Graphene sensors: introduction and market status - Page 13

A Penn State-led international research team (led by Professor Huanyu Larry Cheng at Penn State) recently published two studies that could boost research and development of future motion detection, tactile sensing and health monitoring devices.

There are various substances that can be converted into carbon to create graphene through laser radiation, in a process called laser-induced graphene (LIG). The resulting product can have specific properties determined by the original material. The team set out to test this process and has reached interesting conclusions.

Researchers at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), led by Prof. Chen Tao, have developed a flexible and self-adaptive airflow sensor enabled by a graphene and CNTs membrane, which is mediated by the reversible microspring effect.

Airflow sensors based on the mechanical deformation mechanism have been drawing increasing attention thanks to their excellent flexibility and sensitivity. However, fabricating highly sensitive and self-adaptive airflow sensors via facile and controllable methods remains a challenge. Recently, inspired by the bats' wing membrane which shows unique airflow sensing capacity, the researchers at NIMTE prepared graphene/single-walled nanotubes (SWNTs)-Ecoflex membrane (GSEM), which can be arbitrarily transferred and subsequently adapt to diverse flat/bend and smooth/rough surface. Relying on the reversible microspring effect, the researchers developed a highly sensitive and self-adaptive GSEM-based airflow sensor.

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A University of Alberta researcher is working with Canada-based Davey Textile Solutions and other industry partners to reduce the risk of faulty protective gear used by firefighters, with a graphene-based sensor that can detect the gradual breakdown in garments from exposure to heat, moisture and ultraviolet (UV) light.

These fibers age silently and lose their performance, so this sensor technology is a breakthrough in terms of safety for workers exposed to heat and flame, said clothing and textiles scientist Patricia Dolez, the project’s lead researcher and an assistant professor in the U of A Faculty of Agricultural, Life & Environmental Sciences (ALES).

Researchers from Nagoya University in Japan have designed highly efficient computing devices using graphene-diamond junctions that mimic some of the human brain's functions.

A phenomenon crucial for memory and learning is "synaptic plasticity," the ability of synapses (neuronal links) to adapt in response to increased or decreased activity. Scientists have tried to recreate a similar effect using transistors and "memristors" (electronic memory devices whose resistance can be stored). Recently developed light-controlled memristors, or "photomemristors," can both detect light and provide non-volatile memory, similar to human visual perception and memory. These excellent properties have opened the door to new materials that can act as artificial optoelectronic synapses.

Researchers from North Carolina State University have developed graphene-based patches that plants can wear to monitor continuously for plant diseases or other stresses, such as crop damage or extreme heat.

We’ve created a wearable sensor that monitors plant stress and disease in a noninvasive way by measuring the volatile organic compounds (VOCs) emitted by plants, says Qingshan Wei, co-corresponding author of a paper on the work and an assistant professor of chemical and biomolecular engineering at NC State.

Researchers at the University of Illinois Chicago (UIC) have used sheets of graphene to rapidly detect COVID-19 in laboratory experiments, an advance that could potentially detect variants of the virus.

The white rectangle represents the substrate with graphene functionalized with SARS-CoV-2 antibody (shown in yellow). When the graphene detector interacts with the virus’ spike protein in a COVID-positive sample, its atomic vibration frequency changes.

According to UIC, the researchers combined sheets of graphene with an antibody designed to target the spike protein on the coronavirus. They then measured the atomic-level vibrations of these graphene sheets when exposed to COVID-positive and COVID-negative samples in artificial saliva. The sheets were also tested in the presence of other viruses, such as Middle East respiratory syndrome.

Scientists from UC Berkeley and Stanford University have captured the real-time electrical activity of a beating heart, using a sheet of graphene to record an optical image — almost like a video camera — of the faint electric fields generated by the rhythmic firing of the heart’s muscle cells.

The 'graphene camera' is a new type of sensor that could prove useful for studying cells and tissues that generate electrical voltages, including groups of neurons or cardiac muscle cells. To date, electrodes or chemical dyes have been used to measure electrical firing in these cells. But electrodes and dyes measure the voltage at one point only; a graphene sheet measures the voltage continuously over all the tissue it touches.

Paragraf recently introduced the GHS-C Graphene Hall Sensor (GHS), providing a viable approach to measuring magnetic field strengths of 7 Tesla (T) and above, at temperature extremes below 3 Kelvin (K).

Graphene Hall sensor enables the accurate measurement of high magnetic field strengths at cryogenic temperatures, increasing manufacturing throughput by quicker magnet mapping, replacing existing NMR probe mapping stages. The cryogenic sensor also allows measurements directly in cold bore, removing the need for room temperature inserts giving quality data and time savings.

The European Space Agency (ESA) has announced that a project it has backed has yielded a combined temperature and magnetism sensor. Any time we can do more with less is a good result for the space sector, notes ESA materials specialist Ugo Lafont. Thanks to the unique properties of graphene, our prototype bi-functional sensor can measure magnetic field strength at the same time as taking temperature readings.

Prototypes of bi-functional sensor by ESA and AGP image

And our tests show the sensor operates reliably from room temperature down to 12 degrees Kelvin. Normally separate temperature sensors are required to accurately measure such wide temperature ranges, right down to cryogenic levels.