About me
I am a Marie Curie Intra European Fellow working at
Prof. Julia Yeomans group
at the University of Oxford and a Fulford Junior Research Fellow
at Somerville College.
My current research project is in soft-matter physics, specifically in numerical simulations of
the dynamics of microscopic swimmers at low Reynolds numbers and the driven translocation of polymer chains through nanopores.
I am also interested in the dynamics of fluids in microfluidic environments, particularly in capillary
flows on hydrophilic and hydrophobic surfaces.
I graduated as a Doctor in Physics from the University of Barcelona in 2009, where I worked with
Prof. Aurora Hernández-Machado and
Prof. Ignacio Pagonabarraga.
Before that, I obtained my Diploma in
Chemical Engineering in 2004 from the National Autonomous University of Mexico, where I worked under
the supervision of
Prof. Eugenia Corvera Poiré.
You can check my CV here.
Preprints
- with Aurora Hernández-Machado and Ignacio Pagonabarraga
Impact of wetting on the stability of forced advancing contact lines
- with Hartmut Loewen and Julia Yeomans
A circle swimmer at low Reynolds number
- with Damien P. Foster and Julia Yeomans
Translocation of neutral polymers against flow
Publications
- R. Ledesma-Aguilar, T. Sakaue and J.M. Yeomans
Easier sieving through narrower pores: fluctuations and barrier crossing in flow-driven polymer translocation.
Soft Matter 8 4306-4309 (2012).
- R. Ledesma-Aguilar, T. Sakaue and J.M. Yeomans
Length-dependent translocation of polymers through nanochannels.
Soft Matter 8 1884-1892 (2012).
- R. Ledesma-Aguilar, R. Nistal, A. Hernández-Machado and I. Pagonabarraga.
Controlled drop emission by wetting properties in driven liquid filaments.
Nature Materials 10 367-371 (2011).
- R. Ledesma-Aguilar, A. Hernández-Machado and I. Pagonabarraga.
Growth saturation of unstable thin films on transverse-striped hydrophilic-hydrophobic
micropatterns.
Soft Matter 7 6051 (2011).
- R. Ledesma-Aguilar, A. Hernández-Machado and I. Pagonabarraga.
Dynamics of gravity driven three-dimensional thin films on hydrophilic-hydrophobic
patterned substrates.
Langmuir 26 3292 (2010).
- R. Ledesma-Aguilar, A. Hernández-Machado and I. Pagonabarraga.
Dynamics of driven three-dimensional thin films. From hydrophilic to superhydrophobic regimes.
Phys. Fluids. 20 072101 (2008).
- R. Ledesma-Aguilar, I. Pagonabarraga and A. Hernández-Machado.
Three-dimensional aspects of fluid flows in channels. II. Effects of meniscus and thin film regimes
on viscous fingers.
Phys. Fluids 19 102113 (2007).
- R. Ledesma-Aguilar, A. Hernández-Machado and I. Pagonabarraga.
Three-dimensional aspects of fluid flows in channels. I. Meniscus and thin film regimes.
Phys. Fluids 19 102112 (2007).
- R. Ledesma-Aguilar, M. Quevedo-Reyes, E. Corvera Poiré and A. Hernández-Machado.
Lateral instability in normal viscous fingers.
Phys. Rev. E 71 016312 (2005).
Teaching
1st year Physics: mechanics, special relativity, optics, vectors and matrices, vector calculus and multiple integrals, normal modes and wave motion. 2nd year Physics: statistical mechanics and kinetic theory of gases, electromagnetism.
Press
My research with Prof. Hernández-Machado and Prof. Pagonabarraga on microscale drop production was featured by the University of Barcelona press office. You can see the note here.
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Microswimmers and their environment
Based on theoretical and numerical modeling, we are currently studying the interplay between microswimmers and
their environment. We are interested in understanding how single and collective interactions between swimmers
are affected by structured surfaces
and interfaces, external biasing and local fluid properties. We hence aim at applications
that exploit active systems, by controlling existing biological environments, such as bacterial baths and biofilms, and
by developing new tailored technologies, such as swimmer-actuated microfluidic devices.
Polymer translocation through narrow pores
The passage of polymer chains through narrow pores is an ubiquitous process in nature. Biopolymers, such as DNA and RNA,
have to cross a multitude of barriers to perform different biological functions, for example, in translocating through cellular
membrane pores or when ejecting from viral capsids. Understanding the way in which polymer chains translocate through nanometric
pores is very important, as it may open the possibility of new and powerful technologies, as for example, the potential sequencing
of DNA molecules or the sorting of polymer chains according to their instrinsic properties (chain or monomer size, etc.) using
smart entropic traps.
We are currently studying the way in which single polymer chains get into a nanopore when forced by an underlying fluid flow. We focus
on situations where the translocation of the chain is affected by its length and by the geometry of the constriction.
Making drops using wetting properties
The controlled formation of microdrops is a very important process in microfluidics. We
have found that it is possible to exploit the wettability of a solid substrate when forcing a
liquid microfilament on it to trigger a new kind of instability. The instability is related to how
fast the contact line of the filament moves relative to the motion of the filament as a whole, and it
involves the balance of capillary forces versus viscous and driving forces. It turns out that this
balance is impossible to sustain above a critical velocity that depends on the wetting properties of the
solid, and leads to the controlled formation of microsized drops. By tuning the wettability of the substrate
and the driving velocity of the filament, it is possible to control the size and the rate emission of the
droplets.
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