Modeling of Bio-Electrochemical and Mechanical Interactions in a Photosynthetic Cell

Micro photosynthetic cell (µPSC) is an electrochemical device, which generates electricity, by harnessing the electrons from photosynthesis and respiration processes of the photoautotrophs.

Till date, focus has been mostly on experimental aspects of  and very little work has been pursued on the development of mathematical models for µPSC.  Modeling a system like µPSC is complex due to the fact that the device operation depends on interactions of microorganisms with several operational parameters such as light intensity, quantum yield and so on. Further, the electrode structure and the electrochemical interactions at the surface of the electrodes affect the device performance.

 Modeling of µPSC could help in understanding the performance limiting step(s) in the series of processes that occur during the operation of device. The performance of the device can be improved by focusing on the rate of limiting steps. Modeling could also help in determining optimal design and operational parameters which can maximize the device performance.

 A simple mathematical model based on first principles is proposed to predict the performance of the µPSC. Sensitivity analysis is performed to obtain the most sensitive rate parameters of the model. The optimal values of sensitive rate constants are obtained from the experimental data through optimization. The developed model is validated by comparing the predictions of the model with the experimental data obtained from the response of the system to step changes in load. Figures 1 and 2 show the model performance in terms of i-V characteristics and comparison of experimental and estimated voltage profiles for step changes in external loads.

 Keywords:, First principles model, Parameter estimation, and Optimization and Sensitivity analysis.