Metallic micro/nanostructured surfaces exhibit significant application potential due to their distinctive physicochemical properties. However, conventional fabrication techniques often suffer from a trade-off between production throughput and structural accuracy. To address this challenge, this study presents a novel shock imprinting method based on underwater pulsed spark discharge (UPSD)-induced shock waves. In this approach, a polycarbonate (PC) film on digital video disc (DVD) with nanostructures on its surface serves as the mold, and an aluminum foil acts as the workpiece. During the shock imprinting process, the foil is compressed into the mold by the shock wave of ultra-high strain rate (~10⁷ Pa·s^–1) generated by UPSD, thereby replicating the nanostructures onto the foil. Experimental results confirm the successful fabrication of micro/nanostructures on aluminum foil using the proposed method.

To systematically evaluate the imprinting performance-characterized by structural fidelity and imprinting area-the influence of the water gap distance is first investigated. At a fixed charging voltage of 30 kV, both the imprinting area and fidelity exhibit a non-monotonic trend with increasing gap distance, peaking at 3 mm. Under optimal conditions, the proposed method achieves large-area imprinting (20 mm diameter) with a maximum fidelity of 0.7. Meanwhile, repeated experiments under identical conditions reveal stochastic variation in imprinted height, attributed to the randomness of the discharge dynamics, likely associated with stochastic streamer initiation and propagation. To further elucidate the dominant factors governing imprinting fidelity, the correlation between fidelity and deposited energy is analyzed using data from experiments with varying gap distances and charging voltages. Results indicate that imprinting fidelity correlates more strongly with the first half-cycle deposited energy than with the total deposited energy. Furthermore, imprinting fidelity follows a piecewise-linear relationship as the first half-cycle deposited energy increases: below a threshold energy (~280 J), the imprinted height remains negligible (<0.2); beyond a saturation energy (~380 J), fidelity plateaus at ~0.7 despite further increases in deposited energy. Maintaining the deposited energy slightly above the saturation threshold is essential to achieve high-fidelity imprinting with enhanced energy efficiency.