Espectrometría de masa y rigidez basada en resonadores nanomecánicos

Este trabajo de tesis doctoral está centrado en el uso de los resonadores nanomecánicos como Este trabajo de tesis doctoral está centrado en el uso de los resonadores nanomecánicos como sensores biológicos. Se han estudiado diferentes tipos de resonadores nanomecánicos, tanto desde un punto de vista teórico como experimental, incluyendo el estudio de nanohilos de silicio cónicos y microcapilares de sílice fundido, así como de micropalancas. El objetivo central ha sido el desarrollo de un espectrómetro de masa y rigidez basado en resonadores nanomecánicos para la detección biológica. Se ha utilizado la técnica de ionización mediante electrospray para depositar las partículas biológicas sobre la superficie de una micropalanca. Mediante la medida del cambio en la frecuencia de resonancia de la micropalanca, y un algoritmo matemático, se obtiene la masa y rigidez del adsorbato. Este sistema se ha utilizado para calcular la masa y rigidez de nanopartículas y bacterias, siendo esta la primera vez que se mide la rigidez en tiempo real mediante espectrometría nanomecánica

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

Eliminating ground current in a transformerless photovoltaic application

For low-power grid-connected applications, a single-phase converter can be used. In photovoltaic (PV) applications, it is possible to remove the transformer in the inverter to reduce losses, costs, and size. Galvanic connection of the grid and the dc sources in transformerless systems can introduce additional ground currents due to the ground parasitic capacitance. These currents increase conducted and radiated electromagnetic emissions, harmonics injected in the utility grid, and losses. Amplitude and spectrum of the ground current depend on the converter topology, the switching strategy, and the resonant circuit formed by the ground capacitance, the converter, the ac filter, and the grid. In this paper, the ground current in a 1.5-kW PV installation is measured under different conditions and used to build a simulation model. The installation includes a string of 16 PV panel, a full-bridge inverter, and an LCL filter. This model allows the study of the influence of the harmonics injected by the inverter on the ground current.Ministerio de Ciencia e Innovación | Ref. DPI2009-0700

Silicon nanowires: where mechanics and optics meet at the nanoscale

Mechanical transducers based on nanowires promise revolutionary advances in biological sensing and force microscopy/spectroscopy. A crucial step is the development of simple and non-invasive techniques able to detect displacements with subpicometer sensitivity per unit bandwidth. Here, we design suspended tapered silicon nanowires supporting a range of optical resonances that confine and efficiently scatter light in the visible range. Then, we develop an optical method for efficiently coupling the evanescent field to the regular interference pattern generated by an incoming laser beam and the reflected beam from the substrate underneath the nanowire. This optomechanical coupling is here applied to measure the displacement of 50 nm wide nanowires with sensitivity on the verge of 1 fm/Hz1/2 at room temperature with a simple laser interferometry set-up. This method opens the door to the measurement of the Brownian motion of ultrashort nanowires for the detection of single biomolecular recognition events in liquids, and single molecule spectroscopy in vacuum.We acknowledge financial support from the Spanish Science Ministry (MINECO) through projects TEC2011-29120-C05-04; and from European Research Council through Starting Grant NANOFORCELLS (ERC-StG-2011-278860).Peer reviewe

Space-vector PWM with common-mode voltage elimination for multiphase drives

Switching common-mode voltage (CMV) generated by the pulse width modulation (PWM) of the inverter causes common-mode currents, which lead to motor bearing failures and electromagnetic interference problems in multiphase drives. Such switching CMV can be reduced by taking advantage of the switching states of multilevel multiphase inverters that produce zero CMV. Specific space-vector PWM (SVPWM) techniques with CMV elimination, which only use zero CMV states, have been proposed for three-level five-phase drives, and for open-end winding five-, six-, and seven-phase drives, but such methods cannot be extended to a higher number of levels or phases. This paper presents a general (for any number of levels and phases) SVPMW with CMV elimination. The proposed technique can be applied to most multilevel topologies, has low computational complexity and is suitable for low-cost hardware implementations. The new algorithm is implemented in a low-cost field-programmable gate array and it is successfully tested in the laboratory using a five-level five-phase motor drive.Ministerio de Ciencia e InnovaciónEuropean CommissionMinisterio de Economía y Competitividad | Ref. DPI2012-31283Ministerio de Economía y Competitividad | Ref. DPI2015-6541

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

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

Lugar(es)

Catálogo de la exposición colectiva celebrada en la sala de exposiciones de la Facultad de Bellas Artes de la Universidad Complutense de Madrid entre el 14 y el 30 de enero de 201