Ultrathin graphene oxide lens could revolutionise next-gen devices

Researchers at Swinburne University of Technology, collaborating with Monash University, have developed an ultrathin, flat, ultra-lightweight graphene oxide optical lens with unprecedented flexibility. The ultrathin lens enables potential applications in on-chip nanophotonics and improves the conversion process of solar cells. It also opens up new avenues in:
  • – non-invasive 3D biomedical imaging
  • – photonic chips
  • – aerospace photonics
  • – micromachines
  • – laser tweezing – the process of using lasers to trap tiny particles.
graphene oxide lens Optical lenses are indispensable components in almost all aspects of technology including imaging, sensing, communications, and medical diagnosis and treatment. The rapid development in nano-optics and on-chip photonic systems has increased the demand for ultrathin flat lenses with three-dimensional subwavelength focusing capability – the ability to see details of an object smaller than 200 nanometres. Recent breakthroughs in nanophotonics have led to the development of a number of ultrathin flat lens concepts, however their real-life application is limited due to their complex design, narrow operational bandwidth and time consuming manufacturing processes. “Our lens concept has a 3D subwavelength capability that is 30 times more efficient, able to tightly focus broadband light from the visible to the near infrared, and offers a simple and low-cost manufacturing method,” research leader in nanophotonics at Swinburne’s Centre for Micro-Photonics (CMP), Associate Professor Baohua Jia, said. The researchers produced a film that is 300 times thinner than a sheet of paper by converting graphene oxide film to reduced graphene oxide through a photoreduction process. “These flexible graphene oxide lenses are mechanically robust and maintain excellent focusing properties under high stress,” lead author of the research, PhD candidate Xiaorui Zheng said. “They have the potential to revolutionise the next-generation integrated optical systems by making miniaturised and fully flexible photonics devices.” CMP Director, Professor Min Gu, said: “The newly demonstrated laser nano-patterning method in graphene oxides holds the key to fast processing and programming of high capacity information for big data sectors.” Professor Dan Li, Co-director of the Monash Centre for Atomically Thin Material, which provided the graphene oxide film for this research said this work opens up a new high-tech application for graphene oxide and demonstrates how nanotechnology can add significant value to natural graphite. The research is published in ("Highly efficient and ultra-broadband graphene oxide ultrathin lenses with three-dimensional subwavelength focusing") and has been funded by the Australian Research Council under its Discovery Early Career Researcher Award, Discovery Project and Laureate Fellowship scheme.
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Low-cost nanomembrane a new option for high-temperature fuel cells

Obtaining energy from fuel cells is an important issue nowadays to conserve the environment and membranes play the role of electrolyte in fuel cells and are solid electrolytes in proton exchanging fuel cells, which allow the pass of ions. Researchers from New Energies Research Center of Amirkabir University of Technology produced nanomembranes that can be used in the production of high temperature fuel cells ("Fabrication BaZrO3/PBI-based nanocomposite as a new proton conducting membrane for high temperature proton exchange membrane fuel cells"). The membrane has been made of a cheap nanocomposite through a simple method. The production and evaluation of the nanomembrane have been carried out at laboratorial scale. Nefion is one of the most common polymeric membranes used in fuel cells. Despite its numerous advantages, Nefion membrane has a weak performance at temperatures higher than 80°C. Therefore, it cannot be used in polymeric fuel cells that work at temperatures higher than 100°C. In addition, it is very expensive to buy Nefion. The nanocomposite membrane produced in this research has appropriate thermal stability and performance at high temperatures, and its production cost is much cheaper. Therefore, it can be considered as a promising option in the production of membranes. A simple and cost-effective solution casting method was used to produce the membrane, without the need for complicated processes. The cost to produce polymeric membranes to be used in fuel cells can be reduced in this method so their application has an economic justification. In case of being mass produced, the nanocomposite membrane presented in this research can help the development of fuel cells as an option for reducing pollution.
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Molecular diagnostics at home: Chemists design rapid, simple, inexpensive tests using DNA

Chemists at the University of Montreal used DNA molecules to developed rapid, inexpensive medical diagnostic tests that take only a few minutes to perform. Their findings, which will officially be published tomorrow in the ("A highly selective electrochemical DNA-based sensor that employs steric hindrance effects to detect proteins directly in whole blood"), may aid efforts to build point-of-care devices for quick medical diagnosis of various diseases ranging from cancer, allergies, autoimmune diseases, sexually transmitted diseases (STDs), and many others. portable sensor that enables fast and easy detection of multiple diagnostically relevant proteins The sensing principle is straightforward: the diagnostically relevant protein (green or red), if present, binds to an electro-active DNA strand and limits the ability of this DNA to hybridize to its complementary strand located on the surface of a gold electrode. This causes a reduction of electrochemical signal, which can be easily measured using inexpensive devices similar to those used in the home glucose self-test meter. Using this sensor, the researchers were able to detect several proteins directly in whole blood in less than 10 minutes. (Image: Ryan & Peter Allen) The new technology may also drastically impact global health, due to its low cost and easiness of use, according to the research team. The rapid and easy-to-use diagnostic tests are made of DNA and use one of the simplest force in chemistry, steric effects - a repulsion force that arises when atoms are brought too close together - to detect a wide array of protein markers that are linked to various diseases. The design was created by the research group of Alexis Vallée-Bélisle, a professor in the Department of Chemistry at University of Montreal. "Despite the power of current diagnostic tests, a significant limitation is that they still require complex laboratory procedures. Patients typically must wait for days or even weeks to receive the results of their blood tests," Vallée-Bélisle said. "The blood sample has to be transported to a centralised lab, its content analyzed by trained personnel, and the results sent back to the doctor's office. If we can move testing to the point of care, or even at home, it would eliminates the lag time between testing and treatment, which would enhance the effectiveness of medical interventions." The key breakthrough underlying this new technology came by chance. "While working on the first generation of these DNA-base tests, we realised that proteins, despite their small size (typically 1000 times smaller than a human hair) are big enough to run into each other and create steric effect (or traffic) at the surface of a sensor, which drastically reduced the signal of our tests," said Sahar Mashid, postdoctoral scholar at the University of Montreal and first author of the study. "Instead of having to fight this basic repulsion effect, we instead decided to embrace this force and build a novel signaling mechanism, which detects steric effects when a protein marker binds to the DNA test." The sensing principle is straightforward: the diagnostically relevant protein (green or red), if present, binds to an electro-active DNA strand, and limits the ability of this DNA to hybridize to its complementary strand located on the surface of a gold electrode. Francesco Ricci, a professor at University of Rome Tor Vergata who also participated in this study, explains that this novel signaling mechanism produces sufficient change in current to be measured using inexpensive electronics similar to those in the home glucose test meter used by diabetics to check their blood sugar. Using this DNA-base assay, the researchers were able to detect multiple protein markers directly in whole blood in fewer than 10 minutes, even if their concentration is 1,000 000 times less concentrated than glucose. "A great advantage of this DNA-based electrochemical test is that its sensing principle can be generalized to many different targets, allowing us to build inexpensive devices that could detect dozens of disease markers in less than five minutes in the doctor's office or even at home," concludes Vallée-Bélisle. A patent has been submitted for this invention, and many other applications are envisaged, including pathogen detection in food or water and therapeutic drug monitoring at home, a feature which could drastically improve the efficient of various class of drugs and treatments.
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