Large Scale Nanomaterial Production Using Microfluidizer High Shear Processing Kenneth. J. Chomistek and Thomai Panagiotou, Ph.D. Microfluidics Corporation, 30 Ossipee Rd., Newton, MA 02464, USA Microfluidics has developed scalable and low cost award winning technologies, capable of producing nanomaterials with desirable properties for a wide variety of applications. The industries served are pharmaceuticals and biotech, energy, specialty chemicals, cosmetics and nutraceuticals. Microfluidics approach is based on an in-depth understanding of applications, unique design of high shear fluid processors, and development of processes tailored for each individual application. The understanding of the requirements and ecosystem of specific applications includes the desired end properties of the material, the production environment requirements, time and cost restrictions. Pharmaceutical and biotech applications include the development and the production of FDA approved nanotechnology drugs such as vaccines, cancer drugs, anesthetics, controlled delivery systems that include polymers drugs and proteins, etc. Chemical applications include inkjet inks, fuel cell and battery electrodes, and carbon nanotube dispersion. Cosmetics include nanoencapsulation of oxygen carriers and nutrients, and collagen processing. Nutraceuticals include nanoencapsulation of fish oil for protection of omega-3 fatty acids and odor control, nanoemulsions that contain plant sterols and vitamins. Two main methods are used for production of nanomaterials: (a) the “top down”, particle size reduction method, and (b) the “bottom up”, Microfluidics reaction Technology (MRT) for production of nanoparticles through chemical reactions and physical processes, such as crystallization. This technology received the Nano50 Award in 2007. Both technologies are continuous and can be used in line with upstream or downstream processes such as premixing, filtration, etc., and are consistent with process intensification principals. The heart of the technology is the interaction chamber which consists of “fixed geometry” microchannels. Flow through the chamber is characterized by high fluid velocities (up to 500 m/s) and subsequent impingement of fluid jets to the chamber walls or to one another. The unique “fixed geometry” feature combined with the high shear rates ensure that varied formulations (emulsions, liposomes and dispersions) achieve the smallest particle size and the narrowest particle size distribution when compared to other particle reduction techniques. The technology is fully scalable and has been used extensively from lab scale to production of market drugs, nutraceuticals and inks, among others. Microfluidizer® processors offer a variety of options, such as steam sterility, cleanability and data acquisition capabilities, so they are cGMP compliant, CE certified, ATEX and explosion proof, and therefore are suitable for a variety of manufacturing environments.

The field of major applications of transparent conducting oxides (TCOs) continues to expand, thus generating a growing demand for new materials with lower resistivity and higher transparency over extended wavelength ranges. Moreover, p-type TCOs are opening new horizons for high-performance devices based on p-n junctions. Among the most commonly used TCO materials are zinc oxide (ZnO), indium tin oxide (ITO), tin oxide (SnO2), and indium oxide (In2O3). Still, design and synthesis of improved TCO materials leading to a marked increase in conductivity and robustness remain highly desirable while a more detailed understanding of the conductivity mechanisms is critical to further improvement. For example, there is an accelerating effort worldwide by both academia and industry to develop a transparent conductor that can meet or beat the performance of the commonly used ITO at lower costs and with more physical resilience. This article reviews new developments in TCO materials to be used in various applications spanning from photovoltaics to lighting, smart windows, or gas sensors. The financial stakes, far from being negligible in the TCOs market, and the current scientific and technological challenges to be taken up are analyzed.

The article addresses an experimental approach, which proved to be indispensable in basic and applied hydrogen storage R&D—the preparation and modification of hydrogen-rich materials using mechanical processing. A possible mechanism of mechanically induced transformations in solid materials is highlighted.

A new class of porous membrane has been fabricated that is unique in its combination of nanoscale thickness (<50 nm) with macroscopic, yet robust, millimeter-scale lateral dimensions and tunable pore size in the range of ˜5nm to ˜100nm. The membrane material is porous nanocrystalline Si (pnc-Si)1, and is being scaled-up to commercial volumes by a startup company, SiMPore, Inc. Standard commercial separation membranes with pores in this size regime are polymeric materials (poly ether sulphone, cellulose, etc.), microns in thickness, leading to pore morphologies that resemble long narrow tubes or tortuous-path 3-D matrices. As pnc-Si membrane thickness approaches the pore diameters, a simplified structure of holes in a thin sheet results, greatly enhancing both diffusive and forced flow transport through the membrane, as predicted by classical transport theories2. Pnc-Si has confirmed these theoretical predictions, demonstrating record-breaking transport rates, in addition to precise size-separation of nanoparticles, viruses, proteins, and nucleic acids. Applications for this highly precise silicon-based membrane range from highly efficient separations and purification of biomolecules, complexes, and nanoparticles, to substrates for microscopy to cell culture and co-culture. SiMPore is focused on navigating this application space with the goal of quickly introducing products that will allow the company to become self-sustaining and profitable though direct sales or partnerships with market leaders. Key product development drivers include potential competitive performance advantages and perceived value to a particular market, the IP landscape, development costs of the membrane and the device package/interface, and alignment with existing in-house capabilities.

Ventilator associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation over 24 hours increases the risk of VAP and is associated with high morbidity, mortality and medical costs. This complication is especially hard to diagnose in children because of non-specific clinical signs and lack of established diagnostic methods. Cost effective endotracheal tubes (ETTs) that are resistant to bacterial infection would be essential tools for the prevention of VAP. In addition to their bacterial resistance, ETT with magnetic nanoparticles could aid in the diagnosis of VAP allowing physicians to locate infections with greater accuracy. The objective of this study was twofold, first to develop strategies to decrease bacterial adhesion on nano-rough ETT and secondly to develop better methods to assess in vitro bacterial adhesion or biofilm formation on ETT. In preliminary tests, nanomodified polyvinyl chloride (PVC) ETTs has been shown to be effective at reducing bacterial colonization. This study also sought to evaluate the bacterial resistance of these ETTs more effectively by creating a bench top airway model, which can create a similar environment to the flow system that ETTs are exposed to in vivo. The airway model designed to test ETTs has two Plexiglas chambers representing the oropharynx and the lungs, a tube representing the trachea and finally an intricate pumping system to the oropharynx with bacteria flow and to the lung with simulated compliance and resistance. ETTs were connected to a ventilator and passing the oropharynx into the trachea and observed under the mechanical ventilation and continuous bacterial flow system. In addition, the study examined dual gas flow conditions and their effect on bacterial growth of ETT. In no less than three separate trials in the airway chamber, each ETT will be tested for its effectiveness at the reduction of bacterial growth within the airway by sampling from both lung and oropharynx chambers during continuous operation. Special attention will be given to the long-term effects on the ETT by including a study that lasts longer than ten days. Both the bacterial proliferation in the two chambers and on the ETT itself will be carefully analyzed. This specialized testing should yield valuable information on the efficacy of nanomodified ETT in airway conditions and will provide further evidence to determine if nanomodified ETTs are a valid solution to VAP.

The current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generated due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 0.001 Torr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed.