Abstract
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.
Highlights
The provision of clean water is essential to allow economic growth and environmental sustainability (WWAP (United Nations World Water Assessment Programme), 2015)
The degree of crosslinking of the cellulose fibers was determined by measurement of glycolic acid post treatment, as previously described (Schramm and Rinderer, 2000): cross-linked paper samples (0.4 g accurately weighed) were treated with 5 mL of 4 M NaOH at 100 °C for 25 min; the extract diluted by a factor of 10 and filtered through a 0.2 μm nylon filter before High-performance liquid chromatography (HPLC) analysis was performed (Shimatzu Class-VP HPLC with an Aminex HPX-87H column thermostated at 50 °C 15 min isocratic elution with 10 mM H2SO4 at a flow rate of 0.6 mL min−1; UV–vis. detection at 210 nm)
To increase the paper tensile strength, improve its robustness and enhance the operational lifetime of the device, the cellulose fibers in the paper and the cellulose in the ink binder of the paper microbial fuel cell (pMFC) were cross-linked by reaction with glyoxal (a common cross-linking agent (Xu et al, 2002))
Summary
The provision of clean water is essential to allow economic growth and environmental sustainability (WWAP (United Nations World Water Assessment Programme), 2015). Power (W) Peak area (–) Resistance (Ω) Voltage (V) Initial weight of paper sample (mg) Despite their promise, practical implementation of MFCs as sensors is still restricted by the use of expensive manufacturing materials (Winfield et al, 2015) and device designs that are not suitable for portable applications, due to the need for pumps and tubing during operation (Hashemi et al, 2016). Practical implementation of MFCs as sensors is still restricted by the use of expensive manufacturing materials (Winfield et al, 2015) and device designs that are not suitable for portable applications, due to the need for pumps and tubing during operation (Hashemi et al, 2016) All these aspects reflect in an increase in both capital and operating costs. We report on increased baseline current and enhancement of the sensor sensitivity by the simple design modification of folding two paper MFCs back-to-back, electrically connected in parallel
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