About me

I am a CNRS researcher working at IRPHE in Marseille, France.

My research lies at the crossroads of fluid mechanics, artificial intelligence and biophysics. I aim at deciphering the algorithms that living entities use to navigate their complex environment, from immune cells in human tissues to insects in turbulent flows. My goal is also to find ways to outsmart them, with applications to the design of artificial microswimmers and microdrones.

I am the main developer of OTTO, a software dedicated to olfactory navigation and its solutions. It implements an original reinforcement learning algorithm that trains a deep neural network at finding an odor source in turbulence faster than any other known strategy.

Job openings

A PhD position on reinforcement learning for olfactory navigation in turbulent flows is available.

Highlights

In 2022, we trained a deep neural network to locate an odor source, a task relevant to insects looking for food but also sniffer robots tracking down gas leaks [09]:

• Centrale Marseille Actualités: Entraîner une intelligence artificielle pour faire aussi bien que l’Humain dans la recherche olfactive

On the same year, we showed that planktonic organisms can exploit turbulent fluctuations to migrate much more efficiently in the ocean by ‘surfing’ the flow [11]:

• Le Monde Science & Médecine: Comment le copépode ‘surfe’ pour monter et descendre plus vite dans l’océan, by David Larousserie
• Physics Magazine: Turbulence-Surfing Plankton Can Double Their Speed, by Katherine Wright
• CNRS INSIS Actualités: Pour aller deux fois plus vite, le plancton peut surfer sur les turbulences

In 2018, we demonstrated that mechanical energy can be extracted from an ‘active’ fluid such as a bacterial suspension [05]. This implies that bacteria can be harnessed to power a (tiny) motor:

• Quanta Magazine: Swarming Bacteria Create an ‘Impossible’ Superfluid, by Charlie Wood

Publications

[13] Deep reinforcement learning for the olfactory search POMDP: a quantitative benchmark
A. Loisy and R. A. Heinonen
The European Physical Journal E 46, 17 (2023)
[DOI] [arXiv] [download]

[12] The nonlinear motion of cells subject to external forces
A. Ioratim-Uba, A. Loisy, S. Henkes, and T. B. Liverpool
Soft Matter 18, 9008–9016 (2022)
[DOI] [arXiv] [download]

[11] Surfing on Turbulence: A Strategy for Planktonic Navigation
R. Monthiller, A. Loisy, M. A. R. Koehl, B. Favier, and C. Eloy
Physical Review Letters 129, 064502 (2022)
[DOI] [arXiv] [download]

[10] OTTO: A Python package to simulate, solve and visualize the source-tracking POMDP
A. Loisy and C. Eloy
Journal of Open Source Software 7, 4266 (2022)
[DOI] [download]

[09] Searching for a source without gradients: how good is infotaxis and how to beat it
A. Loisy and C. Eloy
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 478, 20220118 (2022)
[DOI] [arXiv] [download]

[08] How many ways a cell can move: the modes of self-propulsion of an active drop
A. Loisy, J. Eggers, and T. B. Liverpool
Soft Matter 16, 3106–3124 (2020)
[DOI] [arXiv] [download]

[07] Tractionless self-propulsion of active drops
A. Loisy, J. Eggers, and T. B. Liverpool
Physical Review Letters 123, 248006 (2019)
[DOI] [arXiv] [download]

[06] Exact results for sheared polar active suspensions with variable liquid crystalline order
A. Loisy, A. P. Thompson, J. Eggers, and T. B. Liverpool
Journal of Chemical Physics 150, 104902 (2019)
[DOI] [arXiv] [download]

[05] Active suspensions have nonmonotonic flow curves and multiple mechanical equilibria
A. Loisy, J. Eggers, and T. B. Liverpool
Physical Review Letters 121, 018001 (2018) [DOI] [arXiv] [download]

[04] The effective diffusivity of ordered and freely evolving bubbly suspensions
A. Loisy, A. Naso, and P. D. M. Spelt
Journal of Fluid Mechanics 840, 215–237 (2018)
[DOI] [HAL] [download]

[03] Buoyancy-driven bubbly flows: ordered and free rise at small and intermediate volume fraction
A. Loisy, A. Naso, and P. D. M. Spelt
Journal of Fluid Mechanics 816, 94–141 (2017)
[DOI] [HAL] [download]

[02] Interaction between a large buoyant bubble and turbulence
A. Loisy and A. Naso
Physical Review Fluids 2, 014606 (2017)
[DOI] [HAL] [download]

[01] Role of meteorological processes in ozone responses to emission controls in California’s San Joaquin Valley
L. Jin, A. Loisy, and N. J. Brown
Journal of Geophysical Research: Atmospheres 118, 8010–8022 (2013)
[DOI] [download]

PhD thesis

Direct numerical simulation of bubbly flows: coupling with scalar transport and turbulence
A. Loisy
Université de Lyon (2016)
[HAL] [download]