Droplet manipulation enabled by bio-inspired high-aspect-ratio micropumps via mold-assisted microfabrication

Miniaturized functional fluidic pumps have found broad applications across various fields; however, the fabrication and dimensional limitations of their electrodes remain a significant challenge. Conventional manufacturing techniques often fail to achieve high aspect ratio structures exceeding 2 and electrode heights greater than 1 mm. In this work, we propose a novel extreme microfabrication strategy that integrates flexible molding techniques with advanced microfabrication processes to develop high-precision pump electrodes. These electrodes are successfully implemented in droplet manipulation applications. First, we selected suitable microfabrication-compatible materials and developed a conductive, flexible liquid elastomer, along with a tailored fabrication process. Next, a functional working fluid compatible with the electrodes was synthesized and characterized in terms of its viscosity, electrical conductivity, dielectric constant, and interfacial behavior with aqueous phases. A corresponding microfluidic chip was also fabricated to assess its droplet generation performance. Both duty cycle-based and frequency-based droplet manipulation strategies were investigated using this chip. Finally, a machine learning approach was employed to model the droplet generation process and evaluate the influence of four key parameters on device performance. This study establishes a foundational platform and design pathway for future development of integrated on-chip pumping systems in microfluidic applications.