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Llera Miguel

Adjoint-e scientifique HES

Main skills

Adjoint-e scientifique HES

Phone: +41 32 930 13 81

Haute Ecole Arc - Ingénierie
Espace de l'Europe 11, 2000 Neuchâtel, CH

Institute
Arc-Ingénierie

BSc HES-SO en Industrial Design Engineering - Haute Ecole Arc - Ingénierie

Métrologie
Microscopie

Ongoing

I-CARE - Identification de tissus ovariens CAncéRogènes à l’aide de l’Endoscopie et oxymétrie colorimétrique in-situ

Role: Collaborator

Financement: Fonds HES-SO - Fond de recherche et d'impulsions - Programme du rectorat (REC)

Description du projet :

Nous proposons une méthode spectroscopique pour surveiller l'ablation chirurgicale des tumeurs ovariennes. Malgré les
améliorations apportées au diagnostic préopératoire, il est encore difficile de délimiter précisément les limites des tumeurs.
Les tissus cancéreux présentent un plus grand nombre de vaisseaux sanguins que les tissus sains, mais sont moins saturés
en oxygène. Ici, nous proposons l’oxymétrie pour mesurer le taux d'oxygène dans le tissu à analyser, sans prélever
directement d'échantillon en salle d'opération. L'hémoglobine oxygénée et l'hémoglobine désoxygénée possèdent des
coefficients d'absorption optiques différents, et donc il est possible de les discriminer par oxymétrie. Ces mesures se feront
avec des sondes à fibres optiques souples.

Research team within HES-SO: Jeandupeux Laure , Laux Edith , Llera Miguel , Potty Philippe

Durée du projet: 01.11.2023 - 30.06.2024

Montant global du projet: 80'000 CHF

Statut: Ongoing

EFOCT Novel current measurement system for power applications based on fibre optics sensing

Role: Collaborator

Financement: Innosuisse

Description du projet :

A current measurement system is developed for applications in high-voltage power grid facilities.

Research team within HES-SO: Llera Miguel

Partenaires académiques: EPFL

Partenaires professionnels: Condis SA

Durée du projet: 01.07.2021 - 30.05.2023

Montant global du projet: 1'500'368 CHF

Statut: Ongoing

Flexfiber

Role: Main Applicant

Financement: Innosuisse

Description du projet :

Flexfiber aims to develop highly flexible optical fibers for Human physiological parameters measurement in delicate organs. The fiber, 10-15 cm long, must be fully biocompatible and will have a strong impact on standalone implants monitoring and also on surgical tooling.

Research team within HES-SO: Llera Miguel

Durée du projet: 01.11.2019 - 31.01.2021

Statut: Ongoing

Completed

Capidel - Capteur tactile capillaire avec IA embarquée pour robotique

Role: Collaborator

Financement: HES-SO

Description du projet :

Capteur tactile avec capillaires et intelligence embarquée pour des manipulations robotiques délicates

Research team within HES-SO: Upegui Posada Andres , Lopez De Meneses Yuri , Llera Miguel , Gantel Laurent , Berthet Quentin

Durée du projet: - 15.11.2023

Montant global du projet: 220'000 CHF

Statut: Completed

Endosafe

Role: Collaborator

Financement: HES-SO

Description du projet :

Le présent projet visait à utiliser des fibres optiques hautement flexibles en polyuréthane thermoplastique (TPU) pour la réalisation de systèmes endoscopiques faiblement invasifs. Effectivement, l’utilisation de fibres en TPU au lieu de la silice traditionnelle, permettrait de réduire les risques de rupture des fibres et les perforations d’organes qui s’en suivraient. Plusieurs voies de recherche étaient prévues comme la réalisation de préformes optiques par impression 3D, la fabrication de fibre multicoeurs pour réaliser des systèmes d’oxymétrie dipolaire et la réalisation de fibres multicoeurs à haute densité pour le transfert d’images (endoscopie).

