As the oceans play a crucial role in the future of our civilization (natural resource, climate regulationâ¦), it is important to build very accurate model to predict their evolution. One important part of this model is to know our impact on the environment such as the pollution which can be assessed by knowing the different populations of phytoplankton or algae at different depths. Currently the only solution available on a large scale is to obtain water samples for laboratory analysis which induce many issues of cost, contamination, sample degradation, and poor sample frequency in both space and time. However, if an integrated and small flow cytometer system could be realized, platforms such as Argo floats, AUVs (autonomous underwater vehicle) or gliders could be used to bring the system at different depths and to obtain in-situ measurements. Thus, this part of the project has as an aim to develop an integrated flow-cytometer on chip for in situ particle counting and sampling. The targeted species are phytoplankton with a size in the 2 to 50 Âµm range. The detection of the different species is realized by measuring the fluorescence and the scattered light of the particles when they are illuminated by a laser in the visible wavelength range. As each particle can have different fluorescence properties and as the scattered light is proportionnal to the size (for small angle) and to the granularity/shape of the particles (big angle), we are able to distinguish them.