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IFIMUP's Master student awarded at the 2018 National Meeting of Physics Students (ENEF'18)

Ludgero Peixoto, won best project in Materials Physics and Condensed Matter at the 2018 National Meeting of Physics Students (ENEF’18), that took place in the Faculty of Sciences of the University of Porto. The presentation entitled “Magnetic nanostructures for biotechnological applications” focused on his master thesis, supervised by Dr. Célia Sousa and João Pedro Araújo. The work intends to develop magnetic nano-discs in a spin-vortex state, and its morphological, structural and magnetic characterization, aiming for application in mechanical cancer cells destruction. The work is in the framework of the European Project H2020-MSCA-RISE-734801-MAGNAMED.


Periodic meetings - 2018 IFIMUP Talks - # 3 presented by Post-Doc researcher Fábio G. Figueiras

Next Wednesday, 28th of Februray at 11h30 on room 106 (DFA),  Fábio G. Figueiras will give the third session of the IFIMUP Talks series. IFIMUP Talks consists on periodic meetings where IFIMUP researchers present their current state of work, focusing on the open questions and difficulties. The presentation is followed by an open discussion with possible suggestions presented by the audience.  Fábio G. Figueiras is a Post-doc Researcher in Physics and Materials Science & Engineering at IFIMUP (University of Porto) and at CICECO-AIM (located at the University of Aveiro). The 3rd IFIMUP Talk will be focused on “Thriving Narrow Band Gap Ferroelectric Oxides for Photovoltaic applications:  Bi2ZnTiO6 Thin Films deposited by RF Sputtering".


The structural, optical and ferroelectric properties of Bi2ZnTiO6 thin films, deposited by rf-sputtering onto Pt/Si-based substrates, were investigated. The thin films grow as polycrystalline perovskite-like phase, exhibiting the tetragonal P4mm symmetry and band gap of 1.48 eV (on the range of Si-based devices). Evidences of the ferroelectric nature of this material which is calculated to reach 100 microC.cm-2 were demonstrated through piezo-response force microscopy. However, this exceptional material is scarcely studied, because it is not easily synthetized using conventional ceramic methods. The results obtained in this work evidences the potential applications of this material for a next generation of photovoltaic and functional devices.” 


J. Ramiro A. Fernandes (UTAD, FCUP)
P. Basto da Silva (UM, FCUP)
Denis O. Alikin (UA)
Pedro B. Tavares (UTAD)
Andrei L. Kholkin (UA)
J. Agostinho Moreira (FCUP)
Abílio Almeida (FCUP)

Show up! And help each other making progress in our research!

P.s. If you are interested to present and discuss your work contact PhD student Catarina Dias


Mariana Proença was interviewed by Repsol Foundation for the International day of Women and Girls in Science

Due to the current need to reduce the gender inequality that exists today in science, the United Nations Educational, Scientific and Cultural Organization (UNESCO) established February 11th as the "International Day of Women and Girls in Science". As part of the commemorations of this day, the Repsol Foundation interviewed Mariana Proença, a postdoctoral researcher at IFIMUP, and co-founder and Marketing Director of inanoEnergy, startup and spin-off of the University of Porto. Read the whole interview in the following link.



Sphere Ultrafast Photonics, spin-off founded by IFIMUP researchers, receives Marie Curie grant

Benjamim Alonso has received a Marie Curie grant to carry out a new research project at Sphere Ultrafast Photonics. The Marie Skłodowska-Curie action of the European Commission's H2020 program funds excellent and high-impact research projects, carried out by researchers of recognized merit and potential. This action has a specific panel, Society and Enterprise, established for non-academic beneficiaries. In this call, 58 projects were funded within this panel, two of which in Portugal, and seven more in Spain. Out of the total number of projects, only two were awarded in the field of physics, which includes the one awarded to Dr. Benjamín Alonso and the high-tech spin-off company Sphere Ultrafast Photonics. The project is funded at 160,000 euros for a period of 24 months, which covers the researcher's salary, research-related expenses, and management expenses. 

