Synthesis Routes on Electrochemical Behavior of Co-Free Layered LiNi0.5Mn0.5O2 Cathode for Li-Ion Batteries.

Co-free layered LiNi0.5Mn0.5O2 has received considerable attention due to high theoretical capacity (280 mAh g-1) and low cost comparable than LiCoO2. The ability of nickel to be oxidized (Ni2+/Ni3+/Ni4+) acts as electrochemical active and has a low activation energy barrier, while the stability of Mn4+ provides a stable host structure. However, selection of appropriate preparation method and condition are critical to providing an ideal layered structure of LiNi0.5Mn0.5O2 with good electrochemical performance. In this study, Layered LiNi0.5Mn0.5O2 has been synthesized by sol-gel and solid-state routes. According to the XRD, the sol-gel method provides a pure phase, and solid-state process only minimize the secondary phases to certain limit. The Ni2+/Mn4+ content in the sol-gel process was higher than in the solid-state reaction, which may be due to the chemical composition homogeneity of the sol-gel samples. Regarding the electrochemical behavior, sol-gel process is better than solid-state reaction. The discharge capacity is 145 mAh/g and 91 mAh/g for the sol-gel process and solid-state reaction samples, respectively.

Fabrication and Characterization of a Composite Ni-SDC Fuel Cell Cathode Reinforced by Ni Foam.

High-temperature fuel cells (namely, molten carbonate and solid oxide; MCFCs and SOFCs) require the cathode to be designed to maximize oxygen catalytic reduction, oxygen ion transport, electrical conductivity, and gas transport. This then leads to the optimization of the volume fraction and morphology of phases, as they are a pathway for electrons, ions, and gases to be continuous and self-interpenetrating. Apart from the functional properties, the cathode must be mechanically stable to prevent cracking during fuel cell assembly and operation. The manufacturing process of the composite cathode was optimized to meet such requirements in this research work. The tape casting technique and further firing process were used to fabricate the cathodes. The slurry for the green tape was composed of nickel (Ni), cerium oxide doped with samarium oxide (SDC), water (solvent), and an organic binder (which becomes pore space after firing). Each of these elements is necessary for the effective transport of specific species: electrons, oxygen, ions, and gas particles, respectively. Moreover, the nickel foam was embedded into the powder-based structure to improve mechanical strength. The study involved many technological issues, such as the effect of the SDC fraction on the cathode microstructure, mechanical strength, and chemical stability at high temperatures, and also involved environmental issues.

Rapid Drug-Screening Platform Using Field-Effect Transistor-Based Biosensors: A Study of Extracellular Drug Effects on Transmembrane Potentials.

Ion channel-modulating drugs play an important role in treating cardiovascular diseases. Facing the demands for continuous monitoring of drug effectiveness, the conventional techniques have become limited when investigating a long-term cellular physiology. To address the challenge, we propose a drug-screening platform using the stretch-out electrical double layer (EDL)-gated field-effect transistor-based biosensors (BioFETs). In this work, BioFETs were utilized to amplify electrophysiological signals from the mammalian cardiomyocytes (H9c2). The stretch-out configuration avoided a chemical corrosion on FETs and prolonged the lifetime of a BioFET system. A physical model is presented to elucidate the signal response to a drug effect on a cell. Fibronectin and gelatin were coated on sensors and served as the adhesive layers where H9c2 cells attached. BioFETs demonstrated an ability to qualitatively distinguish a depolarization and a polarization of the cytomembranes. The signal responses to the changes of transmembrane potentials were monitored in real-time, and they were highly correlated. The effects of nifedipine and calcium ions on cellular electrophysiology were examined and discussed. Due to the capability of a rapid detection, a prolonged lifetime, and an excellent sensitivity to an electrical change, a stretch-out EDL-gated BioFET can be a drug-screening platform for ion channel modulators.

Rapid ß-human chorionic gonadotropin detection in urine with electric-double-layer gated field-effect transistor biosensors and a handheld device.

In this experimental study, a portable biosensor was developed to detect ß-human chorionic gonadotropin (ß-hCG), which is extensively used in pregnancy tests and serves as a biomarker for ectopic pregnancy. The sensor used is an electric-double-layer field-effect transistor biosensor with the extended-gate design. Bias voltage is applied on the sensor to measure the resulting drain current signals. Gold electrode surface is functionally activated with an anti-ß-hCG antibody to capture ß-hCG protein. Fluorescence imaging technique is utilized to confirm the surface functionalization. The biosensor demonstrates a dynamically wide range of molecules as detection targets at very low sample concentrations, which shows the potential to detect ectopic pregnancy in very early stages and easily keep track of its periodic changes. It can be produced en masse and does not use additional labels/reagents or pre-processing techniques for the sample. This biosensor can significantly reduce the manufacturing costs and is comparable with the currently available commercial ß-hCG assays. It is suitable for early diagnosis of ectopic pregnancy with low cost and easy operation at home with urine samples.