1,721,042 research outputs found
Effect of NiFeCr seed and capping layers on exchange bias and planar Hall voltage response of NiFe/Au/IrMn trilayer structures
No full textThin films and cross junctions, based on NiFe/Au/IrMn structures, were grown on Ta and NiFeCr seed layers by magnetron sputtering. The effects of substitution of Ta with NiFeCr in seed and capping layers on an exchange bias field are studied. A threefold improvement of the exchange bias value in the structures, grown with NiFeCr seed and capping layers, is demonstrated. The reasons for this effect are discussed. Formation of clusters in the NiFeCr capping layer is proved by atomic force microscopy technique. Ta replacement on NiFeCr in the capping layer results in the enhancement of magnetoresistive response and a reduction of noise. © 2018 Author(s).1
Equisensitive adjustment of planar Hall effect sensor's operating field range by material and thickness variation of active layers
No full textA novel technique of operating field range adjustment using varying thicknesses of spacer and capping layers is proposed for planar Hall effect (PHE) magnetic sensors. In terms of this technique, the spacer and capping layer thicknesses are varied interdependently, in a way that the variation of the operating magnetic field range is performed without a change of sensitivity. The relationship between the thicknesses of spacer and capping layers required for this 'equisensitive' variation of field range are calculated and experimentally approved. The active layer material substitution effect on the performance of PHE sensor is studied. The sensitivity, output voltage, operating field range, and shunt current are compared for PHE sensors, based on NiFe and NiFeMo active ferromagnetic layers. The NiFe/IrMn and NiFeMo/IrMn interface coupling energies are compared and the effect of IrMn crystallinity on their difference is discussed. The range of active layer thicknesses, at which the operating field range can be varied while maintaining the sensitivity at the same value, has been determined. © 2019 IOP Publishing Ltd.1
On-demand distributed energy-aware routing with limited route length
No full textIn ad hoc networks, energy preservation on communication is crucial because most of nodes are battery-powered. On the other hand, communication delay is an important factor of real-time communications. Since energy-aware routes commonly have long route lengths, which commonly result long communication delays, a trade-off has to be made on route setup between energy preservation and communication delay. Moreover, long route length also incurs high packet drop rate, which causes low reliability and high retransmission cost. We propose on-demand energy-aware route search algorithms with limited route length (ODEAR-LRL). ODEAR-LRL exploits timer-based RREQ flooding method. Even though timer based RREQ flooding does not guarantee the optimality, our evaluation shows that our on-demand algorithms fairly approximate to the optimal cost
Energy-aware routing with limited route length for multimedia applications
No full textIn ad hoc networks, energy preservation on communications is crucial because most of nodes are battery-powered. On the other hand, communication delay is an important factor of real-time communications. Since energy-aware routes commonly have long route lengths, which commonly result long communication delays, a trade-off has to be made on route setup between energy preservation and communication delay. Moreover, long route length also incurs high packet drop rate, which causes low reliability and high retransmission cost. We propose energy-aware route search algorithms with limited route length (EAR-LRL). We show that the computational complexities of the centralized version of our algorithms are polynomial. The simulation results show that EARLRL generates routes with limited route length with resonably low total transmission power
Planar Hall Resistance Sensor With Improved Thermal Stability
No full textHigh thermal stability of the planar Hall resistance (PHR) signal in magnetic sensors, configured as a cross-junction and as a Wheatstone bridge, has been demonstrated. The thermal drift of the PHR signal, which is proportional to the PHR offset at zero field, is few orders of magnitude less than the thermal drift of the anisotropic magnetoresistance signal. The thermal drift of the PHR originates from two independent components: baseline drift and signal amplitude drift. The temperature coefficient of baseline drift, normalized by zero-field offset, is similar to the temperature coefficient of resistance. This makes it possible to characterize drift in any temperature range by a single measurement of PHR under ambient conditions. Signal amplitude drift is shown to be dependent on a sensor's geometry, and becomes higher with a reduction of the width of the current path. The temperature coefficients of baseline drift and signal amplitude drift are of opposite sign. The possibility of mutual compensation of signal amplitude drift and baseline drift by a slight imbalance in a bridge-type sensor is demonstrated. © 2010-2012 IEEE.1
Highly sensitive electrochemical biosensor based on naturally reduced rGO/Au nanocomposite for the detection of miRNA-122 biomarker
