New Device quickly captures viable sperms to fast track IVF process

Good news for couples hoping for a baby via in vitro fertilization. Cornell University scientists have created a microfluidic device that quickly corrals strong and speedy sperm viable for fertilization which abruptly reduced the processing time to minutes which once took hours. The study was published in the journal PNAS.

The separation of motile sperm from semen samples is required for medical infertility treatments and clinical studies. Conventional methods are time-consuming and labour-intensive and could be potentially hazardous to the morphology and paternal content of the sperm.

"Trying to find the highly motile sperm has been difficult to do, but this improves the chances of insemination," said chemist Alireza Abbaspourrad, Cornell's Yongkeun Joh Assistant Professor of Food Chemistry and Ingredient Technology.

Taking advantage of sperm's ability to go against the flow-a process called rheotaxis, the researchers devised a microfluidic channel through which the sperms swim. They added a microscopic corral shaped like a "C" that features a retaining wall that attracts the strongest swimmers.

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Using a microfluidic corral system and the ability of viable sperm to swim against the flow, the researchers were able to passively isolate motile sperm from the semen sample inside a corral. This device can separate sperm with velocities higher than a cutoff, which is tunable with the injection rate.

“Here, we took advantage of sperm's natural tendency to redirect against fluid flow, once the sperm reaches a certain velocity," said Cheong, co-author of the study. "Once the sperms detect interference, they can use it to swim upstream. That's when we can trap them. We could separate the good sperm from the not-so-strong in a reasonably elegant way. We are able to fine-tune our selection process," he added.

The authors concluded that the microfluidic device is simple to use, is robust, and has a high throughput compared with traditional methods of motile sperm separation, fulfilling the needs for sperm sample preparation for medical treatments, clinical applications, and fundamental studies.

This device may certainly increase the success rates of in vitro fertilization in coming years.