Samenvatting

During recreational activities, people can be exposed to toxins produced by cyanobacteria by
ingesting contaminated water, inhaling toxic fumes or direct skin contact. Short term exposure
may cause varying complaints like mild nausea and skin problems. Long term exposure may lead
to sub-chronic conditions. Determining the presence of cyanobacteria is done by visual inspection
and laboratory tests for over 650 recreational inland bathing waters in The Netherlands. A major
obstacle is the time that is lost between sampling and taking actions. In this project was focused
on the development of an optical sensor that can perform ad hoc measurements signicantly
faster. In vivo phycocyanin in cyanobacteria cells emits light at 610nm{630nm when excited at
a wavelength of 645nm. The intensity of fluorescent light was measured with an optical sensor
that was constructed for less than 70 Euro. The designed photospectrometer has measured in vivo
phycocyanin in a Microcystis sample that contained between 534g/L and 686g/L phycocyanin.