Suchergebnisse

In this work we study the different phenomena taking place when a hydrostatic pressure is applied in the inner fluid of a suspended microchannel resonator. Additionally to pressure-induced stiffness terms, we have theoretically predicted and experimentally demonstrated that the pressure also induces mass effects which depend on both the applied pressure and the fluid properties. We have used these phenomena to characterize the frequency response of the device as a function of the fluid compressibility and molecular masses of different fluids ranging from liquids to gases. The proposed device in this work can measure the mass density of an unknown liquid sample with a resolution of 0.7 µg/mL and perform gas mixtures characterization by measuring its average molecular mass with a resolution of 0.01 atomic mass units ; This work was supported by the European Union's Horizon 2020 research and innovation program under European Research Council grant 681275-LIQUIDMASS-ERC-CoG-2015 and the Spanish Science Ministry (MINECO) through project MOMPs TEC2017-89765-R. The service from the Micro and Nanofabrication Laboratory (MiNa) and X-SEM Laboratory, is funded by MCIU (CSIC13-4E-1794) and EU (FEDER, FSE). ; Peer reviewed

Trabajo presentado en la 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), celebrada en Berlín (Alemania), del 23 al 27 de junio de 2019 ; Hollow nanomechanical resonators represent a promising technique for particle spectrometry, as their design allows highly sensitive particle mass sensing in liquid environments by putting together the good mechanical behavior of a nanomechanical resonator vibrating in vacuum or gas environment with physiological compatibility of liquid environments for biological applications. Nevertheless, for real-world practical applications these sensors require not only a high mass sensitivity but also a high-throughput particle flow. In this work, we use a fast-response and low-cost hollow nanomechanical resonator which let us measure up to 10 particles per second. However, this unprecedented particle velocities brings new implications related to the entanglement between the mechanics and the microfluidics in this structure. We realized that the measured particle masses depend on the fluid velocity. The study of this phenomenon demonstrates the need to introduce a correction factor in mass sensing dependent on particle velocity. ; This work was supported by the European Union's Horizon 2020 program under European Research Council grant 681275 – LIQUIDMASS- ERC- CoG-2015 and by the Comunidad de Madrid (iLUNG B2017/BMD-3884) - co-funded by FSE & FEDER and the Spanish Science Ministry(MINECO) through project TEC2017-89765-R. All authors acknowledge the service from the X-SEM Laboratory at IMN and MINECO under project CSIC13- 4E-1794, also with support from EU (FEDER, FSE). All the authors also acknowledge the service from the MiNa Laboratory at IMN, and funding from CM (project SpaceTec, S2013/ICE2822), MINECO (project CSIC13- 4E-1794) and EU (FEDER, FSE). ; Peer reviewed

Characterization of micro and nanoparticle mass has become increasingly relevant in a wide range of fields, from materials science to drug development. The real-time analysis of complex mixtures in liquids demands very high mass sensitivity and high throughput. One of the most promising approaches for real-time measurements in liquid, with an excellent mass sensitivity, is the use of suspended microchannel resonators, where a carrier liquid containing the analytes flows through a nanomechanical resonator while tracking its resonance frequency shift. To this end, an extremely sensitive mechanical displacement technique is necessary. Here, we have developed an optomechanical transduction technique to enhance the mechanical displacement sensitivity of optically transparent hollow nanomechanical resonators. The capillaries have been fabricated by using a thermal stretching technique, which allows to accurately control the final dimensions of the device. We have experimentally demonstrated the light coupling into the fused silica capillary walls and how the evanescent light coming out from the silica interferes with the surrounding electromagnetic field distribution, a standing wave sustained by the incident laser and the reflected power from the substrate, modulating the reflectivity. The enhancement of the displacement sensitivity due to this interferometric modulation (two orders of magnitude better than compared with previous accomplishments) has been theoretically predicted and experimentally demonstrated. ; This work was supported by the European Union's Horizon 2020 program under European Research Council grant 681275—LIQUIDMASS-ERC-CoG-2015 and by the Comunidad de Madrid (iLUNG B2017/BMD-3884)—co-funded by FSE & FEDER and the Spanish Science Ministry (MINECO) through project MOMPs TEC2017-89765-R. All authors acknowledge the service from the X-SEM Laboratory at IMN and MINECO under project CSIC13-4E-1794, also with support from EU (FEDER, FSE).

