When a water droplet is in contact with a water reservoir, it will quickly pinch off from the reservoir and form a smaller daughter droplet, while this daughter droplet will continue to go through a similar contact-pinch off-splitting process until completed coalescence into the reservoir, the combination or summary of these self-similar coalescence processes is called coalescence cascade.[19] The underlying mechanism of coalescence cascade has been studied in detail but there has been mere attempt to control and make use of it.[20][21][22].