FlowNMR spectroscopy is an excellent technique for non-invasive real-time reaction monitoring under relevant conditions that avoids many of the limitations that bedevil other reaction monitoring techniques.

Access to safe drinking water is a human right, crucial to combat inequalities, reduce poverty and allow sustainable development. In many areas of the world, however, this right is not guaranteed, in part because of the lack of easily deployable diagnostic tools. Low-cost and simple methods to test water supplies onsite can protect vulnerable communities from the impact of contaminants in drinking water. Ideally such devices would also be easy to dispose of so as to leave no trace, or have a detrimental effect on the environment. To this aim, we here report the first paper microbial fuel cell (pMFC) fabricated by screen-printing biodegradable carbon-based electrodes onto a single sheet of paper, and demonstrate its use as a shock sensor for bioactive compounds (e.g. formaldehyde) in water. We also show a simple route to enhance the sensor performance by folding back-to-back two pMFCs electrically connected in parallel. This promising proof of concept work can lead to a revolutionizing way of testing water at point of use, which is not only green, easy-to-operate and rapid, but is also affordable to all.

No abstract

Microbial fuel cell (MFC) technology holds enormous potential for inexpensive real-time and onsite testing of water sources. With the intent of defining optimal operational conditions, we investigated the effect of environmental factors (changes in temperature, pH and ionic strength), on the performance of a single chamber miniature MFC sensor. The pH of the influent had the greatest effect on the MFC performance, with a 0.531 ± 0.064 μA cm−2 current variation per unit change of pH. Within the range tested, temperature and ionic strength had only a minor impact (0.010 ± 0.001 μA °C−1 cm−2 and of 0.027 ± 0.003 μA mS−1 cm cm−2 respectively). Under controlled operational conditions, for the first time, we demonstrated the ability of this biosensor to detect one of the most commonly applied pesticides worldwide, atrazine. The sensitivity to atrazine was 1.39 ± 0.26 ppm−1 cm−2, with a detection range of 0.05–0.3 ppm. Guidelines for systematic studies of MFC biosensors for practical applications through a factorial design approach are also provided. Consequently, our work not only enforces the promise of miniature MFC biosensors for organic pollutants detection in waters, but it also provides important directions towards future investigations for infield applications.