Graphene sensors: introduction and market status - Page 40

A team of researchers at the University of California, San Diego, is developing a chip that has a graphene field effect transistor which contains a DNA probe. The double-stranded DNA has a sequence coding engineered to detect DNA or RNA with a specific single nucleotide mutation. An electrical signal is produced by the chip whenever this targeted type of DNA or RNA binds to the probe.

Attached to the probe is a regular strand of DNA, and bonded to this strand is a weak strand. The weak strand has four G’s in its sequence replaced with inosines, effectively weakening its bond. Together, the two strands create a double helix which operates DNA strand displacement. Any DNA strands which perfectly complement the normal strand will bind to the normal strand, and the weak strand will be knocked off. Because the DNA probe is connected to the graphene transistor, the chip is able to operate electronically. Eventually, this information could then be wirelessly transmitted to a mobile device.

The National Graphene Institute (NGI) recently signed a collaborative partnership with Haydale to accelerate the commercialization of applications. Haydale has been working closely with the NGI, and has now entered into a formal partnership which aims to leverage each party’s particular expertise in order to seek opportunities to develop and commercialize graphene products and applications.

This collaboration will likely see the NGI utilizing the Haydale patented process incorporated in its R&D plasma reactor for research into the functionalization of graphene and other nanomaterials. It will also look into the use, process and identification of nanomaterials to enhance performance in composites, sensors, printable inks, supercapacitators, rubbers and elastomers.

ICFO researchers have developed a hybrid photodetector capable of reaching improved performance features in terms of speed, quantum efficiency and linear dynamic range, operating not only in the visible but also in the near infrared (NIR: 700-1400nm) and SWIR range (1400-3000nm). In addition, this technology is based upon materials that can be monolithically integrated with Si CMOS electronics as well as flexible electronic platforms.

To achieve this, the team of researchers developed a hybrid device by integrating an active colloidal quantum dot photodiode with a graphene phototransistor. By including an "active" quantum dot photodiode, they were able to increase charge collection in a highly absorbing thick QD film, which in turn increased the quantum efficiency as well as the photoresponse. The active quantum dot layer enabled a more effective charge collection by exploiting carrier drift towards the graphene layer instead of relying only on diffusion. The researchers then combined this scheme with a graphene transistor to register ultra-high-gains and record gain-bandwidth products, thanks to Graphene's 2D character and remarkably high carrier mobility.

Researchers at the University of Central Florida (UCF) have been awarded $1.3 million by the Defense Advanced Research Projects Agency to develop graphene-based next-generation infrared detectors. The award will fund the team's research for the next 3.5 years.

The detector could potentially be used for night vision, meteorology and even space exploration. It is based on a novel infrared detection and imaging technology that is said to be very different than what is being currently used, since most portable infrared cameras (such as those used by police and firefighters) produce extremely blurry images. Other, more powerful infrared detectors (such as the ones used by NASA) are extremely large, expensive and only operate in low temperatures. The main obstacle is that most infrared detectors need cryogenic cooling, which is large and hard to handle.

CealTech aims to become a leading global producer of high volume, high quality graphene, ultra-fine graphite and fine graphite. Production will be done by CealTech's independently-developed FORZA 3D graphene production unit (patent pending).

The FORZA prototype unit is currently under development and should be ready for operation by October 2016. CealTech's daily single layer graphene production capabilities starting October 2016 will be 1600m², and are planned to grow to 150,000 m² starting 2020.

Graphene 3D Lab has announced a new class of graphene materials with exceptional oil absorbance properties. The Company has commissioned a new production reactor that results in a 5-fold increase in the production capabilities of Graphene Oxide and Reduced Graphene Oxide; Using this extended capacity, the Company produced a new class of materials: Graphene Oxide and Reduced Graphene Oxide Foams. These foams are in the class of ultralight materials and have density of approximately 20 mg/cm 3 , which is only about 17 times heavier than air.

These new materials are able to hold up to 3,500%-8,000% of their own weight of organic solvents and oils, all while being unaffected by water. This attribute could be significant in minimizing the damage caused by oil spills. Due to its high oil absorption capacity, these porous solid state foams are an excellent solution for fast and effective oil clean-up. In addition, they may also have commercial application in energy storage devices, chemical catalysts and ultrasensitive sensors.

A collaborative team of researchers from the University of Maryland (UMD), Monash University and the United States Naval Research Laboratory has designed a Tunable Large Area Hybrid Metal-Graphene Terahertz Detector, an innovation based upon a successful demonstration of plasmonic resonance in graphene micro-ribbons that are connected to metal electrodes. This work may be a significant step toward practical graphene terahertz optoelectronic devices.

Graphene is interesting for terahertz range applications (the part of electromagnetic spectrum between microwaves and infrared light) because the free electrons in the material oscillate collectively at these frequencies. The resonance frequency can be tuned by applying an electric voltage at the gate. Being able to tune the resonance frequency allows the resonator to be adjusted, making it usable in a broad range of applications, both scientific and commercial.

Researchers at the University of Southampton and the Japan Advanced Institute of Science and Technology have designed a graphene-based sensor that can detect harmful air pollution in the home with very low power consumption.

The sensor detects individual CO2 molecules and volatile organic compound (VOC) gas molecules found in building and interior materials, furniture and even household goods. These harmful chemical gases have low concentrations of ppb (parts per billion) levels and are extremely difficult to detect with current environmental sensor technology, which can only detect concentrations of parts per million (ppm). According to the team, the new sensing technology allows realizing significant miniaturization, resulting in weight and cost reduction in addition to the remarkable improvement in the detection limit from the ppm levels to the ppb levels.

Haydale recently reported on a presentation given at the recent Advanced Functional & Industrial Printing 2016 meeting that describes the development of roll-to-roll gravure printing of biosensors based on electrically conductive graphene structures and adherence proteins.

The described development was a result of a project undertaken by a consortium of organizations lead by the Frauhofer Institut fur Biomedizinische Technik (IBMT) and involving Haydale in the development of biocompatible and electrically conductive graphene ink suited for gravure printing. The next stage of this project is to validate the performance of the biosensors in a series of target applications.

Researchers from the University of Illinois at Urbana-Champaign have demonstrated a new approach to modifying the light absorption and stretchability of 2D materials by surface topographic engineering using only mechanical strain. The highly flexible system has future potential for wearable technology and integrated biomedical optical sensing technology when combined with flexible light-emitting diodes.

The researchers state that this is the very first stretchable photodetector based exclusively on graphene with strain-tunable photoresponsivity and wavelength selectivity; Increasing graphene's low light absorption in visible range is an important prerequisite for its broad potential applications in photonics and sensing. The key element enabling increased absorption and stretchability requires engineering the 2D material into 3D "crumpled structures," increasing the graphene's areal density. The continuously undulating 3D surface induces an areal density increase to yield higher optical absorption per unit area, thereby improving photoresponsivity. Crumple density, height, and pitch are modulated by applied strain and the crumpling is fully reversible during cyclical stretching and release, introducing a new capability of strain-tunable photoabsorption enhancement and allowing for a highly responsive photodetector based on a single graphene layer.