The separation of motile from lesser-motile and/or non-motile particles has numerous applications, including water supply analysis and biogenetics, but heretofore has been technologically difficult. An especially significant application is the sorting of sperm cells in in vitro fertilization, where the success rate is raised considerably when the motile sperm are used substantially for fertilization attempts. Sperm cells from donors with oligozoospermia (low sperm count) have previously been concentrated and to some degree separated by centrifugation, but this technique damages sperm with the pressure and allows incorporation of non-gametes into the enriched sperm sample. Another option is hand sorting, a very time-consuming process.
Researchers at the University of Michigan have developed a method using a microfluidic sorting device wherein a stream of sort fluid containing motile and non-motile particles is caused to flow adjacent a media stream; this provides an exit stream for at least a portion of a motile particle-enriched media flow stream, and an exit stream for a motile particle-depleted sort stream. The mobility of the motile particles allows them to enter the media stream along the interface between the media and sort streams, while non-motile or lesser-motile particles remain substantially within the sort stream. The sorting devices are easily and inexpensively fabricated and have numerous uses, in particular sorting of motile from non-motile sperm.
Applications and Advantages
- Concentration of viable sperm for-nl-in vitro fertilization
- Analysis of microorganisms in water supplies
- Direct the gender of domesticated mammal-nl-offspring, e.g milk cows.
- Biotechnology and microrobotics
- Saves time over hand sorting
- Easily and inexpensively fabricated -nl-sorting devices
- Small devices, with potential integration onto a single chip