Benjamín Alonso has a Bachelor's Degree (2007), a Master's Degree (2008) and a Doctorate Degree (2012) from the University of Salamanca, having received several awards throughout his research career. During his thesis work, he also completed internships at the Femtolab laboratory (IFIMUP and DFA-FCUP) and later won an individual post-doctoral fellowship from FCT (2013-2014), working in the same laboratory under the supervision of Helder Crespo, researcher of IFIMUP, assistant professor at DFA and CTO of Sphere Ultrafast Photonics. Since then, Dr. Alonso has held several teaching appointments at the University of Salamanca. The project now granted counts with the supervision and support of Helder Crespo (science and technology) and Rosa Romero (technology transfer and product development). It will enable the development of techniques and products at the highest level for the measurement and control of ultrashort laser pulses in the femtosecond range, being a clear example of the capability and relevance that a national high-tech SME can have at the European level


IFIMUP Seminar presented by Dr. Hab. Oleksandr Dobrovolskiy

Next Friday, 9th of February at 14h30 on room -117 (DFA), Dr. Hab. Oleksandr Dobrovolskiy will give the IFIMUP seminar entitled “Super meets Nano: From nanopatterned superconductors to fluxonic metamaterials seminar”. Dr. Hab. Oleksandr Dobrovolskiy is a physics researcher and an Assoc. Prof. at the Faculty of Physics of the Goethe University of Frankfurt am Main, in Germany. His research work focus on solid state physics as well on the nanotechnology field, showing interest, for e.g., on understanding on how nanofabricated pinning landscapes affect the flux-flow instability velocity and current in superconducting materials.

Seminar abstract:

A blank piece of paper is open for further patterning. It can be covered with words,  symbols,  or  colors,  breaking  the  symmetry  of the  blank paper and producing a sensory or abstract pattern. This pattern tells us a  story,  depicts  an  object,  invokes  a  hidden  feeling...  . In this  sense, patterning can generate a variety of new properties. In analogy to that, breaking  the  symmetry  of  superconducting  films  by nano-patterning results  in  novel  properties  unseen  in  pristine  materials. This sets  the stage  for  a  new fascinating  domain  of  science  and engineering at  the interface  between  superconductivity  research  and nanotechnology  – Abrikosov fluxonics – which will be introduced in the present talk with a  particular  focus  on  microwave  applications  and metamaterials  as miniature  device.”  


Periodic meetings - 2018 IFIMUP Talks - # 2 presented by visiting PhD student Ylla Grasielle

Next thursday, 1st of Februray at 11h30 on room 106 (DFA),  Ylla Grasielle will give the second session of the IFIMUP Talks series. IFIMUP Talks consists on periodic meetings where IFIMUP researchers present their current state of work, focusing on the open questions and difficulties. The presentation is followed by an open discussion with possible suggestions presented by the audience.  Ylla Grasielle is a visiting PhD student from the Federal University of Sergipe, Brazil, and the 2nd IFIMUP Talk will be focused on “Laser sintering of ceramic materials". A discussion will be given on the novel synthesis technique as 
well on the dielectric characterization technique that is performed at IFIMUP.

Show up! And help each other making progress in our research!

P.s. If you are interested to present and discuss your work contact PhD student Catarina Dias


Periodic meetings - 2018 IFIMUP Talks - # 1 presented by PhD student Paula Quitério

On next tuesday, 16th January at 11h45 on room 106 
(DFA)  Paula Quitério will give the first session of the IFIMUP Talks series. IFIMUP Talks consists on periodic meetings where IFIMUP researchers present their current  work, focusing on the open questions and difficulties. The presentation is followed by an open discussion with possible suggestions presented by the audience. The first talk of the series will be given by Paula Quitério and will be focused on “Hydrothermal synthesis of hematite nanostructures for water splitting".

Show up! And help each other making progress in our research!

P.s. If you are interested to present and discuss your work contact PhD student Catarina Dias. 


IFIMUP is member of the BioBrillouin COST Action

IFIMUP is a member of the BioBrillouin COST Action. BioBrillouin is a pan-European network established to advance the field of Brillouin Light Scattering as applied for life science and biomedical research and applications. Networking activities are funded largely by an EU COST grant (CA16124). More information on BioBrillouin COST Action can be accessed in the following link.


