Eduardo Fernández

BCMaterials - Basque Center for Materials, Applications and Nanostructures | BCMaterials

Incorporation of ionic liquids into ZIF-8 pores to obtain solid-ionic conductors that work as active layers in printed gas capacitive sensors to detect water and non-methane volatile organic vapours.

Functional electrospun fibers incorporating ionic liquids (ILs) present a novel approach in the development of active microenviroments due to their ability to respond to external magnetic fields without the addition of magnetic particles. In this context, this work reports on the development of magnetically responsive magneto-ionic fibers based on...

In article number 2010703, Eduardo Fernandez, Stefan Wuttke, Roberto Fernández de Luis, and co‐workers create a 2D printed capacitive gas sensor based on a metal‐organic framework (MOF)/ionic liquid (IL) composite material. Encapsulation of the IL within porous MOFs leads to solid porous ionic conductors that exhibit fast and repetitive electrical...

Smartphones are becoming increasingly versatile thanks to the wide variety of sensor and actuator systems packed in them. Mobile devices today go well beyond their original purpose as communication devices, and this enables important new applications, ranging from augmented reality to the Internet of Things. Personalized diagnostics is one of the a...

In this paper, the potential of 2D printing technologies to create thin film gas sensors from ionic liquid (IL)/metal–organic framework (MOF) composites is evaluated. To accomplish this, the MOF is synthesized solvothermally, and impregnated with the IL. The structure and basic properties of the IL/MOF composites are characterized using thermal, sp...

Multifunctional materials with sensor and actuator capabilities play an increasing role in modern technology. In this scope, hybrid materials with magnetic sensing and an electromechanical actuator response based on magnetic ionic liquids (MILs) and the polymer poly(vinylidene fluoride) (PVDF) have been developed. MILs comprising different cation a...

Thermoactive materials changed minds in smart materials research some years ago, resulting in a generation of new high-performance materials and an increased focus on controlling structure, flexibility and smart output, as well as implementation into device applications. Particularly, thermoelectric (TE) and thermomagnetic (TM) materials have been...

The work details the experimental and numerical methodologies followed for a better characterization of the thermoelectric/thermomagnetic phenomena and the impact that these effects can have on the measurement conditions of highly sensitive measuring equipment’s. It is, also, proposed a thermomagnetic numerical analysis procedure for the quantifica...

Arrays of 14 nm thick L10-FePt nanodots with diameter of 27 nm and center-to-center spacing of 39 nm were produced by block copolymer patterning of a FePt film and their magnetic reversal and thermal stability were characterized. A self-assembled polystyrene-b-polydimethylsiloxane diblock copolymer film was used as a lithographic mask and a pattern...

Dense arrays of pillars, with diameters of 64 and 25 nm, were made from a perpendicular CoFeB magnetic tunnel junction thin film stack using block copolymer lithography. While the soft layer and hard layer in the 64 nm pillars reverse at different fields, the reversal of the two layers in the 25 nm pillars could not be distinguished, attributed to...

Ferrogels are composite materials widely introduced in the area of biomedical engineering as magnetic field sensitive transformers. These biomimetic materials can be prepared by incorporating monodomain magnetic nanoparticles into chemically crosslinked hydrogels. The properties of a biomimetic ferrogels taken for the study unlike that of the biolo...

Magnetoimpedance has been proposed as a sensible detection method for quantifying the concentration of magnetic micro- and nano-particles. The use of samples with severe surface roughness, induced by acid treatments, seems to enhance the detection power. Here we clarify the role of surface modification in the detection of magnetic particles and fer...

The self-assembly of block copolymers with large feature sizes is inherently challenging as the large kinetic barrier arising from chain entanglement of high molecular weight polymers limits the extent over which long-range ordered microdomains can be achieved. Here, we illustrate the evolution of thin film morphology from a diblock copolymer of po...

Magnetoimpedance sensitive element that consists of one FeNi[125 nm]/Cu[3 nm])3FeNi[125 nm]/Cu[500 nm]/(FeNi[125 nm]/Cu[3 nm])3/FeNi[125 nm] multilayered structure was designed for the magnetic field detection in the wide range angular interval and its magnetoimpedance was measured experimentally. Double rectangle sensitive element with improved pe...