Ultrahigh sensitivity temperature measurement is becoming increasingly relevant for different scientific and technological fields from fundamental physics to high-precision engineering applications. Here, we demonstrate the use of a nanomechanical resonator - free standing silicon nitride membranes with thicknesses in the nanoscale - for room temperature thermometry reaching an unprecedented resolution of 15 μK. These devices were characterized by using an interferometric system at high vacuum, where there are only two possible mechanisms for heat transfer: thermal conductivity and radiation. While the expected behavior should be to decrease the frequency of the mechanical resonance due to the thermoelastic effect, we observe that the nanomechanical response can be both positive and negative depending on the thermal flux: a heat point source always shifts the mechanical resonance to lower frequencies, while a distributed heat source shifts the resonance to higher frequencies. ; This research is funded by the Spanish Ministry of Science under project MOMPs reference TEC2017-89765-R and the European Association of National Metrology Institutes (JRP f14 PhotOQuanT17FUN05). E.G.-S acknowledges financial support by the Spanish Ministry of Science under the project MicroBIOMS, reference PID2019-109765RA-I00. This project has received funding from the EMPIR program co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation program. The service from the Micro and Nanofabrication Laboratory (MiNa) and X-SEM Laboratory is funded by MCIU (CSIC13-4E-1794) and EU (FEDER, FSE).

Carbapenem-resistant Enterobacteriaceae have recently become an important cause of morbidity and mortality due to healthcare-associated infections. Most commonly used diagnostic methods are incompatible with fast and accurate directed therapy. We report here the direct identification of the blaOXA48 gene, which codes for the carbapenemase OXA-48, in lysate samples from Klebsiella pneumoniae. The method is PCR-free and label-free. It is based on the measurement of changes in the stiffness of DNA self-assembled monolayers anchored to microcantilevers that occur as a consequence of the hybridization. The stiffness of the DNA layer is measured through changes of the sensor resonance frequency upon hybridization and at varying relative humidity. ; This work was supported by the Spanish Science Ministry (MINECO) through project MAT2015-66904-R and by European Research Council through NANOFORCELLS project (ERC-StG-2011-278860) and European Union's Horizon 2020 research and innovation program under grant agreement No. 731868-VIRUSCAN. D.R. acknowledges the Ramon y Cajal fellowship supported by Spanish Ministry MINECO. Authors also acknowledge the service from the XSEM Laboratory at IMN and funding from MINECO under project CSIC13-4E-1794 with support from EU (FEDER, FSE). ; Peer reviewed

The properties of water at the nanoscale are crucial in many areas of biology, but the confinement of water molecules in sub-nanometre channels in biological systems has received relatively little attention. Advances in nanotechnology make it possible to explore the role played by water molecules in living systems, potentially leading to the development of ultrasensitive biosensors. Here we show that the adsorption of water by a self-assembled monolayer of single-stranded DNA on a silicon microcantilever can be detected by measuring how the tension in the monolayer changes as a result of hydration. Our approach relies on the microcantilever bending by an amount that depends on the tension in the monolayer. In particular, we find that the tension changes dramatically when the monolayer interacts with either complementary or single mismatched single-stranded DNA targets. Our results suggest that the tension is mainly governed by hydration forces in the channels between the DNA molecules and could lead to the development of a label-free DNA biosensor that can detect single mutations. The technique provides sensitivity in the femtomolar range that is at least two orders of magnitude better than that obtained previously with label-free nanomechanical biosensors and with label-dependent microarrays. ; D.R. acknowledges the fellowship funded by the Autonomic Community of Madrid (CAM). J.T, M.C, J.M and D.R acknowledge financial support by Spanish Ministry of Science (MEC) under grant No. TEC2006-10316 and CAM under grant No. 200550M056. C.B. acknowledges funding provided by MEC under grant No. BIO2007-67523. Work at Centro de Astrobiología was supported by European Union (EU), Instituto Nacional de Técnica Aeroespacial (INTA), MEC and CAM. All the authors acknowledge A. Cebollada, J.M. García-Martín, J. García, J.L. Costa-Kramer, M. Arroyo-Hernández and J.V. Anguita for their assistance in the gold deposition on the cantilevers. ; Peer reviewed

