A new open-source hardware device to measure vertical sperm motility and concentration

Sperm motility and concentration are commonly evaluated parameters in semen analysis. Those parameters are assessed objectively with commercial instrumentation such as computer-assisted sperm analysis systems (CASA) and hemocytometer. In CASA systems, sperm motility is assessed in the horizontal plane imposed by the stage of the microscope. Thus, there is lack of measurement of the vertical velocity of sperm. The female reproductive tract is a tridimensional space which the sperm traverse to reach the ovum, and there is a need for instruments measuring parameters more relevant to this real-world situation. In this report we describe the design, construction and use of an open-source hardware (OSH) device for evaluation of the vertical velocity of sperm, called UPSPERM. This device was also used to measure sperm concentration, and agreement with hemocytometer was evaluated. Bland-Altman analysis shows good agreement between these two methods of sperm counting. As a first application of UPSPERM, we evaluated the changes in boar sperm motility at distinct pH values between 7.0 and 8.0. The UPSPERM results showed that the vertical velocity of sperm was highest at pH 7.6 and 7.8. We propose that our UPSPERM offers a reliable and affordable option for obtaining measurements of vertical velocity and sperm concentration.