Dr. João Horta Belo defended his PhD Thesis

Dr. João Horta Belo defended today his PhD Thesis on “Nanostructuring Gd5(Si,Ge)4 multifunctional materials”. Our warmest congratulations to him and to his supervisors, Prof. João Pedro Araújo and Dr. André Pereira. The work focusedon potential multifunctional thin film materials, aiming to take advantage of theirmagnetocaloric effect and nanosize for a new class of miniaturized refrigerators.The interplay between magnetic and atomic lattice degrees of freedom makes these materials, capable to undergo magnetostructural transitions by the variation of external magnetic fields, pressure and/or temperature. Here, a thorough and advanced characterization was performed on nanogranular Gd5(SixGe1–x)4 thin films, including the magnetocaloric effect, thermal expansion, electrical resistivity and how these properties varied along different thermal treatments and cycling laser deposition, as well as the optimizing of the 5:4 phase, Gd5(SixGe1–x)4, for continuous thin films.

Tailoring the Magnetism of Tb5Si2Ge2 Compounds by La Substitution , J. H. Belo, A. M. Pereira, J. P. Araujo, C. de la Cruz, A. M. dos Santos, J. N. Gonçalves, V. S. Amaral, P.A. Algarabel, C. Magen, L. Morellon, M.R. Ibarra and J.P. Araú́jo, Phys. Rev. B 86, 014403 (2012). https://journals.aps.org/prb/abstract/10.1103/PhysRevB.86.014403

Critical magnetic behavior of magnetocaloric materials with the Gd5Si4-type structure, J. H. Belo, A. M. Pereira, C. Magen, L. Morellon, P. A. Algarabel, M. R. Ibarra and J. P. Araújo, J. Appl. Phys. 113, 133909 (2013). http://aip.scitation.org/doi/10.1063/1.4798578

Insights on the origin of the Tb5Ge4 magnetocaloric effect, J. H. Belo, M. B. Barbosa, A. L. Pires, R. M. Costa, J. G. V. Teixeira, J. Silva, P. A. Algarabel, C. Magen, L. Morellon, J. S. Amaral, U. Zeitler, G. Veerendra, A. M. dos Santos, Y. Ren, M. R. Ibarra, J. P. Araújo and A. M. Pereira, Physica B 513, 72-76 (2017). http://www.sciencedirect.com/science/article/pii/S0921452617301114


European Materials Research Society (E-MRS) Award attributed to Ana Pires, a PhD student at IFIMUP-IN.

Ana Lúcia Pires, PhD student of the MAP-Fis Doctoral program at the Physics and Astronomy Department of The Faculty of Sciences of University of Porto was one of the awarded researchers of the 2017 Spring Meeting. The award was attributed by European Materials Research Society (E-MRS) in Strasbourg, France. The PhD student attended the symposium H, with an oral communication concerning her PhD Thesis theme, Inorganic Thermoelectric Materials.

This work, recognized by E-MRS, is being developed in the group of Thermoelectrics led by Prof. André Pereira at the Institute of Physics of Materials at the University of Porto Institute of Nanoscience and Nanotechnology (IFIMUP-IN/DFA).

The prize, which has a financial component, is aimed at students whose scientific contribution materials and devices’s research area, present a significant impact in nowadays’ society. E-MRS is one of the largest worldwide events in the materials research’s field and houses more than 2,500 participants and 26 seminars, which are spread across several areas of research.

The work carried out by the student concerns the development of new devices for capturing electric energy. This project is stablished in the XXI century, in which great efforts in the development of a new energy paradigm are being taken, namely for energy saving and alternative methods of production and recovery of energy: called energy collectors. Numerous strategies have been used to capture energy, such as: solar, vibration, magnetism, radiofrequency and thermoelectricity. It is in this last strategy that the student Ana Pires has focused her PhD, having developed flexible devices using low cost and ecological processes. The thermoelectric device is safe, clean, and the challenge is now to increase its efficiency.

Besides being a personal prize it is a group prize, reflecting the dynamics and persistence of the Porto group, which has secured jobs, collaborations and an international scientific exposure.


