Examinando por Autor "Del Real, R. P."

Mostrando 1 - 8 de 8

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A Sol–Gel based magneto-optical device for the NANOSAT space mission
(Springer Link, 2009-03-31) Zayat, M.; Pardo, R.; Rosa, G.; Del Real, R. P.; Díaz Michelena, M.; Arruego, I.; Guerrero, H.; Levy, D.
On December 2004, the Spanish Space Agency INTA (Instituto Nacional de Técnica Aeroespacial) launched the first nanosatellite called NANOSAT (Fig. 1) on board an European rocket Ariane 5, from the French Guyana. The satellite consists of a hexagonal device of <19 kg of weight with a diameter of about 50 cm, which describes a LEO orbit of 655 km of altitude. The main objective of the satellite is to probe the operation and performance of micro- and nanotechnologies in space environment. One of the scientific experiments implemented on board was the Sol–Gel based magnetic nanosensor.
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Comparative performance of static-mode ferrous MEMS gradiometers fabricated by a three-step DRIE process
(IOP Science Publishing, 2010-05-21) Campanella, H.; Del Real, R. P.; Duch, M.; Guerrero, H.; Esteve, J.; Díaz Michelena, M.; Plaza, J. A.
Two MEMS structures—a cantilever beam and a quad-beam—have been designed and fabricated through a three-step deep reactive ion etching (DRIE) process. Devices feature target patterns to align with an external optical detection system and a micromachined cavity to embed an NdFeB hard mini-magnet, thus releasing the stress of structures. Structures are intended for magnetostatic gradient measurements. Induced magnetic fields generate an attracting force on the magnet that deflects the sensor. Deflection is optically detected through nanometer-resolution confocal microscopy. The static-mode sensitivity of up to 1.86 × 10−4 T m−1 demonstrates that MEMS gradiometers are able to perform in situ gradiometry with a single sensor and miniaturized size. Suitable techniques for integrated detection are discussed.
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Focused-Ion-Beam-Assisted Magnet Fabrication and Manipulation for Magnetic Field Detection Applications
(ACS Publications, 2009-02-16) Campanella, H.; Del Real, R. P.; Díaz Michelena, M.; Duch, M.; Guerrero, H.; Esteve, J.; Plaza, J. A.
A focused-ion-beam-assisted technique intended for ultrasmall, hard-magnet fabrication has been developed. By means of ion-beam-induced milling and deposition, reduced-size NdFeB magnets were extracted from a macroscopic quarry and bonded to the surface of a thin-film bulk acoustic resonator (FBAR). Electrical characterization of the FBAR before and after bonding of the magnet was carried out, thus observing both a downshifting of the resonance frequency and a reduction of the quality factor of the resonator. The magnetic behavior of the nanomagnet has been confirmed by means of magnetometry measurements based on atomic force microscopy.
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In situ MEMS gradiometer with nanometer-resolution optical detection system
(Elsevier, 2010-04-05) Campanella, H.; Del Real, R. P.; Duch, M.; Serre, C.; Lucas, I.; De Manuel, V.; Guerrero, H.; Esteve, J.; Díaz Michelena, M.; Plaza, J. A.
Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurements are presented. Suspended quad-beams with proof mass have been designed to improve their sensitivity and to simplify the detection. Fabricated devices exhibit the compact size of current MEMS technologies and are built within a simple deep-reactive-ion etching-based process. Nanometer-resolution detection based on optical interferometry and signal processing techniques have been employed to find out dynamic-mode transformation factors of 6.25 × 10−3 T/m/Hz with 0.1-Hz resolution. The device performs in situ gradiometry with a single-sensor structure, which represents a technological advance to current-art gradiometers.
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Magnetic giant magnetoresistance commercial off the shelf for space applications
(AIP Publishing, 2008-02-13) Díaz Michelena, M.; Oelschlägel, W.; Arruego, I.; Del Real, R. P.; Mateos, J. A. D.; Merayo, J. M.
