Nur Aji Wibowo, Juharni Juharni, Harsojo Sabarman, Edi Suharyadi

DOI: 10.1149/ 2162-8777/ac2d4e

Journal: ECS Journal of Solid State Science and Technology

Volume 10, October 2021, 107002

Abstract

The availability of rapid-portable instruments to monitor the bovine serum albumin (BSA) concentration is vital in the early detection of disease. In this research, an original biosensing method based on a spin-valve giant magnetoresistance as a transducer and magnetite@silver core–shell magnetic nanoparticles (MNPs) as a tag has been proposed for detecting BSA. The synthesized magnetite@silver MNPs tag size is ≈15 nm with ≈52 emu g−1 of saturation magnetization. This proposed biosensor performs rapid detection of BSA through the shifting of the switching magnetic field and the increasing of the output voltage. The effectivity of the sensor in monitoring the BSA concentration was shown by a strong linear correlation with ≈0.06 mV/(mg/ml) of the sensitivity and ≈0.44 mg ml−1 of the detection limit. Moreover, the measurement result can be acquired rapidly up to 1 min with low external magnetic field assistance. Therefore, this biosensing technique can be promoted as a real-time portable biosensor.

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Siti Amalia Sasmito, Muhammad Anshory, Ibnu Jihad, Moh. Adhib Ulil Absor

DOI: 10.1103/PhysRevB.104.115145

Journal : Physical Review B 104

Volume 104, September 2021, 115145

Abstract

The coexistence of ferroelectricity and spin-orbit coupling in noncentrosymmetric systems may allow for a nonvolatile control of spin textures in the momentum space by tuning the ferroelectric polarization. Based on first-principles calculations, supplemented with k⋅p analysis, we report the emergence of the reversible spin textures in the two-dimensional (2D) GaXY (Se, Te; Cl, Br, I) monolayer compounds, a new class of 2D materials exhibiting in-plane ferroelectricity. We find that due to the large in-plane ferroelectric polarization, unidirectional out-of-plane spin textures are induced in the topmost valence band having giant spin splitting. Importantly, such out-of-plane spin textures, which can host a long-lived helical spin mode known as a persistent spin helix, can be fully reversed by switching the direction of the in-plane ferroelectric polarization. We show that the application of an external in-plane electric field oriented oppositely to the in-plane ferroelectric polarization direction is an effective method to flip the orientation of the out-of-plane spin textures. Thus, our findings can open avenues for interplay between the unidirectional out-of-plane spin textures and the in-plane ferroelectricity in 2D materials, which is useful for efficient and nonvolatile spintronic devices.

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Edi Suharyadi, Taufikuddin Alfansuri, Lia Saptini Handriani, Nur Aji Wibowo, Harsojo Sabarman

https://doi.org/10.1007/s10854-021-06859-6

Journal: Journal of Materials Science: Materials in Electronics

Volume 32, August 2021, 23958–23967

Abstract

Simple Wheatstone bridge-giant magnetoresistance (GMR) sensors with one and two spin-valve (SV) thin films were developed for detecting magnetic nanoparticles (MNPs). SV thin films with a Ta(2 nm)/Ir20Mn80(10 nm)/Co90Fe10(3 nm)/Cu(2.2 nm)/(Co90Fe10)92B8(10 nm)/Ta(5 nm) structure were fabricated using RF magnetron sputtering on Si/SiO2 substrates. Inverse spinel-structured Fe3O4 and Fe3O4/polyethylene glycol (PEG) MNPs were synthesized by coprecipitation methods. To investigate the GMR sensor response, MNPs-ethanol (10 μL) solutions were dropped on the surface of the thin films. The following changes in Fe3O4 were observed after coating with PEG: the size of the nanoparticles increased from 11 to 13 nm, and the saturation magnetization of Fe3O4 decreased from 77.0 to 49.6 emu/g, which can be attributed to the surface modifications by PEG polymer; furthermore, the coercivity increased from 51.2 to 61.5 Oe owing to the existence of the antiferromagnetic phase α-Fe2O3. The output voltage of the GMR sensor with one and two SV thin film elements for Fe3O4 changed by 2.2 and 5.5 mV, respectively, and the output voltage decreased to 1.4 and 1.5 mV, respectively, in the case of Fe3O4/PEG. The decrease in the output voltage was caused by the decrease in the saturation magnetization of Fe3O4 after coating with PEG.