European Project H2020-MSCA-RISE-734801-MAGNAMED: Novel magnetic nanostructures for medical applications

IFIMUP is member of the recent financed European Project H2020-MSCA-RISE-734801-MAGNAMED (Novel magnetic nanostructures formedical applications), a Marie Sklodowska-Curie project whose major goal is to build a dynamic Research and Innovation Staff Exchange between several international recognized institutions in Europe and America. In 4th and 5th May, Célia Sousa (Scientist in Charge), David Navas and João Pedro Araújo participated in the Grant Agreement Meeting in Madrid Spain. This project has 850 kEuros for the next 4 years and the participation of 15 Institutions:

  • Uiversidad Del Pais Vasco UPV, Spain
  • IMG Pharma Biothech SL, Spain
  • Nanovex Biothechnologies SL, Spain
  • Universidad Complutense de Madrid UCM, Spain
  • INESC-MN, Portugal
  • Universidade do Porto – IFIMUP, Portugal
  • Vienna Biocenter VBCF, Austria
  • ICETA-UP, Portugal
  • Universidade de Santiago de Chile USACH, Chile
  • Comision Nacional de Energia Atómica CNEA, Argentina
  • Comissão Nacional de Energia Nuclear CDTN, Brasil
  • Universidad Tecnica Federico Santa Maria USM, Chile
  • Universidade Estadual de Campinas UNICAMP, Brasil
  • The University of Texas System UTSA, USA
  • University of California UCSD, USA

The aim of the MAGNAMED project is the design, fabrication, and assessment of novel magnetic nanostrutures (MNS) with unique spin configurations for innovative diagnostics and therapy techniques. Several nanofabrication techniques will be used to fabricate MNS in vortex and antiferromagnetic spin configurations covering a broad size range (40 to 4000 nm). After functionalization, MNS will be exploited in:

  1. Diagnostics, using giant magnetoresistance (GMR) sensors for the detection of tumoral biomarkers, and
  2. Therapy, effectiveness of tumoral cell annihilation by the magnetomechanical action of MNS will be evaluated in vitro assays of melanoma and colorectal cancer cells.

MAGNAMED is a cross-sectoral and interdisciplinary project involving Physics, Chemistry and Medicine. Findings will have a medium-term impact on the European strategy for early stage detection of cancer and a long-term impact on the development of novel and groundbreaking therapeutics techniques.

The Scientific Coordination Board is composed of the Coordinator of the project, Rafael Morales (UPV) and the Work Package Leaders: Celia Sousa (UP), Gabriel Barreda (IMG), Susana Cardoso (INESC-MN), and Cláudia Nunes (ICETA). Where Portugal has 3 WPL, two of them from Porto University.


European Physical Society prize attributed to IFIMUP's PhD student. 

Miguel Canhota, PhD student of MAP-fis doctoral 
program working at IFIMUP in Faculty of Sciences of University of Porto, was 1 of the 10 receivers of the students prize from European Physical Society (EPS), through the Quantum Electronic and Optics Division (QEOD) and the Young Minds Action Committee.This prize, the EPS-QEOD Travel Grant Student Award, is to students whose scientific research in optics and photonics is considered of the highest quality, including a certificate and financial support to the participation in the international Conference on Lasers and Electro-Optics - European Quantum Electronics Conference (CLEO/Europe-EQEC 2017). The CLEO Europe conference takes place each 2 years, being the most important and biggest scientific event in optics, lasers and photonics in all of Europe. 

