Tag: Laura Pérez García

Optimal calibration of optical tweezers with arbitrary integration time and sampling frequencies – A general framework published in Biomedical Optics Express

Different sampling methods for the trajectory of a particle. (Adapted from the manuscript.)
Optimal calibration of optical tweezers with arbitrary integration time and sampling frequencies — A general framework
Laura Pérez-García, Martin Selin, Antonio Ciarlo, Alessandro Magazzù, Giuseppe Pesce, Antonio Sasso, Giovanni Volpe, Isaac Pérez Castillo, Alejandro V. Arzola
Biomedical Optics Express, 14, 6442-6469 (2023)
doi: 10.1364/BOE.495468
arXiv: 2305.07245

Optical tweezers (OT) have become an essential technique in several fields of physics, chemistry, and biology as precise micromanipulation tools and microscopic force transducers. Quantitative measurements require the accurate calibration of the trap stiffness of the optical trap and the diffusion constant of the optically trapped particle. This is typically done by statistical estimators constructed from the position signal of the particle, which is recorded by a digital camera or a quadrant photodiode. The finite integration time and sampling frequency of the detector need to be properly taken into account. Here, we present a general approach based on the joint probability density function of the sampled trajectory that corrects exactly the biases due to the detector’s finite integration time and limited sampling frequency, providing theoretical formulas for the most widely employed calibration methods: equipartition, mean squared displacement, autocorrelation, power spectral density, and force reconstruction via maximum-likelihood-estimator analysis (FORMA). Our results, tested with experiments and Monte Carlo simulations, will permit users of OT to confidently estimate the trap stiffness and diffusion constant, extending their use to a broader set of experimental conditions.

Laura Pérez García defended her PhD thesis on 12 October 2023. Congrats!

A dielectric particle under the influence of the gradient and scattering force. (Image by L. Pérez García.)
Laura Pérez  García defended her PhD thesis on the 12th of October at 13:15. Congrats!
The defense took place in Faraday, Institutionen för fysik, Origovägen 6b, Göteborg.

Title: Advanced methods for the calibration of optical tweezers

Abstract: Optical tweezers have enabled the manipulation of micron-sized particles with great accuracy since their invention by Arthur Ashkin and colleagues in the 1980s. This technique has had an impact in multiple areas, including biology, physics, nanotechnology, spectroscopy, soft matter and nanothermodynamics.
To perform experiments requiring quantitative transduction
of forces with optical tweezers, the optical tweezers need to be calibrated; that is their stiffness needs to be determined. In this thesis, I present the results that I have obtained for the calibration of optical tweezers using probabilistic approaches.
The goal of these approaches is to use the available data most efficiently and even be able to have an estimation of the error associated with the calibration. This is of the utmost importance when one has limited data, as is often the case with systems out of equilibrium, low signal-to-noise ratios, and systems in which the conditions change with time quite fast. This thesis is divided into two problems. The first problem I had was the unavailability of a comprehensive method to measure force fields in extended, non-conservative, and unstable equilibrium points. For this problem I used Bayesian inference in the form of a maximum likelihood estimator, which allowed me to characterize the force field even in conditions previously not possible to tackle. This parameter-free method called FORMA proved to be more precise, accurate, faster, and less data-intensive than the previous conventional method, i.e. equipartition, MSD, ACF, and PSF. Not only that, but it allowed me to characterize the force field generated by Laguerre-Gaussian beams with different orbital/spin angular momentum, a double-well potential, and a speckle pattern.
The second problem I tackled was the error in the estimators due to
limited bandwidth and finite integration time. For this, we developed the joint probability density function of observing the particle at a given set of positions and times. We derived generalized formulas for the calibration methods; these new formulas successfully correct for the overestimation of the stiffness and the underestimation of the diffusion coefficient caused by a finite integration time; it also accounts for the limited sampling frequency and the trajectory length.
In general, this thesis shows the potential of having a probabilistic and inference approach to the problem of deducing the set of parameters that characterize the Langevin equation of motion of a particle from a time series of its position. The solution to this problem has applications not only to the calibration of optical tweezers but also to microrheology, the behavior of single molecules inside a cell, and animal migration.

