Significant technological advances in 3D electrochemical electrodes, microalgae cultivation and growth monitoring systems and in cooperative signalling mechanisms in microorganisms have been achieved. In concordance to the project objectives written in the Description of Action, we have been able to:
1) Devise a new electrochemically stable and biocompatible 3D porous electrode capable of comprising large cell densities. Here, several commercially available sponges have been bought and characterized for porosity, mechanical and electrical properties, electrochemical stability, and hydrophilic properties. A new infrastructure and methodology to fabricate and characterize conducting 3D sponges has been devised. Protocols for (1) cleaning, (2) coating, (3) annealing, (4) electrical and mechanical characterization have been investigated and optimized. In addition, viability, adhesion and electrical signalling of thirteen different microorganisms to the developed 3D sponges, have been investigated with electrical and optical measurements.
2) Determine which microorganisms, provide the higher output magnitudes. Here, the infrastructure to culture and grow microalgae strains has been installed, calibrated and is now fully operational. We successfully manage to select, purchase and maintain different microalgae strains and bacteria. We have determined the required water, carbon dioxide, minerals and light, for long-term cultivation of our strains. Also, all different strains have been analysed for viability on the developed conductive sponges. The electrogenicity of strains is ongoing and preliminary evidences, using ion channel inhibitors and fluorescence microscopy, ascertain the role of Ca2+ in community reactions to environmental stress, particularly the absence of light. A comprehensive database with the electrical signatures, including noise spectra, magnitude and frequency of spikes occurrence, of microalgae and bacteria populations, under different growth stages, light, temperature and nutrient conditions is ongoing. A model on the origin of bioelectricity in microalgae has been published in a high impact publication (Amaral et al 2023).
Finally, we have also started to address the specific output power of selected microorganisms and performing circuit/component optimization in existing energy harvesting circuits, including the LTC310, ADP5091 and the LTC3588, as described in the already published high impact publication (Amiri et al 2023).
New research directions have also been planned in concordance with the Description of Action. New research projects have been submitted to:
• Human Frontier Science Program
• Doctoral Networks proposal submitted under HORIZON-MSCA-2022-DN-01-01
• NATO’s Science and Security Programme
We have also been able to organize the first international GREEN workshop in Coimbra, and to present our work in multiple national and international conferences and workshops, as described in the Description of Action.
