A team at Florida Atlantic University created a microfluidic chip that can sort and collect healthy sperm cells for fertility procedures. The chip takes advantage of the fact that healthy sperm will naturally swim against cervical mucus flows and uses fluid flow to guide the cells to swim into a collection chamber. The simple approach ensures that the collected cells are intact and motile, unlike currently used centrifugation techniques, which can take a long time, with multiple steps, and which can actually damage sperm cells in the process.
Sperm cells have a perilous journey before they can fertilize the egg, with a long swim against cervical mucus flows before they reach their goal, in a process called rheotaxis. Consequently, sperm motility is a key factor in male fertility. With declining sperm rates in many regions of the world, fertility treatments are in demand, but obtaining a healthy sperm sample with plenty of cells that are motile is key in ensuring the success of such procedures. However, current techniques to isolate living sperm cells from those that are dead, deformed, or otherwise damaged have their limitations.
Typically, a centrifuge is used to separate sperm cells, but this procedure is time-consuming and can actually damage the sperm. “Conventional centrifugation often compromises the integrity of sperm cells. This research study demonstrates that the microfluidic chip developed by professor Asghar and his colleagues eliminates this issue,” said Stella Batalama, a researcher at Florida Atlantic University. “This novel technology offers a platform where the sperm cells experience different shear stress in different parts of the chip, which facilitates the isolation of competent sperm cells without impacting their integrity.”
The newly developed chip relies on an inexpensive and simple technique that exploits the natural tendency of healthy motile sperm to swim against fluid flow. A raw semen sample is added to one chamber within the chip and then a syringe pump provides fluid flow. The healthy cells will naturally swim against this and end up in a collection chamber from where they can easily be removed with no damage or fuss.
“Operating our chip is very easy. Once the semen is loaded into the sample inlet chamber, the competent sperm cells start moving against the fluid flow toward the collecting chamber from where they can easily be collected,” said Waseem Asghar, a researcher involved in the study. “Furthermore, this chip offers a one-step, one-hour operational benefit, which an operator can use with minimal training.”
See a video of the tiny sperm cells swimming about the chip:
Study in journal Analyst: Selection of healthy sperm based on positive rheotaxis using a microfluidic device