Paste-Press Packing Method for Through-Hole Loading to Fabricate Vertical Closed Bipolar Electrode Arrays and Micro-Rods

A paste-press packing (PPP) method is proposed for loading pastes and suspensions into micro- and nano-sized through-holes in thin membranes. First, the effectiveness of the PPP method was evaluated by electrochemiluminescence (ECL) imaging and scanning electron microscopy (SEM) using carbon paste (CP)-packed track-etched membranes. Uniform and dense packing of CP into 8 μm-diameter through-holes was achieved by the PPP method, enabling the membranes to function as closed bipolar electrode arrays suitable for bipolar electrochemical microscopy. Next, the versatility of the PPP method was demonstrated by successfully packing silver paste and an alumina suspension into micro-sized through-holes, despite their different compositions and rheological properties. Finally, Au micro- and nano-rods with diameters ranging from 12 to 0.6 μm were fabricated from Au paste-packed track-etched membranes by removing the membranes either by dissolution in organic solvents or by calcination. These results demonstrate that the PPP method provides a simple and versatile approach for uniformly packing various functional materials into membrane through-holes and for fabricating micro- and nano-rod structures, offering a broadly applicable platform for microfabrication.