Chip for measuring male fertility is first stage in home testing kit
23 February 2010
A new ‘fertility chip’, developed by researchers at the
University of Twente’s MESA+ Institute for Nanotechnology, can
accurately count spermatozoa in semen. This is an important step towards
the development of a compact device for reliable ‘pre-scanning’ of male
fertility. The researchers are publishing the invention of the chip in
the scientific journal Lab on a Chip.
Every year more than 10,000 couples in the Netherlands apply for
help because of involuntary childlessness. A sperm analysis is
typically the first step of fertility research. Testing sperm
quality requires stringent pre-test preparations and a specialized
laboratory. Tests often have to be repeated two to five times for
sufficient reliability. If men can carry out the tests in the
privacy of their own home this makes the procedure much less awkward
for them, the probability of a reliable diagnosis is increased, and
the costs of testing reduced.
Sperm counting chip
Concentration is an important indication of sperm count: the norm
for fertility is 20 million spermatozoa per millilitre of ejaculate.
Simple home tests are available, but these can only indicate that
the sperm count is 'above or below the norm'. These tests are too
limited because they do not actually measure the concentration of
spermatozoa. The chip developed by researcher Loes Segerink,
however, can accurately count spermatozoa. An artist's impression of
what an analyser with the chip could look like is shown below.
the new chip, the spermatozoa flow through a fluid channel, above
which electrodes are fitted. When a cell flows under this 'bridge',
its electrical resistance changes momentarily, and this event is
counted. It is important that the count distinguishes between
spermatozoa and other particles or cells in the fluid: if other
particles are included the count will be unreliable.
Segerink added minuscule balls to the fluid to test its
selectivity. The method proved to be selective enough to distinguish
between the balls and the spermatozoa. White blood cells were also
distinguished by the chip. The number of white blood cells tells us
something about sperm quality and so this is important additional
information for the gynaecologist.
Activity and shape
Concentration is not the only indicator of sperm quality.
Spontaneous activity — also known as motility — and the shape of the
spermatozoa are also important factors. Further research will need
to establish whether these two quality characteristics can be
measured in a similar manner, so that a compact device can be
developed in which a chip can be inserted for single use. The user
will only be able to see that the test has been completed
successfully; the gynaecologist will inform him of the actual
1. Loes Segerink, Ad Sprenkels, Paul ter Braak, Istvan Vermes and
Albert van den Berg. On-chip determination of spermatozoa
concentration using electrical impedance measurements. Lab on a
Chip. It has been published online in the form of an Advance
Publication, and will appear in print in the near future.