Near‐Field Electrospinning Micro‐Printhead Achieves Precise Control of Nanofiber Deposition

As a high-resolution, cost-effective, and rapid fabrication method, near-field electrospinning enables the formation of micro- and nanostructures, positioning it as a promising tool also for advanced nanomanufacturing. However, stable fabrication of sub-100-nm well-aligned fibers remains challenging due to the complex interplay of process parameters. In this work, reliable nanofiber fabrication is established using a custom-built near-field electrospinning setup, based on a micro-printhead having an inner nozzle diameter below 50 µm. A voltage-based classification of jetting region cutoff, fiber formation, and supersaturation is proposed, indicating that continuous nanofiber fabrication is only achievable within a fiber formation parameter region. Thus, augmented by an increase in the relative printhead-substrate velocity, well-placed nanofibers with diameters down to 50 nm are fabricated reproducibly. Additionally, the influence of nozzle outlet size on the required operating voltage and resulting fiber morphology is investigated. This work deepens understanding of the near-field electrospinning process and provides a robust and precise method for fabricating polymer nanofibers as low as 25 nm diameter, contributing a decided advance in facile 3D nanostructuring.