The real-time analysis of single analytes in flow is becoming increasingly relevant in cell biology. In this work, we theoretically predict and experimentally demonstrate hydrodynamic focusing with hollow nanomechanical resonators by using an interferometric system which allows the optical probing of flowing particles and tracking of the fundamental mechanical mode of the resonator. We have characterized the hydrodynamic forces acting on the particles, which will determine their velocity depending on their diameter. By using the parameters simultaneously acquired: frequency shift, velocity and reflectivity, we can unambiguously classify flowing particles in real-time, allowing the measurement of the mass density: 1.35 ± 0.07 g·mL-1 for PMMA and 1.7 ± 0.2 g·mL-1 for silica particles, which perfectly agrees with the nominal values. Once we have tested our technique, MCF-7 human breast adenocarcinoma cells are characterized (1.11 ± 0.08 g·mL-1) with high throughput (300 cells/minute) observing a dependency with their size, opening the door for individual cell cycle studies. ; This work was supported by the European Union's Horizon 2020 research and innovation program under European Research Council Grant 681275-LIQUIDMASS-ERC-CoG-2015, project CELLTANGLE reference RTI2018-099369-B-I00, project MOMPs reference TEC2017-89765-R, Asociación Elena Torres (contract OTR04893) and FERO Foundation (Grant OTR06145). The service from the Micro and Nanofabrication Laboratory (MiNa) and X-SEM Laboratory, is funded by MCIU (CSIC13-4E-1794) and EU (FEDER, FSE). ; Peer reviewed

The study of biophysical properties of single cells is becoming increasingly relevant in cell biology and pathology. The measurement and tracking of magnitudes such as cell stiffness, morphology, and mass or refractive index have brought otherwise inaccessible knowledge about cell physiology, as well as innovative methods for high-throughput labelfree cell classification. In this work, we present hollow resonator devices based on suspended glass microcapillaries for the simultaneous measurement of single-cell buoyant mass and reflectivity with a throughput of 300 cells/minute. In the experimental methodology presented here, both magnitudes are extracted from the devices' response to a single probe, a focused laser beam that enables simultaneous readout of changes in resonance frequency and reflected optical power of the devices as cells flow within them. Through its application to MCF-7 human breast adenocarcinoma cells and MCF-10A nontumorigenic cells, we demonstrate that this mechano-optical technique can successfully discriminate pathological from healthy cells of the same tissue type. ; This work was supported by the European Union's Horizon 2020 research and innovation program under European Research Council Grant 681275-LIQUIDMASS-ERC-CoG2015 and by the Spanish Science, Innovation and Universities Ministry through project CELLTANGLE reference RTI2018- 099369-B-I00, project MOMPs reference TEC2017-89765-R and Ramon y Cajal grant RYC-2017-21640 to P.M.K.; by the ́ Comunidad de Madrid (iLUNG B2017/BMD-3884) with support from EU (FEDER, FSE). E.G.-S. received funding from Fundacion General CSIC (Programa ComFuturo), as ́ well as Marie-Sklodowska Curie Actions (H2020-MSCA-IF2015) under NOMBIS project (703354).The service from the Micro and Nanofabrication Laboratory (MiNa) and X-SEM Laboratory, is funded by MCIU (CSIC13-4E-1794) and EU (FEDER, FSE). We have received support for part of the publication fee by CSIC open access publication support initiative through URICI. ; Peer reviewed

Free-standing dielectric structures with a substrate underneath, as the SiN microdrums studied here, are the basis of optomechanical devices. Optimization of the optomechanical coupling is demanding in order to enhance the performance of these devices. The optomechanical coupling in the case of drum resonators critically depends on the thickness of the drum, the surface stress, the cavity length and the wavelength. Here, we develop a methodology that combines spatially multiplexed microspectrophotometry, optical modelling of the cavity and finite element method simulation of the mechanical eigenmodes that enables obtaining the properties of the optomechanical cavity and predicting the wavelength that optimizes the optomechanical coupling. By choosing this illumination wavelength we are able to spatially resolve the thermal motion of the microdrums up to the fourth mechanical mode ~ 20 MHz. The presented study opens the door for further optimization pathways for optomechanical detection and actuation. ; This work was supported by the Spanish Science Ministry (MINECO) through project MAT2015-66904-R and by the European Union's Horizon 2020 research and innovation program under grant agreement No 731868–VIRUSCAN. D.R. acknowledges the RyC fellowship supported by MINECO. ; Peer reviewed