Power-free water pump based on a superhydrophobic surface: generation of a mushroom-like jet and anti-gravity long-distance transport

Spontaneous anti-gravitational transportation of liquids across long distances has been widely discovered in nature, such as water transportation from the root to the crown of a tree. However, artificial liquid delivery remains a challenge. In this work, a new power-free pump composed of a superhydrophobic plate with a pore mounted on a leak-proof cylindrical container filled with water is presented for sustained anti-gravity and long distance transport. Water droplets can be spontaneously captured through the pore by the lower water column, forming a mushroom-like jet due to the energy transition from surface energy to kinetic energy. The spontaneously increased inside pressure in the container will push the water out, through another thin tube, realizing the energy transition from surface energy to gravitational potential energy. The dynamic driving and moving model of the pivotal mushroom-like jet were analyzed. The maximum transport height and transport abilities of the water pump were also discussed. The results show that Laplace pressure is the main driving pressure of the mushroom-like jet and that the developed power-free pump can effectively transport water to over 100 mm in height with an average transport speed of 4500 mL h(-1), showing potential for application in microfluidic systems and medical devices where micropumps are needed.