Teoría de sensores nanomecánicos aplicados a la detección biológica

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 14-11-2016Esta tesis tiene embargado el acceso al texto completo hasta el 14-05-2018En los últimos años los sensores basados en dispositivos micro y nanomecánicos han demostrado su gran potencial en campos como la medicina o la biología para la detección de complejos biológicos así como la medición de su masa o incluso sus propiedades mecánicas. Generalmente, estos sensores operan en dos modos distintos: el modo estático y el modo dinámico. El modo estático consiste en medir una deformación de la estructura debida a la acción de un agente externo. Un tipo de estructura muy utilizada en este caso es una palanca anclada en un extremo y libre por el otro extremo. Cuando se funcionaliza una de las superficies de la palanca y se adsorbe una capa de biomoléculas se produce una tensión superficial que hace que la palanca se doble. Ésta deformación está directamente relacionada con la tensión superficial aplicada. La teoría más utilizada a día de hoy que relaciona la deformación de la palanca con la tensión superficial aplicada fue formulada en 1909 por George Gerald Stoney. El problema de esta teoría es que no tiene en cuenta los efectos de anclaje de la palanca, y estos efectos son muy importantes a la hora de cuantificar de una manera precisa la tensión superficial actuando sobre la palanca. Matemáticamente, el hecho de incluir el efecto de anclaje en el problema lo complica enormemente hasta tal punto que no existen soluciones analíticas del mismo. En una primera parte de esta tesis doctoral se desarrolla una teoría rigurosa para incluir los efectos de anclaje de la palanca en las ecuaciones de la deformación. Se utilizan condiciones de contorno más relajadas promediando valores a lo largo de la coordenada transversal para finalmente llegar a ecuaciones muy compactas y precisas. El modo dinámico es más comúnmente utilizado para medición de masa. El concepto se basa fundamentalmente en medir el cambio en las frecuencias de resonancia de la estructura cuando una pequeña masa se adhiere a la superficie. El incremento de masa en el sensor que supone esta adhesión hace que sus frecuencias de resonancia bajen en mayor o menor medida dependiendo de la posición de adsorción. Recientemente se ha demostrado que la adhesión de un adsorbato en la superficie del resonador no solo tiene el efecto de aumentar la masa sino que también puede incrementar la rigidez del resonador produciendo consigo un aumento de las frecuencias de resonancia. Este aumento de las frecuencias de resonancia está directamente relacionado con diversas propiedades del adsorbato como por ejemplo su módulo de Young, forma, orientación o área de contacto con la superficie del resonador. Un estudio riguroso que relacione todas estas propiedades con el cambio en las frecuencias de resonancia falta claramente en la literatura a día de hoy. Es por eso que el segundo gran pilar de esta tesis doctoral se centra en el desarrollo de una teoría que explique en detalle en efecto de rigidez de un adsorbato sobre las frecuencias de resonancia de una estructura resonante, en concreto se focaliza en el caso particular de palancas o puentes obteniéndose fórmulas fáciles de implementar que relacionan los cambios en frecuencia con el módulo de Young, área de contacto, orientación o forma del adsorbato. La última parte de esta tesis doctoral se centra en el desarrollo de un algoritmo para resolver el denominado ‘problema inverso’ que consiste en la obtención de información valiosa del adsorbato como su masa, posición de adsorción o su rigidez efectiva a partir de los cambios relativos en frecuencia en varios modos de vibración de la estructura. El método se probó satisfactoriamente con nanopartículas de oro y con bacterias Escherichia coli (E. Coli), experimentos que sirvieron a su vez para confirmar experimentalmente las teorías desarrolladas sobre la rigidez del adsorbato en esta misma tesis

Physics of nanomechanical spectrometry of viruses

There is an emerging need of nanotools able to quantify the mechanical properties of single biological entities. A promising approach is the measurement of the shifts of the resonant frequencies of ultrathin cantilevers induced by the adsorption of the studied biological systems. Here, we present a detailed theoretical analysis to calculate the resonance frequency shift induced by the mechanical stiffness of viral nanotubes. The model accounts for the high surface-to-volume ratio featured by single biological entities, the shape anisotropy and the interfacial adhesion. The model is applied to the case in which tobacco mosaic virus is randomly delivered to a silicon nitride cantilever. The theoretical framework opens the door to a novel paradigm for biological spectrometry as well as for measuring the Young's modulus of biological systems with minimal strains.We acknowledge financial support from the Spanish Science Ministry (MINECO) through projects MAT2012-36197 and from European Research Council through Starting Grant NANOFORCELLS (ERC-StG-2011-278860).Peer Reviewe

