Electricity generation using a microbial 3D bio-anode embedded bio-photovoltaic cell in a microfluidic chamber†

New-generation sustainable energy systems serve as major tools to mitigate the greenhouse gas emissions and effects of climate change. Biophotovoltaics (BPVs) presents an eco-friendly approach by employing solar energy to ensure self-sustainable bioelectricity. In contrast to other microbial fuel cells (MFCs), carbon feedstock is not essential for generating electricity with BPVs. However, the low power outputs (μW cm⁻²) obtained from the current systems limit their practical applications. In this study, a new generation polydimethylsiloxane (PDMS) based BPV cell unit was developed with a 3D hydrogel scaffold-based bio-anode to enable microbial biofilm formation for substantial electron capture and extracellular electron transfer. Moreover, the fabricated device was supported using an air-cathode electrode to elevate the gas exchange, thereby enabling optimum photosynthesis. Synechocystis sp. PCC 6803 seeded the 3D bio-anode embedded BPV cell, whose electrical characteristics were analyzed under the illumination of white light as day/night cycles with continuous feeding by the microchannel. For the first five days, the results indicated that the maximum power densities were 0.0534 W m⁻² for dark hours and 0.03911 W m⁻² for light hours without causing any effect on the cellular morphology of the cyanobacteria. As a result, the developed hydrogel scaffold-based bio-anode embedded BPV cell led to higher power densities via enabling a simple, self-sustainable, biocompatible, and eco-friendly energy harvesting platform with a possible capability in the applications of power lab-on-a-chip (LOC), point-of-care (POC), and small-scale portable electronic devices.