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 G-FET sensorG-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

Graphene Flagship team designs graphene-based terahertz absorbers

Sep 13, 2017

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.

Graphene based Terahertz Absorbers by Graphene Flagship image

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.

Swinburne University and IIM announce graphene smart composites project

Sep 11, 2017

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.

Graphene Oxide market report

Graphene takes part in $4.4 million international initiative for early diagnosis of brain cancer

Sep 05, 2017

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.

NSF grant to fund development of inkjet-printed graphene-based water quality sensors

Sep 04, 2017

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.

Inkjet-printed graphene-based water quality sensors image

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.

Graphene enables detection of single photons

Sep 04, 2017

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.

Graphene-based single photon detector image

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.”

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