Spatially Multiplexed Micro-Spectrophotometry in Bright Field Mode for Thin Film Characterization

Thickness characterization of thin films is of primary importance in a variety of nanotechnology applications, either in the semiconductor industry, quality control in nanofabrication processes or engineering of nanoelectromechanical systems (NEMS) because small thickness variability can strongly compromise the device performance. Here, we present an alternative optical method in bright field mode called Spatially Multiplexed Micro-Spectrophotometry that allows rapid and non-destructive characterization of thin films over areas of mm2 and with 1 μm of lateral resolution. We demonstrate an accuracy of 0.1% in the thickness characterization through measurements performed on four microcantilevers that expand an area of 1.8 mm2 in one minute of analysis time. The measured thickness variation in the range of few tens of nm translates into a mechanical variability that produces an error of up to 2% in the response of the studied devices when they are used to measure surface stress variations.The authors acknowledge the financial support by European Research Council through Starting Grant NANOFORCELLS (ERC-StG-2011-278860). P. M. Kosaka acknowledges funding from the Fundación General CSIC ComFuturo program. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI

Development of nanomechanical biosensors for the determination of cell mechanical properties

Póster presentado en el GEM4 Summer school, celebrado en Londres del 10 al 14 de septiembre de 2012.Peer Reviewe

Optomechanical devides for mechanobiological fingerprinting

Resumen del trabajo presentado en el Frontiers of Nanomechanical Systems (FSN2021), celebraod de forma virtual del 19 al 21 de enero de 2021Twenty years have passed since the first detection of biomolecular recognition using micromechanical systems[1]. In the last two decades, micro- nanomechanical systems have been refined to achieve amazing detection limits in force and mass that have enabled different schemes for ultrasensitive measurements of biological interactions as well as new ways of biological spectrometry. More recently, these figures of merit have been improved by coupling optical cavities to mechanical systems. In this talk, I will review the use of micro- nanomechanical systems for mechanobiological fingerprinting of biological entities, particularizing in the contributions of our group [2]. An essential core of this topic is the discussion about the mechanical coupling between a biological particle and a mechanical resonator, an issue that it is has been often oversimplified. We show that the biomechanical coupling that emerges between a bioparticle and a mechanical resonator is more complex than previously expect and it can give rise to different interaction regimes, in which the resonator response is dominated by different physical parameters of the analyte [3-4]. In particular, we will show experiments done with a variety of micro- nano- optomechanical systems using different measurement schemes where the mass, the stiffness and even the vibration modes of single biological entities can be measured with high sensitivity. It is now widely appreciated the essential role of mechanics in relevant biological processes and how disease can be revealed as changes in the mechanical properties of biological matter. I am pretty sure that future developments in optomechanical devices will contribute for major understanding of diseases as well as for new avenues in diagnosis and therapy

High-Throughput Mass Measurement Of Single Bacterial Cells By Silicon Nitride Membrane Resonators

Trabajo presentado en la 36th International Conference on Micro Electro Mechanical Systems (MEMS), celebrada en Munich (Alemania), del 15 al 19 de enero de 2023.© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.We present a technological approach to precisely measure the dry mass of many individual cells of a bacteria colony. In this technique, bacteria are transported from aqueous solution into gas phase and subsequently guided to the surface of a silicon nitride membrane resonator. Abrupt downshifts in the membrane eigenfrequencies are measured upon every bacterium adhesion and are related to the dry mass of the cell by theoretical methods. We measure the dry mass of Escherichia coli K-12 and Staphylococcus epidermidis with an unprecedented throughput of 20 cells/min and with a mass resolution of ⁓1%. Finally, we apply the Koch & Schaechter model to assess the intrinsic sources of growth stochasticity.This work was supported by the European Union’s Horizon 2020 Research and Innovation Program under Grant Agreement No. 731868-VIRUSCAN and by the ERC CoG Grant 681275 “LIQUIDMASS”. We acknowledge the service from the Micro and Nanofabrication Laboratory an X-SEM laboratory at IMNCNM funded by the Comunidad de Madrid (Project S2018/NMT-4291 TEC2SPACE) and by MINECO (Project CSIC12-4E-1794 with support from FEDER, FSE). E. G. S. acknowledges financial support by the Spanish Science and Innovation Ministry through Ramón y Cajal grant RYC-2019-026626-I

