Graphene sensors: introduction and market status - Page 48

Researchers at the University of Nebraska-Lincoln found that coats of graphene are able to protect delicate nanostructures from high temperatures. 

The scientists have shown that graphene makes nanostructures thermally stable, which means it expands their working range of temperatures. They established that graphene protects nanostructures based on cobalt and titanium, metals that feature significantly different physical and chemical properties. Their results suggest that graphene might be employed to also protect other metallic (and possibly nonmetallic) materials that might be used in nanotechnology.

The Spanish Graphenea collaborated with researchers from the French CNRS and SENSIA SL to design a graphene-based biosensor and develop a graphene-based method to destroy harmful bacteria.

The researchers studied the possibility to kill E. coli pathogens using reduced graphene oxide (rGO-PEG-NH2) and Au nanorods (Nrs) coated with rGO-PEG-NH2 by laser irradiation. The encapsulation of Au NRs with rGO-PEG not only decreases the toxicity of Au NRs, but also enhances the overall photothermal process and thus the temperatures which can be reached. 99% killing efficiency of bacteria was demonstrated in a water solution, at low concentrations (20-49 mg/ml).

President Obama recently visited Boise State University to take in some of the school's 3D printing technology, as well as the new College of Innovation. Obama went to Boise State’s College of Engineering and the school’s New Product Development Lab, which is a collaboration at the Engineering school and managed by the College of Business and Economics.

Among the various prototypes and 3D printed objects, Obama was exposed to Boise State's work on 3D printing electronics, using flexible, light, and conductive graphene nano-materials, which can be printed in stacks onto small, inexpensive sensors, and resistors. 

Scientists from ICFO, MIT, CNRS, CNISM and Graphenea collaborated to demonstrate how graphene can enable the electrical control of light at the nanometer level. Electrically controlled modulation of light emission is crucial in applications like sensors, displays and various optical communication system. It also opens the door to nanophotonics and plasmonics-based devices. 

The researchers managed to show that the energy flow from erbium into photons or plasmons can be controlled by applying a small electrical voltage. The plasmons in graphene are unique, as they are very strongly confined, with a plasmon wavelength that is much smaller than the wavelength of the emitted photons. As the Fermi energy of the graphene sheet was gradually increased, the erbium emitters went from exciting electrons in the graphene sheet, to emitting photons or plasmons. The experiments showed the graphene plasmons at near-infrared frequencies, which may be beneficial for communications applications. In addition, the strong concentration of optical energy offers new possibilities for data storage and manipulation through active plasmonic networks.

Researchers at Penn University designed a unique graphene-based sensor that works in three ways simultaneously. Since proteins trigger three different types of signals, the sensor can calculate that data to produce sensitive and accurate results, far superior to typical one-trigger sensors. This integration of data from multiple factors on chip can be greatly beneficial to various fields that require sensing abilities, like advanced disease detection.

This technique is said to provide more accurate data on the quantity of a given protein in a sample, and could also be used to eventually make a single sensor that could detect a wide range of triggers. The researchers' sensors are built with a base of silicon nitride, coated with a layer of graphene. Graphene’s extreme thinness and electrical properties allow for the mechanical, electrical, and optical modes to operate simultaneously without interfering with one another, and it is also helpful since it is carbon-based and so it is an attractive bonding surface for proteins.

Researchers from the Institute of Optoelectronics & Nanomaterials at Nanjing University of Science and Technology used density functional theory computations to identify novel 2D wide band gap semiconductors called arsenene and antimonene.

The materials are typical semimetals in their natural layered state. However, monolayered arsenene and antimonene are indirect wide band gap semiconductors, and under strain they become direct band-gap semiconductors. Scientists believe that such dramatic transitions of electronic properties could bring new possibilities for nanoscale transistors with high on/off ratio, optoelectronic devices and sensors based on new ultrathin semiconductors.

An Irish 16-year-old student named Elle Loughran used graphene to construct a sensor that can detect brain tumors. The sensor, designed with the support of CRANN in Trinity College Dublin, was featured in the BT Young Scientist & Technology Exhibition event in Dublin, Ireland.

The sensor measures levels of a protein called attractin in the cerebrospinal fluid, which can be sampled from a patient through a lumbar puncture procedure. As elevated levels of this protein indicate a glioma (a type of brain tumor), detecting it can be helpful in detecting tumors. 

Researchers from Nanyang Technological University in Singapore tested different graphene platforms for the detection of caffeine in samples. The ability of analysis of food components is crucial for various food safety applications.

The researchers compared the performances of graphite oxide (GPO), graphene oxide (GO), and electrochemically reduced graphene oxide (ERGO) for caffeine detection. ERGO performed best and showed lower oxidation potential, sensitivity, linearity and reproducibility of the response. ERGO managed to test caffeine levels of soluble coffee, teas and energetic drinks were measured without the need of any sample pre-treatment.

Scientists from the Indian Institute of Technology, Hyderabad, and Indian Institute of Science, Bengaluru, have designed a unique graphene sheet that can detect the presence of e.coli bacteria that is one of the most common causes of food poisoning and urinary tract infections.

The scientists designed a low-cost acetate-based graphene sensor that can detect the presence of e.coli bacteria, even at concentrations as low as 10 lakh forming units per millilitres (cfu/ml). As the e.coli encounters the graphene sheet, the  bacteria binds to it through a chemical process of creating holes in the sheet, thereby decreasing its resistance. The resistance of the graphene sheet can then be measured using a small device to detect the presence and amount of e.coli in the substance. 

Researchers from Oak Ridge National Laboratory (ORNL) found that incorporating crown ethers into a graphene framework can drastically increase their binding strength and selectivity. This discovery holds great potential for various sensor, battery and biotech applications. 

Ethers are simple organic molecules in which an oxygen atom connects two carbon atoms. Ethers are the building blocks of common products like propellants, solvents, pharmaceuticals and cosmetics. When ethers are linked together in the form of large molecular rings, they form crown ether molecules, which are of great scientific significance as the initial prototype in hostguest chemistry, a promising field for applications like sensors and separators.