Recent Patents on Materials Science - Volume 6, Issue 3, 2013

Electromechanical resonators in the micro (MEMS) and nano (NEMS) regimes have emerged as promising tools for use in such diverse applications as ultrasensitive physical, chemical, and biological sensors, with detection limits as low as a single molecule. The advent of state-of-the-art micro-fabrication techniques has enabled a high throughput platform for commercialization. However, the sensitivity and reliability of such devices are highly dependent on the employed detection technique. This article summarizes the popularly implemented actuation and detection methods, and presents a review of the patented highly useful yet simple electrical detection schemes, the Harmonic Detection of Resonance (HDR) method and the pulsed ring-down method. The prominent HDR features are elucidated, and their advantages are highlighted with respect to other techniques. A theoretical model of the system is presented, and the origin of harmonics in the signal is explained. The applications of HDR range from using microcantilevers as sensors to probing mechanical properties in nano-cantilever systems. Finally, the technique based on the ring-down phenomenon is introduced as an alternative to HDR, and its effectiveness is illustrated in gas sensing applications.

In this paper, recent patents along with recent published literature on functional coatings generated on different substrates for solar thermal applications are reviewed with a special focus on coatings derived by the sol-gel method. In solar thermal power plants, solar radiation is used to heat a thermic fluid in the primary circuit, which is subsequently used to run a turbine for generation of electric power. Functional coatings on components of a solar thermal device, viz. focusing aluminum mirrors, stainless steel absorber tubes and borosilicate cover glass tubes, improve the efficiency of the solar to thermal energy conversion. Though, currently there are several coating techniques available, most of them are based on vapor deposition that require high vacuum and are cost-intensive. Therefore, it is necessary to adopt an environmental- friendly and cost-effective coating process such as hybrid sol-gel coating technique that is also amenable to scaleup in addition to providing multi-functional properties.

The present review of the most recent patents outlines the progress made over the last several years in the search for evaporators of reactive metals. The miniaturization of modern devices using multilayer films brought about a new formulation of the requirements of evaporators of reactive metals (i.e., alkali and alkali-earth metals). One approach to satisfying these new requirements is the use of encapsulated intermetallic evaporators produced by droplet casting. The fusible metal protective film on the surface of the evaporator provides fine control over the process of thermal deposition for typical atomic layer deposition rates. Droplet casting simplified the assembly of the evaporators, which are currently produced by casting the reactive melt into the enclosure of the evaporator. Uniting these two solutions, the fusible protective shell and the automated assembly based on droplet casting, provides the intermetallic evaporators with highly technical characteristics at a low cost, which has been the target of the developments of the last 10-15 years.

The review is devoted to the recent publications and patents focusing on drug-eluting stents (DESs), which due to their ability in reducing restenosis are becoming the lead player for the treatment of coronary artery disease (CAD). Various approaches have been used in development of these medical devices. Most DES architecture includes three components: a stent platform, a drug delivery vehicle and therapeutic agent; each part has significant impact on the biological performance of DES. The paper outlines the new developments on drug-eluting stents sustained by patents literature.

The present review briefly outlines the most recent patents and journals on various aspects of porous calcium phosphate bioceramics including techniques of preparation, properties and bone implant applications. Bioactive ceramics are a class of materials that have capability to bond directly with the host bone. These materials can be easily assimilated by the body and are considered to be biodegradable. Researches have revealed that artificial bones made from hydroxyapatite or a combination of hydroxyapatite (HA) and tricalcium phosphate (TCP) is a perfect substitute for natural bone owing to its excellent biocompatibility and properties close to that of human bone. Bioceramics made of HA are available in dense and porous forms. Several efforts on the fabrication of porous calcium phosphate bioceramics have been carried upon in the field of clinical orthopaedics. The realisation of these efforts can be observed from the fact that numerous patents have been filed on methods of preparing porous calcium phosphate bioceramics for bone implant applications. A number of porous HA ceramics have been developed for applications in both tissue engineering and drug delivery systems. Porous bodies are decomposable in human body and provide a surface for proliferation and growth of cells that are infiltrated from the surrounding tissues so that a new bone grows into the pores and prevents any movement or loosening of the implants. Consequently, these can be used for filling the damaged bone, repair of fractured bone and even can be used as hard tissue replacements. Several processing techniques have been employed for fabrication of porous scaffolds. Among prominent techniques are gel casting, slip casting, camphene-based freeze casting and polymeric-sponge method.

We suggest a method of growing silicon carbide crystal layers on carbon foil. The material is produced by moving a carbon foil tape at a speed up to 2.5 m/min in dynamic vacuum against a graphite capillary feeder that contains molten silicon. As a result of various chemical vapor reactions, SiC crystals grow at a speed up to 1.5 mm/s.. The crystals and the foil form a composite material with semiconducting properties. In this article, we have discussed relevant patents.

The present paper reviews recent patents on polymer-inorganic particle blends with reference to silver particulate films on softened polymer composites of polystyrene (PS)/ poly (2-vinyl pyridine) (P2VP) and PS/ poly (4- vinylpyridine) (P4VP) deposited at a rate of 0.4 nm/s held at a temperature of 457 K in vacuum of 8x10-6 Torr by evaporation. There has been continuous development in the field of polymer-inorganic nano particle blends. Polymer-inorganic particle blends are incorporated into structures involving interfaces with additional materials can be used for forming desirable devices. Polymer blends with a vast variety of characteristics, architectures with properties that are often not accessible with individual components are prepared. A method is used to form metal nanoparticles having a desired shape and size by combining in a single solution, solvent, metal ions and copolymers under conditions such that metal nanoparticles are formed. Nanoparticles layers can be distributed on a substrate using various methods. Blending of insulating polymers with metal particle provides an insulating cover and cost reduction. Various methods are used to design nanoparticle on a dielectric substrate for desired applications like charge storage in electronic devices, system and optical sensors.