The increase of complexity and miniaturizing level of Aerospace platforms make use of commercial off the shelf (COTS) components constitute a plausible alternative to the use of military or rad-tolerant components. In this work, giant magnetoresistance commercial sensors are studied to be used as COTS, the next missions to be launched in the framework of the Spanish National Space Program: OPTOS and SEOSAT. This technology of magnetic sensors is interesting due to their high operating range up to 2mT and the high temperature dynamic range from −50 up to 150°C. However, in contrast, it presents high hysteresis and nonlinearity, temperature dependence, and poor repeatability. To improve the hysteretic, nonlinear and nonrepetitive behavior, a method consisting of a combination of reset and biasing has been designed and implemented for the ±75𝜇T linear region centered around 300–375𝜇T biasing field.
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Magnetic Technologies for Space: COTS Sensors for Flight Applications and Magnetic Testing Facilities for Payloads
(Ingenta Connect, 2007-03-01) Díaz Michelena, M.; Del Real, R. P.; Guerrero, H.
The increasing trend of using Commercial of the Shelf components for Aerospace Applications makes Space Agencies open a brand new testing line devoted to the up-screening and characterization in extreme conditions of these "underqualified" components. The up-screening needs to deal with the tasks of degassing, temperature testing and thermal shock, vibration, ageing and stressing, and irradiation of the component under test. In this paper we report on the up-screening process, the previous magnetic characterization and the in-flight resulting data obtained with the magnetic sensors of NANOSAT-01 mission, one and a half years after the launch. The up-screening of the magnetic sensors used in this mission succeed. Their final in-flight qualification is on the road as the behavior of the sensors is nominal.
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Resonance frequency dependence on out-of-plane forces for square silicon membranes: Applications to a MEMS gradiometer
(Elsevier BV, 2010-09-12) Lucas, I.; Del Real, R. P.; Díaz Michelena, M.; De Manuel, V.; Duch, M.; Esteve, J.; Plaza, J. A.
The dynamic properties of membranes have been object of many researches since they can be used as sensor heads in different devices. Some methods have been proposed to solve the problem of determining the resonance frequencies and their dependence on the stress caused by forces applied on the membrane surface. The problem of the vibrating rectangular membrane under a stress caused by a uniform in-plane force is well known. However, the resonance frequency behaviour when the force is out-of-plane instead of in-plane, is not so well understood and documented. A gradiometer which uses a silicon square membrane with a magnet fixed on it as a sensor head has been developed in a previous work. This device reports a quadratic dependence of the frequency on the out-of-plane magnetic force. In this work, simulations to obtain the dependence of the frequency of the fundamental flexural mode on the stress have been performed. It has been studied the influence of in-plane and out-of-plane forces applied to the membrane. As expected, a square root dependence has been found for in-plane forces. Nevertheless, the problem is more complex when out-of-plane forces are considered. Out-of-plane forces give rise to an initial quadratic dependence which turns into a square root dependence from a certain stress value. The quadratic range increases and the rate of change of the frequency decreases as the surface of the magnet fixed on the membrane increases. The study has addressed these problems and both, experimental and simulated results have been compared and a good agreement between experimental and simulated results has been found.
Restringido
Resonance frequency dependence on out-of-plane forces for square silicon membranes: Applications to a MEMS gradiometer
(Elsevier, 2010-09-10) Lucas, I.; Del Real, R. P.; Díaz Michelena, M.; De Manuel, V.; Duch, M.; Esteve, J.; Plaza, J. A.
The dynamic properties of membranes have been object of many researches since they can be used as sensor heads in different devices. Some methods have been proposed to solve the problem of determining the resonance frequencies and their dependence on the stress caused by forces applied on the membrane surface. The problem of the vibrating rectangular membrane under a stress caused by a uniform in-plane force is well known. However, the resonance frequency behaviour when the force is out-of-plane instead of in-plane, is not so well understood and documented. A gradiometer which uses a silicon square membrane with a magnet fixed on it as a sensor head has been developed in a previous work. This device reports a quadratic dependence of the frequency on the out-of-plane magnetic force. In this work, simulations to obtain the dependence of the frequency of the fundamental flexural mode on the stress have been performed. It has been studied the influence of in-plane and out-of-plane forces applied to the membrane. As expected, a square root dependence has been found for in-plane forces. Nevertheless, the problem is more complex when out-of-plane forces are considered. Out-of-plane forces give rise to an initial quadratic dependence which turns into a square root dependence from a certain stress value. The quadratic range increases and the rate of change of the frequency decreases as the surface of the magnet fixed on the membrane increases. The study has addressed these problems and both, experimental and simulated results have been compared and a good agreement between experimental and simulated results has been found.