This work reports a novel approach for the design and fabrication of controllable nucleation sites in pool boiling, with the aim to study the correlation of boiling curves and number of nucleation sites. Each nucleation site was designed to be a cavity with hydrophobic micropillar arrays. The dimensions of micropillars were carefully selected so that Cassie wetting can be guaranteed. Therefore, the designed structure allows to trap vapor and evolve as an effective nucleation site in pool boiling environment. Compared to traditional nucleation sites with hole-shaped cavities, these Cassie-wetting nucleation sites own unique advantages including easiness of activation and reliability of enduring harsh boiling perturbations. A correlation of boiling curves and number of nucleation sites is obtained by systematically examining the pool boiling performance of surfaces with different numbers of nucleation sites. (C) 2018 Elsevier Ltd. All rights reserved.