Research team within HES-SO: Llera Miguel

Durée du projet: - 31.07.2023

Montant global du projet: 50'000 CHF

Statut: Completed

FLEXFIBER

Role: Main Applicant

Financement: Innosuisse

Description du projet :

Flexfiber vise à développer des fibres optiques hautement flexibles pour la mesure des paramètres physiologiques humains dans les organes délicats. La fibre, d'une longueur de 10 à 15 cm, doit être entièrement biocompatible et aura un fort impact sur le suivi des implants autonomes et également sur l'outillage chirurgical.

Research team within HES-SO: Flahaut Frédéric , Llera Miguel

Durée du projet: 01.11.2019 - 31.01.2021

Statut: Completed

ACCORD

AGP

Role: Main Applicant

Financement: IMEC, Belgique

Description du projet : Projet européen de type SSA (Specific Support Action). Le projet vise à mettre en place une plate-forme pour stimuler les collaborations universités-industrie au niveau européen dans le domaine de la photonique. Le but étant de stimuler l'intégration des étudiants de la photonique dans l'industrie européenne et de faire converger la recherche dans le domaine aux besoins réels de l'industrie européenne. EU N° 034041

Research team within HES-SO: Banakh Oksana , Llera Miguel

Partenaires académiques: Metrologie Qualité; Llera Miguel, Metrologie Qualité

Durée du projet: 01.06.2006 - 31.03.2010

Montant global du projet: 134'592 CHF

Statut: Completed

Les fibres multimodes et leur limite pour une application LAN

AGP

Role: Collaborator

Financement: HES-SO Rectorat; ARC Ingénierie; ARC Ingénierie

Description du projet : L'augmentation du trafic de données dans les réseaux locaux (LAN) impose une augmentation de leur bande passante. La solution la plus viable à moyen terme d'un point de vue technique et économique se base sur la fibre optique. Deux types principaux de fibres optiques existent : La fibre monomode et la fibre multimode. La monomode présente une bande passante très élevée, mais, dû au faible diamètre de son c'ur, nécessite une connectique très précise et de ce fait présente un coût relativement élevé. La fibre multimode, par contre, ne nécessite pas de connectique précise et présente donc un coût moindre. Le problème actuel de cette dernière est que sa bande passante a été qualifiée pour des longues distances (~km) mais qu'elle n'est pas maîtrisée pour les distances courtes.

Research team within HES-SO: Donzelot Christophe , Llera Miguel , Prieur Claudio

Durée du projet: 01.01.2004 - 30.12.2005

Montant global du projet: 125'707 CHF

Statut: Completed

2025

Soft elastomeric optical fibers for oxygen change measurements of blood and living tissues :

Scientific paper ArODES

a thermoplastic polyurethane assessment

Miguel Llera, Edith Laux, Frédéric Flahaut, Laure Jeandupeux, Esteban Alvarez Seoane, Maxime Zerbib, Jean-Charles Beugnot, Philippe Potty

Biomedical Optics Express, 2025, 16, 2, 426

Link to the publication

Summary:

This paper discusses the design, fabrication, and use of thermoplastic polyurethane optical fibers intended for oxygen saturation measurements. It includes an evaluation of the fiber attenuation and the creation of two probes for the measurement assessment. For comparison, a third probe is made using conventional glass optical fibers. The assessment is conducted in two stages: first, absorption measurements are performed using a mixture of methylene blue and intralipid diluted in deionized water; second, a measurement with human blood is conducted to demonstrate the effectiveness of such fibers in measuring blood oxygen saturation. Additionally, a comprehensive study of measurement stability is provided.

