Researchers from North Carolina State University and the University of North Carolina at Chapel Hill have developed a drug delivery technology that consists of an elastic patch that can be applied to the skin and will release drugs whenever the patch is stretched ("Stretch-Triggered Drug Delivery from Wearable Elastomer Films Containing Therapeutic Depots"). For example, if applied to the elbow, the patch would release a drug when the elbow bends and stretches the patch. “This could be used to release painkillers whenever a patient with arthritic knees goes for a walk, or to release antibacterial drugs gradually as people move around over the course of a day,” says Zhen Gu, co-senior author of a paper describing the work and an assistant professor in the joint biomedical engineering program at NC State and UNC-Chapel Hill. 
NC State researchers create a stretchable drug delivery mechanism. The technology consists of an elastic film that is studded with biocompatible microcapsules. These microcapsules, in turn, are packed with nanoparticles that can be filled with drugs. Here’s how it works: The microcapsules stick halfway out of the film, on the side of the film that touches a patient’s skin. The drugs leak slowly out of the nanoparticles and are stored in the microcapsules. When the elastic film is stretched, it also stretches the microcapsules – enlarging the surface area of the microcapsule and effectively squeezing some of the stored drug out onto the patient’s skin, where it can be absorbed. “When the microcapsule is stretched from left to right, it is also compressed from bottom to top,” says Yong Zhu, co-senior author of the paper and an associate professor of mechanical and aerospace engineering at NC State. “That compression helps push the drug out of the microcapsule.” After being stretched, the microcapsule is “re-charged” by the drugs that continue to leak out of the nanoparticles. “This can be used to apply drugs directly to sites on the skin, such as applying anti-cancer medications to melanomas or applying growth factors and antibiotics for wound healing,” says Jin Di, co-lead author and a Ph.D student in Gu’s lab. The researchers also incorporated microneedles into the system, applying them on top of the microcapsules. In this configuration, the drugs can be squeezed through the microneedles. The microneedles are small enough to be painless, but large enough to allow drugs to diffuse into the bloodstream through tiny capillaries underneath the skin. “This expands the range of drugs that can be applied using the technology,” says Shanshan Yao, co-lead author and a Ph.D student in Zhu’s lab. “We’re now exploring how this tool can be used to apply drugs efficiently and effectively to burn patients, and we plan to look at how this could be used for pain relief as well,” Gu says. “The materials are relatively inexpensive, and the manufacturing process is fairly straightforward, so we’re optimistic that this could be scaled up in a cost-effective way,” Zhu says.
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NC State researchers create a stretchable drug delivery mechanism. The technology consists of an elastic film that is studded with biocompatible microcapsules. These microcapsules, in turn, are packed with nanoparticles that can be filled with drugs. Here’s how it works: The microcapsules stick halfway out of the film, on the side of the film that touches a patient’s skin. The drugs leak slowly out of the nanoparticles and are stored in the microcapsules. When the elastic film is stretched, it also stretches the microcapsules – enlarging the surface area of the microcapsule and effectively squeezing some of the stored drug out onto the patient’s skin, where it can be absorbed. “When the microcapsule is stretched from left to right, it is also compressed from bottom to top,” says Yong Zhu, co-senior author of the paper and an associate professor of mechanical and aerospace engineering at NC State. “That compression helps push the drug out of the microcapsule.” After being stretched, the microcapsule is “re-charged” by the drugs that continue to leak out of the nanoparticles. “This can be used to apply drugs directly to sites on the skin, such as applying anti-cancer medications to melanomas or applying growth factors and antibiotics for wound healing,” says Jin Di, co-lead author and a Ph.D student in Gu’s lab. The researchers also incorporated microneedles into the system, applying them on top of the microcapsules. In this configuration, the drugs can be squeezed through the microneedles. The microneedles are small enough to be painless, but large enough to allow drugs to diffuse into the bloodstream through tiny capillaries underneath the skin. “This expands the range of drugs that can be applied using the technology,” says Shanshan Yao, co-lead author and a Ph.D student in Zhu’s lab. “We’re now exploring how this tool can be used to apply drugs efficiently and effectively to burn patients, and we plan to look at how this could be used for pain relief as well,” Gu says. “The materials are relatively inexpensive, and the manufacturing process is fairly straightforward, so we’re optimistic that this could be scaled up in a cost-effective way,” Zhu says.
