Scientists have created a device that quickly traps strong and speedy sperm, improving the chances for couples trying for a baby via in-vitro-fertilisation (IVF). Conventional methods to separate vigorous, motile sperm is tedious and may take up to several hours to perform, according to the research published in the journal PNAS. "Trying to find the highly motile sperm has been difficult to do, but this improves the chances of insemination," said Alireza Abbaspourrad, an assistant professor at the Cornell University in the US. Taking advantage of sperm's ability to go against the flow - a process called rheotaxis - the researchers devised a microfluidic channel through which the sperm swim. They added a microscopic corral - shaped like a C - that features a retaining wall that attracts the strongest swimmers. "The older method is tedious, time-consuming and not efficient. It's the time that laboratory technicians and physicians expend that makes the process expensive," said Abbaspourrad. "With this method, it's five minutes instead of several hours," Abbaspourrad said. "We took advantage of sperm's natural tendency to redirect against fluid flow, once the sperm reach a certain velocity," said Soon Hon Cheong, an assistant professor at Cornell. "Once the sperm detect interference, they can use it to swim upstream. That's when we can trap them," Cheong said. "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," said Cheong. These findings represent a broad range of applications beyond humans, such as using the device to separate motile bovine sperm for the dairy and beef industries, researchers said.