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Brownian Movements

The Experts below are selected from a list of 120 Experts worldwide ranked by ideXlab platform

Gou-jen Wang – 1st expert on this subject based on the ideXlab platform

  • Measurement and control of the ion diffusion coefficient in a nanochannel
    Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, 2013
    Co-Authors: Yu-tze Tsai, Kang J. Chang, Gou-jen Wang

    Abstract:

    In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal–semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the initial ion concentration difference across a nanochannel is larger than a certain threshold.

  • Control of the ion diffusion coefficient in a nanochannel
    2012 Symposium on Design Test Integration and Packaging of MEMS MOEMS, 2012
    Co-Authors: Yu-tze Tsai, Gou-jen Wang

    Abstract:

    In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal-semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the the initial ion concentration difference across a nanochannel is larger than a certain threshold.

Yu-tze Tsai – 2nd expert on this subject based on the ideXlab platform

  • Measurement and control of the ion diffusion coefficient in a nanochannel
    Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, 2013
    Co-Authors: Yu-tze Tsai, Kang J. Chang, Gou-jen Wang

    Abstract:

    In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal–semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the initial ion concentration difference across a nanochannel is larger than a certain threshold.

  • Control of the ion diffusion coefficient in a nanochannel
    2012 Symposium on Design Test Integration and Packaging of MEMS MOEMS, 2012
    Co-Authors: Yu-tze Tsai, Gou-jen Wang

    Abstract:

    In this study, we first propose a simple yet novel method to measure the diffusion coefficient of ions through a nanochannel. Back-side track etching is used for the fabrication of a nanochannel on an n-type silicon substrate. A metal-oxide semiconductor field-effect transistor (MOSFET) like device named the metal-semiconductor-solution field-effect transistor (MSSFET) is implemented to control the ion diffusion current. When a negative gate voltage is applied, positive ions that travel along the nanochannel are confined to the central zone of the nanochannel allowing the radial Brownian Movements to be reduced. The effect is equivalent to an increase of the diffusion coefficient. However, a positive gate voltage can produce an opposite Zeta potential on the nanochannel surface. The cations in the nanochannel are dragged to the channel surface. This condition can be regarded as a decrease of the diffusion coefficient. Experimental results illustrate that the transfer characteristics of the MSSFET are similar to those of a p-channel depletion-type MOSFET. The ion diffusion coefficient in a nanochannel can be controlled when the the initial ion concentration difference across a nanochannel is larger than a certain threshold.

Tseng-hsin Wu – 3rd expert on this subject based on the ideXlab platform

  • Enhancement of Phase Change Heat Transfer by using Surface Energy Patterning Techniques
    2006 1st IEEE International Conference on Nano Micro Engineered and Molecular Systems, 2006
    Co-Authors: Tseng-hsin Wu

    Abstract:

    Using phase change of working fluid to remove heat in a heat exchanger device is a high efficiency method. When superheated vapor passes over a sub-cooled substrate, water droplets nucleate and grow by coalescence with the surrounding drops. The merging droplets exhibit two-dimensional random motion somewhat like the Brownian Movements of colloidal particles. If surface energy patterns are designed on the substrate surface, the random condensing droplets will nucleate and grow to a certain size and move toward the more hydrophilic side of the surface. Powered by this forces, condenser surface will not grow into film-wise condensation situation. Thus condensation speeds are faster than those of typical surfaces without any surface modification. This effect has implications for passively enhancing heat transfer in heat exchangers or heat pipes