Exotic droplets formed in microfluidic chips with uniform wettability

Microdroplets are widely used in industrial processes. In the absence of external forces, droplets generally assume a spherical shape. Here, we present two methods to form non-spherical droplets in microfluidic glass chips. A uniformly hydrophobized chip has been successfully used to dynamically control the width and length of elongated water-in-oil droplets; on a hydrophilic chip, we generated non-spherical double droplets that consisted of two different oils in a water continuous phase.