A microfluidic device includes a first substrate, and a phase change ink deposited on a surface of the first substrate. The phase change ink includes an ink vehicle including a polymeric material having one or more acidic groups, and an optional colorant, wherein the phase change ink is solid at room temperature but is liquid at a jetting temperature of from about 60 to about 150° C., and an acidic group mass percentage, measured as a total mass of acid groups to an entire weight of the ink, is from about 1% to about 35%.