arXiv subjects

Fernando Benito-Lopez

Publications and source records attributed to Fernando Benito-Lopez.

3 recordsLinked to original sources

arXiv2024

Microfluidic front dynamic for the characterization of pumps for long-term autonomous microsystems

To facilitate the use and portability of Lab on a chip technology, it is desirable to avoid the use of bulky electronic systems for flow control. Developed self-powered microsystems typically move only small volumes of fluid performing up to one or two hours. We have previously shown that polymeric micropumps combined with plastic microfluidic cartridges constitute a universal self-powered modular microfluidic architecture suitable for moving large volumes of fluids in short times. Herein, we show that polymeric micropumps can provide self-powered flow control for long periods of time in the range of hours and days. The calibration curves of various types of micropumps were obtained including one that maintained the movement of the fluid for 23 hours, advancing the fluid front up to 1.8 meters through a channel with a section of 0.127 mm2. We found that the actuation time of the pump was related to degassing time, the effective surface area and the air recovery rate of the pump. This is the first example of a long operating self-powered microsystem, which may have a great impact in those cases where controlled flow is needed for a long period of time and the use of electronic equipment is not desirable.

physics.flu-dyn↗

arXiv2024

Mathematical model of fluid front dynamics driven by porous media pumps

Air-permeable porous media hosts air within their pores. Upon removal from the interior of the material, these porous media have the tendency to reabsorb air from the surrounding, acting as a suction pump. Therefore, the technique used to convert porous media into a pump, consists of degassing the material to remove their air inside. The suction property when recovering the air, can be used to move a liquid through a microfluidic channel. Porous media pumps are very accurate devices to move liquids in a completely controlled way. {By studying the dynamics of the liquid front moved by these pumps, it is possible to extract characteristic properties of both the fluid and the porous material.} In this article, we have developed a theoretical mathematical model that precisely characterizes the dynamics of a liquid moved by a degassed porous media pump through a microchannel by comparing it with experimental data. {We have seen the differences between sealing the external surface of the pump so that it cannot absorb air from the outside, both mathematically and experimentally.} We have observed that, in all cases, the theory fits satisfactorily with the experiments, corroborating the validity of the model. The creation of microfluidic pumps using porous media can be a very useful tool in various fields due to its long operating time, small size and the fact that it operates without any external power source.

physics.flu-dyn↗

arXiv2022

Evaporation of water in a microfluidic channel under magnetic field

The evaporation of drops of water placed at the center of long poly(methyl methacrylate) microfluidic channels with a rectangular cross section of 0.38 mm2 is studied by simultaneously monitoring the shapes of two samples, one is in a 300 mT magnetic field, the other is in no field. A magnetic enhancement of the evaporation rate of up to 140 % is observed, which can be understood by treating the ortho and para nuclear isomers of water vapor as quasi-independent gasses with an ortho:para ratio in fresh vapor close to 2:3. It would take much longer than the 2 - 4 h duration of an experiment in the channel, for the ratio to approach the 3:1 equilibrium value. Magnetic field influences evaporation rate by equalizing the isomeric populations in the vapor phase. The atmosphere in the channel is saturated with water vapor yet the evaporation rate far exceeds that in open beakers.

physics.chem-ph↗