Optofluidics for Energy: Fuel and Electricity From Plasmonically-Excited Photosynthetic Bacteria

Microalgae have been demonstrated to be the only viable major biofuel avenue due to globally finite cropland[1]. Traditional photobioreactors used to cultivate microalgae and cyanobacteria for biofuel production are plagued by low cell density due to limited light penetration depth [2]. An optofluidic approach to cultivation of cyanobacteria provides an opportunity to overcome these difficulties by leveraging the inherent density advantages of biofilm growth [3]. A biophotovoltaic cell (BPV) is presented that is capable of high-density cultivation of cyanobacteria using surface plasmon resonance (SPR) enhanced evanescent fields as well as producing electrical power. This device, a photosynthetic-plasmonic-voltaic cell (PPV), demonstrated significant power output under direct illumination and plasmonic excitation and demonstrates for the first time the dual use of a gold film for photosystem excitation and electron harvesting. The techniques used in this device are amenable to scale up of an ultra-high density photobioreactor that is capable of coproducing electrical power and biofuel.