The magnetic and magnetoimpedance (MI) properties of a Permalloy-based thin-film structure, deposited onto a polymeric flexible substrate, are investigated as a function of the applied stress. The selected structure, a sandwich of NiFe/Ti multilayers with a central Cu layer, has been previously shown to produce extraordinary MI performance when dep...

In this work we have developed low-cost, renewable and sustainable materials based on cellulose for electronic applications. The UV-Vis spectroscopy, water contact angle and differential scanning calorimetry results reveal a marked effect of absorbed water on the physical properties of cellulose nanopaper. Morphological observations reveal that the...

Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their str...

The detection limit of thin film giant magneto-impedance (GMI) magnetic sensors has been investigated by measuring their magnetic noise. The GMI sensing elements are multilayers based on Fe20Ni80 Permalloy (Py), deposited by sputtering and patterned by photolithography in the form of 2-mm long and 50- to 130- $mu text{m}$ wide stripes. The multilay...

Thin-film based magnetoimpedance (MI) sensors were used for quantitative determination of the concentration of magnetic nanoparticles (MNPs) in ferrogels. Ferrogels (model systems for biological tissue) were synthesized by radical polymerization of acrylamide in a stable aqueous suspension of γ-Fe2O3 MNPs fabricated by laser target evaporation. MI...

The Magneto-impedance (MI) effect accounts for the large change of the electrical impedance experienced by soft magnetic materials when a magnetic field modifies its magnetic permeability. MI and related phenomena have been extensively studied in different soft magnetic materials with varied shapes and configurations for a wide range of frequencies...

Development of accurate measuring techniques is an important task for the high-frequency materials characterization. The magnetoimpedance (MI) of [Py(170 nm)/Ti(6 nm)]3/Cu(250 nm)/[Ti(6 nm)/Py(170 nm)]3 multilayer sandwiched structures is measured using two different high-frequency test fixtures and the results are compared for both cases. Sets of...

The detection limit of thin film giant magnetoimpedance (GMI) magnetic sensors has been investigated by measuring their magnetic noise. Samples were patterned by photolithography from sputtered multilayers, in the form of stripes with lengths of 0.5 to 2 mm and widths of 50 to 130 μm. The layer structure [Ni80Fe20(170nm)/Ti(6nm)]3 /Cu(250nm)/[Ti(6n...

The outstanding properties of selected soft magnetic materials make them successful candidates for building high performance sensors. In this paper we present our recent work regarding different sensing technologies based on the coupling of the magnetic properties of soft magnetic materials with their electric or elastic properties. In first place...

Giant magnetoimpedance (GMI) [FeNi/Cu]4/FeNi/Cu/[FeNi/Cu]4/FeNi sensing meander elements were designed and tested aiming to develop a new instrumentation for characterization of polymer/magnetic nanoparticles composites. Acrylic copolymer of 95% of butyl methacrylate and 5% of methacrylic acid was used as polymer matrix of the composite. It was sho...

We describe a method to determine the magnetic anisotropy distribution in thin films based on Kerr magnetometry, well adapted for single micro- and nanostructures. When the sample is excited by an ac field of small amplitude, for each value of a longitudinal dc field H, the second harmonic of the Kerr signal gives the contribution of the correspond...

The sensitivity of magnetic sensors based on the Giant Magneto-Impedance effect can be enhanced using high permeability materials with a well-defined but small transverse anisotropy. We describe an experimental study performed on multilayered, permalloy-based thin films deposited by sputtering under a magnetic field that produces a homogeneous unia...

Nanostructured multilayers are proposed as a competitive alternative to magnetoimpedance (MI) thick films. However, the effect of the thickness of the magnetic layers on the properties of MI multilayers is still unclear. To perform a systematic study, three multilayered structures consisting of magnetic Fe20Ni80 layers and nonmagnetic Ti layers wer...

We propose a detailed design of a reluctance position sensor for determining the penetration of the welding tool in a friction stir welding machine. It functions by sensing the variations of the inductance of a coil due to the changes in the gap of the magnetic circuit created by the welding tool and the working bench. Intensive finite element simu...