Supercapacitors of various sizes – but none of them small enough, yet. (Image: Maxwell, CC BY-SA) Your next battery may be a supercapacitor Another technique is to use graphene as the energy-storage medium itself. This has been used to construct supercapacitors – perhaps the strongest future competitor to Li-ion batteries in uses that require very rapid charge times, such as in the case of electric cars. This is arguably their critical feature. A supercapacitor can go from fully discharged to fully charged many orders of magnitude faster than comparable Li-ion batteries. In this context, it is the large surface area of graphene that is important, because the amount of charge that can be stored is related to the surface area of the materials from which it’s made. So again, graphene is ideal. Despite supercapacitors’ potential to challenge the ubiquitous Li-ion battery, current supercapacitors are invariably too large and too expensive to replace them in the same roles. However, prototypes indicate that superconductors may meet the requirements necessary to replace conventional batteries in the not too distant future. Ultimately, the challenge with any of these prototypes is the ability to scale production to meet the demands of the consumer electronics industry. Graphene-based solutions have so far been notoriously difficult to manufacture on a large scale, thanks in part to the difficulty of isolating high-quality graphene. Nevertheless, the future for energy storage and energy-efficient technology looks bright. Whether graphene ultimately plays a part in the revolution or not, its clear that the research into these technologies will eventually lead to the introduction of cheaper and more durable products with a higher capacity. It’s no understatement to say that an energy revolution awaits as a result of next-generation energy-storage devices, which could help usher in the age of fully electric vehicles, large-scale renewable energy generation and the end of our reliance on fossil fuels.
[Clockwise from top left] Circular grating for extracting single photons from a quantum dot. For optimal performance, the quantum dot must be located at the center of the grating. Image taken with the camera-based optical location technique. A single quantum dot appears as a bright spot within an area defined by four alignment marks. Electron-beam lithography is used to define a circular grating at the quantum dot's location. Image of the emission of the quantum dot within the grating. The bright spot appears in the center of the device, as desired. (Image: NIST) “Self-assembled, epitaxially grown” quantum dots have the highest optical quality. They randomly emerge (self-assemble) at the interface between two layers of a semiconductor crystal as it is built up layer-by-layer (epitaxially grown). They grow randomly, but in order for the dots to be useful, they need to be located in a precise relation to some other photonic structure, be it a grating, resonator or waveguide, that can control the photons that the quantum dot generates. However, finding the dots—they’re just about 10 nanometers across—is no small feat. Always up for a challenge, researchers working at the National Institute of Standards and Technology (NIST) have developed a simple new technique for locating them, and used it to create high-performance single photon sources. This new development, which appeared in ("Nanoscale optical positioning of single quantum dots for bright and pure single-photon emission"), may make the manufacture of high-performance photonic devices using quantum dots much more efficient. Such devices are usually made in regular arrays using standard nanofabrication techniques for the control structures. However because of the random distribution of the dots, only a small percentage of them will line up correctly with the control structures. This process produces very few working devices. “This is a first step towards providing accurate location information for the manufacture of high performance quantum dot devices,” says NIST physicist Kartik Srinivasan. “So far, the general approach has been statistical—make a lot of devices and end up with a small fraction that work. Our camera-based imaging technique maps the location of the quantum dots first, and then uses that knowledge to build optimized light-control devices in the right place.” According to co-lead researcher Luca Sapienza of the University of Southampton in the United Kingdom, the new technique is sort of a twist on a red-eye reducing camera flash, where the first flash causes the subject’s pupils to close and the second illuminates the scene. Instead of a xenon-powered flash, the NIST team uses two LEDs. In their setup, one LED activates the quantum dots when it flashes (so the LED gives the quantum dots red-eye). At the same time, a second, different color LED flash illuminates metallic orientation marks placed on the surface of the semiconductor wafer the dots are embedded in. Then a sensitive camera snaps a 100-micrometer by 100-micrometer picture. By cross-referencing the glowing dots with the orientation marks, the researchers can determine the dots’ locations with an uncertainty of less than 30 nanometers. The coordinates in hand, scientists can then tell the computer-controlled electron beam lithography tool to place the control structures in the correct places, with the result being many more usable devices. Using this technique, the researchers demonstrated grating-based single photon sources in which they were able to collect 50 percent of the quantum dot’s emitted photons, the theoretical limit for this type of structure. They also demonstrated that more than 99 percent of the light produced from their source came out as single photons. Such high purity is partly due to the fact that the location technique helps the researchers to quickly survey the wafer (10,000 square micrometers at a time) to find regions where the quantum dot density is especially low, only about one per 1,000 square micrometers. This makes it far more likely that each grating device contains one—and only one—quantum dot. This work was performed in part at NIST's Center for Nanoscale Science and Technology (CNST), a national user facility available to researchers from industry, academia and government. In addition to NIST and the University of Southampton, researchers from the University of Rochester contributed to this work.