Emerging microfluidic technologies for sperm sorting

Sorting high-quality sperm with intact DNA, normal morphology, and active motility is crucial for clinically assisted reproductive technology, which influences the success of treatment and the health of offspring. Currently, microfluidic technology has been developed as a powerful platform for sperm sorting owing to its ability to manipulate fluid at the microscale and handle small samples. Specifically, microfluidic technology provides the necessary stimuli including fluid stimulus, chemical induction, and shape sift, which supports researchers in developing various sperm-sorting devices. According to the sorting principle, these devices can be divided into three categories: active sorting devices based on sperm rheological properties, passive sorting devices based on sperm physical properties, and external stimuli-induced sorting devices. Hence, we review a broad range of researches about sperm sorting with microfluidics and briefly present the properties of sperm and female reproductive tract to assist the design of microfluidic sperm sorting devices.