Predicting Dimensions in Microfluidic Paper Based Analytical Devices

The main problem for the expansion of the use of microfluidic paper-based analytical devices and, thus, their mass production is their inherent lack of fluid flow control due to its uncontrolled fabrication protocols. To address this issue, the first step is the generation of uniform and reliable microfluidic channels. The most common paper microfluidic fabrication method is wax printing, which consists of two parts, printing and heating, where heating is a critical step for the fabrication of reproducible device dimensions. In order to bring paper-based devices to success, it is essential to optimize the fabrication process in order to always get a reproducible device. Therefore, the optimization of the heating process and the analysis of the parameters that could affect the final dimensions of the device, such as its shape, the width of the wax barrier and the internal area of the device, were performed. Moreover, we present a method to predict reproducible devices with controlled working areas in a simple manner.The authors would like to acknowledge funding support from Gobierno de España, Ministerio de Economía y Competitividad, with Grant No. BIO2016-80417-P (AEI/FEDER, UE), the Gobierno Vasco Dpto. Educación for the consolidation of the research groups (IT1271-19) and from Proyectos Colaborativos from the University of the Basque Country UPV/EHU, BIOPLASMOF (COLAB19/05). This project received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778001

Ionogel-based hybrid polymer-paper handheld platform for nitrite and nitrate determination in water samples.

[EN] Nowadays, miniaturization and portability are crucial characteristics that need to be considered for the development of water monitoring systems. In particular, the use of handheld technology, including microfluidics, is exponentially expanding due to its versatility, reduction of reagents and minimization of waste, fast analysis times and portability. Here, a hybrid handheld miniaturized polymer platform with a paper-based microfluidic device was developed for the simultaneous detection of nitrite and nitrate in real samples from both, fresh and seawaters. The platform contains an ionogel-based colorimetric sensor for nitrite detection and a paper-based microfluidic device for the in situ conversion of nitrate to nitrite. The platform was fully characterized in terms of its viability as a portable, cheap and quick pollutant detector at the point of need. The calibration was carried out by multivariate analysis of the color of the sensing areas obtained from a taken picture of the device. The limits of detection and quantification, for nitrite were 0.47 and 0.68mgL-1, while for nitrate were 2.3 and 3.4mgL-1, found to be within the limits allowed by the environmental authorities, for these two pollutants. Finally, the platform was validated with real water samples, demonstrating its potential to monitor nitrite and nitrate concentrations on-site as a first surveillance step before performing extensive analysis.This project has received funding from the European Union Seventh Framework Programme (FP7) for Research, Technological Development and Demonstration under grant agreement no. 604241. The funding support from Gobierno de España, Ministerio de Ciencia y Educación de España” under grant PID2020-120313 GB-I00/AIE/10.13039/501100011033, and Gobierno Vasco Dpto. Educación for the consolidation of the research groups (IT1271-19) are also acknowledged. RC-C acknowledges funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778001. Special thanks to (SGIker) of the University of the Basque Country (UPV/EHU). FB-L and LB-D acknowledge the “Red de Microfluídica Española” RED2018-102829-T

Microfluidics and materials for smart water monitoring: A review

Water quality monitoring of drinking, waste, continental and seawaters is of great importance to ensure safety and wellbeing for humans, fauna and flora. Researchers are developing robust water monitoring microfluidic devices but, the delivery of a cost-effective, commercially available platform has not been achieved yet. Conventional water monitoring is mainly based on laboratory instruments or on sophisticated and expensive handheld probes for on-site analysis, both requiring trained personnel and being time-consuming. As an alternative, microfluidics has emerged as a powerful tool with the capacity to displace conventional analytical systems. Nevertheless, microfluidic devices largely use conventional pumps and valves for operation, and electronics for sensing, that increment the dimensions and costs of the final platforms, diminishing their commercialization perspectives. In this review, we critically analyze the characteristics of conventional microfluidic devices for water monitoring, focusing on different water matrices (drinking, waste, continental and seawaters), towards their application in potential commercial products. Moreover, we introduce the revolutionary concept of using functional materials such as hydrogels, poly(ionic liquid) hydrogels and ionogels as alternatives to conventional fluidic handling and sensing tools for water monitoring in microfluidic devices.This project has received funding from the European Union Seventh Framework Programme (FP7) for Research, Technological Development and Demonstration under grant agreement no. 604241 and the Gobierno Vasco Dpto. Educación for the consolidation of the research groups (IT1271-19). RCC thanks the European Union DNASURF (H2020-MSCA-RISE-778001). University of the Basque Country UPV/EHU with collaborative project COLAB19/05. Sincere thanks to Sarah Barron for her diligent proofreading of this review