High-throughput nanomechanical mass spectrometry of bacterial cells

Trabajo presentado en el 19th International Workshop on Nanomechanical Sensing (NMC 2024), celebrado en Viene (Austria), del 24 al 27 de junio de 202

Optomechanical disk resonators for real-time environmental monitoring and single-nanoparticle detection

Trabajo presentado en el 13th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META), celebrado en París (Francia), del 18 al 21 de julio de 202

Multifrequency Nanomechanical Mass Spectrometer Prototype for Measuring Viral Particles Using Optomechanical Disk Resonators

Nanomechanical mass spectrometry allows characterization of analytes with broad mass range, from small proteins to bacterial cells, and with unprecedented mass sensitivity. In this work, we show a novel multifrequency nanomechanical mass spectrometer prototype designed for focusing, guiding and soft-landing of nanoparticles and viral particles on a nanomechanical resonator surface placed in vacuum. The system is compatible with optomechanical disk resonators, with an integrated optomechanical transduction method, and with the laser beam deflection technique for the measurement of the vibrations of microcantilever resonators. The prototype allows the in-vacuum alignment of resonators thanks to a dedicated visualization system. Finally, in this work, we have demonstrated the detection of gold nanoparticles, polystyrene nanoparticles and phage G viruses with optomechanical disks and microcantilever resonators.Peer reviewe

First results of the CAST-RADES haloscope search for axions at 34.67 μeV

We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part of the CERN Axion Solar Telescope (CAST), searching for axion dark matter in the 34.67μeV mass range. A radio frequency cavity consisting of 5 sub-cavities coupled by inductive irises took physics data inside the CAST dipole magnet for the first time using this filter-like haloscope geometry. An exclusion limit with a 95% credibility level on the axion-photon coupling constant of gaγ & 4 × 10−13 GeV−1 over a mass range of 34.6738μeV < ma < 34.6771μeV is set. This constitutes a significant improvement over the current strongest limit set by CAST at this mass and is at the same time one of the most sensitive direct searches for an axion dark matter candidate above the mass of 25μeV. The results also demonstrate the feasibility of exploring a wider mass range around the value probed by CAST-RADES in this work using similar coherent resonant cavitiesWe wish to thank our colleagues at CERN, in particular Marc Thiebert from the coating lab, as well as the whole team of the CERN Central Cryogenic Laboratory for their support and advice in speci c aspects of the project. We thank Arefe Abghari for her contributions as the project's summer student during 2018. This work has been funded by the Spanish Agencia Estatal de Investigacion (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) under project FPA-2016-76978-C3-2-P and PID2019-108122GB-C33, and was supported by the CERN Doctoral Studentship programme. The research leading to these results has received funding from the European Research Council and BD, JG and SAC acknowledge support through the European Research Council under grant ERC-2018-StG-802836 (AxScale project). BD also acknowledges fruitful discussions at MIAPP supported by DFG under EXC-2094 { 390783311. IGI acknowledges also support from the European Research Council (ERC) under grant ERC-2017-AdG-788781 (IAXO+ project). JR has been supported by the Ramon y Cajal Fellowship 2012-10597, the grant PGC2018-095328-B-I00(FEDER/Agencia estatal de investigaci on) and FSE-GA2017-2019-E12/7R (Gobierno de Aragón/FEDER) (MINECO/FEDER), the EU through the ITN \Elusives" H2020-MSCA-ITN-2015/674896 and the Deutsche Forschungsgemeinschaft under grant SFB-1258 as a Mercator Fellow. CPG was supported by PROMETEO II/2014/050 of Generalitat Valenciana, FPA2014-57816-P of MINECO and by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreements 690575 and 674896. AM is supported by the European Research Council under Grant No. 742104. Part of this work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344