with the high sensitivity and resolution achieved by the current state of the art.
The device consists of an array of silicon nanowires densely packed on a small chip patterned with nickel electrode leads that are coated with silica. The nanowires poke inside cells without damaging them and are sensitive enough to measure small potential changes that are a fraction of or a few millivolts in magnitude. Researchers used the nanowires to record the electrical activity of neurons that were isolated from mice and derived from human induced pluripotent stem cells. These neurons survived and continued functioning for at least six weeks while interfaced with the nanowire array in vitro. A patent is pending for this technology.
Dayeh noted that the technology needs further optimization for brain-on-chip drug screening. His team is working to extend the application of the technology to heart-on-chip drug screening for cardiac diseases and in vivo brain mapping, which is still several years away due to significant technological and biological challenges that the researchers need to overcome. “Our ultimate goal is to translate this technology to a device that can be implanted in the brain.”
XPRIZE (Los Angeles) has announced that 147 teams representing 22 countries are advancing in the $5-million IBM Watson AI XPRIZE, a four-year global competition to develop and demonstrate how humans can collaborate with powerful artificial intelligence (AI) technologies to tackle some of the world’s greatest challenges.
This is XPRIZE’s first “open” competition, wherein teams defined their own goals and will create AI applications that solve some of humanity’s most pressing challenges. Competing teams aim to develop AI to address problems across a number of domains, with some teams focusing on solutions that may leapfrog these domains, or challenge underlying assumptions about AI, including teams focusing on encoding human ethics within AI, imbuing AI with human social norms, and AI for understanding human emotional cues.
Some other teams will focus on domain-specific solutions, such as health and wellness; learning and human potential; civil society; space and new frontiers; shelter and infrastructure; energy and resources; and planet and environment. The IBM Watson AI XPRIZE’s independent panel of experts verified the teams who will move forward onto the next phase. Teams come from the United States, Canada, Australia, Barbados, China, Czech Republic, Ecuador, France, Germany, Hungary, India, Israel, Italy, Japan, Netherlands, Norway, Poland, Romania, Spain, Switzerland, United Kingdom and Vietnam. For more information, visit ai.xprize.org.
TechFront is edited by Senior Editor Patrick Waurzyniak.
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