Infertility is a health issue with sociological and psychological implications that affects approximately 50 million couples worldwide and therefore receives global attention. Among fertility issues, male infertility is diagnosed in about 40% of all cases and the major causes are poor motility of spermatozoa (asthenospermia), low sperm count (oligospermia), abnormal sperm morphology (teratospermia) and/or combinations of these, leading to their inability to fertilize an oocyte. Such problems have been mainly addressed by artificial insemination (AI) and in vitro fertilization (IVF). AI involves introducing sperms into a woman’s uterus with a medical instrument, but its applicability is limited and its success rate is below 30%. In contrast, IVF and intracytoplasmic sperm injection can be more effective but implicate more invasive procedures such as removing oocytes from a woman’s ovaries, fertilize them outside of the body and then transfer the embryos back to the uterus a few days later. These difficulties demand rethinking of assisted fertilization and the sought after novel approaches that offer more natural procedures with high success rate. Hence, we propose untethered medical microbots to assist sperm cells to fertilize an oocyte in living organisms (mice model). The MicroRepro project will bring advances in areas such as bioimaging, nanomaterials science and fundamental biology, boosting the whole field of medical microbots in the process, as was recently highlighted by the PI in an extended comment [Nature 545, 406(2017)]. The PI has decisively contributed to the field of microrobotics and invented the sperm-robot (Spermbot) concept together with his team in two previous patent applications and several publications. The mere concept has attracted worldwide attention. However, even in vitro fertilization has never been achieved – therefore, targeting the challenges leading to the first spermbot fertilization will be the main objective of this project.