High-throughput flowing upstream sperm sorting in a retarding flow field for human semen analysis

Abstract

In this paper, we propose a microfluidic device capable of generating a retarding flow field for the sorting and separation of human motile sperm in a high-throughput manner. The proposed sorting/separation process begins with a rapid flow field in a straight-flow zone to carry sperm into a sorting zone to maintain the sperm's mobility. The sorting zone consists of a diffuser-type sperm sorter to differentiate sperm with different motilities based on the flowing upstream nature of human sperm in a retarding flow field. The dead sperm will then be separated from the live ones by passing through a dumbbell flow field to the outlet for disposal. The proposed flowing upstream sperm sorter (FUSS) is designed to imitate the selection mechanism found in the female body when sperm swim into the uterus. The experimental results demonstrate the utility of this device with regard to throughput (approximately 200 000 sperm per minute and a maximum of 200 million cells per mL), efficiency (90% of selected sperm are mobile), and the ability to select sperm with high motility (∼20% of sperm with a velocity exceeding 120 μm s). The proposed device is suitable for intrauterine insemination as well as in vitro fertilization thanks to the highly efficient sorting process not interfering with the natural function and energy resource of human sperm.

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

“… 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 ). …”

“…The most direct selection of fast swimming sperm was made by Wu and coworkers utilizing a microfluidic system ( 52 ). In this system, Wu and coworkers created a triangular flow zone in which the microchannel’s geometry ( Figure 1B ) essentially created a gradient of mainstream flow speed along the geometry’s length.…”

Effect of microfluidic processing on the viability of boar and bull spermatozoa

“…The separated spermatozoa were, however, not tested for viability or motility. Wu et al 23 separated spermatozoa of different motilities based on the cell's swimming abilities in a retarding flow field. A flow field (0.3 × 10 −3 ml/min, estimated shear stress of 0.033 N/m 2 ) was needed to carry the spermatozoa to the separation zone.…”

An automated instrument for intrauterine insemination sperm preparation

“…Numerous microfluidic devices that perform both motility-based and shape-based sperm selection have been developed. Microfluidic motility-based methods select sperm based on their ability to swim across streamlines 8,9 , against a flow 10 , through long channels 11 , or through filter membranes 12 . While motility-based selection is advantageous for selecting a subpopulation of only motile sperm cells with low DNA damage 11 , the selection results in the loss of a substantial portion of viable sperm cells.…”