The prize will be awarded in a Plenary Session of CLEO, in Munich (Germany), next 27th
 of June.The PhD of Miguel Canhota is being developed at the Ultra-fast Lasers and Magnetodynamic Spectroscopies Group of IFIMUP (Prof. Hélder Crespo) 
in collaboration with the Physics of Laser, Quantum Optics and Non-linear Optics Group of Universidade Complutense in Madrid (Prof. Rosa Weigand). In the CLEO conference, the PhD student Miguel Canhota will present 2 works (an oral presentation and a poster) entirely performed in the laboratory of ultra-shot laser pulses Femtolab of IFIMUP. Large efforts have been carried out to maintain this advanced laboratory working and to publish the obtained results in reference scientific journals, efforts that were now acknowledged by the European Physical Society. In the first work (oral presentation) a new time characterization method of ultra-short light pulses was developed in the regime of few femtoseconds (1 femtosecond = 0.000 000 000 000 001 seconds), able to measure pulses with only optic cycle of duration and in a spectral range from infra-red to ultra-violet, which has applications in several scientific and technological areas. The second work (poster) is related with the study and characterization of a new method of high-energy ultra-short light pulses based in the non-linear propagation in thin and transparent mediums, which might be in the basis for new coherent X-ray generation systems at the atosecond scale (1 atosecond = 0.001 femtoseconds) and for laser acceleration of particles. 
The group in Porto had also 3 other oral presentations accepted in the CLEO conference, resultant from work developed in collaboration with the Universities of Salamanca (Spain), Lund (Sweden) and the technological spin-off from University of Porto, Sphere Ultrafast Photonics. The complete laureates list can be found in this link.


Dr. José Diogo Costa defended today his PhD Thesis

Dr. José Diogo Costa defended today his PhD Thesis on “Spin-transfer-torque nano-oscillators: fabrication, characterization and dynamics"Our warmest congratulations to José Diogo Costa and to his supervisors, Prof. João Oliveira Ventura  and Dr. Ricardo Alexandre de Matos Antunes Ferreira In this thesis, magnetic dynamics were exploited for novel nanoelectronic devices. In particular, a cleanroom nanofabrication process was developed to successfully achieve nanosized radiofrequency emitters. These devices use the current-induced dynamics (through the spin transfer torque effect) in conjugation with the nanometric dimensions to operate. Their output power could be enhanced through the optimization of the insulating barrier thickness and several geometries (vortices, point-contacts and perpendicular polarizer) were built. Moreover, fundamental studies concerning the ultrafast magnetic and electric dynamics were also performed, pushing the field of spintronics to the THz range.

Terahertz dynamics of spins and charges in CoFe/Al2O3 multilayers, J. D. Costa, T. J. Huisman, R. V. Mikhaylovskiy, I. Razdolski, J. Ventura, J. M. Teixeira, D. S. Schmool, G. N. Kakazei, S. Cardoso, P. P. Freitas, Th. Rasing, and A. V. Kimel, Phys. Rev. B, 91, 104407 (2015). http://journals.aps.org/prb/abstract/10.1103/PhysRevB.91.104407  

Impact of MgO thickness on the performance of spin transfer torque nano-oscillators, J. D. Costa, S. Serrano-Guisan, J. Borme, F. L. Deepak, M. Tarequzzaman, E. Paz, J.Ventura, R. Ferreira and P.P. Freitas, IEEE Trans. Magn., 51, 11 (2015). http://ieeexplore.ieee.org/document/7117429/

Femtosecond control of electric currents in metallic ferromagnetic heterostructures, T. J. Huisman, R. V. Mikhaylovskiy, J. D. Costa, F. Freimuth, E. Paz, J. Ventura, P. P. Freitas, S. Blügel, Y. Mokrousov, Th. Rasing, and A. V. Kimel, Nat. Nanotech., 11, 455-459 (2016). http://www.nature.com/nnano/journal/v11/n5/full/nnano.2015.331.html 


Dr. Mariana Proença was one of the Outstanding Reviewers of Nanotechnology in 2016

IOP Publishing has just announced that Mariana Proença, a postdoc researcher from IFIMUP, was one of the Outstanding Reviewer Award winners for 2016, in recognition of the high quality and timeliness of her reviews for Nanotechnology. You can check the list of winners in the following link: http://iopscience.iop.org/journal/0957-4484/page/IOP-Publishing-Outstanding-Reviewer-2016


Dr. Gonçalo Oliveira defended today his PhD Thesis

Dr. Gonçalo Oliveira defended today his PhD Thesis on “Local probing spinel and perovskites complex magnetic systems”. Our warmest congratulations to Dr. Gonçalo Oliveira and to his supervisors, Prof. João Pedro Araújo and Dr. Armandina Lopes. The work focused on potential multifunctional bulk materials, aiming to enhance their multiferroic properties and to contribute to the fundamental understanding of its magnetoelectric coupling (its origin and how to enhance it). Here, the combination of local scale information (analysis of the magnetic hyperfine field, electric field gradient and local structural information) with macroscopic data allowed to obtain local signatures of the magnetoelectric effect and in this way better understand from a fundamental point of view, the origin of the macroscopic properties they exhibit.

