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What is a sensor?

A sensor is a device that detects events that occur in the physical environment (like light, heat, motion, moisture, pressure, and more), and responds with an output, usually an electrical, mechanical or optical signal. The household mercury thermometer is a simple example of a sensor - it detects temperature and reacts with a measurable expansion of liquid. Sensors are everywhere - they can be found in everyday applications like touch-sensitive elevator buttons and lamp dimmer surfaces that respond to touch, but there are also many kinds of sensors that go unnoticed by most - like sensors that are used in medicine, robotics, aerospace and more.

Traditional kinds of sensors include temperature, pressure (thermistors, thermocouples, and more), moisture, flow (electromagnetic, positional displacement and more), movement and proximity (capacitive, photoelectric, ultrasonic and more), though innumerable other versions exist. sensors are divided into two groups: active and passive sensors. Active sensors (such as photoconductive cells or light detection sensors) require a power supply while passive ones (radiometers, film photography) do not.

Where can sensors be found?

Sensors are used in numerous applications, and can roughly be arranged in groups by forms of use:

  • Accelerometers: Micro Electro Mechanical technology based sensors, used mainly in mobile devices, medicine for patient monitoring (like pacemakers) and vehicular systems.
  • Biosensors: electrochemical technology based sensors, used for food and water testing, medical devices, fitness tracker and wristbands (that measure, for example, blood oxygen levels and heart rate) and military uses (biological warfare and more).
  • Image sensors: CMOS (Complementary Metal-Oxide Semiconductor) based sensors, used in consumer electronics, biometrics, traffic and security surveillance and PC imaging.
  • Motion Detectors: sensors which can be Infrared, Ultrasonic or Microwave/Radar technology. They are used in video games, security detection and light activation.

What is graphene?

Graphene is a two-dimensional material made of carbon atoms, often dubbed “miracle material” for its outstanding characteristics. It is 200 times stronger than steel at one atom thick, as well as the world’s most conductive material. It is so dense that the smallest atom of Helium cannot pass through it, but is also lightweight and transparent. Since its isolation in 2004, researchers and companies alike are fervently studying graphene, which is set to revolutionize various markets and produce improved processes, better performing components and new products.

Graphene and sensors

Graphene and sensors are a natural combination, as graphene’s large surface-to-volume ratio, unique optical properties, excellent electrical conductivity, high carrier mobility and density, high thermal conductivity and many other attributes can be greatly beneficial for sensor functions. The large surface area of graphene is able to enhance the surface loading of desired biomolecules, and excellent conductivity and small band gap can be beneficial for conducting electrons between biomolecules and the electrode surface.

Graphene-based chemical sensor photo

Graphene is thought to become especially widespread in biosensors and diagnostics. The large surface area of graphene can enhance the surface loading of desired biomolecules, and excellent conductivity and small band gap can be beneficial for conducting electrons between biomolecules and the electrode surface. Biosensors can be used, among other things, for the detection of a range of analytes like glucose, glutamate, cholesterol, hemoglobin and more. Graphene also has significant potential for enabling the development of electrochemical biosensors, based on direct electron transfer between the enzyme and the electrode surface.

Graphene will enable sensors that are smaller and lighter - providing endless design possibilities. They will also be more sensitive and able to detect smaller changes in matter, work more quickly and eventually even be less expensive than traditional sensors. Some graphene-based sensor designs contain a Field Effect Transistor (FET) with a graphene channel. Upon detection of the targeted analyte’s binding, the current through the transistor changes, which sends a signal that can be analyzed to determine several variables.

Graphene-based nanoelectronic devices have also been researched for use in DNA sensors (for detecting nucleobases and nucleotides), Gas sensors (for detection of different gases), PH sensors, environmental contamination sensors, strain and pressure sensors, and more.

Commercial activities in the field of graphene sensors

In June 2015, A collaboration between Bosch, the Germany-based engineering giant, and scientists at the Max-Planck Institute for Solid State Research yielded a graphene-based magnetic sensor 100 times more sensitive than an equivalent device based on silicon.

In August 2014, the US based Graphene Frontier announced raising $1.6m to expand the development and manufacturing of their graphene functionalized GFET sensors. Their “six sensors” brand for highly sensitive chemical and biological sensors can be used to diagnose diseases with sensitivity and efficiency unparalleled by traditional sensors.

Graphene Frontiers' GFET Six-Sensors photoG-FET Six-Sensors

In September 2014, the German AMO developed a graphene-based photodetector in collaboration with Alcatel Lucent Bell Labs, which is said to be the world’s fastest photodetector.

