Characterization of leaf-inspired microfluidic chips for pumpless fluid transport

Microfluidic networks are extensively used in miniaturized lab-on-a-chip systems. However, most of the existing microchannels are simply designed and the corresponding microfluidic systems commonly require external pumps to achieve effective fluid transport. Here we employed microfabrication techniques to replicate naturally-optimized leaf venations into synthetic hydrogels for the fabrication of pumpless microfluidic chips. The unique properties of leaf-inspired microfluidic network in convectively transporting fluid were characterized at different inclination angles. Flow velocity inside these microfluidic networks was quantitatively measured with Particle Image Velocimetry (PIV). Mass diffusion from biomimetic microfluidic network to surrounding bulk hydrogels was investigated. The results demonstrate that the leaf-inspired microfluidic network can not only effectively transport fluid without the use of external pumps, but also facilitate rapid mass diffusion within bulk hydrogel chips. These leaf-inspired microfluidic networks could be potentially used to engineer complex pumpless organ-on-a-chip systems.