No full textHerein, we have developed a novel high-resolution electrochemical biosensor for the detection of the microRNA-122 (miRNA-122) using gold nanoparticles dotted reduced graphene oxide (rGO/Au) nanocomposite. The natural soapnut solution was used as a reducing agent for the synthesis of the nanocomposite. The naturally reduced rGO/Au nanocomposite was confirmed through various characterization techniques. When rGO/Au nanocomposite was coated on to the gold electrode and checked the electrochemical performance, the nanocomposite shows superior analytical performance. The probe DNA was anchored onto the binding sites of rGO/Au nanocomposite through thiol linker and recognized the target miRNA-122. The developed rGO/Au based electrochemical biosensor demonstrated a linear response for various target miRNA-122 concentrations with a range from 10 μM to 10 pM and, with a detection limit of 1.73 pM. The developed biosensor also shows good stability and reproducibility, could be used for the detection of miRNA-122 and, also can be used for the basic research and clinical studies. Besides, the demonstrated rGO/Au nanocomposite-based sensing strategy could be used to detect various miRNA and protein biomarkers. Furthermore, the green synthesis approach could also be useful for the synthesis of various nanomaterials and nanocomposites for various biomedical applications. © 2020 The Korean Society of Industrial and Engineering Chemistry1
Highly Bendable Planar Hall Resistance Sensor
No full textA set of Planar Hall Resistance (PHR) sensors has been fabricated on rigid and flexible substrates. High signal-to-noise ratio, low offset voltage, nearly zero hysteresis of signal and excellent linearity has been demonstrated for sensors, based on Ta (5 nm)/NiFe (10 nm)/IrMn (10 nm)/Ta (5 nm) thin films, grown on PDMS and Parylene C polymeric substrates. Effect of bending on the performance of the PHR sensors has been studied. The effect of bending deformation on the performance characteristics of the fabricated PHR sensors is reversible until the bending angle reaches a critical one. The critical bending angle is shown to be dependent on the substrate composition. An irreversible deformation of sensor's film, accompanied by the formation of wrinkles and cracks, occurs when the bending angle exceeds the critical one. This deformation originates from the difference between the values of Young's modulus of the substrate and the film. The bending stability of PHR sensor, grown on PDMS substrate, has been improved by deposition of 1 μm of Parylene C both as a buffer and as a capping layer. The performance characteristics of the designed shapeable PHR sensors are compatible with requirements for applications in wearable electronics and medical diagnostic devices. IEEE1
Performance Validation of a Planar Hall Resistance Biosensor through Beta-Amyloid Biomarker
Full text linkMagnetic sensors have great potential for biomedical applications, particularly, detection of magnetically-labeled biomolecules and cells. On the basis of the advantage of the planar Hall effect sensor, which consists of improved thermal stability as compared with other magnetic sensors, we have designed a portable biosensor platform that can detect magnetic labels without applying any external magnetic field. The trilayer sensor, with a composition of Ta (5 nm)/NiFe (10 nm)/Cu (x = 0 nm~1.2 nm)/IrMn (10 nm)/Ta (5 nm), was deposited on a silicon wafer using photolithography and a sputtering system, where the optimized sensor sensitivity was 6 μV/(Oe∙mA). The detection of the magnetic label was done by comparing the signals obtained in first harmonic AC mode (1f mode) using an external magnetic field and in the second harmonic AC mode (2f mode) with a self-field generated by current passing through the sensor. In addition, a technique for the β-amyloid biomarker-based antibody-antigen sandwich model was demonstrated for the detection of a series of concentrations of magnetic labels using the self-field mode method, where the signal-to-noise ratio (SNR) was high. The generated self-field was enough to detect an immobilized magnetic tag without an additional external magnetic field. Hence, it could be possible to reduce the device size to use the point-of-care testing using a portable circuit system
Phase controlled one-pot synthesis of heterostructured FePt–Fe(3)O(4) nanocubes with excellent biocompatibility
No full textWe demonstrated a simple one-pot synthesis approach for the controlled composition of homogeneous FePt and phase-controlled heterostructured FePt/Fe(3)O(4) nanocubes (NCs) utilizing 1,2-hexadecanediol and 1-octadecene as the reducing agents, respectively. When the Fe : Pt precursor ratio was varied from 1 : 1 to 4 : 1 and 1,2-hexadecanediol was utilized as the reducing agent, homogeneous FePt NCs were formed, whereas the heterostructures of FePt/Fe(3)O(4) NCs were obtained when utilizing 1-octadecene as the reducing agent at Fe : Pt ratio of 4 : 1. The initial domination of nucleation of Pt-rich species and the subsequent deposition of Fe atoms leads to the formation of homogeneous FePt NCs. Heterostructured FePt/Fe(3)O(4) NCs were obtained by the initial FePt seed formation, which was then followed by the heterogeneous growth of Fe(3)O(4). The heterostructured FePt/Fe(3)O(4) NCs exhibited two phases, i.e., FePt phase with a (111) facet of the fcc and Fe(3)O(4) phase with an inverse cubic spinel structure. Moreover, both the FePt and the FePt/Fe(3)O(4) NCs demonstrated almost negligible coercivity, which confirmed a typical superparamagnetic behavior. Furthermore, the cell viability tests of the FePt and FePt/Fe(3)O(4) NCs demonstrated excellent biocompatibilities. Hence, the NCs could be useful for various biomedical applications, including MRI contrast agents, hyperthermia, and as a label in magnetic biochips
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