PROFILES OF HUMAN SPERM DENSITY IN LONG ASYMMETRIC MICROCHANNELS

The development of microfluidic devices presents itself as an innovative approach to improving current assisted reproduction techniques, which are far from being highly efficient. The design of these microdevices is generally very flat, is characterized by many channels and all the walls play a fundamental role, located at micrometric distances from each other. To study this high-confinement effect, human sperm motion was modeled in two dimensions using Langevin dynamics. The cellular density was calculated within channels (with asymmetric entry and exit) of micrometric width and an aspect ratio (width/length, w/L) less than one. To achieve an accurate representation of the oscillatory dynamics, a phenomenological model with experimentally obtained sperm motility parameters was used. As the channel width decreases, the proximity to the walls significantly influences the density distribution, primarily when the distance between them is a few cells, making the effects of the device’s high confinement evident. It was observed that the transverse profile varies for different positions along the channel, especially near the entrances and exits, and remains constant around the middle of the lenght (L/2). For example, for length of 300 μm, the profile remains constant along 125 μm, instead, in very short channels as L = 50 μm the profiles vary along the length of the channel, that is, the asymmetry dominates.