Browsing by Author "Woon, Wei-Yen"

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Collective flow dynamics across a bacterial carpet: Understanding the forces generated
(2014-11-17)
Hsiao, Yi-Teng
;
Wang, Jing-Hui
;
Wu, Kuan-Ting
;
Tsai, Jengjan
;
Chang, Cheng-Hung
Bacterial carpets consist of randomly anchored uni-polar-flagellated sodium-motive bacterial matrix are prepared by flow deposition. Collective flow dynamics across the bacterial carpets are probed with optical tweezers-microsphere assay. Around the center of a uniform bacterial cluster, collective forces that pull microsphere towards carpet surface are detected at a distance of 10 mu m away from carpets. At sodium-motive driving over a critical value, the force magnitudes increase abruptly, suggesting a threshold-like transition of hydrodynamic synchronization across bacterial carpet. The abrupt force increase is explained in term of bifurcation to phase synchronization in a noisy non-linearly coupled rotor array mediated by hydrodynamic interactions. (C) 2014 AIP Publishing LLC.
Two-dimensional dopant profiling by electrostatic force microscopy using carbon nanotube modified cantilevers
(2008-08-13)
Chin, Shu-Cheng
;
Chang, Yuan-Chih
;
Hsu, Chen-Chih
;
Lin, Wei-Hsiang
;
Wu, Chih-I
A two-dimensional (2D) dopant profiling technique is demonstrated in this work. We apply a unique cantilever probe in electrostatic force microscopy (EFM) modified by the attachment of a multiwalled carbon nanotube (MWNT). Furthermore, the tip apex of the MWNT was trimmed to the sharpness of a single-walled carbon nanotube (SWNT). This ultra-sharp MWNT tip helps us to resolve dopant features to within 10 nm in air, which approaches the resolution achieved by ultra-high vacuum scanning tunnelling microscopy (UHV STM). In this study, the CNT-probed EFM is used to profile 2D buried dopant distribution under a nano-scale device structure and shows the feasibility of device characterization for sub-45 nm complementary metal-oxide-semiconductor (CMOS) field-effect transistors.