Performance Validation of a Planar Hall Resistance Biosensor through Beta-Amyloid Biomarker

Does hypopharyngeal-esophageal multichannel intraluminal impedance-pH monitoring for the diagnosis of laryngopharyngeal reflux have to be 24 h?

PURPOSE

To investigate the diagnostic value of combined multi-timepoint salivary pepsin testing (MTPSPT) and hypopharyngeal-esophageal multichannel intraluminal impedance-pH monitoring (HEMII-pH) for laryngopharyngeal reflux (LPR) and whether an appropriate reduction in the duration of HEMII-pH would affect the accuracy of diagnosis of LPR.

METHODS

Recruited patients were studied with both MTPSPT and HEMII-pH. The diagnosis of LPR was based on the occurrence of > 1 reflux event and/or positive results on any of the MTPSPT. The diagnostic value of combined diagnosis was studied through combining a breakdown of the 24-h HEMII-pH finding and the results of the MTPSPT. The diagnostic value was expressed in terms of sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

RESULTS

Based on 24-h HEMII-pH and MTPSPT, the positive rate of LPR was 83.33% and 74.69%, respectively. According to the combined diagnosis, the positive rate of LPR was 90.74%. The sensitivity and specificity of the combined diagnosis both were 89.51% and 100%, when the HEMII-pH intervals were 7 a.m.-6 p.m. and 7 a.m.-7 p.m., respectively. However, when the monitoring time was extended to 8 p.m. and bedtime, the sensitivity, specificity, PPV and NPV of the combined diagnosis both were 100%.

CONCLUSIONS

The combination of MTPSPT and HEMII-pH increased the sensitivity and accuracy of diagnosis of LPR. For patients with positive MTPSPT results, the duration of HEMII-pH can be appropriately shortened to reduce patient sufferings.

Biological sensing using anomalous hall effect devices

This paper outlines an approach to biological sensing involving the use of spintronic devices to sense magnetic particles attached to biological carriers. We developed an enzyme-linked immunosorbent assay (ELISA)-based Anomalous Hall Effect magnetic sensor via surface functionalization using Triethoxysilylundecanal (TESUD). The proposed sensor uses a CoFeB/MgO heterostructure with a perpendicular magnetic anisotropy. Through several sets of magnetic layer thickness, this work also explored the optimization process of ferromagnetic layer used. Our spintronics-based biosensor is compatible with semiconductor fabrication technology and can be effectively miniaturized to integrate with semiconductor chips, which has the advantage of reduced manufacturing cost and reduced power consumption. The proposed sensor provides real-time measurement results and it is competitive to conventional biological colorimetric measurement systems in terms of accuracy and immediacy.

Solanaceous plants switch to cytokinin-mediated immunity against Ralstonia solanacearum under high temperature and high humidity

Plant diseases generally tend to be more serious under conditions of high temperature and high humidity (HTHH) than under ambient temperature, but plant immunity against pathogen attacks under HTHH remains elusive. Herein, we used pepper as an example to study how Solanaceae cope with Ralstonia solanacearum infection (RSI) under HTHH by performing RNA-seq combined with the reverse genetic method. The result showed that immunities mediated by salicylic acid (SA) and jasmonic acid (JA) in pepper roots were activated by RSI under ambient temperature. However, upon RSI under HTHH, JA signalling was blocked and SA signalling was activated early but its duration was greatly shortened in pepper roots, instead, expression of CaIPT5 and Glutathione S-transferase encoding genes, as well as endogenous content of trans-Zeatin, were enhanced. In addition, by silencing in pepper plants and overexpression in Nicotiana benthamiana, CaIPT5 was found to act positively in the immune response to RSI under HTHH in a way related to CaPRP1 and CaMgst3. Furthermore, the susceptibility of pepper, tomato and tobacco to RSI under HTHH was significantly reduced by exogenously applied tZ, but not by either SA or MeJA. All these data collectively suggest that pepper employs cytokinin-mediated immunity to cope with RSI under HTHH.

Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

The resolution of planar-Hall magnetoresistive (PHMR) sensors was investigated in the frequency range from 0.5 Hz to 200 Hz in terms of its sensitivity, average noise level, and detectivity. Analysis of the sensor sensitivity and voltage noise response was performed by varying operational parameters such as sensor geometrical architectures, sensor configurations, sensing currents, and temperature. All the measurements of PHMR sensors were carried out under both constant current (CC) and constant voltage (CV) modes. In the present study, Barkhausen noise was revealed in 1/f noise component and found less significant in the PHMR sensor configuration. Under measured noise spectral density at optimized conditions, the best magnetic field detectivity was achieved better than 550 pT/√Hz at 100 Hz and close to 1.1 nT/√Hz at 10 Hz for a tri-layer multi-ring PHMR sensor in an unshielded environment. Furthermore, the promising feasibility and possible routes for further improvement of the sensor resolution are discussed.

Bridge Resistance Compensation for Noise Reduction in a Self-Balanced PHMR Sensor

Advanced microelectromechanical system (MEMS) magnetic field sensor applications demand ultra-high detectivity down to the low magnetic fields. To enhance the detection limit of the magnetic sensor, a resistance compensator integrated self-balanced bridge type sensor was devised for low-frequency noise reduction in the frequency range of 0.5 Hz to 200 Hz. The self-balanced bridge sensor was a NiFe (10 nm)/IrMn (10 nm) bilayer structure in the framework of planar Hall magnetoresistance (PHMR) technology. The proposed resistance compensator integrated with a self-bridge sensor architecture presented a compact and cheaper alternative to marketable MEMS MR sensors, adjusting the offset voltage compensation at the wafer level, and led to substantial improvement in the sensor noise level. Moreover, the sensor noise components of electronic and magnetic origin were identified by measuring the sensor noise spectral density as a function of temperature and operating power. The lowest achievable noise in this device architecture was estimated at ~3.34 nV/Hz at 100 Hz.

Phase controlled one-pot synthesis of heterostructured FePt-Fe3O4 nanocubes with excellent biocompatibility

We demonstrated a simple one-pot synthesis approach for the controlled composition of homogeneous FePt and phase-controlled heterostructured FePt/Fe₃O₄ 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/Fe₃O₄ 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/Fe₃O₄ NCs were obtained by the initial FePt seed formation, which was then followed by the heterogeneous growth of Fe₃O₄. The heterostructured FePt/Fe₃O₄ NCs exhibited two phases, i.e., FePt phase with a (111) facet of the fcc and Fe₃O₄ phase with an inverse cubic spinel structure. Moreover, both the FePt and the FePt/Fe₃O₄ NCs demonstrated almost negligible coercivity, which confirmed a typical superparamagnetic behavior. Furthermore, the cell viability tests of the FePt and FePt/Fe₃O₄ 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.

We demonstrated a simple one-pot synthesis approach for the controlled composition of homogeneous FePt and phase-controlled heterostructured FePt/Fe₃O₄ nanocubes (NCs) utilizing 1,2-hexadecanediol and 1-octadecene as the reducing agents, respectively.

A Comprehensive Review of Integrated Hall Effects in Macro-, Micro-, Nanoscales, and Quantum Devices

A comprehensive review of the main existing devices, based on the classic and new related Hall Effects is hereby presented. The review is divided into sub-categories presenting existing macro-, micro-, nanoscales, and quantum-based components and circuitry applications. Since Hall Effect-based devices use current and magnetic field as an input and voltage as output. researchers and engineers looked for decades to take advantage and integrate these devices into tiny circuitry, aiming to enable new functions such as high-speed switches, in particular at the nanoscale technology. This review paper presents not only an historical overview of past endeavors, but also the remaining challenges to overcome. As part of these trials, one can mention complex design, fabrication, and characterization of smart nanoscale devices such as sensors and amplifiers, towards the next generations of circuitry and modules in nanotechnology. When compared to previous domain-limited text books, specialized technical manuals and focused scientific reviews, all published several decades ago, this up-to-date review paper presents important advantages and novelties: Large coverage of all domains and applications, clear orientation to the nanoscale dimensions, extended bibliography of almost one hundred fifty recent references, review of selected analytical models, summary tables and phenomena schematics. Moreover, the review includes a lateral examination of the integrated Hall Effect per sub-classification of subjects. Among others, the following sub-reviews are presented: Main existing macro/micro/nanoscale devices, materials and elements used for the fabrication, analytical models, numerical complementary models and tools used for simulations, and technological challenges to overcome in order to implement the effect in nanotechnology. Such an up-to-date review may serve the scientific community as a basis for novel research oriented to new nanoscale devices, modules, and Process Development Kit (PDK) markets.