Recently, investigation of eco-friendly way of energy harvesting using biomaterials has increased in the last decade. Extracting photosynthetic electrons (PEs) from sub-cellular extracts of photosynthetic plants for energy harvesting has an advantage of minimum loss in the energy conversion. Extraction of PEs from spinach thylakoids has been reported using various types of electrodes. However, when a flat-shaped electrode is used, electrochemical interactions between thylakoids and electrodes is limited to the electrode size. In this study, in order to maximize the interaction area between thylakoids and electrodes, silicon-based micro-pillar shaped electrodes with different aspect ratios (ARs) were fabricated using metal-assisted chemical etching (MAC-etching). In particular, the heights and spacings of the micro-pillar electrode arrays were varied to find the optimum geometry for maximum PE extraction. Morphological analysis of interactions between thylakoids and micro-pillar electrodes with different geometry were performed by optical microscopy and scanning electron microscopy (SEM). Then, light- dependent photosynthetic currents from the micro-pillar electrodes were monitored by chronoamperometry (CA) with 0.4V bias applied, and the data were compared for different micro-pillar electrodes.