In November 2013, Nokia’s Cambridge research center developed a humidity sensor based on graphene oxide which is incredibly fast, thin, transparent, flexible and has great response and recovery times. Nokia also filed for a patent in August 2012 for a graphene-based photodetector that is transparent, thin and should ultimately be cheaper than traditional photodetectors.

Further reading

Latest Graphene Sensors news

Nanomedical Diagnostics announces partnership with Rogue Valley Microdevices to deliver graphene biosensors

Mar 09, 2017

Nanomedical Diagnostics announced a partnership with Rogue Valley Microdevices to deliver their graphene-based biosensors, AGILE R100. The partnership between Nanomedical Diagnostics and Rogue Valley Microdevices will open the novel sensing technique to any pharmaceutical company seeking to characterize biomolecules quickly and easily.

Nanomedical Diagnostics Agile R100 photo

The AGILE R100 is designed to provide biophysical data to pharmaceutical and biotherapeutics companies seeking more informed decisions earlier in the drug discovery process. However, the company also plans a significant impact on the healthcare industry with innovative new products that enable cutting-edge life science research, drug discovery applications, and diagnostic and health monitoring platforms.

Zenyatta Ventures' graphite successfully turned into graphene oxide for sensing applications

Mar 02, 2017

Zenyatta logo imageZenyatta Ventures has announced that a team of scientists at Lakehead University in Canada has made significant progress in developing sensing applications with the first graphene oxide (GO) produced from the Company’s Albany graphite.

The team has developed a novel one-pot synthesis of fluorine functionalized graphene oxide (F-GO) which can be used in many energy, environmental and electrochemical sensing applications. The produced F-GO has been tested for the simultaneous detection of various toxic metal ions (e.g. mercury, lead, cadmium and copper) and a substantial improvement in the electrochemical sensing performance was achieved in comparison with GO.

Graphene Oxide market report

Improved graphene-based transistors to detect disease-causing genes

Feb 26, 2017

Researchers in India and Japan have developed an improved method for using graphene-based transistors to detect disease-causing genes.

GFETs to detect harmful genes image

The team improved sensors that can detect genes through DNA hybridization, which occurs when a 'probe DNA' combines with its complementary 'target DNA.' Electrical conduction changes in the transistor when hybridization occurs. The improvement was done by attaching the probe DNA to the transistor through a drying process. This eliminated the need for a costly and time-consuming addition of 'linker' nucleotide sequences, which have been commonly used to attach probes to transistors.

KAUST team uses laser scribing to create graphene electrodes for biosensors

Feb 15, 2017

Researchers at the King Abdullah University of Science and Technology (KAUST) have created graphene electrodes that function as effective biosensors, by using a laser inscribe patterns into a polymer sheet. The laser scribing technique locally heats parts of a flexible polyimide polymer to 2500 degrees Celsius or more to form carbonized patterns of patches on the surface that act as electrodes.

KAUST uses laser scribing to make biosensors

The black patches are about 33-micrometers thick, with a highly porous nature that allows molecules to permeate the material. Inside the patches, the graphene sheets have exposed edges that are effective at exchanging electrons with other molecules. "Graphene-based electrodes with more edge-plane sites are effectively better than those relying on carbon or carbon-oxygen sites in the plane of the material," said a member of the KAUST team.

Graphene enables ultrahigh sensitivity infrared detectors

Feb 02, 2017

Researchers from the Graphene Flagship, working at the University of Cambridge (UK), Emberion (UK), the Institute of Photonic Sciences (ICFO; Spain), Nokia UK, and the University of Ioannina (Greece) have developed a novel graphene-based pyroelectric bolometer - an infrared (IR) detector with record high sensitivity for thermal detection, capable of resolving temperature changes down to a few tens of µK. This work may open the door to high-performance IR imaging and spectroscopy.

Cambridge team develops sensitive IR bolometer

The technology is focused on the detection of the radiation generated by the human body and its conversion into a measurable signal. The key point is that using graphene, the conversion reaches performance more than 250 times better than the best sensor already available. But the high sensitivity of the detector could be of use for spectroscopic applications beyond thermal imaging. With a high-performance graphene-based IR detector that gives a strong signal with less incident radiation, it is possible to isolate different parts of the IR spectrum. This is of key importance in security applications, where different materials – explosives, for instance – can be distinguished by their characteristic IR absorption or transmission spectra.