Graphene sensors: introduction and market status - Page 33

A common challenge when attempting to make a graphene-based sensor is the high levels of electronic noise that are caused, reducing its effectiveness. In a recent work, an international team of researchers proposed a graphene-based semiconductor device that reduces electronic noise when its electric charge is neutral (referred to as its neutrality point). The group achieved this neutrality point without the need for bulky magnetic equipment that had previously prevented these approaches from being used in portable sensor applications.

In a proof-of-concept device, the researchers used their new sensing scheme to detect HIV-related DNA hybridization at picomolar concentrations. The team fabricated a charge detector out of graphene that can detect very small amounts of charges close to its surface. The sensing principle of the device relies on charge species detection through the field-effect, which brings about a change in electrical conductance of graphene upon adsorption of a charged molecule on the sensor surface.

Researchers from the University of Nebraska-Lincoln, University of Illinois at Urbana-Champaign, and Russia’s Saratov State Technical University have shown that adding a graphene nanoribbons to gas sensors can significantly increase their sensitivity compared to traditional ones.

This rendering shows gas molecules widening the gaps between rows of the team's GNRs. This was proposed as a partial explanation to how the nano-ribbons grant sensors an unprecedented boost

The team integrated the nano-ribbons into the circuity of the gas sensor where it reportedly responded about 100 times more sensitively to molecules than did sensors featuring even the best performing carbon-based materials. With multiple sensors on a chip, we were able to demonstrate that we can differentiate between molecules that have nearly the same chemical nature, said the study author and associate professor of chemistry at the University of Nebraska. For example, we can tell methanol and ethanol apart. So these sensors based on graphene nano-ribbons can be not only sensitive but also selective.

An international research team at Swansea University in the UK recently received an international award for developing a graphene biosensor-based diagnostic test for ovarian cancer that is said to offer quicker and more accurate results in a less expensive, as well as portable way.

The team received the i3S-Hovione Capital Health Innovation Prize, an international award aimed at distinguishing innovative ideas in the health sector, for developing a device — called ‘MagCyte’ — that can diagnose ovarian cancer in a couple of minutes using only a single drop of blood. The portable technology is different from the tests currently used in hospitals and allows for increased flexibility when monitoring patients, even if they have already been diagnosed with ovarian cancer. According to the development team, the innovative technology allows for the diagnosis of ovarian cancer up to four years before it can be diagnosed through the technology currently available.

Researchers with Johns Hopkins University and MIT have shown a way to cause flat sheets of graphene to self-fold into 3D geometric shapes. The group explains how they prepared the sheets and then used heat to cause them to fold. The ability to create 3D objects from sheets of graphene can advance opportunities in fields like sensors, wearables and more.

In their work, the researchers developed a micro-patterning technique that leads to the flat graphene sheets bending along predesignated lines when heat is applied, causing the sheet to form into shapes. The new method not only preserves the intrinsic properties of the graphene, but it was also found that the creases can cause a band gap in the graphene, which can be extremely useful.

Researchers from South Korea have created a graphene nanoribbon sensor which can measure high vacuum pressures.

The Researchers synthesized a mixture of graphene nanoribbons (of varying size and chemical composition) from a combination of multi-walled carbon nanotubes, sulphuric acid and phosphoric acid in a chemical exfoliation approach. The result was a mixture of several graphene nanoribbons which were separated and purified ready for device implementation and testing. The Researchers also synthesized graphene oxide through a modified Hummers’ method for use as a reference material.

Researchers from CNR-Istituto Nanoscienze, Italy and the University of Cambridge, UK, associated with the ​Graphene Flagship, have shown that it is possible to create a terahertz saturable absorber using graphene, produced by liquid phase exfoliation and deposited by transfer coating and ink jet printing. The paper reports a terahertz saturable absorber with an order of magnitude higher absorption modulation than other devices produced to date.

A terahertz saturable absorber decreases its absorption of light in the terahertz range (far infrared) with increasing light intensity and has great potential for the development of terahertz lasers, with applications in spectroscopy and imaging. These high-modulation, mode-locked lasers open up many prospects in applications where short time scale excitation of specific transitions are important, such as time-resolved spectroscopy of gasses and molecules, quantum information or ultra-high speed communication.

Imagine Intelligent Materials and Swinburne University have announced a collaborative six-month project aiming to develop graphene-reinforced smart composites. The composite will be able to report on the condition of large structures, and will have major commercial potential in the transport sector, including automotive and aerospace.

The project is supported by a $20,000 Seed grant from the university under a program, targeting interdisciplinary projects that are aligned with the Swinburne research institutes’ external partnership and collaboration objectives. It will combine expertise from experts in sensors, electronics engineering and aerospace manufacturing at the university.

The European Commission recently awarded nearly €3.7 million ($4.4 million USD) to an international initiative in the field of early diagnosis of brain cancer. The four-year program, which will be led by Plymouth University, is called An Integrated Platform for Developing Brain Cancer Diagnostic Techniques, or AiPBAND. It will focus on gliomas with specific objectives to identify new blood biomarkers for the disease, design plasmonic-based, graphene-based, and digital ELISA assay-based multiplex biosensors; and to develop a big data-empowered intelligent data management infrastructure and cloud-based diagnostic systems.

Through the initiative, which also includes partner organizations from China, an estimated 14 research fellows will be trained by academic and private sector experts from participating organizations in fields including neuroscience, engineering, healthcare, and economics. Individual research projects under the nonprofit Vitae Researcher Development Framework will be arranged into local training courses, network-wide events, secondments, and personalized career development plans with private sector involvement, according to Plymouth University.

The National Science Foundation recently awarded University of Wisconsin-Milwaukee scientists $1.5 million to perfect a method of mass-producing graphene-based small water sensors using inkjet printing. The goal is to determine whether the process can be customized in order to scale up production and in a more economic way than traditional manufacturing methods.

The graphene-based sensors, developed at UWM, reportedly outperform current technologies in accuracy, sensitivity and sensing speed. Their performance and size make them useful for continuously monitoring drinking water for miniscule traces of contaminants like lead.

A team of researchers led by the Massachusetts Institute of Technology and Raytheon BBN Technologies developed a new device that can detect single photons across a wide range of the electromagnetic spectrum, from the higher energy visible to much lower energy radio frequencies. The device consists of a sheet of graphene contacted on two ends by superconductors - a configuration called a Josephson junction.

The ability to detect terahertz and microwave photons in this way could allow for observations of some of the faintest objects in the universe, say the researchers who report on the new technique, as well as open up new opportunities in quantum information processing.