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-based sensor may improve the diagnosis and treatment of asthma

May 22, 2017

Rutgers University scientists have created a graphene-based sensor that could lead to earlier detection of asthma attacks and improve the management respiratory diseases, possibly preventing hospitalizations and deaths.

Rutgers team's graphene sensor to diagnose asthma image

The Rutgers team aims for the sensor to pave the way for the development of devices - possibly resembling fitness trackers - which people could wear and then know when and at what dosage to take their medication.

A new collaborative project will design a graphene sensor to diagnose hepatitis

May 18, 2017

A collaborative project, supported by the UK’s Newton Fund and led by BIOVICI, will bring together the National Physical Laboratory (NPL), the University of Chongqing in China, Swansea University and industry partner CTN, to develop an innovative graphene-based sensor. The aim is to provide an easy, low-cost method of diagnosing hepatitis on the spot, and the graphene sensor is planned to be the first to simultaneously test for three types of hepatitis – A, B and C.

The team explained that to date, graphene electrochemical biosensors exist for diagnosing one type of hepatitis. This project, however, will develop sensors for the detection of three hepatitis types at a time, by using three graphene sensors, each tailored to identify the antibodies associated with a certain strain of hepatitis, integrated in a single test. Unlike conventional blood tests, this sensor will provide a non-invasive, quick and less expensive screening method. The ease and speed of this method will reportedly be beneficial for bulk testing of the food, agriculture and education workforces in China, for whom tests are obligatory.

The Graphene Catalog - find your graphene material here

Graphenea and U of Hamburg team upscale high-quality graphene devices

May 07, 2017

Researchers from the University of Hamburg and Graphenea have succeeded in upscaling high-quality graphene devices to the 100-micron scale and beyond. By perfecting CVD graphene production, transfer and patterning processes, the team managed to observe the quantum Hall effect in devices longer than 100 micrometers, with electronic properties on par with micromechanically exfoliated devices.

Graphenea upscales graphene devices

The work started from graphene grown by chemical vapor deposition (CVD) on a copper substrate. Since graphene on metal is not useful for applications in electronics, the material is usually transferred onto another substrate before use. The transfer process has proven to be a challenge, in many cases leading to cracks, defects, and chemical impurities that reduce the quality of the graphene.

Graphene-based contact lens sensor for diabetes monitoring

May 03, 2017

Researchers affiliated with UNIST have raised the possibility of in-situ human health monitoring by wearing a contact lens with built-in wireless smart sensors. Towards this end, the team made use of smart contact lens sensors with electrodes made of graphene sheets and metal nanowires.

Graphene lens sensor for disease monitoring image

The smart contact lens sensor could help monitor biomarkers for intraocular pressure (IOP), diabetes mellitus, and other health conditions. The research team expects that this research breakthrough could lead to the development of biosensors capable of detecting and treating various human diseases, and used as a component of next-generation smart contact lens-related electronic devices.

Researchers succeed in imaging how electrons move in graphene

Apr 27, 2017

Researchers at the University of Melbourne succeeded in imaging how electrons move in 2D graphene, an achievement which may boost the development of next-generation electronics. The new technique overcomes usual limitations of existing methods for understanding electric currents in devices based on ultra-thin materials, and so it is capable of imaging the behavior of moving electrons in structures only one atom in thickness.

Mapping electrons in graphene using diamonds image

The team used a special quantum probe based on an atomic-sized 'color center' found only in diamonds to image the flow of electric currents in graphene. The technique could be used to understand electron behavior in a variety of new technologies.