Thesis: https://hdl.handle.net/2077/78214

Supervisor: Giovanni Volpe
Examiner: Mattias Goksör
Opponent: Balpreet Singh Ahluwalia
Committee: Thomas Huser, Juliane Simmchen, Kirstine Berg-Sørensen
Alternate board member: Mattias Marklund

Roadmap for Optical Tweezers published in Journal of Physics: Photonics

Illustration of an optical tweezers holding a particle. (Image by A. Magazzù.)
Roadmap for optical tweezers
Giovanni Volpe, Onofrio M Maragò, Halina Rubinsztein-Dunlop, Giuseppe Pesce, Alexander B Stilgoe, Giorgio Volpe, Georgiy Tkachenko, Viet Giang Truong, Síle Nic Chormaic, Fatemeh Kalantarifard, Parviz Elahi, Mikael Käll, Agnese Callegari, Manuel I Marqués, Antonio A R Neves, Wendel L Moreira, Adriana Fontes, Carlos L Cesar, Rosalba Saija, Abir Saidi, Paul Beck, Jörg S Eismann, Peter Banzer, Thales F D Fernandes, Francesco Pedaci, Warwick P Bowen, Rahul Vaippully, Muruga Lokesh, Basudev Roy, Gregor Thalhammer-Thurner, Monika Ritsch-Marte, Laura Pérez García, Alejandro V Arzola, Isaac Pérez Castillo, Aykut Argun, Till M Muenker, Bart E Vos, Timo Betz, Ilaria Cristiani, Paolo Minzioni, Peter J Reece, Fan Wang, David McGloin, Justus C Ndukaife, Romain Quidant, Reece P Roberts, Cyril Laplane, Thomas Volz, Reuven Gordon, Dag Hanstorp, Javier Tello Marmolejo, Graham D Bruce, Kishan Dholakia, Tongcang Li, Oto Brzobohatý, Stephen H Simpson, Pavel Zemánek, Felix Ritort, Yael Roichman, Valeriia Bobkova, Raphael Wittkowski, Cornelia Denz, G V Pavan Kumar, Antonino Foti, Maria Grazia Donato, Pietro G Gucciardi, Lucia Gardini, Giulio Bianchi, Anatolii V Kashchuk, Marco Capitanio, Lynn Paterson, Philip H Jones, Kirstine Berg-Sørensen, Younes F Barooji, Lene B Oddershede, Pegah Pouladian, Daryl Preece, Caroline Beck Adiels, Anna Chiara De Luca, Alessandro Magazzù, David Bronte Ciriza, Maria Antonia Iatì, Grover A Swartzlander Jr
Journal of Physics: Photonics 2(2), 022501 (2023)
arXiv: 2206.13789
doi: 110.1088/2515-7647/acb57b

Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.

Presentation by L. Pérez at ELS 2021, 13 July 2021

Laura Pérez presented the work “FORMA and BEFORE: expanding applications of optical tweezers” at the ELS conference (online) on the 13th of July.

The main objective of the Electromagnetic and Light Scattering Conference (ELS) is to bring together scientists and engineers studying various aspects of light scattering and to provide a relaxed academic atmosphere for in-depth discussions of theoretical advances, measurements, and applications.

FORMA allows to identify and characterize all the equilibrium points in a force field generated by a speckle pattern.
FORMA and BEFORE: Expanding Applications of Optical Tweezers. Laura Pérez Garcia, Martin Selin, Alejandro V. Arzola, Giovanni Volpe, Alessandro Magazzù, Isaac Pérez Castillo.
ELS 2021
Date: 13 July 2021
Time: 15:45 (CEST)

Abstract: 
FORMA (force reconstruction via maximum-likelihood-estimator analysis) addresses the need to measure the force fields acting on microscopic particles. Compared to alternative established methods, FORMA is faster, simpler, more accurate, and more precise. Furthermore, FORMA can also measure non-conservative and out-of-equilibrium force fields. Here, after a brief introduction to FORMA, I will present its use, advantages, and limitations. I will conclude with the most recent work where we exploit Bayesian inference to expand FORMA’s scope of application.

Laura Pérez García wins the paper prize student at OSA OMA Biophotonics 2021

Laura Pérez Garcia won the prize for 2021 OSA Biophotonics Congress: Optics in the Life Sciences Student Paper Prize in the OSA-OMA Biophotonics 2021, with the work titled FORMA and BEFORE: expanding applications of optical tweezers.

Soft Matter Lab’s presentations at OSA-OMA 2021

The Soft Matter Lab is involved in six presentations at the OSA Biophotonic Congress: Optics in the Life Sciences 2021, topical meeting of Optical Manipulation and its Applications.
Moreover, three of the presentations were selected as finalists for the best student paper in the topical meeting of Optical Manipulation and its Applications.

