Advanced Materials Research Vol. 528

Abstract: In this paper, a novel control system is introduced for a micro process system for the manufacturing of nanoparticles. An impinging-jet micromixer is used as the microreactor for mixing two fluid phases. In order to increase the scalability of the manufacturing system, a high speed image acquisition and processing subsystem is utilized to provide real-time visual feedback. Jet slope and shape are calculated automatically to evaluate the outcome of the mixing. A control algorithm consisting of a feedforward and feedback components is then implemented to control the pump’s flowrate to deliver guaranteed performance even with the presence of external disturbance and system uncertainty. Experimental results show the feasibility of the proposed solution.

Abstract: The purpose of this study was to develop the anodized titanium oxide nanotubes (ATONs) as a pH electrode with amperometric and potentiometric method. Titanium oxide nanotubes film was produced on pure titanium piece by titanium anodization at room temperature. The best one ATONs electrode has a linear pH response approximately 53 mV/pH with potentiometric method and 13 A/pH with amperometric method in the concentration range between pH 2 and 12.

Abstract: Carbon nanotube (CNT) sponges are three-dimensional frameworks of interconnected CNTs with great potentials in composite and environmental applications. CNT sponges with lateral sizes of centimeters have been prepared through chemical vapor deposition (CVD), and their compressive mechanical properties are studied. To gain deep insight on the microstructure and how CNTs are connected within the sponges, we propose a simple theoretical model to understand the arrangement as well as the interconnection of CNTs. The mechanical properties of CNT sponges can be well explained and predicted using this model.

Abstract: This paper proposes a novel approach for micropump driven, namely laser shock wave, with the advantages of high energy efficiency, remote control and wireless energy supply. The pump used here has the characteristics of simple structure, easy fabrication and low cost comparing to the traditional micropump. Firstly, a valveless micropump was designed and then manufactured through lithography and bonding. Secondly, modal analysis of the fluid-structure coupling system, i.e. micropump, was calculated, and the first natural frequency was chosen as the frequency of the laser pulse. Finally, experiments were done to validate the feasibility of the driving mode. Results show the new driving mode works well and may provide an alternative approach for microsystem driven.

Abstract: In this paper, a novel MEMS-fabricated thermal bubble pump is proposed. By using thermocapillary effect in a microchannel loop, bubbles are designed to move only in one direction of the loop. Driving heater with a square-wave signal, bubble nucleates and grows asymmetrically above the heater. As soon as the heating pulse is turned off, an interesting phenomenon is found. Instead of bubble collapse, bubble moves toward growing direction. Continuous bubbles grow and move periodically when square-wave pulsing signals are applied. Thermocapillary pumping phenomena are achieved successfully in the experiments. By adjusting background temperature field, thermocapillary pumping phenomena can be sustained. Detailed mechanism for pumping force will be discussed in this paper.

Abstract: Nanometer titanium dioxide powders were prepared by hydrolysis of titanium-tetrabutoxide with ethanol. The powder particle size of TiO₂ in the structure of anatase-type is mainly between 5 and 10 nm. Using the process that titanium alloys were embedded by the nanometer TiO₂ powders and sintered in the high temperature furnace, the nano-TiO₂/titanium alloy biomaterials was fabricated out. The particle size of TiO₂ particles on the surface of Ti alloy was mainly 50-70 nm. The method is a simple and adaptable technique for surface modification of the titanium alloys.

Abstract: Attapulgite is a natural rod-like nanomaterial. The surface of natural attapulgite nanoparticles was cleaned, modified with silane coupling agent 3-aminpropyltriethoxysilane (KH550). The structure and morphology of the modified attapulgite were characterized by infrared spectroscopy, scanning electron microscope (SEM). The methane absorption capacity of the modified attapulgite was recorded by intelligent gravimetric analyzer. SEM revealed that 3-aminpropyltriethoxysilane was modified on the surface of rod-like attapulgite nanoparticles. The 3-aminpropyltriethoxysilane can obviously increase the methane absorption capacity of the nanoparticles almost about twice. This result may provide the attapulgite nanoparticles a new way to industrial application.

Abstract: Reinforcement of polymer with plant whiskers is a way of improving mechanical properties. Cellulose nanowhiskers (CNW) were separated from commercially available wood pulpboard. Different microscopy techniques, thermal gravimetric analysis, X-ray diffraction were used to study the structure and properties of the microcrystalline cellulose (MCC) and CNW. Because of the high specific surface area of CNW, the increases in total amorphous character of the cellulose decrease the relative degree of crystallinity. After chemical and physical treatment, the CNW in the length of several μm and diameters ranging from 20 - 50 nm was obtained. Both the initial decomposing temperature and temperature of maximum decomposing rate of CNW is higher than MCC, but lower than wood pulpboard.

Abstract: In order to prepare chitosan-based nanoparticles for drug delivery, we synthesis chitosan-poly(methacryloyl polyethylene glycol succinic acid, MA-PEG400-SA) nanoparticles in aqueous solution via template polymerization. The structure of the chitosan-poly(MA-PEG400-SA) nanoparticles was characterized by FT-IR spectra, and the particles size and surface charge were analyzed by zetasizer, respectively. The average size of chitosan-poly(MA-PEG400-SA) nanoparticles was approximate 325 nm, and the surface charge was 33mv. Using hydrophilic drug 5-FU as the model drug, the drug loading efficiency was about 6%. In the further study, we will optimize the synthesis conditions and study on the drug release properties of the nanoparticles.