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Moh. Adhib Ulil Absor, Yusuf Faishal, Muhammad Anshory, Iman Santoso, Sholihun, Harsojo, Fumiyuki Ishii

DOI 10.1088/1361-648X/ac0383

Journal of Physics: Condensed Matter

Volume 33, June 2021, 305501

Abstract

The ability to control the spin textures in semiconductors is a fundamental step toward novel spintronic devices, while seeking desirable materials exhibiting persistent spin texture (PST) remains a key challenge. The PST is the property of materials preserving a unidirectional spin orientation in the momentum space, which has been predicted to support an extraordinarily long spin lifetime of carriers. Herein, by using first-principles density functional theory calculations, we report the emergence of the PST in the two-dimensional (2D) germanium monochalcogenides (GeMC). By considering two stable formation of the 2D GeMC, namely the pure GeX and Janus Ge2XY monolayers (X, Y = S, Se, and Te), we observed the PST around the valence band maximum where the spin orientation is enforced by the lower point group symmetry of the crystal. In the case of the pure GeX monolayers, we found that the PST is characterized by fully out-of-plane spin orientation protected by C2v point group, while the canted PST in the y–z plane is observed in the case of the Janus Ge2XY monolayers due to the lowering symmetry into Cs point group. More importantly, we find large spin–orbit coupling (SOC) parameters in which the PST sustains, which could be effectively tuned by in-plane strain. The large SOC parameter observed in the present systems leads to the small wavelength of the spatially periodic mode of the spin polarization, which is promising for realization of the short spin channel in the spin Hall transistor devices.

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Edi Suharyadi, Taufikuddin Alfansuri

https://doi.org/10.4028/www.scientific.net/KEM.884.348

Journal: Key Engineering Materials

Vol. 884, May 2021, 348-352

Abstract

The Wheatstone bridge-giant magnetoresistance (GMR) sensor with single and double spin valve thin film was successfully developed for potential biomolecular detection. The GMR sensor with spin valves structure of [Ta (2nm)/IrMn (10nm)/CoFe (3nm)/Cu (2,2nm)/CoFeB (10nm)/Ta (5nm)] was fabricated using DC Magnetic Sputtering method. The Fe3O4 magnetic nanoparticles were synthesized by the co-precipitation method as a magnetic label. The magnetic properties of the Fe3O4 nanoparticles measured are the saturation magnetization (Ms) of 77.7 emu/g, remanence magnetization (Mr) of 7.7 emu/g, and coercivity (Hc) of 49 Oe. The X-ray diffraction pattern showed the inverse cubic spinel structure with an average crystal size of about 20.1 nm. Fe3O4 magnetic nanoparticles with various concentrations were used to be detected using a GMR sensor. The output voltage of the GMR sensor with the single and double spin-valve increased from 1.7 to 3.9 mV and 2.9 to 5.3 mV with the increase of the Fe3O4 concentration from 0 to 20 mg/mL, respectively.

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Juharni Juharni, Ilyas Maulana, Edi Suharyadi, Takeshi Kato, Satoshi Iwata

https://doi.org/10.4028/www.scientific.net/KEM.884.337

Journal: Key Engineering Materials

Vol. 884, May 2021, 337-341

Abstract

The objective of this research is to advance the affectability of Surface Plasmon Resonance (SPR) biosensor utilizing core-shell Fe3O4@Ag nanoparticles (Fe3O4@Ag NPs) with a variation of Ag concentration (20, 40, 60, 80, 100) mM. Fe3O4@Ag NPs were synthesized by the aqueous solution method. The characterization by utilizing X-ray Diffractometer (XRD) depicts that the crystal structure of Fe3O4 compares to the cubic inverse spinel structure and based on Transmission Electron Microscopy (TEM) estimation, the particle size average of Fe3O4@Ag NPs is 14.45 nm. The magnetic properties of Fe3O4@Ag NPs were evaluated by Vibrating Sample Magnetometer (VSM), the result appears that the more concentration of Ag increases, the more remanent magnetization (Mr), saturation magnetization (Ms), and coercitivity field (Hc) diminishes. In this research, a Fe3O4@Ag NPs, a spherical nanoparticle consisting of a spherical Fe3O4 core covered by an Ag shell, was used as an active material to enhance the signal detection of SPR, with a wavelength of 632.8 nm in the Kretschmann configuration. The system consists of a four-layer material, i.e., prism/Au film/ Fe3O4@Ag NPs. The results show that the SPR angle shifted to the larger angle of incident light by using Fe3O4@Ag NPs. However, the effect of Ag concentration appears that the more concentration of Ag extends, the lower angle of SPR shifts. The addition of a core-shell in the conventional SPR-based biosensor leads to the enhancement of the SPR biosensor sensitivity if the fractional volume of the core-shell is large.