G.N.P.Oliveira,A.M.Pereira,A.M.L.Lopes,J.S.Amaral,A.M.dosSantos,Y.Ren, T.M. Mendonça, C.T. Sousa, V.S. Amaral, J.G. Correia, and J.P. Araújo, Dynamic off-centering of Cr3+ ions and short-range magneto-electric clusters in CdCr2S4, Phys. Rev. B 86, 224418 (2012).  https://doi.org/10.1103/PhysRevB.86.224418

G.N.P. Oliveira, R. Teixeira, T.M. Mendonça, M.R. Silva, J.G. Correia, A.M.L. Lopes, and J.P. Araújo, Local symmetry lowering in CdMn2O4 spinel, J. Appl. Phys. 116, 223907 (2014). https://doi.org/10.1063/1.4903949 


IFIMUP members won Pitch Day at the Startups School of UPTEC 

The WEStoreOnTEX business project won the Pitch Day contest of UPTEC Startups School. The team is constituted by Clara Pereira (Researcher REQUIMTE / LAQV at DQB), André Pereira (Professor at DFA and Researcher at IFIMUP-IN) and Rui Costa (a Master in Physical Engineering at FCUP). In this event, 17 business projects were presented by their managers. The Pitch Day event took place on the 2nd of February, and marked the closing of the 8th edition of School of Startups for Science and Technology of the University of Porto. This school consists in a 3-month period of mentoring and training, that allows participants to develop and promote their business ideas in the technological, scientific and creative areas. 
WEStoreOnTEX is developing flexible textiles and accessories that store energy, enabling to power electronic devices and sensors, that may be integrated into the clothing itself. The target market is wellness and fitness market.

An hologram of the president of the Portuguese Republic, Marcelo Rebelo de Sousa, was performed by researchers from IFIMUP-IN
The president of the Portuguese Republic, Prof. Marcelo Rebelo de Sousa, visited the Faculty of Sciences of the University of Porto to celebrate its 105th Anniversary. He visited several departments such as the Department of Physics and Astronomy, where researchers from the FEMTOLAB, one of the research Units of IFIMUP-IN, performed the hologram of the president (a three-dimensional laser picture). This technique was already used in 2003 to obtain the hologram of the president of the Republic Jorge Sampaio. 
More details about the president visit as well as the hologram techniques can 
be found out on the online video where Prof. Hélder Crespo, 
a member of IFIMUP-IN, was interviewed. 


Researchers from IFIMUP-IN published a scientific article on Triboelectric Nanogenerators in Nano Energy
A recent study on the development of an innovative type of triboelectric nanogenerators (TENGs) to effectively harvest water energy led by researchers from the Institute of Physics of Materials of the University of Porto (IFIMUP), located in the Faculty of Sciences of University of Porto and a member of the National Associate Laboratory Institute of Nanoscience and Nanotechnology (IN), was published on the prestigious Nano Energy journal (http://authors.elsevier.com/a/1TyTt7soS7iZxq).

Triboelectric nanogenerators are a new promising energy harvesting technology that has a simple working mechanism, produces high output power and has the ability of harvesting energy from a wide range of sources and under various conditions. In this research, the authors of the study developed a rotary triboelectric nanogenerator designed to harvest small-scale water energy in our normal living environment, using polytetrafluoroethylene (PTFE) and Nylon 6.6 as the pair of triboelectric materials. The operation mechanism of the fabricated rotary TENG is a hybridization of the contact and sliding modes by using the triboelectrification and electrostatic induction effects.

