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In this work, we prepared spinel-type NiCo2O4 (NCO) nanopowders as a low-cost and sensitive electrochemical sensor for nonenzymatic glucose detection. A facile and simple chemical bath method to synthesize the NCO nanopowders is demonstrated. The effect of pH and annealing temperature on the formation mechanism of NCO nanoparticles was systematically investigated. Our studies show that different pHs of the precursor solution during synthesis result in different intermediate phases and relating chemical reactions for the formation of NCO nanoparticles. Different morphologies of the NCO depending on pHs are also discussed based on the mechanism of growth. Electrochemical performance of the prepared NCO was characterized towards glucose, which reveals that sensitivity and selectivity of the NCO are significantly related with the final microstructure combined with constituent species with multiple oxidation states in the spinel structure.

The influence of surface activated bonding (SAB) on adhesion strength between a metal and ceramic including Al/AlN and Cu/AlN is investigated. Plasma pre-treatments can significantly increase the adhesion strength between the metal and ceramic through surface activation, which can enlarge the contact area between metal and ceramic. Bonding pressure is also an important factor to improve the adhesion between metal and ceramic during SAB. Successful bonding between the metal and ceramic via SAB can be attributed to the formation of the interface layer where plastic deformation and rearrangement of metal to the ceramic occurs, which improves the atomic scale interconnection between the metal and ceramic. In this study, the influence of experimental SAB conditions for processing such as plasma power, degree of vacuum and bonding pressure on adhesion strength is investigated. Also, the thermal conduction of metal/ceramic laminates is discussed for its potential application as a heat spreader of LED chips.

Diabetes is a chronic disease, which can give serious damages to the human organs that affect life expectancy. Such a life-threatening diabetes is diagnosed by systematic monitoring of blood glucose levels; thus, accurate detection of glucose within a specified target range becomes more important for glucose sensor to provide detailed information relating with diabetes, which can result in reliable decision for diabetes treatment. Thanks to many efforts developing the reliable glucose sensors, electrochemical performance of the sensor including sensitivity and selectivity in response to glucose is gradually improved. Herein, we developed spinel type NiCo2O4 (NCO) nanostructure with excellent sensitivity, selectivity and chemical robustness for glucose detection. NCO was prepared by conversion of NiCo-layered double hydroxide (NCH) at comparatively low temperature, which is synthesized by simple and facile chemical bath method and following post-heat treatment of the NCH. Electrochemical sensitivity, selectivity and detection time of the NCO in response to glucose was investigated, compared to those of the NCH. Also, long-term stability of the NCO on repetitive glucose detection was evaluated. Based on the systematic analysis on materials properties and electrochemical performance of the NCO, possible mechanism of the glucose oxidation, which significantly improves electrochemical performance of the NCO, is discussed.

The evaporation behavior and characteristics of jet milled RuCr alloy powders processed by radio-frequency (RF) plasma treatment were evaluated during this study. RF plasma treatment was found to be effective in eliminating internal pores and in manufacturing spherical powder. However, the RF plasma treatment resulted in the evaporation of Cr. The degree of evaporation of Cr was significantly affected by the powder feeding rate. As a result, it was found that controlling the torch power was more effective than controlling the powder feeding rate for obtaining desirable RuCr alloy powders.