Papers by Author: C. Liu

Abstract: Thermal barrier coatings (TBCs) fabricated by electron-beam physical-vapor deposition (EB-PVD) were irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100 A/cm2 with a shot number of 1-10. Microstructural features of the irradiated EB-PVD TBCs were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. All the HIPIB-irradiated EB-PVD TBC surfaces present smooth and densified features. The originated intercolumnar channels growing out to the top-coat surface and nanometer-scale gaps inside each single column were sealed after the remelting of TBC surface induced by HIPIB, resulting in formation of a continuous remelted layer about 1-2 μm in thickness. The dense remelted layer can work as a barrier against the heat-flow and corrosive gases, and gives the possibility of improving thermal conductivity and oxidation resistance of the HIPIB irradiated EB-PVD TBC.

Abstract: Micro hot embossing mold of microfluidic chip used in flow cytometry is designed and microfabricated. After some kinds of microfabrication processes are tried, this paper presents a novel microfabrication technology of micro hot embossing metal mold. Micro metal mold is fabricated by low-cost UV-LIGA surface micro fabrication process using negative thick photoresist, SU-8. Different from other micro hot embossing molds, the micro mold with vertical sidewalls is fabricated by micro nickel electroforming directly on Nickel base. Based on the micro Nickel mold and automation fabrication system, high precision and mass-producing microfluidic chips have been fabricated and they have been used in flow cytometry

Abstract: As one part of the efforts to break the bottleneck of power sources in development of integrated micro systems, a silicon based air-breathing micro direct methanol fuel cell (μDMFC) was developed in this work. By using micro-machining technologies compatible with that in processing of the other MEMS devices, the anode and cathode micro flow-field plates had been successfully fabricated on a pair of 2-inch silicon wafers. The silicon μDMFC was evaluated under ambient conditions using aqueous methanol solution with different concentrations. Results show that open circuit potential (OCP) of the μDMFC was above to 0.6 V, and by using 3mol/L methanol, the peak current density and power density of the silicon μDMFC could reach 28mA/cm2 and 8mW/cm2, respectively.

Abstract: In micro stereovision system, false matching due to the randomicity of image signal makes 3D reconstruction data contain a large amount of abnormal data in the form of noise (pulse noise, Gauss noise). In order to obtain a more accurate 3D reconstruction shape, a novel method of 3D scattered data processing, which is a combination of wavelet transform and extended Vector Median Filters, is proposed to use wavelet transform to realize primary denosing, and use extended Vector Median Filters to further denoise thereby achieving higher precision 3D measurement. In wavelet based denosing, wavelet based edge detector in vector space removes edge abnormal points effectively, moreover, boundary tracking is used to prune out the image background from the matching area to remove exterior abnormal points. Then the local areas determined by edges are filtered by extended vector median filter. Experimental results indicate that the method proposed is effective to removing abnormal data from the 3D reconstructed data and enables 3D measurement position accuracy to reach 3 m µ .