The optimization of the developed setup for the effective generation of electricity showed that the best configuration consists in a triboelectric structure with four Nylon and one PTFE plate for a water flow of 44 L/min. With this configuration, the rotary TENG delivers a mean voltage value of 102.2 V, a short-circuit current density 120 mA/m2 and a maximum power density of 6.1 W/m2. With this device, it was possible to light more than 50 serial-connected light emitting diodes, fully charge a 1.0 μF capacitor with 15.2 V in just 65 s and feed a commercial temperature and humidity sensor.

With small changes in the structure of the rotary TENG, it is possible to place the device in any environment (water pipelines, taps of housing, etc) because it was built to function as watertight. This guarantees a longer durability of the material because there is less wear and no influence on the triboelectrification effect by other external agents. The developed device can also be redesigned to work for very small water flows.

The results obtained in this research open the prospect for the future development and optimization of these devices, along with the possibility to apply them as autonomous sensors to monitor water supply systems that can work and send data using the energy produced by water movement in plumbing. Additionally, the rotary TENG can be miniaturized to apply this technology in the microfluidics field.

The authors acknowledge funding from FEDER and ON2 through projects Norte-070124-FEDER-000070, FSE/POPH and PTDC/CTM-NAN/3146/2014 and from FCT through the Associated Laboratory - IN.

18.11.2016 This is my text .

IFIMUP-IN researchers publish scientific article about Magnetically activated Thermal Switches in Nano Energy journal

A recent study on the development of an innovative magnetically activated thermal switch led by researchers from the Institute of Physics of Materials of the University of Porto (IFIMUP), located in the Faculty of Sciences of University of Porto and a member of the National Associate Laboratory Institute of Nanoscience and Nanotechnology (IN), was published on the prestigious Nano Energy journal (http://dx.doi.org/10.1016/j.nanoen.2016.11.031).

With the exponential rise of power dissipation in electric devices such as integrated circuits or micro/nano electro mechanical systems (MEMS/NEMS), new thermal management solutions are in high demand. Thermal switches, being devices capable of controlling the temperature flow between two surfaces, are one of the solutions capable of effectively tackling this problem.

In this research, the authors present an innovative magnetically actuated thermal switch based on nanofluids capable of controlling both the magnitude and direction of the heat flux. This device takes advantage of the thermal conductivity increase in magnetic nanofluids when submitted to an applied magnetic field parallel to the temperature gradient. The increase of thermal conductivity and the movement of the nanofluid inside the thermal switch prototype reduces the temperature gradient across the device.

The magnetically actuated thermal switch comprises of a thermally insulator body with two thermally conductive windows at the top and bottom. This forms a closed container where the magnetic nanofluid is confined. The device has two operating states (ON and OFF) depending whether heat is being transported between the two windows or not. In the OFF state no magnetic field is applied and the MNF remains in the bottom of the insulator cage (heat source). When an external magnetic field is applied (ON state), the MNF moves from the bottom of the insulator cage to the top surface, carrying the heat absorbed from the heat source and releasing it at the heat sink.

The researchers built two prototypes with different heights between the top and bottom (3 and 1 cm). Both devices were tested for a range of magnetic field frequencies between 0.01 and 30 Hz with an initial temperature gradient of approximately 35 ºC. The experimental results showed a clear dependence between operation performance and the thermal switch size. While the larger prototype showed a decrement in heat transport for frequencies above 10 Hz, the smaller one showed no operational frequency limitations up to 30 Hz. For the maximum temperature gradient variation it was calculated that the thermal conductivity variation between the ON and OFF stages was of 260%. Finally, the researchers tested the applicability of magnetically actuated thermal switch in the thermal management of a LED and demonstrated the possibility to enhance heat removal and control the LED maximum temperature.

With a novel operating principle, simple design, wide range of operating temperatures and the potential for downsize, it is expected that the presented magnetically actuated thermal switch can be adapted to numerous applications of thermal management such as light sources, electronic devices, bio-devices, thermal storage systems or magnetocaloric refrigerators.

The authors acknowledge funding from FEDER and ON2 through projects Norte-070124-FEDER-000070, FSE/POPH, EXPL/EMS-ENE/2315/2013 and PTDC/CTM-NAN/3146/2014 and from FCT through the Associated Laboratory - IN.