Research lines

These are some of our lines of research...

Numerical prototyping of LFIA and μPADs

Lateral flow immunoassays (LFIA) and microfluidic paper based analytical devices (μPADs) represent a group of portable and autonomous devices for the rapid and simple detection of various biochemical indicators of pathogens and diseases. In addition to health applications, the use of LFIAs and μPADs extend to environmental, phytosanitary and bromatological control, among other fields. The development and optimization of new LFIA and μPAD devices implies significant experimental efforts given the need to explore designs, characterize the materials used as a substrate, control the kinetic parameters, improve the sensitivity of detection and finally the integration of these aspects to achieve a better overall performance of the device.

In this context, having tools to reduce costs and experimentation times is a key aspect for the effective implementation of the technology in the country. Also, new designs require a comprehensive understanding of all the bio-physical-chemical phenomena involved. Thus, the development of numerical prototypes to efficiently simulate new LFIA and μPAD designs is very useful.

One such tool is Fronts, a numerical library that can solve the Richards equation of flow in porous media in cases of lateral flow. The tool, developed members of our group, is fully available as open source software.

In this line of research, we develop the fundamentals, the mathematical models and their numerical implementation required for the LFIA and μPAD simulation.

Modeling and Simulation of electrophoretic problems using OpenFOAM®

Electroosmotic and electrophoretic processes are transport processes of fluids and electrolytes, through the application of electric fields. These phenomena are more efficiently used in the microscale, thus, in the last two decades, microfluidic analytical platforms (Lab-on-a-chip) have been the main scenario for the development of methods and technologies related to electroosmotic and electrophoretic processes.

The modeling and simulation of the electroosmotic and electrophoretic processes in the microscale presents a certain complexity due to both, its multiphysics and multiscale nature, as well as the difficulties involved in the instrumentation and measurement of physical parameters in microdevices. In order to correctly represent the physicochemistry of the processes, electrical, fluidic, material transport and chemical reactions models must be included. The successful implementation of models and numerical simulations of these processes allow a better understanding and a better use, to improve microdevices and Lab-on-a-chip designs, increasing their performance and also expanding their applicability.

There is particular interest in modeling electroosmotic and electrophoretic processes in porous media (in particular on paper), due to the boom of paper-based analytical microfluidic devices (μPADs). Within this sub-field. there are particular challenges, because much of the fundamental aspects have not been yet studied.

In this line of research, the implementation of the numerical simulation of electroosmotic and electrophoretic processes is sought through the coupling of the different equations that model the electric field, the velocity and pressure fields, the solute and electrolyte concentration fields and the acid-base balance. The heterogeneities of charge concentrations in the walls that give rise to the electrical double layer, which ultimately allows electroosmotic flow, also need to be considered in a special way. The implementation is carried out using the finite volume method using the OpenFOAM® platform.