Search Results (4)

Implantable and wearable bioelectronic systems can enable tailored therapies for the effective management of long-term diseases, thus minimising the risk of associated complications. In this context, glucose fuel cells hold great promise as in- or on-body energy harvesters for ultra-low-power bioelectronics and as self-powered glucose sensors. We report here the generation of gold nanostructures through a gold electrodeposition method in a soft template for the abiotic electrocatalysis of glucose in glucose fuel cells. Two different types of soft template were used: a lipid cubic phase-based soft template composed of Phytantriol and Brij^®-56, and an emulsion-based soft template composed of hexane and sodium dodecyl sulphate (SDS). The resulting gold structures were first characterised by SAXS, SEM and TEM to elucidate their structure, and then their electrocatalytic activity towards glucose was compared in both a three-electrode set-up and in a fuel cell set-up. The Phytantriol/Brij^®-56 template led to a nanofeather-like Au structure, while the hexane/SDS template led to a nanocoral-like Au structure. These templated electrodes exhibited similar electrochemical active surface areas (0.446 cm² with a roughness factor (RF) of 14.2 for Phytantriol/Brij^®-56 templated nanostructures and 0.421 cm² with an RF of 13.4 for hexane/SDS templated nanostructures), and a sensitivity towards glucose of over 7 μA mM⁻¹ cm⁻². When tested as the anode of an abiotic glucose fuel cell (in a phosphate-buffered solution with a glucose concentration of 6 mM), a maximum power density of 7 μW cm⁻² was reached; however the current density in the case of the fuel cell with the Phytantriol/Brij^®-56 templated anode was approximately two times higher, reaching the value of 70 μA cm⁻². Overall, this study demonstrates two simple, cost-effective and efficient strategies to manipulate the morphology of gold nanostructures, and thus their catalytic property, paving the way for the successful manufacturing of functional abiotic glucose fuel cells. Full article

The increasing use of fertilisers rises the risk of eutrophication, a sudden algal bloom that seriously damage ecosystems due to critical oxygen depletion. Continuous monitoring of oxygen in environmental waters could improve the detection of eutrophication and prevent anoxic conditions. However, online and in situ dissolved oxygen sensors are yet to be implemented due to poor portability and power requirements. Here, we propose a ceramic soil microbial fuel cell as a self-powered sensor for algal growth detection via monitoring of dissolved oxygen in water. The sensor signal follows the characteristic photosynthetic cycle, with a maximum day current of 0.18 ± 0.2 mA and a minimum night current of 0.06 ± 0.34 mA, which correlates with dissolved oxygen (R² = 0.85 (day); R²= 0.5 (night)) and algal concentration (R² = 0.63). A saturated design of experiments on seven factors suggests that temperature, dissolved oxygen, nitrates, and pH are the most influential operational factors in the voltage output. Moreover, operating the system at maximum power point (R_ext = 2 kΩ) improves the sensor sensitivity. To the best of our knowledge, this is the first proposed MFC-based biosensor for in-field, early detection of eutrophic events. Full article

With the rapid progress in nanotechnology and microengineering, point-of-care and personalised healthcare, based on wearable and implantable diagnostics, is becoming a reality. Enzymatic fuel cells (EFCs) hold great potential as a sustainable means to power such devices by using physiological fluids as the fuel. This review summarises the fundamental operation of EFCs and discusses the most recent advances for their use as implantable and wearable self-powered sensors. Full article

The provision of safe water and adequate sanitation in developing countries is a must. A range of chemical and biological methods are currently used to ensure the safety of water for consumption. These methods however suffer from high costs, complexity of use and inability to function onsite and in real time. The microbial fuel cell (MFC) technology has great potential for the rapid and simple testing of the quality of water sources. MFCs have the advantages of high simplicity and possibility for onsite and real time monitoring. Depending on the choice of manufacturing materials, this technology can also be highly cost effective. This review covers the state-of-the-art research on MFC sensors for water quality monitoring, and explores enabling factors for their use in developing countries. Full article