2024

Weight Measurement and Vibration Detection Sensor Based on a Thermoplastic Polyurethane Optical Fiber

Scientific paper

Llera Miguel

Journal of Lightwave Technology, 2024

Link to the publication

Summary:

An elastomeric optical fiber core was fabricated by drawing a 1160-D thermoplastic polyurethane preform. The cut-back technique was used to measure fiber attenuation for a light spectrum ranging from 550 nm to 875 nm, resulting in an average value of less than 0.25 dB/cm, which is suitable for use in short-distance applications. The potential of the fiber was evaluated in two applications where the advantages of this type of optical fiber, its elasticity and flexibility, are important. In the first application, for weight measurement, the sensor response showed asymptotic behavior at high weights that can be divided into two linear sections of 2.9 dB/N for weights ranging from 0 N up to 1 N, and 2.1 dB/N for 1 N to 1.7 N. In the second application, as a vibration sensor, signals were detected between 1 kHz and 20 kHz with an amplitude of approximately 35 dB above the background noise.

2021

Few-mode elastomeric optical fibers

Scientific paper ArODES

Miguel Llera, Frédéric Flahaut, Sylvain Bergerat, Justin Benoit, Rowan Lüthi, Frédéric Mathez, Sébastien Le Floch, Yves Salvadé

Optical Materials Express, 2021, vol. 11, no. 7, pp. 2288-2299

Link to the publication

Summary:

We present a new approach for producing elastomeric optical fibers with an optical behaviour corresponding to a few-mode optical fiber. Different fibers have been produced by first fabricating thermoplastic polyurethane preforms and subsequently drawing them. The fiber attenuation has been measured by the cut-back technique and the fiber bending transmission tolerance evaluated. The fiber potential has been assessed through two basic experiments in order to highlight the benefits of elasticity and a reduced core diameter. Future potential of the proposed fiber is discussed and shows a very auspicious path towards new and unexplored applications.

Few-mode elastomeric optical fibers

Scientific paper

Llera Miguel

Optical Materials Express, 2021 , vol. 11, no 7, pp. 2288-2299

Link to the publication

Summary:

2019

Fiber Bragg grating-based thermometer for drill bit temperature monitoring

Scientific paper ArODES

Miguel Llera, Kenny Hey Tow, Sylvain Bergerat, Yves Meyer, Serge Monnerat, Olivier Gloriod, Sébastien Le Floch, Yves Salvadé, Luc Thévenaz

Applied Optics, 2019, vol. 58, no. 22, pp. 5924-5930

Link to the publication

Summary:

The temperature measurement of a drill bit during an implantology drilling process is proposed by using a fiber Bragg grating fitted inside the drill bit. Due to the rotational nature of the drilling process, a free-space fiber-optic rotary joint is used for interrogating the fiber Bragg grating. Due to mechanical clearances and interferometric noise induced at this rotary joint, signal integrity is strongly deteriorated and is not workable without adequate measures. These measures involve a proper fiber lensing and a signal processing in order to remove the interferometric noise. Finally, a heating measurement on an implantology drill bit is performed and discussed for drilling several holes on a pork jaw sample.

2017

Cyclic coding for Brillouin optical time-domain analyzers using probe dithering

Scientific paper ArODES

Haritz Iribas, Alayn Loayssa, Florian Sauser, Miguel Llera, Sébastien Le Floch

Optics Express, 2017, vol. 25, no. 8, pp. 8787-8800

Link to the publication

Summary:

We study the performance limits of mono-color cyclic coding applied to Brillouin optical time-domain analysis (BOTDA) sensors that use probe wave dithering. BOTDA analyzers with dithering of the probe use a dual-probe-sideband setup in which an optical frequency modulation of the probe waves along the fiber is introduced. This avoids non-local effects while keeping the Brillouin threshold at its highest level, thus preventing the spontaneous Brillouin scattering from generating noise in the deployed sensing fiber. In these conditions, it is possible to introduce an unprecedented high probe power into the sensing fiber, which leads to an enhancement of the signal-to-noise ratio (SNR) and consequently to a performance improvement of the analyzer. The addition of cyclic coding in these set-ups can further increase the SNR and accordingly enhance the performance. However, this unprecedented probe power levels that can be employed result in the appearance of detrimental effects in the measurement that had not previously been observed in other BOTDA set-ups. In this work, we analyze the distortion in the decoding process and the errors in the measurement that this distortion causes, due to three factors: the power difference of the successive pulses of a code sequence, the appearance of first-order non-local effects and the non-linear amplification of the probe wave that results when using mono-color cyclic coding of the pump pulses. We apply the results of this study to demonstrate the performance enhancement that can be achieved in a long-range dithered dual-probe BOTDA. A 164-km fiber-loop is measured with 1-m spatial resolution, obtaining 3-MHz Brillouin frequency shift measurement precision at the worst contrast location. To the best of our knowledge, this is the longest sensing distance achieved with a BOTDA sensor using mono-color cyclic coding.

2016

Liquid-air based Fabry-Pérot cavity on fiber tip sensor

Scientific paper ArODES

Miguel Llera, Thierry Aellen, javier Hervas, Yves Salvadé, Pascal Senn, Pascal Senn, Sébastien Le Floch, Herbert Keppner

Optics Express, 2016, vol. 24, no. 8, pp. 8054-8065

Link to the publication

Summary:

This paper presents a Fabry-Perot fiber tip sensor based on an air-liquid filled cavity. The cavity is sealed off by a thin gold coated membrane of parylene C, between 300 and 350 nm, creating a particularly flexible diaphragm. In order to retrieve and track the cavity of interest from other cavities formed within the sensor tip, a signal processing of the feedback signal is performed by inverse fast Fourier transform. The experimental sensor has been manufactured and tested for temperature, giving cavity length sensitivities of 6.1 nm/°C and 9.6 nm/°C for temperature increase and decrease respectively. The external gas pressure response gives a sensitivity of 15 nm/kPa. The fiber sensor has also been adapted for force sensing after silicone embedment and has shown a sensitivity of about 8.7 nm/mN. Finally, the sensor has been tested on insertion into a human temporal bone, proving that it could be an interesting candidate for insertion force monitoring for robotic cochlear implantation.

Interferometric measurements beyond the coherence length of the laser source

Scientific paper

Salvadé Yves, Frank Przygodda, Marcel Rohner, Albert Polster, Meyer Yves, Monnerat Serge, Gloriod Olivier, Llera Miguel, Renaud Matthey, Joab Di Francesco, Florian Gruet, Gaetano Mileti

Optics Express, 2016 , vol. 24

Link to the publication

Liquid-air based Fabry-Pérot cavity on fiber tip sensor

Scientific paper

Llera Miguel

Optics Express, 2016 , vol. Vol. 24, no Issue 8, pp. 8054-8065

Link to the publication

Summary:

2017

NANOCI—Nanotechnology based cochlear implant with gapless interface to auditory neurons

Conference ArODES

Pascal Senn, Marta Roccio, Stefan Hahnewald, Claudia Frick, Monika Kwiatkowska, Masaaki Ishikawa, Peter Bako, Hao Li, Fredrik Hedin, Wei Liu, Helge Rask-Andersen, Ilmari Pyykkö, Jing Zou, Marika Mannerström, Herbert Keppner, Alexandra Homsy, Edith Laux, Miguel Llera, Jean-Paul Lellouche, Stella Ostrovsky, Ehud Banin, Aharon Gedanken, Nina Perkas, Ute Wank, Karl-Heinz Wiesmüller, Pavel Mistrik, Heval Benav, Carolyn Garnham, Claude Jolly, Filippo Gander, Peter Ulrich, Marcus Müller, Hubert Löwenheim

Otology Neurotology ; Proceedings of the ACI Alliance 14th International Cochlear Implants on Children Conference, San Francisco, CA, USA

Link to the conference

Summary:

