Microfluidic-based sperm sorting & analysis for treatment of male infertility

Abstract

Microfluidics technology has emerged as an enabling technology for different fields of medicine and life sciences. One such field is male infertility where microfluidic technologies are enabling optimization of sperm sample preparation and analysis. In this chapter we review how microfluidic technology has been used for sperm quantification, sperm quality analysis, and sperm manipulation and isolation with subsequent use of the purified sperm population for treatment of male infertility. As we discuss demonstrations of microfluidic sperm sorting/manipulation/analysis, we highlight systems that have demonstrated feasibility towards clinical adoption or have reached commercialization in the male infertility market. We then review microfluidic-based systems that facilitate non-invasive identification and sorting of viable sperm for in vitro fertilization. Finally, we explore commercialization challenges associated with microfluidic sperm sorting systems and provide suggestions and future directions to best overcome them.

Keywords: Microfluidics; semen; sperm sorting and analysis.

Figure 1

Microfluidic systems designed for separation of sperm based on sperm motility. (A) Motile sperm can be selected from immotile sperm due to their ability to swim across channel width (51); (B) motile sperm are selected and sorted by swimming speed using the imposed velocity gradient (52); (C) a series of parallel, long narrow channels are used to select motile, viable sperm (53).

Figure 2

This figure depicts a microfluidic system designed for rapid separation of sperm from epithelial cells with application in forensics related to sexual assaults. (A) A picture of the actual device; (B) the cell mixture is aligned against the top wall in the pinched segment, and then the position difference of different sized cells is amplified in the expansion region; (C) sperm recovery rate is improved in the parallel capillary tubes (61).

Figure 3

The figure depicts the function of spiral microchannels to isolate sperm from pyospermic semen samples. The sample in injected at the inlet (part a), and based on the size-based lateral migration (part b and part c), sperm and white blood cells are collected in different outlets (part d). Size-based lateral migration of different cells is depicted in part (c) where two different forces (lift force “F_L”, dean drag “F_D”) distinctly position different-shaped cells along cross section of the channel (18).