Dr. Javier Martínez Rodrigo receives the Award for the Incorporation of Research Excellence to the UPM 2021.

Dr. Javier Martínez Rodrigo, ICTS Manager at the Institute of Optoelectronic Systems and Microtechnology (ISOM), has received the Award for the Incorporation of Research Excellence to the UPM 2021, according to the resolution of December 20, 2021 of the Rector of the Polytechnic University, which makes public the final list of beneficiaries of the Annual Call for Research and Innovation Awards in the framework of the Own Program of R+D+i 2021.

You can see the contents of the Rector’s Resolution in the following link:

https://www.upm.es/sfs/Rectorado/Vicerrectorado%20de%20Investigacion/ProgramaPropio/ProgramaPropio2021/PPI21_Premios_RD.pdf

Other ISOM Awards click on link

A novel design of a racetrack memory based on functional segments

Speaker: Dr. Javier Rial
Organization: Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), de la E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid.

Data:  December 17th, 2021.
Hours: 10.00 hours.
Place: Room B-222 of the ETSI of Telecommunications of the UPM [Cómo llegar]

ABSTRACT

A racetrack memory is a device where the information is stored as magnetic domains (bits) along a nanowire (track). To read and record the information, the bits are moved along the track by current pulses until they reach the reading/writing heads. In particular, 3D racetrack memory devices use arrays of vertically aligned wires (tracks), thus enhancing storage density. In this work, we propose a novel 3D racetrack memory configuration based on functional segments inside cylindrical nanowire arrays. The use of selective magnetic segments inside one nanowire allows the creation of writing and storage sections inside the sametrack, separated by chemical constraints identical to those separating the bits.

The epitaxial growth of InAs/GaAs quantum dots for optoelectronic devices

Speaker: D. Lazar Stanojevic
Organization: Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), de la E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid.

Data:  December 3rd, 2021.
Hours: 10.00 hours.
Place: Room B-222 of the ETSI of Telecommunications of the UPM [Cómo llegar]

ABSTRACT

Quantum dots (QDs), which are usually seen as artificial atoms (nanocrystals, zero-dimensional nanostructures) in general have attracted a lot of attention of the scientific community due to, on one hand, a wide range of possibilities to tune their optical and other properties, and on the other hand, their incredibly diverse potential for applications that includes biology and medicine, so as optoelectronics, or more specifically, LEDs, laser diodes, single electron transistors (SETs), quantum computing, displays, photodetectors, photovoltaics etc.. Apart from colloidal QDs, which are more commonly studied, the epitaxially grown semiconductors InAs/GaAs QDs have been specially investigated for optoelectronic applications. Here I present the key tunability features and the most recent breakthroughs in InAs QD tunability, so as their potential applications in the field of photovoltaics.

It is on the cover of UPM News of 22.11.2021. Bone cements with graphene to increase the quality of life of our elders.

The results of a study conducted by researchers at the Polytechnic University of Madrid reveal that the addition of reduced graphene oxide improves the mechanical and thermal properties of bone cements used to fix prostheses.

22.11.2021.

Bone cements are materials used as adhesives to fix bone prostheses (hip, knee, shoulder…) when the quality of the patient’s bone is insufficient. However, since their manufacturing process reaches high temperatures, they can cause necrosis in the patient’s surrounding tissues. Adding highly reduced graphene oxide helps to avoid this problem and also improves the mechanical and thermal properties of the materials, according to a study carried out by researchers at the Polytechnic University of Madrid (UPM). Given that this type of surgery (insertion of prostheses fixed with bone cements) is mostly performed on the elderly, improvements in its implementation have a growing social and health impact on our society.

 

The implantation of prostheses is an increasingly common practice throughout the world, due to causes such as the increase and aging of the population, and to a higher incidence of pathologies such as obesity or osteoarthritis. Bone cements are used to adhere and fix prostheses to the damaged bone when the bone does not have sufficient mechanical resistance and is unable to grow over the prosthesis and stabilize it. In addition, these bone cements distribute the loads on the bone and help to cushion the stresses at the prosthesis-bone junction.

However, this material has some limitations. Let us imagine that the maximum life of this bone cement is 20 years, and that statistically it is too risky to operate on people over 85 years of age. Thus, after that age, it would no longer be appropriate to repair a prosthesis whose materials have deteriorated. Therefore, a 65-year-old patient who is implanted with a hip prosthesis fixed to the bone with a bone cement will be exposed to the risk of the bone cement degrading or breaking, due to cracks that grow slowly over time, which would cause discomfort for the rest of his or her life because a new surgery is not feasible.

“Improving the durability of these bone cements is essential to improve the quality of life of our elders. In other words, to prevent them from having to endure an existence with chronic pain due to the broken prosthesis,” says José Ygnacio Pastor, a researcher at the UPM who participated in the study.

In the research conducted by members of the Center for Research in Structural Materials (CIME) of the UPM, several materials have been developed with potentially interesting results, such as reducing the maximum curing temperature that damages adjacent tissues.

