Emerging water pollutants such as pharmaceutical contaminants are suspected to induce adverse effects to human health. These molecules became worrisome due to their increasingly high concentrations in surface waters. Despite this alarming situation, available data about actual concentrations in the environment is rather scarce, as it is not commonly monitored or regulated. This is aggravated even further by the absence of portable and reliable methods for their determination in the field. A promising way to tackle these issues is the use of enzyme-based and miniaturized biosensors for their electrochemical detection. Here, we present an overview of the latest developments in amperometric microfluidic biosensors that include, modeling and multiphysics simulation, design, manufacture, testing, and operation methods. Different types of biosensors are described, highlighting those based on oxidases/peroxidases and the integration with microfluidic platforms. Finally, issues regarding the stability of the biosensors and the enzyme molecules are discussed, as well as the most relevant approaches to address these obstacles.

Magnetite nanoparticles (MNPs) have attracted basic and applied research due to their immense potential to enable applications in fields as varied as drug delivery and bioremediation. Conventional synthesis schemes led to wide particle size distributions and inhomogeneous morphologies and crystalline structures. This has been attributed to the inability to control nucleation and growth processes under the conventional conditions of bulk batch processes. Here, we attempted to address these issues by scaling down the synthesis process aided by microfluidic devices, as they provide highly controlled and stable mixing patterns. Accordingly, we proposed three micromixers with different channel configurations, namely, serpentine, triangular, and a 3D arrangement with abrupt changes in fluid direction. The micromixers were first studied in silico, aided by Comsol Multiphysics® to investigate the obtained mixing patterns, and consequently, their potential for controlled growth and the nucleation processes required to form MNPs of uniform size and crystalline structure. The devices were then manufactured using a low-cost approach based on polymethyl methacrylate (PMMA) and laser cutting. Testing the micromixers in the synthesis of MNPs revealed homogeneous morphologies and particle size distributions, and the typical crystalline structure reported previously. A life cycle assessment (LCA) analysis for the devices was conducted in comparison with conventional batch co-precipitation synthesis to investigate the potential impacts on water and energy consumption. The obtained results revealed that such consumptions are higher than those of the conventional process. However, they can be reduced by conducting the synthesis with reused micromixers, as new PMMA is not needed for their assembly prior to operation. We are certain that the proposed approach represents an advantageous alternative to co-precipitation synthesis schemes, in terms of continuous production and more homogeneous physicochemical parameters of interest such as size, morphologies, and crystalline structure. Future work should be directed towards improving the sustainability indicators of the micromixers’ manufacturing process.

The use of micromixers and catalytically active nanocomposites can be an attractive alternative for the treatment of wastewaters from the textile industry, due to their high activity, low consumption of such nanocomposites, short reaction times and the possibility to work under continuous operation. In this study, 6 different designs of micromixers were modeled and evaluated for the treatment of wastewaters. Velocity profiles, pressure drops, and flows were analyzed and compared for the different devices under the same mixing conditions. In addition, Life cycle assessment (LCA) methodology was applied to determine their performance in terms of environmental impact. Considering the high environmental impact of water sources contaminated by dyes from the textile industry, it becomes critically important to determine when the proposed micromixers are a suitable alternative for their remediation. The LCA and operational efficiency studies results shown here provide a route for the design of novel wastewater treatment systems by coupling low-cost and high-performance micromixers.

Magnetite nanoparticles (MNPs) have important applications in several industrial and scientific fields for the remediation of contaminated soil and water, for instance. Emerging technologies such as microfluidic techniques have been adapted to continuously synthesize MNPs showing appealing results, such as a narrower size distribution. Therefore, this approach might become important for producing MNPs to meet industrial requirements. In this study, a life cycle assessment (LCA) is conducted to analyze and evaluate the impacts of the synthesis of MNPs performed in microfluidic devices. This LCA considers all of the steps required for MNP production at a laboratory and possible industrial scales. The LCA results showed that the rivets suitable for device inlets and outlets and the chemicals required for the synthesis process have the highest contribution to all impact categories, i.e., 80 and 90%, respectively. These results thus contribute to determining the overall environmental performance of each step during the synthesis of MNPs. The contribution analysis reveals that the manufacturing stage has a contribution of 97% at the lab scale, while the operation stage shows a contribution of 82% at the industrial scale. Finally, a sensitivity analysis is performed to identify the possible scenarios for replacing rivets required to manufacture microfluidic devices.

The objective of this study was to assess the effectiveness of functionalized bionanocompounds with ice nucleation protein (INP) as a novel approach for freezing applications in terms of how much energy is used during each step of freezing when water bionanocompound solutions were compared with pure water. According to the results of the manufacturing analysis, water required 28 times less energy than the silica + INA bionanocompound and 14 times less than the magnetite + INA bionanocompound. These findings showed that water used the least energy during the manufacturing process. In order to determine the associated environmental implications, an analysis of the operating stage was also conducted, taking the defrosting time of each bionanocompound during a 4 h work cycle into account. Our results showed that bionanocompounds may substantially reduce the environmental effects by achieving a 91% reduction in the impact after their use during all four work cycles in the operation stage. Additionally, given the energy and raw materials needed in this process, this improvement was more significant than at the manufacturing stage. The results from both stages indicated that, when compared with water, the magnetite + INA bionanocompound and the silica + INA bionanocompound would save an estimated 7% and 47% of total energy, respectively. The study’s findings also demonstrated the great potential for using bionanocompounds in freezing applications to reduce the effects on the environment and human health.