As the world’s population ages, the incidence of chronic disorders is on the rise. Active Implantable Medical Devices are, therefore, evolving to meet the challenge. As the size of these devices decreases to facilitate implantation, the challenge of providing stable, continuous power becomes significant. Lithium batteries provide reliable, stable power to implants; however, their miniaturization leads to a reduction in the stored energy capacity, total lifespan, and overall capability. Consequently, there is a need for on-body energy harvesting alternatives. This study utilizes literature data on abiotic glucose fuel cells to feed into a finite element model incorporating both diffusion and reaction aspects to investigate how the 3D macro-architecture of the fuel cell device can be used to optimize the energy output. Accordingly, optimal 3D architectures are determined to enable power outputs ranging from several tens of microwatts to one hundred microwatts from an implantable package. This will help with the 3D architecture design of future similar abiotic fuel cell units and speed up the process of figuring out the best settings for key parameters (like shape, size, and separation).

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.

As the world's population ages, the incidence of chronic disorders is on the rise. Active Implantable Medical Devices are therefore evolving to meet the challenge. As the size of these devices decreases to facilitate implantation, the challenge of providing stable, continuous power becomes significant. Lithium batteries provide reliable, stable power to implants, however, their miniaturization leads to a reduction in the stored energy capacity, total lifespan and overall capability. Consequently, there is need for on-body energy harvesting alternatives. This study utilizes literature data on abiotic glucose fuel cells to feed into a Finite Element model incorporating both diffusion and reaction aspects to investigate how the 3D macro architecture of the fuel cell device can be used to optimize the energy output. Accordingly, optimal 3D architectures are determined to enable power outputs ranging from several tens to one hundred microwatts from an implantable package.. This will help with the 3D architecture design of future similar abiotic fuel cell units and speed up the process of figuring out the best settings for key parameters (like shape, size, and separation).

The concept of the water-food-energy nexus (WFE) was initially configured from the Bonn Conference in 2011, in Germany, under the theme "The water, energy and food security nexus-Solutions for the Green Economy" in which it sought to contribute directly to the United Nations Conference on Sustainable Development (Rio +20), held in 2012, in the city of Rio de Janeiro (Hoff, 2011). The Nexus, according to Karlberg et al. (2015), emphasizes the interconnections between the environment and human development, and the need for integrated and intersectoral coordination, management and governance. Thus, the WFE nexus approach analyzes the interconnections between the uses of these resources in the environment, essential for social well-being, sustainable development and the preservation of biodiversity (Albrecht et al., 2018). However, such studies are incipient and based on mostly top-down quantitative methodologies, with few examples of participatory and local-scale approaches. Water, food and energy problems tend to increase due to the scenario of the COVID-19 pandemic, especially in the most socio-environmentally vulnerable communities. Furthermore, world population growth has direct consequences on the demand for natural resources, meaning that growing numbers of people will continue to depend on and impact on these elements. Thus, studying the nexus directly implies eradicating poverty and reducing social inequalities, in addition to meeting energy security, combating hunger and malnutrition, increasing access to water and sanitation, as set out by the Sustainable Development Goals (SDGs) of the 2030 Agenda of the United Nations (UN).

The fabrication of stable and highly performing enzyme-based electrodes is key for the effective generation of biodevices and bioelectronics, such as electrochemical biosensors. In this context, redox-active lyotropic liquid crystals based on 3D nanomaterials, known as lipid cubic phases (LCP), hold great potential due to the large specific surface area and the possibility to be functionalized. In this study, we functionalized a monoolein (MO) LCP matrix by incorporating an amphiphilic redox shuttle within its matrix with the aim to enhance the electrochemical performance of a glucose oxidase (GOx) based electrode and we investigated the stability of the overall system. The use of dodecyl(ferrocenylmethyl)dimethylammonium bromide (Fc12-Br) resulted in an electroactivity loss with time of the resulting Fc12-Br/MO electrode, probably due to the formation of a passivating layer between the bromide counterions and the electrode surface. Hence, bromine (Br-) was replaced with hexafluorophosate (PF6-), leading to Fc12-PF6/MO. Both structures were used for GOx entrapment and the resulting electro-activity towards glucose was assessed. Though the sensitivity obtained with the Fc12-Br/MO/GOx and Fc12-PF6/MO/GOx systems was comparable, the latter showed superior stability over time, with more than 80% activity retained for > 20 days. Moreover, when the concentration of the Fc12 redox shuttle within the cubic phase was increased by 10, a 4 times greater current density was generated. Consequently, the Fc12-PF6/MO electrode shows superior stability and performance than previously reported redox lyotropic LCP systems, thus paving the way for promising applications in enzyme-based biodevices.