Pseudo-nitzschia fraudulenta diatoms. (a) Fluorescence image of diatoms. The orange spots indicate the choroplasts (Chl). Calcium in the cytosol (Cyt) is shown in green. (b) Bright field optical micrograph taken 24 hours after depositing cells on the transducer. The dotted line separates the Au electrode and the glass substrate. The blue circle is centered at a single diatom and represents an area with a radius of 120 µm. (c) Growth curves in triplicate. The red trace corresponds to diatoms grown at 19 °C in light-dark cycles of 12 hours each using a photosynthetic photon flux density of 120 µmol m−2 s−1. The black curve corresponds to diatoms grown first kept in light until day 4, followed by complete darkness to day 11.