More than 70 million couples around the world are confronted with infertility (1) where male factors contribute to around 45% of the cases (2). Assisted reproductive technologies (ART) have been used to facilitate infertility over the past 40 years. Selection of high-quality sperm is an important step in ART as it influences the treatment success rate, live-birth rate, and offspring health (3). However, current clinical sperm selection methods are highly manual, time-consuming, prone to operator errors and differ significantly from the natural three-dimensional (3D) selections in vivo. Lack of technological developments to improve sperm selection in fertility clinics, to provide the required number and volume of high-quality sperm, has been the main barrier to improving treatment methods (4). Here, we present a scalable and clinically applicable technology to select high-quality sperm via a 3D network of microchannels.
This 3D platform mimics the in vivo sperm selection process and enables a high throughput selection of over 1.5 million sperm in 15 minutes. The device was originally fabricated using a stereolithography 3D printer (5), but to ensure clinical translation, we have developed a new prototype of the device for fabrication using injection molding out of polystyrene. The device is prefilled with buffer and during the selection time, motile sperm swim through a network of microchannels to reach the outlet while debris and non-motile cells remain in the inlet. The device achieves the state-of-the-art retrieval efficiency of 41%, significantly outperforming previous technologies by at least 10%, selecting sperm with more than 65% improvement in both DNA integrity and morphology.
In conclusion, we present a high throughput 3D sperm selection device that provides novel practical opportunities to improve sperm selection practices in assisted reproduction.