One in six couples of reproductive age worldwide are affected at least once by some form of infertility. In vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are widely-available assisted reproductive technologies (ART). The identification and isolation of the most-motile sperm with DNA integrity are essential to IVF and ICSI, ultimately affecting treatment consequences and the health of offspring. Recently, microfluidic technologies been developed to sort sperm according to sperm morphology, motility, DNA integrity, and functionality for IVF techniques. There have also been emerging applications in wildlife conservation, high-throughput single-sperm genomics, sperm-driven robotics, and in-home fertility testing. We review a broad range of studies applying the principles of microfluidics to sperm research.