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 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.
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.
The latest graphene sensor news:
Archer Materials has announced a milestone in the development of its biochip, which is being created to detect various deadly communicable diseases.
The company achieved electronic transport in atom-thin graphene integrated with silicon electronics. Various voltage ranges were repeatedly recorded on the integrated devices when current-voltage traces were performed.
INBRAIN Neuroelectronics signs an agreement to develop neurotechnology patented by six public research institutions
INBRAIN Neuroelectronics has signed an agreement for the exploitation and development of three patents and a trade secret, mainly held by the Institute of Microelectronics of Barcelona (IMB-CNM) of the Spanish Council for Scientific Research (CSIC), the Catalan Institute of Nanoscience and Nanotechnology (ICN2), the Institució Catalana de Recerca i Estudis Avançats (ICREA) and the Biomedical Research Centre Network CIBER BBN. The Universitat Autónoma de Barcelona (UAB) and the Institut de Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) are also co-owners of the patents. This is a successful process of technology transfer in a public-private collaboration with multiple research institutions.
The company will carry out the development and manufacturing of these technologies within the Institut Català de Nanociència i Nanotecnologia (ICN2) and the Micro and Nanofabrication Clean Room of the Institute of Microelectronics of Barcelona (IMB-CNM) of the CSIC.
U.S-based graphene flakes producer Avadain has announced that it will upscale its environmentally friendly process to mass production as part of a two-year project funded by a $3.77 million grant from the U.S. Department of Commerce’s National Institute for Standards and Technology (NIST).
“We are excited to unleash the Graphene Revolution by making large, thin and nearly defect free graphene flakes available in industrial volumes and acceptable cost,” says Bradley Larschan, CEO of Avadain.
Graphenea has released a new product intended to make sensing with graphene easier: The Cartridge S2X, a package that interfaces the graphene microdevice and the electrical equipment used for its readout.
The cartridge has a small cleft onto which to place the GFET die, just below the electronics module with gentle pogo contacts to the graphene chip. The contacts are placed for seamless integration with Graphenea's S20, S21, S20P and S21P graphene chips that are especially designed for biosensing. The design makes use of 8 connections to the chip, including six source electrodes, one drain, and one gate. The pins are routed to a standard 8-pin BNC connector, for an easy and robust link to external measurement equipment.
Researchers from Boston College, Boston University, and Giner Labs have designed a small graphene-based multiplexed bio-sensor that detects opioid byproducts in wastewater.
The novel device uses graphene-based field effect transistors to detect four different synthetic and natural opioids at once, while shielding them from wastewater’s harsh elements. When a specific opioid metabolite attaches to a molecular probe on the graphene, it changes the electrical charge on the graphene. These signals are easily read electronically for each probe attached to the device.