Michelle Rasmussen

Enzymatic biofuel cells: 30 years of critical advancements.

Enzymatic biofuel cells are bioelectronic devices that utilize oxidoreductase enzymes to catalyze the conversion of chemical energy into electrical energy. This review details the advancements in the field of enzymatic biofuel cells over the last 30 years. These advancements include strategies for improving operational stability and electrochemical performance, as well as device fabrication for a variety of applications, including implantable biofuel cells and self-powered sensors. It also discusses the current scientific and engineering challenges in the field that will need to be addressed in the future for commercial viability of the technology.

High performance thylakoid bio-solar cell using laccase enzymatic biocathodes

Thylakoid membranes have previously been used for electrochemical solar energy conversion, but the current output and open circuit voltage are low, in part due to limitations of the cathode. In this paper, a thylakoid bioanode and laccase biocathode were combined in the construction of a bio-solar cell capable of light-induced generation of electrical power. This two-compartment cell showed a greater than 5-fold increase in short circuit current density and an open circuit voltage 0.275 V larger than that of a thylakoid bio-solar cell incorporating an air-breathing Pt cathode. The electrodes were then tested in several solutions of varying pH to evaluate the possibility of constructing a compartment-less bio-solar cell. This membrane-less cell, operating at pH 5.5, generated a short circuit photocurrent density of 14.0 ± 1.8 μA cm(-2) which is 25% larger than the two-compartment cell and a similar open circuit voltage of 0.720 ± 0.018 V.

The photobioelectrochemical activity of thylakoid bioanodes is increased via photocurrent generation and improved contacts by membrane-intercalating conjugated oligoelectrolytes

The photobioelectrochemical impact of a series of conjugated oligoelectrolytes (COEs) with a systematic progression of chemical structures was elucidated by their direct incorporation into thylakoid bioanodes. In both three-electrode electrochemical cells and bio-solar cell devices, significant anodic performance enhancements (p < 0.1) were observed when anodes were modified with certain COEs. Amperometric photocurrent densities increased by up to 2.3-fold for the best COE. In bio-solar cell devices, short-circuit photocurrent increased by up to 1.7-fold and short-circuit dark current increased by up to 1.4-fold, indicating that the best COEs enhance both photocurrent generation and interfacial electron transfer. Trends in these results indicate that the molecular length and pendant charge of COEs differentially contribute to photobioelectrochemical enhancements, and the optimal combination of these features is revealed. Control experiments indicate that COEs augment native thylakoid functionality, as COEs do not have redox activity or undergo chemical degradation.

Long-term arsenic monitoring with an Enterobacter cloacae microbial fuel cell

A microbial fuel cell was constructed with biofilms of Enterobacter cloacae grown on the anode. Bioelectrocatalysis was observed when the biofilm was grown in media containing sucrose as the carbon source and methylene blue as the mediator. The presence of arsenic caused a decrease in bioelectrocatalytic current. Biofilm growth in the presence of arsenic resulted in lower power outputs whereas addition of arsenic showed no immediate result in power output due to the short term arsenic resistance of the bacteria and slow transport of arsenic across cellular membranes to metabolic enzymes. Calibration curves plotted from the maximum current and maximum power of power curves after growth show that this system is able to quantify both arsenate and arsenate with low detection limits (46 μM for arsenate and 4.4 μM for arsenite). This system could be implemented as a method for long-term monitoring of arsenic concentration in environments where arsenic contamination could occur and alter the metabolism of the organisms resulting in a decrease in power output of the self-powered sensor.

Fundamentals and applications of bioelectrocatalysis

This book chapter will detail the fundamentals of direct and mediated bioelectrocatalysis, as well as the applications of bioelectrocatalysis. Applications discussed include environmental, biomedical, and food and drink biosensors, self-powered sensors, biofuel cells, biosolar cells, and bioelectrosynthesis of value added products.