A theoretical model for the radially dependent effective piezoelectric coefficient and corresponding piezoelectric potential in intrinsic ZnO nanowires (NWs)/nanotubes (NTs) is presented. Substrate-bound ZnO structures oriented along the c-axis with diameters of 100–5000 nm (NWs) and inner diameters of 100–900 nm (NTs; fixed outer diameter, 1000 nm) were examined using finite element method analysis. The piezoelectric potential depended nonlinearly on the NT/NW size, which we explain using the effective piezoelectric coefficient and peak piezoelectric potentials. We propose that this coefficient can be used to judge the degree of enhancement of the piezoelectric potential in ZnO NWs/NTs.

Injection mold filling process was analyzed for a rectangular plate with micro patterns on the surface. For products with micro patterns whose dimensions are much larger than the dimensions of the micro patterns, numerical analysis may require a prohibitively large number of numerical grids. In order to solve this problem, anlaysis was done by separating the global flow through the base plate from the filling of the micro patterns. Global flow was analyzed using the generalized Hele-Shaw (GHS) model, while local flow for micro patterns was simulated by the Navier-Stokes equation. The boundary conditions, such as pressure and temperature, for the local analysis were obtained using the results of the global analysis. The proposed method was validated by experiments. Experimental observation showed good agreement with the numerical results. Effect of process parameters on the transcription fidelity was further examined. The numerical approach presented in this paper would enable a more efficient analysis and provide better understanding of filling behavior during injection molding of parts with micro patterns on the surface.

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