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Antonia Morita Iswari Saktiawati, Kuwat Triyana, Siska Dian Wahyuningtias, Bintari Dwihardiani, Trisna Julian, Shidiq Nur Hidayat, Riris Andono Ahmad, Ari Probandari, Yodi Mahendradhata

https://doi.org/10.1371/journal.pone.0249689

Journal : PLOS ONE

Volume 16, April 2021, 0249689

Abstract

Even though conceptually, Tuberculosis (TB) is almost always curable, it is currently the world’s leading infectious killer. Patients with pulmonary TB are the source of transmission. Approximately 23% of the world’s population is believed to be latently infected with TB bacteria, and 5–15% of them will progress at any point in time to develop the disease. There was a global diagnostic gap of 2.9 million between notifications of new cases and the estimated number of incident cases, and Indonesia carries the third-highest of this gap. Therefore, screening TB among the community is of great importance to prevent further transmission and infection. The electronic nose for screening TB (eNose-TB) project is initiated in Yogyakarta, Indonesia, to screen TB by breath test with an electronic-nose that is easy-to-use, point-of-care, does not expose patients to radiation, and can be produced at low cost.

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Sudarmaji Saroji, Ekrar Winata, Putra Pratama Wahyu Hidayat, Suryo Prakoso, Firman Herdiansyah

DOI: 10.13170/aijst.10.1.18749

Journal : Aceh International Journal of Science and Technology

Volume 10, April 2021, 9-17

Abstract

Lithofacies classification is a process to identify rock lithology by indirect measurements. Usually, the classification is processed manually by an experienced geoscientist. This research presents an automated lithofacies classification using a machine learning method to increase computational power in shortening the lithofacies classification process’s time consumption. The support vector machine (SVM) algorithm has been applied successfully to the Damar field, Indonesia. The machine learning input is various well-log data sets, e.g., gamma-ray, density, resistivity, neutron porosity, and effective porosity. Machine learning can classify seven lithofacies and depositional environments, including channel, bar sand, beach sand, carbonate, volcanic, and shale. The classification accuracy in the verification phase with trained lithofacies class data reached more than 90%, while the accuracy in the validation phase with beyond trained data reached 65%. The classified lithofacies then can be used as the input for describing lateral and vertical rock distribution patterns.

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Edi Suharyadi, Sri Handika Pratiwi, I Putu Tedy Indrayana, Takeshi Kato, Satoshi Iwata, Keisuke Ohto

https://doi.org/10.1088/2053-1591/abe986

Journal: Materials Research Express

Volume 8, March 2021, 036101

Abstract

Zn-Ni ferrite nanoparticles were successfully synthesized by coprecipitation method. The samples were annealed at various temperatures, i.e., 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C. The nanoparticles have the mixed spinel phase structure as confirmed by the X-ray diffraction patterns. The crystallite size was 15.1 nm and increased to 25.1 nm after annealing at 1000 °C. Transmission electron microscope images showed that the annealed sample exhibited better dispersion and grain boundaries compared to the as-prepared sample. Fourier transform infra-red spectra showed the existence of vibrations at 378 cm−1 and 555 cm−1, confirming bonding for mixed spinel ferrites. The hysteresis measurement by using vibrating sample magnetometer confirmed that the sample possessed soft magnetic properties with a coercivity of 45 Oe and increased after annealing. The saturation magnetization of the as-prepared sample was 11 emu g−1, and increased to 58 emu g−1 after annealing at a temperature of 800 and 1000 °C. The specific absorption rate (SAR)with an alternating current magnetic field (50 Hz and 100 Oe) of Zn-Ni ferrite before and after annealing (at 800 °C) was 63.7 and 92.4 mW g−1, respectively. The results showed that annealing temperature has a significant role in determining the microstructural, the magnetic properties and the SAR of the nanoparticles.

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Juharni, Ilyas Maulana Yahya, Edi Suharyadi, Takeshi Kato, Satoshi Iwata

Journal : International Journal of Nanoelectronics and Materials

Vol. 14, January 2021, 209

Abstract

The purpose of this study is to enhance the sensitivity of Surface Plasmon Resonance (SPR) sensor using coreshell Fe3O4@Ag nanoparticles (NPs). Fe3O4@Ag NPs were synthesized by co-precipitation method with various concentration of Ag as a shell. The crsytal structure of Fe3O4 corresponds to the cubic inverse spinel structure. The particle size of Fe3O4@Ag NPs with Ag concentration of 40mM is 13.8 nm. The saturation magnetization (Ms), and coercivity field (Hc) of Fe3O4@Ag NPs with Ag concentration of 20mM is 52.9 emu/g and 157.2 Oe, respectively, and then decreased with the increase of Ag concentration. An intensity of absorption peak increased with the increase of Ag concentration. A spherical nanoparticle consisting of a spherical Fe3O4 core covered by an Ag shell, was used as an active material to increase the signal detection of SPR, with a wavelength of 632.8 nm in the Kretschmann configuration. The system consists of a three-layer materials, i.e., prism/Au/Fe3O4@Ag NPs. The results show that the SPR angle shifted to the larger angle of incident light by using Fe3O4@Ag NPs and the addition of a core-shell in the conventional SPR-based biosensor leads to the enhancement of the SPR biosensor sensitivity.

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