The suitability of a thin film multilayer with good magneto-impedance properties to be used as sensible element in geomagnetic detection devices is evaluated. The sensitivity to changes in the orientation of the Earth magnetic field is carefully determined using a specially designed experimental set-up. The performance of the sensor in a Wheatstone...

Magnetic [FeNi (170 nm)/Ti (6 nm)]3/Cu (L(cu) = 250 or 500 nm)/[Ti (6 nm)/FeNi (170 nm)]3 multilayers were designed with focus on high frequency applications. They were deposited onto glass or a microfluidic system compatible flexible Ciclo Olefin Copolymer substrate and comparatively tested. A maximum sensitivity for the total impedance of 110%/Oe...

The role of the geometrical parameters was studied for thin film based [FeNi (100 nm)/Cu (3 nm)]4/FeNi (100 nm)/Cu (500 nm)/[FeNi (100 nm)/Cu (3 nm)]4/FeNi (100 nm) magnetoimpedance elements with open magnetic flux prepared by lithography technique. The maximum magnetoimpedance sensitivity of 17 %/Oe was obtained for meander shaped sample, exceedin...

Nanostructured FeNi-based multilayers are very suitable for use as magnetic sensors using the giant magneto-impedance effect. New fields of application can be opened with these materials deposited onto flexible substrates. In this work, we compare the performance of samples prepared onto a rigid glass substrate and onto a cyclo olefin copolymer fle...

The microstructure and magnetic properties of sputtered permalloy films and FeNi(170 nm)/X/FeNi(170 nm) (X = Co, Fe, Gd, Gd-Co) sandwiches were studied. Laminating of the thick FeNi film with various spacers was done in order to control the magnetic softness of FeNi-based multilayers. In contrast to the Co and Fe spacers, Gd and Gd-Co magnetic spac...

We describe our experience in design, fabrication and advanced characterization of highly sensitive $[{\rm FeNi/Ti}]$- and $[{\rm FeNi/Cu}]_{\rm n}/{\rm Cu}$-based magnetoimpedance multilayers deposited by rf-sputtering onto rigid and flexible substrates. In order to avoid the transition into “transcritical” state and to keep both the low coercivit...

The magnetoimpedance effect is attractive for thin film-based magnetic sensor applications. Recently a significant progress has been made in the development of appropriate theories, preparation and characterization of MI thin film-based structures. In the present work multilayered structures with open magnetic flux have been prepared by rf-sputteri...

Magnetic multilayers consisting of magnetic FeNi and non-magnetic Ti layers were prepared by rf-sputtering. Magnetic measurements and magnetic domain structure observations were used for characterization of the samples. The magnetoimpedance performance of FeNi/Ti-based multilayers is evaluated in terms of the magnitude of the effect and its sensiti...

We describe a microfluidic device for the determination of the concentration of magnetic micro- and nanoparticles, under continuous flow of the carrier fluid, by means of the Giant Magneto-Impedance effect (GMI). The microfluidic chip is composed of a 10 μl chamber situated on top of the GMI sensing material, which is inserted in a microstrip trans...

FeNi films were deposited by DC magnetron sputtering at different Ar pressures. The structure and magnetic properties of the FeNi films are affected by the Ar pressure. Ferromagnetic resonance (FMR) measurements were done at a frequency of about 8.85 GHz. Both the value of resonance field and resonance line width show strong dependence on the Ar pr...

Magnetic properties and the magnetoimpedance (MI) effect were studied for a series of [ Fe ₂₀ Ni ₈₀/ Ti ]_n/ Fe ₂₀ Ni ₈₀ ( n =0 to 5) nanostructures, prepared by dc magnetron sputtering. The thickness of the FeNi layers was selected as 170 nm in order to avoid the appearance of the “transcriti...

The performance of the magnetoimpedance effect in terms of magnitude and sensibility is evaluated for two FeNi/Cu/FeNi multilayer structures with different geometries, such that in one of them the magnetic layers are in contact at the edges, presenting a closed magnetic path that is absent in the other. Magnetization measurements by Kerr effect and...