Micro-electrochemical capacitors: Progress and future status

Self-powered energy autonomy drives the sustainable operation of miniaturized electronics and wireless sensor networks in the current era of emerging internet of things (IoTs). Development and integration of on-chip energy storage with the harvesting modules enables autonomous functioning of microsensors for health tracking and environmental monitoring among many other micro-world requirements. By the virtue of high-power density, ultrahigh rate capabilities and longevity, microsupercapacitors (MSCs) turn out to be the maintenance-free micro-power sources. In this review, we discuss major breakthroughs in the field of MSCs over the past decade in terms of fabrication techniques, processing of electrode materials towards achieving optimal electrochemical performance metrics. The essence of moving from two-dimensional (2D) to three-dimensional (3D) electrode designs, symmetric to asymmetric devices and hybrid metal-ion capacitors is emphasized. Energy harvesting by solar, vibrational, and wireless charging show promise in developing self-powered MSCs in compatible manner. The design of MSCs for alternating current line-filtering applications, which potentially replace bulky low energy density electrolytic capacitors is highlighted. Scalable manufacturing of MSCs, ease of integration and packaging open the avenues for the maintenance-free operation of remote sensors, biomedical implantable chips, and wearable electronic gadgets in a self-sufficient manner. © 2022 Elsevier Lt

Use of intravenous immunoglobulin to successfully treat COVID-19 associated encephalitis

A 58-year-old male patient presented our emergency department with symptoms of fever and cough of one-week duration. CT scan images of the patient’s chest were suggestive of “Coronavirus disease 2019 Reporting and Data System” score of 5, CT severity score of 16 out of 25, and an oxygen saturation of 95% with a positive reverse transcription polymerase chain reaction test for SARS-CoV-2. The patient was administered medications Remdesivir and Methylprednisolone as per the guidelines. He developed altered sensorium during his stay in the hospital and was electively intubated. MRI of the Brain (Plain and Contrast) showed bilateral cerebellar, parieto-occipital hyperintensities on T2/fluid-attenuated inversion recovery mode. Cerebrospinal fluid (CSF) showed five cells (100% lymphocytes), normal protein and glucose. The patient was non-responsive to the standard COVID management guidelines. In suspicion of viral encephalitis/acute disseminated encephalomyelitis, intravenous immunoglobulins (IVIG) were administered for five days. A steady improvement was observed in the patient’s sensorium over a period of seven days following IVIG therapy, and the patient was able to walk with support following infusion. This case report suggests the possibility of an immune-mediated encephalitis with COVID-19 and the beneficial role of IVIG in treating the same

Ultrahigh-Rate Supercapacitors Based on 2-Dimensional, 1T MoS2xSe2(1-x) for AC Line-Filtering Applications

Motivated by the presence of metallic conductivity in the group VI transition metal dichalcogenides, the supercapacitive performance of the 1T phase of molybdenum (MoS2xSe2(1-x))) sulfoselenides is explored. Ultrahigh frequency response (similar to 1.4 kHz) along with excellent electrochemical stability are exhibited by 1T MoS2xSe2(1-x)-based super capacitors. The S:Se ratio in the mixed chalcogenide is shown to influence the rate performance of the device. High areal capacitances of similar to 450 mu F cm(-2) with short RC time constants of similar to 1.3-3.2 ms at 120 Hz are achieved in the case of 1T MoSSe phase. The i-v characteristics are almost rectangular at very high scan rates of similar to 1000 V s(-1). Very stable gravimetric specific capacitance of similar to 36 F g(-1) is retained for several thousands of charge-discharge cycles leading to an energy density of similar to 12.1 Wh kg(-1) at a specific power of similar to 842 W The observed specific power of similar to 50 kW kg(-1) at similar to 1.5 Wh kg(-1) energy density makes the sulfoselenide phase capacitors attractive for high power applications without compromising on the energy density

Alternate to Molybdenum Disulfide: A 2D, Few-Layer Transition-Metal Thiophosphate and Its Hydrogen Evolution Reaction Activity over a Wide pH Range

A two-dimensional, few-layer nickel thiophosphate, NiPS3, was introduced as a hydrogen evolution reaction catalyst from aqueous acidic, alkaline, and neutral solutions. NiPS3 is semiconducting in nature, and its band structure calculations revealed the importance of the P2S6](4-) units in the adsorption of hydrogen and subsequent evolution. Onset potentials of -0.062, -0.065, and -0.298V versus RHE were observed in acidic, alkaline, and neutral media. Tafel slopes of 55, 48, and 94mVdec(-1) and exchange current densities of 1.8x10(-4), 6.1x10(-4), and 3.2x10(-5)Acm(-2) were observed in aqueous 0.5m H2SO4, 1m KOH, and 3.5% NaCl solutions, respectively. The catalyst was found to be very stable, and the constituting elements are earth abundant. The present study opens up a new class of semiconducting layered materials to catalyze various redox reactions. Achieving a single layer will be of great interest to electrical and magnetic devices

Two-dimensional, few-layer NiPS3 for flexible humidity sensor with high selectivity

