Embedded Files
28.11.2016
An hologram of the president of the Portuguese Republic, Marcelo Rebelo de Sousa, was performed by researchers from IFIMUP-IN
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.
By Hélder Crespo
18.11.2016
Researchers from IFIMUP-IN published a scientific article on Triboelectric Nanogenerators in Nano Energy
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.
By João Ventura & André Pereira
18.11.2016
IFIMUP-IN researchers publish scientific article about Magnetically activated Thermal Switches in Nano Energy journal
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.
By João Ventura & André Pereira
Report abuse