When measuring fluorescence, the LED light was passed through a filter cube fitted with a TRITC-A filter set (λ excitation = 543-566 nm, λ emission = 582-636 nm) from Semrock Inc. This allowed emission of the resorufin (peak λ excitation = 571 nm, peak λ emission = 585 nm, see Figure ) to be separated from the excitation. The exposure time was set to a value between 50 and 200 ms, and LUTs were adjusted to accommodate the maximum pixel intensity observed during fluorescence. A rainbow false colour map was use to better visualise the fluorescence. The mean and sum intensities of pixels in the ROI were measured over time and saved as .txt files. The image of the electrode during the fluorescence was saved as a .mp4 file.