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Researchers create tiny self-powered temperature sensors

Posted By Graphene Council, Wednesday, April 15, 2020
A team of researchers from the University of Oxford, Delft University and IBM Zurich have demonstrated that graphene can be used to build sensitive and self-powering temperature sensors. The findings pave the way for the design of highly sensitive thermocouples, which could be integrated in nanodevices and even living cells.

On-chip temperature sensors that are scalable, reliable and can be incorporated into nanodevices are essential for future thermal management in CPUs. By determining the local heating in certain segments of a CPU through the distribution of temperature monitors along critical points, feedback can be provided to a control system. In response, thermal management could allow for the redistribution of the thermal load through spot cooling or load distribution, for instance among different computing cores, avoiding hot spots and enabling a longer device lifetime as well as saving energy. Such temperature sensors should have a small footprint, high accuracy, consume a minimum amount of power and be compatible with established nanofabrication techniques.

On-chip thermometry
Thermocouples are an ideal candidate for low-cost thermometry as they are self-powered and relatively easy to fabricate. They tend to have small variations in sensitivity because their signal stems from intrinsic material properties. Typically, thermocouples are a combination of two materials with different Seebeck coefficients joined at the sensing end, enabling the measurement of a thermovoltage build up between a sensing and reference that is proportional to a temperature difference. In order to achieve on-chip thermometry with conventional thermocouples, normally two separate fabrication runs are required. However, thermocouples that can be readily integrated into current wafer scale integration have already sparked interest, with multiple efforts to fabricate single metal thermocouples reported previously. Yet, these thermocouples have a small sensitivity (on the order of 1 μV/K), tend to have a large footprint and have a relatively large thickness on the order of 100 nanometers.

A team of researchers from the University of Oxford, Delft University and IBM Zurich has now demonstrated that graphene can be used to build sensitive, single-material and self-powering temperature sensors. They patterned graphene, a one atom thick sheet of carbon atoms, into a U-shape, with a wide and a narrow leg joining at the sensing end. By carefully tuning the geometry of the graphene legs and exploiting the effect of electron scattering at the edges of the graphene device, the team achieved a maximum sensitivity of ΔS≈39 μV/K.

The results could pave the way for the design of highly sensitive thermocouples with the possibility of integration in van der Waals structures and future graphene circuits. In addition, due to graphene’s bioinert nature and it’s stability in a variety of circumstances, these thermocouples could also be used as temperature sensors in harsh or sensitive environments, such as cells and other living systems.

Tags:  Delft University  Graphene  nanodevices  Sensors  University of Oxford 

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Posted By Graphene Council, Tuesday, November 26, 2019
Updated: Tuesday, November 26, 2019
The meeting marks the starting point of a 4-year research project that is coordinated by CIC nanoGUNE and integrates IBM Research, Donostia International Physics Center, and University of Santiago de Compostela, Technical University of Delft and the University of Oxford. The consortium of these 6 leading European research institutions has been granted a total of €3.5 million from the European Commission under the highly competitive Horizon 2020 FET-Open call, which funds cutting-edge high-risk / high-impact interdisciplinary research projects that must lay the foundations for radically new future technologies.

The SPRING project combines recent scientific breakthroughs from the consortium members to fabricate custom-crafted magnetic graphene nanostructures and test their potential as basic elements in quantum spintronic devices. The targeted long-term vision is the development of an all-graphene – environmentally friendly – platform where spins can be used for transporting, storing and processing information.

As the name suggests, spin can be loosely understood as the rotation of a fundamental particle of matter around itself. For instance, every electron in any material carries both a charge and a spin, the latter playing a key role in magnetism.

Within the scientific community there is consensus that spin is the ideal property of matter to expand the performance of current charge-based nanoelectronics into a class of faster and more power-efficient components, being the basis for the emerging technology called quantum spintronics. The SPRING project will investigate the fundamental laws for creating and detecting spins in graphene, this is to read and write spins, and using them to transmit information.

Jose Ignacio Pascual, Ikerbasque Research Professor at CIC nanoGUNE and scientific coordinator of the project, explains that “graphene is ideal to host spins and to transport them. This atomically thin material can now be fabricated with atomic precision, opening the door to fabrication of designer structures with precise shape, composition, spin arrangement, and interconnected by graphene electrodes for electrostatic or quantum gates. The potential is a platform for the second quantum revolution as qubit elements for quantum computation.”

Tags:  CIC nanoGUNE  Donostia International Physics Center  Graphene  IBM Research  Jose Ignacio Pascual  nanoelectronics  Technical University of Delft  University of Oxford  University of Santiago de Compostela 

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