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Nanomaterials October 2015 Viewpoints

Technology Analyst: Marianne Monteforte

Graphene-Based Magnetic Sensors

By Alastair Cunningham
Cunningham is a specialist consultant in nanoelectronics and nanomaterials.

Why is this topic significant?

Graphene, as a relatively novel material, holds much promise within the electronics industry. Recent research highlights the potential for graphene in highly sensitive magnetic sensors.

Description

In June 2015, Bosch announced at Graphene Week 2015 that its researchers—along with scientists from the Max-Planck Institute for Solid State Research—fabricated a graphene-based magnetic sensor that is 100 times more sensitive than silicon-based equivalents. Silicon sensors exhibit a sensitivity of approximately 70 volts per amp-tesla; Bosch's graphene-based device has a sensitivity of 7,000 volts per amp-tesla.

The sensor functions using the principal of the Hall effect—the production of a voltage in a conducting material that varies in response to a magnetic field. Two key factors determine the performance of a Hall sensor: The sensitivity of the sensor is largely dependent on the number of charge carriers in the sensing material; charge-carrier mobility governs power consumption. Graphene's exceptionally high charge-carrier mobility makes the material a particularly attractive choice. Bosch's results demonstrated that even given a worst-case scenario, graphene-based Hall sensors match the performance of silicon alternatives. Under optimized conditions, graphene dramatically outperforms silicon, requiring significantly less power for any given sensitivity. In fabricating its sensors, Bosch focused on bottom-up techniques—such as the thermal decomposition of precursor materials or chemical-vapor deposition. These techniques ease the transition to high-volume manufacturing—potentially paving the way for future commercialization.

Implications

Bosch is one of the largest suppliers of sensors in the world and is the largest supplier of microelectromechanical sensors—with annual sales of over €1 billion. Automotive applications represent a large proportion of Bosch's sales in this market. This development could be important for Bosch—expanding its sensor portfolio and exploiting the impressive properties of a relatively new material that has yet to find use in a wide range of commercial applications. The research could help to cement Bosch's position as one of the premier suppliers of sensors and also serves as an indication of how seriously the company views the future commercial importance of graphene technology.

Despite the fabrication of a "high-performance magnetic sensor with low power and footprint requirements," the device will still require a significant amount of additional research and development before it can make a commercial impact. Bosch asserts that its graphene-based sensor applications will be unable to compete with existing technologies for another five to ten years—claiming that this time frame results largely from the technical immaturity and cost of the large-scale manufacturing techniques necessary for high-volume graphene applications.

Impacts/Disruptions

This graphene-based magnetic sensor could potentially prove to be the "killer app" that heralds the beginning of a two-dimensional revolution within the electronics industry and severely disrupts more conventional technologies. The fabrication techniques employed by the researchers also highlight the power of bottom-up and self-assembly methods, demonstrating that such approaches have the potential to gain in commercial importance across a wide range of industrial sectors.

Scale of Impact

  • Low
  • Medium
  • High
The scale of impact for this topic is: High

Time of Impact

  • Now
  • 5 Years
  • 10 Years
  • 15 Years
The time of impact for this topic is: 5 Years to 10 Years

Opportunitites in the following industry areas:

Electronics, sensors, automotive, defense

Relevant to the following Explorer Technology Areas:

Paper-Based Sensors

By Alastair Cunningham
Cunningham is a specialist consultant in nanoelectronics and nanomaterials.

Why is this topic significant?

The advent of cheap diagnostic devices could revolutionize health care in developing countries. Recent developments in paper-based sensors could represent a major step toward the commercialization of such devices.

Description

In June 2015, a collaboration between Diagnostics For All—a nonprofit enterprise that focuses on "the creation of low-cost, easy-to-use, point-of-care diagnostic devices specifically for the developing world"—and Harvard University published the results of its research into a paper-based microfluidic-sensing device. The research yielded a device that prepares blood samples, analyzes the DNA for the presence of pathogenic bacteria (using loop-mediated isothermal amplification), and uses materials that cost less than $2. In testing, the device—which also requires a source of UV light and a smartphone camera to read the results—was capable of detecting as few as five Escherichia coli cells.

In July 2015, researchers from the Catalan Institute of Nanoscience and Nanotechnology (ICN2) also published the results of their research into novel optical sensors fabricated on "nanopaper" substrates. Nanocellulose substrates are of particular interest for a range of applications as a result of their low surface roughness, their relatively high transparency, and their biodegradability. The researchers embedded a range of materials—such as metallic nanoparticles and quantum dots—within the fabric of the substrates in order to impart the sensing properties. The team then measured the modulation of the optical properties of the nanoparticles as a function of the presence of certain biologically relevant analytes.

Implications

Paper-based sensors have the potential to find use in an array of medical applications. The ICN2 developments remain at a fundamental research level and will require significant levels of additional research before they can find use in practical health-care applications. However, the Diagnostics For All work is at a much more advanced stage and could potentially find use in the field within a relatively short time frame.

Both these developments highlight the potential power of simple, portable, versatile, inexpensive, and low-power paper-based sensors for a range of diagnostic methods. This range of qualities makes such devices particularly powerful instruments for the point-of-care detection of infectious diseases in developing economies or remote locations—precisely the goal of Diagnostics For All. The use of cheap and disposable diagnostic tests that do not require highly trained medical practitioners could even remove the need for expensive centralized laboratories—of particular importance in areas where health-care budgets do not extend to major facilities with state-of-the-art equipment.

Impacts/Disruptions

Paper-based sensing systems could have a major role to play across a range of areas. For example, the potential exists for the integration of paper sensors into disposable wearable devices that sense a range of analytes—from chemicals in sweat to air quality. Paper-based sensors—being biodegradable—could also result in environmental benefits, reducing the volume of nonrecyclable waste. Nanocellulose can also find use—beyond in sensing applications—as filters or membranes, wound dressings, and sponges that soak up oil pollution.

Scale of Impact

  • Low
  • Medium
  • High
The scale of impact for this topic is: High

Time of Impact

  • Now
  • 5 Years
  • 10 Years
  • 15 Years
The time of impact for this topic is: 5 Years to 10 Years

Opportunitites in the following industry areas:

Healthcare, wearables, sensors

Relevant to the following Explorer Technology Areas: