Fig. 4: The OptoCube is a home-made device for optogenetic spatial patterning and yeast growth monitoring on solid media at a large scale.

a The OptoCube is composed of a DMD (digital micromirror device) fixed at the top of a temperature-controlled incubator and calibrated to illuminate a scanner placed under an array of Petri dishes. The DMD and the scanner are controlled by a computer and a microcontroller. Under our tested conditions, the light intensities of the DMD pattern on the Petri dishes ranged from 0.0014 mW cm⁻² to 1.13 mW cm⁻². b Cells were grown in a layer of 0.5% agarose gel on top of a layer of Phytagel containing 1% sucrose and yeast SC media (see Methods). c Under these conditions, cells develop into microcolonies with diameters ranging from 10 to 40 µm, consistently observed in all our experiments. In contrast to the microfluidic device (Fig. 2), hexoses and sucrose can diffuse, and cell growth is constrained within the gel. d To illustrate the patterning ability of this device, we projected an image of Maud Menten (courtesy of University Archives, University of Pittsburgh Library System) as a small tribute to her work on the Michaelis-Menten enzymatic kinetic equation, which was developed using invertase as the model⁶⁰. e Blue light pattern projected by the DMD on top of a Petri dish containing OptoSuc2 cells for 45 h. f Scan of the Petri dish showing the regions where yeast has grown (gray areas). The first image of the timelapse was subtracted as the background. g Inverted image of the resulting yeast growth, revealing the image of Maud Menten developed through OptoSUC2-induced cooperation (see also Supplementary Movie 2).