Urine-activated origami microbial fuel cells to signal proof of life

Abstract

The adaptability and practicality of microbial fuel cells (MFCs) are highly desirable traits in the search for alternative sources of energy. An innovative application for the technology could be to power portable emergency locator transmitters (ELTs). Such devices would ideally need to be lightweight, robust and fast-in terms of response. Urine is an abundant resource, and with MFCs, could be the ideal fuel for powering ELTs, with the compelling advantage of also indicating proof of life. We developed novel origami tetrahedron MFCs (TP-MPFCs) using photocopier paper to test different urine-based inoculants.When inoculated with urine extracted from the anode chambers of working MFCs a stack of 6 abiotic MFCs produced a usable working voltage after just 3 h 15 min; enough to energise a power management system. The anodes of established TP-MFCs were then removed and air-dried for 7 days before being inserted into new paper reactors and refrigerated. After 4 weeks, these MFCs displayed an immediate response to fresh urine and achieved a functional working voltage in just 35 minutes. Two paper MFCs connected in parallel were able to transmit 85 radio signals and in a series configuration 238 broadcasts over 24 hours. These findings demonstrate that simple, inexpensive, lightweight paper MFCs can be employed as urine-activated, "proof of life" reporting systems.

High-throughput shadow mask printing of passive electrical components on paper by supersonic cluster beam deposition

“…Its low cost and availability is ideal for rapid prototyping, it can be easily shaped and trimmed with scissors or cutters, and it can be used for complex self-standing 3D structures, fluidics, and electrochemical applications. [3][4][5][6][7] Printing on paper relies on a technological tradition dating back from almost two thousand years and originating from China; it became a mass-producing technology in Europe from the fifteenth century. 7 The direct printing of electronic components with various degrees of complexity on paper has taken inspiration from this tradition, and it is based on techniques such as flexography, offset, and screen printing.…”

“…[1][2][3] Recently, the interest for the use of paper as a substrate for foldable electronic components such as antennas and actuators has substantially increased in view of the realization of the so-called origami electronics, 4,5 self-foldable kirigami soft robots, 6 and power portable emergency locator transmitters based on origami microbial fuel cells. 3 These applications rely on the so-called "chip-on-flex technologies" where electronic components have typical dimension of tens or hundreds of microns so miniaturization is not a critical issue. 1 In this case, substrates must be flexible and foldable, and manufacturing methods should be cheap, easily scalable, compatible with rapid prototyping in order to produce batches of components to be integrated in functional systems.…”

Fade to Green: A Biodegradable Stack of Microbial Fuel Cells

“…However, if we consider the operation of a hypothetical biodegradable robot, if more rapid degradation was required and rigidity was a prerequisite, alternative materials could be employed for the frame/chassis, like for example, composite lignin, wood or even paper. [22] Suitability of conductive synthetic latex CSL works well as the cathode if coated on to a natural rubber membrane [17] however, for the purposes of the current study in which biodegradability is essential, a CSL cathode might not be appropriate. Therefore, CSL was examined for biodegradation alongside natural rubber.…”

Here today, gone tomorrow: biodegradable soft robots

“…Natural rubber has proven to be a viable substitute to conventional membranes over long term operation where the act of biodegradation actually aided performance [22]. Other materials such as paper [16], egg, gelatine, PLA and lanolin have all demonstrated their suitability as viable working components in MFCs [23]. The culmination of that work was the production of a stack of biodegradable MFCs capable of generating usable power, whilst utilising waste liquid such as urine as the fuel source.…”