Cochlear implants (CI) restore functional hearing in the majority of deaf patients. Despite the tremendous success of these devices, some limitations remain. The bottleneck for optimal electrical stimulation with CI is caused by the anatomical gap between the electrode array and the auditory neurons in the inner ear. As a consequence, current devices are limited through 1) low frequency resolution, hence sub-optimal sound quality and 2), large stimulation currents, hence high energy consumption (responsible for significant battery costs and for impeding the development of fully implantable systems). A recently completed, multinational and interdisciplinary project called NANOCI aimed at overcoming current limitations by creating a gapless interface between auditory nerve fibers and the cochlear implant electrode array. This ambitious goal was achieved in vivo by neurotrophin-induced attraction of neurites through an intracochlear gel-nanomatrix onto a modified nanoCI electrode array located in the scala tympani of deafened guinea pigs. Functionally, the gapless interface led to lower stimulation thresholds and a larger dynamic range in vivo, and to reduced stimulation energy requirement (up to fivefold) in an in vitro model using auditory neurons cultured on multi-electrode arrays. In conclusion, the NANOCI project yielded proof of concept that a gapless interface between auditory neurons and cochlear implant electrode arrays is feasible. These findings may be of relevance for the development of future CI systems with better sound quality and performance and lower energy consumption. The present overview/review paper summarizes the NANOCI project history and highlights achievements of the individual work packages.

Brillouin optical time-domain analyzer for extended sensing range using probe dithering and cyclic coding

Conference ArODES

Haritz Iribas, Alayn Loayssa, Florian Sauser, Miguel Llera, Sébastien Le Floch

Proceedings of the 25th International Conference on Optical Fiber Sensors, 24-28 April 2017, Jeju, Korea, Republic of

Link to the conference

Summary:

We present an enhanced performance Brillouin optical time-domain analysis sensor that uses dual probes waves with optical frequency modulation and cyclic coding. The frequency modulation serves to increase the probe power that can be injected in the fiber before the onset of non-local effects and noise generated by spontaneous Brillouin scattering. This leads to higher detected signal-to-noise ratio (SNR), which is further increased by the coding gain. The enhanced SNR translates to extended range for the sensor, with experiments demonstrating 1-m spatial resolution over a 164 km fiber loop with a 3-MHz Brillouin frequency shift measurement precision at the worst contrast position. In addition, we introduce a study of the power limits that can be injected in the fiber with cyclic coding before the appearance of distortions in the decoded signal.

Enhancement of signal-to-noise ratio in Brillouin optical time domain analyzers by dual-probe detection

Conference ArODES

Haritz Iribas, Alayn Loayssa, Florian Sauser, Miguel Llera, Sébastien Le Floch

Proceedings of the 25th International Conference on Optical Fiber Sensors, 24-28 April 2017, Jeju, Korea, Republic of

Link to the conference

Summary:

We demonstrate a simple technique to enhance the signal-to-noise ratio (SNR) in Brillouin optical time-domain analysis sensors by the addition of gain and loss processes. The technique is based on the shift of the pump pulse optical frequency in a double-sideband probe system, so that the gain and loss processes take place at different frequencies. In this manner, the loss and the gain do not cancel each other out, and it makes possible to take advantage of both informations at the same time, obtaining an improvement of 3 dB on the SNR. Furthermore, the technique does not need an optical filtering, so that larger improvement on SNR and a simplification of the setup are obtained. The method is experimentally demonstrated in a 101 km fiber spool, obtaining a measurement uncertainty of 2.6 MHz (2σ) at the worst-contrast position for 2 m spatial resolution. This leads, to the best of our knowledge, to the highest figure-of-merit in a BOTDA without using coding or raman amplification.

Achievements

PEOPLE@HES-SO
Directory and Skills inventory

Llera Miguel

Adjoint-e scientifique HES

Main skills

Optics

Fiber optics engineering

Microtechnique

Adjoint-e scientifique HES

PEOPLE@HES-SO Directory and Skills inventory

Llera Miguel

Adjoint-e scientifique HES

Main skills

Optics

Fiber optics engineering

Microtechnique

Adjoint-e scientifique HES

PEOPLE@HES-SO
Directory and Skills inventory