The deep nickel metal deposition on multiscale features with a single small hole and large sector cavities with depth of 1 mm has been investigated using direct current (DC) and pulse alternating current (AC) electroforming. The diameter of the hole is around 240 μm, and the size of the sector cavity is several mm to cm corresponding to the various aspect ratios from 0.07 to 4.17. The successful metal electroforming into both the hole and cavity features can be obtained by the AC mode, while the DC mode leads to metal electroforming only in sector cavities rather than in the small hole. This is because the surface concentration of the cathode in pulse electroforming is higher than that in DC electroforming, allowing large cations to diffuse into different multiscale features at lower overpotential. The increment factor, i.e., percentage increase in concentration used as an index of the varied surface concentration increases from 0.903 (10-2%) at 1 Hz to 1.077 (10-2%) at 100 Hz. This achievement can be used for the high aspect ratio metal electroforming of a single hole as a micro-sensing tip in different applications.
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