Abstract

The demand for implementing the energy harvesting systems to power up the sensors in the IoT applications attracted the attention of the scientists to bio-energy harvesting systems as a clean source of energy. Micro-photosynthetic power cell (μ-PSC) is a promising technology that uses the photosynthetic microalgae culture to generate power at a micro-scale. The main objective of this thesis is to develop the design, fabrication, and performance investigation of the arrayed μ-PSC. In addition, an improved model to predict the electrical behavior of the μ-PSC is developed and corresponding results have been validated with the experimental characteristics of a single μ-PSC.
In this study, the two techniques of fabricating 1×3 array of μ-PSC are developed. One consists of interconnected μ-PSCs fabricated using 3D-printing of Polylactic Acid plastic frames, and the other design is made of independent μ-PSCs molded with EPON 862 resin in a 3D printed mold. The biocompatibility of the selected materials is tested prior to the fabrication. Experiments are performed on both array designs to investigate the primary electrical parameters, including cell voltage, cell current, I-V characteristics, power characteristics and peak power. Testing of interconnected arrayed μ-PSC showed about three times output current as that of the single chip. The tested performance characteristics of the independently arrayed μ-PSC showed very similar trend as single μ-PSC chip. Hence, by a proper series and parallel connection, higher level of current and voltage can be obtained. Interconnected array produced maximum Open Circuit Voltage (OCV) of about 850mV, Short Circuit Current (SCC) of 2.5mA, peak power of 0.54 mW and Fill Factor of 0.224 while the independent array produced OCV of around 820mV, SCC of 1mA peak power of 0.25 mW and Fill Factor of 0.262.
The modeling was verified with test characteristics and the agreement between prediction and testing was about 90%. The presented fabrication processes for making arrays of μ-PSC are easier and faster compared to the previous techniques used for making single-chip μ-PSC. This study revealed that multiple independently arrayed chips can be used to power-up sensors by proper electrical combination as a future work.