Toughness and hardness are important aspects for coating applications in manufacturing industry. Extensive theoretical and experimental efforts have been made to synthesize and study nanocomposite coatings with super hardness and high toughness. The materials can be hardened through various or combined hardening mechanisms. However, for engineering applications, coating toughness is as important as, if not more than, super hardness. At present, there is neither a standard test procedure, nor a standalone methodology for the assessment of thin film toughness. The determination of the toughness is still a difficult task, and very much a fully open problem. In this article, we review the hardening and toughening mechanisms of nanocomposite films, and the toughness characterization techniques. Based on these reviews, an outlook will be presented in the concluding remarks.magnified image

Microelectromechanical systems (MEMS) technology has provided the platform for the miniaturization of analytical devices for biological applications. Beside the fabrication technology, the study and understanding of flow characteristics of fluid in micrometer or even nanometer scale is vital for the successful implementation of such miniaturized systems. Microfluidics is currently under the spotlight for medical diagnostics and many other bio-analysis as its physical size manifested numerous advantages over lab-based devices. In this review, elementary concepts of fluid and its flow characteristics together with various transport processes and microchannel condition are presented. They are among the fundamental building block for the success in microfluidic systems. Selected application examples include biological cell handling employing different schemes of manipulation and DNA amplification using different microreactor arrangement and fluid flow regime.

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A TiNi/diamond-like-carbon (DLC) microcage has been designed for biological applications. The structure is composed of a top layer of TiNi film and a bottom layer of highly compressively stressed DLC for upward bending once released from the substrate. The fingers of the microcage quickly close through the shape memory effect once the temperature reaches the austenite start transformation point to execute the gripping action. Opening the microcage is realized by either decreasing the temperature to make use of the martensitic transformation or further increasing the temperature to use the bimorph thermal effect. The biocompatibility of both the TiNi and DLC films has been investigated using a cell-culture method.

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