Fertility Chip Measures Sperm Concentration and Motility

The chip can be inserted into a compact device for one-off use and a home test kit will soon make it possible for men to test their sperm in a familiar environment.

A doctoral candidate at the University of Twente (Enshede, The Netherlands) developed the lab-on-a-chip measures sperm concentration. On the chip, sperm flow through a liquid-filled channel, beneath electrode "bridges." When a cell passes beneath one of these electrodes, there is a brief fluctuation in the electrical resistance. These events are counted. To test the reliability of the concentration measurements, microspheres were added to the liquid and the method was selective enough to distinguish sperm from microspheres. The system was also able to distinguish reliably white blood cells from other bodies. In addition to being an indicator of sperm quality, the white cell count provides important additional information to gynecologists.

The importance of the sperm concentration is that the fertility standard states that a milliliter of ejaculate should contain at least 20 million sperm. A second important aspect of fertility is motility. This too can be measured using the lab-on-a-chip. A small adjustment of the lab-on-a-chip is all that is needed to sort motile sperm from nonmotile sperm, after which both can be counted separately. By measuring sperm motility in this way, the chip offers a complete test.

Simple home test kits are already commercially available. These indicate whether the concentration is "above or below the standard value." However, these tests are too limited, as they do not give accurate concentration readings. Loes Segerink, the PhD student, has received a grant, as a first step towards establishing a company. This will provide her with a platform for refining the fertility chip and its accompanying read-out device into a market-ready product.

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