Prof. Roberto Di Leonardo
Dipartimento di Fisica
Sapienza Università di Roma
Piazzale Aldo Moro 5
00185 Roma, Italy
(+39) 06 4991 3518 (office)
(+39) 06 4969 3294 (lab)


From the Brownian movements of inanimate matter to the swimming motility of bacteria, the world at the micron scale is extremely dynamical. We are interested in the origin, the consequences and the applications of these motions. To study that, we build digital microscopes that integrate optical and computer hardware and where light can be used for imaging, manipulation and fabrication of microsystems in 3D.


Watching wall entrapment of bacteria in 3D

Using a combination of our 3-axis holographic microscopy and optical tweezers, we could visualize in 3D the wall entrapment dynamics of swimming cells that are sequentially released from a controlled distance and angle.
article: Phys. Rev. X, 7, 011010, (2017)
video: 3D movie of bacteria colliding with a flat wall.
press: Bacteria bounce along walls like flies bounce along a window


A rotating micromotor can self-assemble starting from randomly distributed Janus particles and microfabricated passive ratchets.
article: Small, 12, 446--451, (2016)
video: Self-assembly of a rotating structure.
press: Microgears rotate when pushed by tiny motors (

Light-to-work conversion at the micron-scale

Light-absorbing microgears, sitting on a liquid-air interface, can efficiently convert light into rotational motion through a thermo-capillary effect.

article: Nat Commun, 6, 7855, (2015)
video: Spinning gears at different light power levels
press: Tiny gears increase light-to-work conversion efficiency by five orders of magnitude (
Powering Gears with Light (APS Physics)

A stationary probability density for active matter

We derive the stationary probability distribution for a non-equilibrium system composed by an arbitrary number of degrees of freedom that are subject to Gaussian colored noise and a conservative potential.
article: Sci. Rep., 5, (2015)
press: CondMat Journal Club

Bacteria can be trapped by convex walls (if curvature is low enough)

E. coli cells can be stabily trapped by the lateral convex surface of micro pillars provided the pillar radius is larger than a critical value.
article: Phys. Rev. Lett., 114, 258104, (2015)

Bacteria deliver colloidal cargoes on tartget sites

Bacteria can autonomously transport colloidal cargoes onto target sites that are surrounded by micro-fabricated asymmetric landscapes in 3D.
article: Nature Communications, 4, 2588, (2013)
press: Le Scienze

Optical trapping at Gigapascal pressures

The full power of holographic optical tweezers can be made available inside diamond anvil cells for high pressure rheological and mechanical studies in physics and biology.
article: Phys. Rev. Lett., 110, 095902, (2013)
press: APS Physics

Seeing and touching through an optical fiber

A single multimode optical fiber can be used as a submillimiter probe for interactive micromanipulation and fluorescence microscopy.
article: Lab Chip, 12, 635-639, (2012)
press: LaserFocusWorld

Light driven micromotors spin in sync

Optically trapped micro-rotors rotate in phase when close enough to interact hydrodynamically.
article: Phys. Rev. Lett., 109, 034104, (2012)
video: Movie showing two "lightmills" spinning in sync.


Roberto Di Leonardo

Associate Professor-Sapienza
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Claudio Maggi

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PhD student-Sapienza


Academic year 2016/2017:
Costruzione di modelli fisici per la biologia - Scuola Superiore di Studi Avanzati Sapienza
Data analysis - Laurea magistrale in Genetica e Biologia Molecolare

Web apps

Trapping force in optical tweezers

A ray optics interactive simulation that illustrates how transfer of optical momentum due to reflection and refraction can lead to the stable 3D trapping of a dielectric sphere.
Go to app page