Chemically and electrically sensitive two-dimensional (2D) nanomaterials are of immense interest as probing electrodes for wearable electronic devices. A new family of two dimensional (2D) layered materials, namely metal phosphochalcogenides (MPX3), are potential candidates towards the development of sensors for various analytes. Herein, we demonstrate the ability of few-layer NiPS3 nanosheets for humidity sensing by fabricating a cost-effective, flexible sensor device. The results indicate that the NiPS3 nanosheet-based humidity sensors possess high sensitivity with a responsivity of similar to 10(6), superior selectivity, and most importantly, rapid response, recovery times and good reproducibility. Response times of similar to 1-2 s at low humidity levels and similar to 3 s at high humidity levels with recovery times of similar to 2-3 s are observed. The device was tested in both flat and bent states, causing no prominent changes in the response; hence, the sensor is an excellent candidate for use in flexible devices. The characteristics of the NiPS3-based sensor were further investigated using complex impedance studies and in situ Raman spectroscopy to understand the sensing mechanism. The fast response and recovery associated with the NiPS3-based humidity sensors allow real time monitoring of human respiration and water evaporation on skin. These humidity sensors can also be utilized for non-contact analysis and hence will be an attractive candidate for health and environmental monitoring

Colloidal europium nanoparticles via a solvated metal atom dispersion approach and their surface enhanced Raman scattering studies

Chemistry of lanthanide metals in their zerovalent state at the nanoscale remains unexplored due to the high chemical reactivity and difficulty in synthesizing nanoparticles by conventional reduction methods. In the present study, europium(0) nanoparticles, the most reactive of all the rare earth metals have been synthesized by solvated metal atom dispersion (SMAD) method using hexadecyl amine as the capping agent. The as-prepared europium nanoparticles show surface Plasmon resonance (SPR) band in the visible region of the electromagnetic spectrum. This lead to the investigation of its surface enhanced Raman scattering (SERS) using visible light excitation source. The SERS activity of europium nanoparticles has been followed using 4-aminothiophenol and biologically important molecules such as hemoglobin and Cyt-c as the analytes. This is the first example of lanthanide metal nanoparticles as SERS substrate which can possibly be extended to other rare-earth metals. Since hemoglobin absorbs in the visible region, the use of visible light excitation source leads to surface enhanced resonance Raman spectroscopy (SERRS). The interaction of biomolecules with Eu(0) has been followed using FT-IR and UV-visible spectroscopy techniques. The results indicate that there is no major irreversible change in the structure of biomolecules upon interaction with europium nanoparticles. (C) 2016 Elsevier Inc. All rights reserved

Shielding effectiveness of multilayer laminate of aluminum metal matrix and micro absorbing materials

Shielding blocks are widely used to protect sensitive electronic components in defense and medical equipment. In many circumstances, acquiring shielding effectiveness is insufficient, with shielding effectiveness having higher priority if the material possesses mechanical characteristics. To achieve the required electromagnetic shielding effectiveness and mechanical properties such as tensile strength and hardness, a laminate sheet with Al6061 material and micro absorbing materials such as MNZC ferrite rubber composite, Ca-NiTi hexaferrite composites, and Carbonyl iron is preferred in the current work. The total work organized as • Selection of the aluminum metal matrix and micro absorbing material. • Finding the electrical parameters using the vector network analyzer (VNA) using Transmission/Reflection method. • The shielding performance was evaluated for different laminate thicknesses at the X-band. • The material mentioned above can be used as a shielding building block in aeronautical applications and near sensitive medical equipment

Ultrahigh-Rate Supercapacitors Based on 2‑Dimensional, 1T MoS_2<i>x</i>Se_{2(1–<i>x</i>)} for AC Line-Filtering Applications

Motivated by the presence of metallic conductivity in the group VI transition metal dichalcogenides, the supercapacitive performance of the 1T phase of molybdenum (MoS_2<i>x</i>Se_{2(1–<i>x</i>)}) sulfoselenides is explored. Ultrahigh frequency response (∼1.4 kHz) along with excellent electrochemical stability are exhibited by 1T MoS_2<i>x</i>Se_{2(1–<i>x</i>)}-based supercapacitors. The S:Se ratio in the mixed chalcogenide is shown to influence the rate performance of the device. High areal capacitances of ∼450 μF cm^–2 with short <i>RC</i> time constants of ∼1.3–3.2 ms at 120 Hz are achieved in the case of 1T MoSSe phase. The <i>i</i>–<i>v</i> characteristics are almost rectangular at very high scan rates of ∼1000 V s^–1. Very stable gravimetric specific capacitance of ∼36 F g^–1 is retained for several thousands of charge–discharge cycles leading to an energy density of ∼12.1 Wh kg^–1 at a specific power of ∼842 W kg^–1. The observed specific power of ∼50 kW kg^–1 at ∼1.5 Wh kg^–1 energy density makes the sulfoselenide phase capacitors attractive for high power applications without compromising on the energy density

Bulk and few-layer MnPS3: a new candidate for field effect transistors and UV photodetectors

Layered metal thiophosphates with the general formula MPX3 (M is a group VI element and X is a chalcogen) have been emerging as a novel group of tunable bandgap semiconductors. Herein, we report the synthesis of high quality MnPS3 crystals, and their mechanical exfoliation onto pre-fabricated devices. The use of atomic force microscopy and Raman spectroscopy yielded information on the number of layers. MnPS3-based field effect transistors (FETs) comprising few-layer and bulk crystals with gold contacts show p-type conductivity with an on-off ratio of approximate to 10(3). Temperature dependent electrical transport measurements yield a Schottky barrier height value of 0.34 eV for few-layer devices. FETs based on multilayer and bulk MnPS3 show very similar transport characteristics. The transistor devices have also been shown to be good ultraviolet photodetectors with photoresponsivity of 288 A W-1 at a wavelength of 365 nm. Density functional theory calculations reveal the parameters that affect the viability of electron/hole doping in MnPS3 and help understand the p-type nature of the FET device