You can find the details below:

12 April

15 April

16 April

  • 16:15 CEST
    Calibration of Force Fields Using Recurrent Neural Networks (AF2D.4)
    Aykut Argun, University of Gothenburg

Presentation by L. Pérez García at OSA-OMA-2021

FORMA allows to identify and characterize all the equilibrium points in a force field generated by a speckle pattern.
FORMA and BEFORE: Expanding Applications of Optical Tweezers. Laura Pérez Garcia, Martin Selin, Alejandro V. Arzola, Giovanni Volpe, Alessandro Magazzù, Isaac Pérez Castillo.
Submitted to OSA-OMA 2021,  ATh1D.5
Date: 15 April
Time: 15:45 (CEST)

Abstract: 
FORMA (force reconstruction via maximum-likelihood-estimator analysis) addresses the need to measure the force fields acting on microscopic particles. Compared to alternative established methods, FORMA is faster, simpler, more accurate, and more precise. Furthermore, FORMA can also measure non-conservative and out-of-equilibrium force fields. Here, after a brief introduction to FORMA, I will present its use, advantages, and limitations. I will conclude with the most recent work where we exploit Bayesian inference to expand FORMA’s scope of application.

Laura Pérez García nominated for a Student Paper Prize at the Biophotonics Congress

FORMA allows to identify and characterize all the equilibrium points in a force field generated by a speckle pattern

Laura Pérez García has been nominated by the Optical Society of America for a Student Paper Prize for Optical Manipulation and its Applications among three other finalists. She will present her work on FORMA and BEFORE: Expanding Applications of Optical Tweezers at the Optical Manipulation and its Applications meeting as part of the 2021 OSA Biophotonics Congress: Optics in Life Sciences.

The final selection will be based on the oral talk and Laura will present her work on the 15th of April at 15:45 (CEST).

Optical Tweezers: A Comprehensive Tutorial from Calibration to Applications accepted on Advances in Optics and Photonics

Schematic of a bistable potential generated with a double-beam optical tweezers.

Optical Tweezers: A Comprehensive Tutorial from Calibration to Applications
Jan Gieseler, Juan Ruben Gomez-Solano, Alessandro Magazzù, Isaac Pérez Castillo, Laura Pérez García, Marta Gironella-Torrent, Xavier Viader-Godoy, Felix Ritort, Giuseppe Pesce, Alejandro V. Arzola, Karen Volke-Sepulveda & Giovanni Volpe
Advances in Optics and Photonics, 13(1), 74-241 (2021)
doi: https://doi.org/10.1364/AOP.394888
arXiv: 2004.05246

Since their invention in 1986 by Arthur Ashkin and colleagues, optical tweezers have become an essential tool in several fields of physics, spectroscopy, biology, nanotechnology, and thermodynamics. In this Tutorial, we provide a primer on how to calibrate optical tweezers and how to use them for advanced applications. After a brief general introduction on optical tweezers, we focus on describing and comparing the various available calibration techniques. Then, we discuss some cutting-edge applications of optical tweezers in a liquid medium, namely to study single-molecule and single-cell mechanics, microrheology, colloidal interactions, statistical physics, and transport phenomena. Finally, we consider optical tweezers in vacuum, where the absence of a viscous medium offers vastly different dynamics and presents new challenges. We conclude with some perspectives for the field and the future application of optical tweezers. This Tutorial provides both a step-by-step guide ideal for non-specialists entering the field and a comprehensive manual of advanced techniques useful for expert practitioners. All the examples are complemented by the sample data and software necessary to reproduce them.

Invited talk by L. Pérez at SPIE Photonics West OPTO

Stable, unstable and saddle points in a speckle optical potential.
FORMA: expanding applications of optical tweezers
Laura Pérez García
Invited talk at SPIE Photonics West OPTO
6 March 2021
Online

In this presentation, Laura Pérez will talk about FORMA  (force reconstruction via maximum-likelihood-estimator analysis) which addresses the need of measuring the force fields acting on microscopic particles. Compared to alternative established methods, FORMA is faster, simpler, more accurate, and more precise. Furthermore, FORMA can also measure non-conservative and out-of-equilibrium force fields. Here, after a brief introduction to FORMA, I will present its use, advantages, and limitations. I will conclude with some recent work where we exploit Bayesian inference to expand the scope of application of FORMA.

References:
Laura Pérez García, Jaime Donlucas Pérez, Giorgio Volpe, Alejandro V. Arzola & Giovanni Volpe, High-Performance Reconstruction of Microscopic Force Fields from Brownian Trajectories, Nature Communications 9, 5166 (2018)

Time: 6 March 2021
Place: Online
Link: FORMA: expanding applications of optical tweezers at SPIE Photonics West OPTO