“So far we have mainly talked about the mechanical strength and durability of bone cement. However, there are more problems associated with the use of these cements in the human body,” says Jaime Orellana, a member of the research team that carried out the work. The usual cements are made up of two components, which, once they come together, begin to react and harden. During this reaction the material solidifies rapidly, and there are only a few minutes to place it between the bone and the prosthesis. In addition, a lot of energy is released during this reaction that reaches the surrounding tissues. Since at 42⁰C and above the proteins denature, if the bone gets too hot the cells die and necrosis of the tissue surrounding the prosthesis occurs. Thus, “it is essential to prevent the bone from heating up, a result we have achieved by slowing down the reaction thanks to the addition of highly reduced graphene,” continues Orellana.

Regarding the mechanical properties mentioned above, the researchers have found that adding an excess of graphene is detrimental and worsens them, but small amounts (between 0.01 % and 0.1 % by weight) could also produce improvements in mechanical properties while maintaining the thermal benefit.

Expectations for these new materials are very promising, as there are also indications that graphene has antibacterial properties, which is ideal for reducing infection problems after surgery. “However, much work remains to be done, since not only must the amount of graphene to be introduced be optimized, but also the chemical treatments that allow the graphene to adhere and disperse better in the bone cement must be studied,” the researchers conclude.

Jaime Orellana, Ynés Yohana Pastor, Fernando Calle and José Ygnacio Pastor. Influence of HRGO Nanoplatelets on Behaviour and Processing of PMMA Bone Cement for Surgery. Polymers (Basel). 2021 Jun; 13(12); DOI: 10.3390/polym13122027.

Ynés Yohana Pastor, Jaime Orellana, Miguel Sánchez-Lozano, Fernando Calle and José Ygnacio Pastor. Physical-Mechanical Behaviour and Processing Evolution of PMMA Bone Cement due to Graphene Addition. Biomedical Journal of Scientific & Technical Research. April, 2021, Volume 35, 1, pp 273

 

POOM

«Óptica Planar con Metamateriales basados en Óxidos: Diseño y procesado de componentes ópticos».

Entidad: Ministerio de Ciencia, Innovación y Universidades. Código:  PID2020-114796RB-C21 (2021-2024). IP: Dr. Adrián Hierro Cano

MAGNATES

«Conmutación magnética en nanoestructuras bajo la influencia de interacciones acústicas, térmicas y de superficie»

Entidad: Ministerio de Ciencia, Innovación y Universidades. Código: PID2020-117024GB-C42  (2021-2024). IP: Dr. José Luis Prieto Martín

How tunnel junctions changed our perception of III-N optoelectronic devices. III-N micro-LEDs

Speakers: M.Sc. Julia Sławińska and Prof. Czesław Skierbiszewski.
Organism:  Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw. Poland.
Date: 16th November, 2021
Time: 12.00h.
Place: Salon de Grados, Building A.

ABSTRACT

Poor conductivity of the ptype region and difficulties with processing of low resistance ohmic ptype contacts are the most challenging issues to address in nitride based devices. Recently, there has been increasing attention given to the interband tunnel junctions (TJs) for efficient carrier conversion between ntype and ptype material region in nitride devices. Application of TJs eliminates the need for ptype contact deposition and create more freedom in device design. It was clearly demonstrated that TJs resistance for wide bandgap semiconductors can be effectively reduced by making use of the piezoelectric fields in the region of the junction. However, for metalorganic vapour phase epitaxy (MOVPE) it is difficult to activate the ptype conductivity in the (In)GaN:Mg layers which are buried below ntype layers due to the fact that diffusion of hydrogen is completely blocked through ntype region. On the other hand, for plasma assisted molecular beam epitaxy (PAMBE) ptype doping is achieved without post growth activation process. Therefore, PAMBE seems to be better suited than MOVPE for practical realization of the vertical devices with buried ptype regions especially for devices containing interband TJs. In this work we will show current status of IIIN TJs grown by PAMBE. Application of TJs enabled us to demonstrate novel types of IIIN devices, like: (1) vertically integrated light emitting diodes (LEDs) or laser diodes (LDs), (2) distributed feedback LDs. We will discuss in detail the inverted LED structures, operating at cryogenic temperatures. These LEDs contain the TJs below active region, which allow to reverse electric polarization of the diode. The application of TJs opens a possibility for novel architecture of microLEDs. We show an alternative method of nitride microLEDs fabrication, where emission surface was defined by size of the TJ embedded inside diode. MicroLEDs and arrays of microLEDs will be presented.

Laser pyrolisis for energy storage

Speaker: D. Andrés Velasco.
Organization: Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), de la E.T.S.I. Telecomunicación, Universidad Politécnica de Madrid.

Data:  November 12th, 2021.
Hours: 10.00 hours.
Place: Room B-222 of the ETSI of Telecommunications of the UPM [Cómo llegar]

ABSTRACT

Energy storage is called to be one of the enablers of the full connectivity of the modern world. We all want all-day (or all-week!) battery life for our smartphones and gadgets, but there’s much more to it. Supercapacitors, in contrast to batteries, can be used to power low energy devices with a virtually infinite lifetime, and with new fabrication techniques such as laser pyrolysis, graphene electrodes can be made in a low cost and quick way. Interconnected sensor networks, wearable electronics and other IoT applications, including health, will benefit soon from the application of these graphene supercapacitors, but still some challenges must be overcome.