Energy-efficient cooling of silicon-based microfluidic chips enabled by integrated microstructural and surface modification strategies

Abstract

• A uniform silicon nanowires coating with 5 µm thickness is fabricated via MACE and photolithographic masking in complex microchannels, enabling precise microstructural control with tunable wettability. • Tunable slip lengths (3 – 30 µm) achieve up to 48.6 % drag reduction and 31.6 % heat transfer boost in super-hydrophobic/hydrophilic droplet-structured microchannels. • Integrated experiments and simulations elucidate the interplay between slip boundary, interfacial thermal resistance and microstructure, guiding energy-efficient microchannel design. Efficient thermal management remains a critical challenge in the miniaturization of microelectronic and lab-on-chip systems, where conventional cooling strategies often fail to meet the competing demands of low drag and high heat transfer. Despite extensive research on surface modification and microstructures, the synergistic design of these critical strategies for thermal-fluidic optimization has not been fully explored. In this work, we present silicon-based microfluidics chips with integrated microstructural and surface modification strategies to reveal the coupling mechanism and enable energy-efficient cooling performance. By integrating metal-assisted chemical etching with photolithographic masking, we fabricate uniform silicon nanowires (at the resolution of 5 μm with tunable wettability—from hydrophilic (21.8 °) to superhydrophobic (164.0 °), enabling precise manipulation of slip boundaries and interfacial thermal resistance. Experimental results show that superhydrophobic straight microchannels achieve up to 30.9 % drag reduction with the cost of 14.3 % drop in heat transfer. Incorporating droplet-shaped cavities further enhances drag reduction to 48.6 %, with a 17.1 % heat transfer penalty. For hydrophilic surfaces, microstructures reduce drag by 14.7 % while suppressing heat transfer by 46.5 %. In contrast, droplet-shaped cavities reverse this trade-off by enhancing heat transfer by 31.6 % and reducing drag by 6.3 %. Complementary simulations elucidate the underlying mechanisms by quantifying slip lengths (∼30 μm for superhydrophobic and ∼3 μm for hydrophilic microchannels) and identifying the dominant roles of pressure loss and interfacial resistance. This integrated approach offers not only immediate benefits but also a scalable platform for future adaptive designs in high-density electronic cooling systems.

Topics & Concepts