In this paper, we present an experimental and numerical study on a Piranha Pin Fin (PPF) micro scale heat sinks. The PPFs were designed to enhance heat transfer by manipulating the flow field, selectively venting the fluid, and adding surface area. The hydraulic and thermal performances are studied for Reynolds numbers ranging from 508 to 2114 based on the channel hydraulic diameter. A conjugate convection/conduction heat transfer model was developed with COMSOL software, which showed good agreement to experiments. Velocity field and temperature distribution obtained from the model were also discussed to obtain a better understanding of the heat sink performance. Extraction effect was evaluated and analyzed. Friction factor and Nusselt number were obtained and compared with available correlations. (C) 2016 Elsevier Ltd. All rights reserved.