Jose Plaza - Profile on Academia.edu (original) (raw)
Papers by Jose Plaza
Advanced materials (Deerfield Beach, Fla.), Jan 9, 2015
A novel suspended planar-array chips technology is described, which effectively allows molecular ... more A novel suspended planar-array chips technology is described, which effectively allows molecular multiplexing using a single suspended chip to analyze extraordinarily small volumes. The suspended chips are fabricated by combining silicon-based technology and polymer-pen lithography, obtaining increased molecular pattern flexibility, and improving miniaturization and parallel production. The chip miniaturization is so dramatic that it permits the intracellular analysis of living cells.
Magnetically actuated microvalve for disposable drug infusor
2007 International Conference on Thermal, Mechanical and Multi-Physics Simulation Experiments in Microelectronics and Micro-Systems. EuroSime 2007, 2007
Abstract A magnetic microfluidic valve has been analyzed to improve its performance. Operation re... more Abstract A magnetic microfluidic valve has been analyzed to improve its performance. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co-Ni on a V-shaped cantilever beam. The deflection caused by the magnetic forces opens or closes the fluid flow. The microvalve performance has been optimized by means of finite element analysis. The FEA model has been experimentally validated using confocal microscopy and used to improve the magnetic circuit. Then, a fluidic cell has been built ...
Reproductive BioMedicine Online, 2015
The increasing number of patients undergoing assisted reproductive technology (ART) treatments an... more The increasing number of patients undergoing assisted reproductive technology (ART) treatments and of cycles performed in fertility centres has led to some traceability errors. Although the incidence of mismatching errors is extremely low, any error is unacceptable, therefore different strategies have been developed to further minimize these errors, such as manual double witnessing or electronic witnessing systems. More recently, our group developed a direct tagging method consisting of attaching microbarcodes directly to the zona pellucida of human oocytes/embryos. Here, this method is taken a step further by using these microbarcodes to tag human semen samples, demonstrating that the barcodes are not toxic and do not interfere in the selection of motile spermatozoa nor in the cryopreservation of the sperm samples. In addition, when this tagging system was applied to an animal model (rabbit), pregnancy rate and kitten viability were not affected.
Design, fabrication and characterization of an externally actuated ON/OFF microvalve
Sensors and Actuators a-Physical, 2008
A magnetic microfluidic valve has been designed, fabricated and tested. Operation relies on the u... more A magnetic microfluidic valve has been designed, fabricated and tested. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co–Ni (soft magnetic material) on a V-shaped cantilever beam. The deflection caused by the magnetic forces opens or closes the fluid flow. The microvalve performance has been optimized by means of finite element analysis (FEA). The FEA model has been experimentally validated using confocal microscopy and used to improve the magnetic circuit. Then, a fluidic cell ...
Design and characterization of a magnetic digital flow regulator
Sensors and Actuators a-Physical, 2010
Design, fabrication and testing of a novel micromachined “quasi-digital” microflow regulator for ... more Design, fabrication and testing of a novel micromachined “quasi-digital” microflow regulator for integrated microfluidic systems. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co–Ni on an array of V-shaped cantilever beams under a constant pressure. Each valve actuates as an on–off fluidic switch, opening or closing its corresponding microchannel. The flow can be adjusted to a set of different values (digital) by changing the position of the magnet. The microflow regulator has been ...
Nanomagnet fabrication on FBAR for magnetic sensor applications
2009 IEEE International Ultrasonics Symposium, 2009
Abstract We report a focused-ion-beam-assisted technique intended for ultra-small, hard magnet f... more Abstract We report a focused-ion-beam-assisted technique intended for ultra-small, hard magnet fabrication and placement on thin-film bulk acoustic resonators (FBAR). Reduced-size NdFeB magnets were extracted from a macroscopic quarry and bonded to the surface of FBARs ...
Small, 2010
Figure 3. CFDA-derivatized ICCs interact with the cell cytoplasm. D. discoideum (A, C) and HeLa c... more Figure 3. CFDA-derivatized ICCs interact with the cell cytoplasm. D. discoideum (A, C) and HeLa cells (B, D) show intracellular ICCs with green fluorescence (yellow arrow). Extracellular ICCs do not display fluorescence and appear as white dots (black arrow) (A, B). Zoom of D. discoideum (C) and HeLa cells (D) showing functionalized ICCs. Images are maximal confocal projections taken with CLSM. Bar ¼ 10 mm.
In situ MEMS gradiometer with nanometer-resolution optical detection system
Sensors and Actuators A: Physical, 2010
Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurement... more Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurements are presented. Suspended quad-beams with proof mass have been designed to improve their sensitivity and to simplify the detection. Fabricated devices exhibit the compact size of current MEMS technologies and are built within a simple deep-reactive-ion etching-based process. Nanometer-resolution detection based on optical interferometry and signal processing techniques have
Sensors and Actuators A: Physical, 2003
The paper is focused on the structuring of glass wafers to obtain high aspect ratio glass columns... more The paper is focused on the structuring of glass wafers to obtain high aspect ratio glass columns with high vertical profile for Micro Electro Mechanical Systems (MEMS). The technique proposed is to pattern columns by mechanical sawing. The sawing parameters have been optimised to achieve a high yield. Different dimensions of the column have been tested and glass columns down to 150 m × 150 m of cross-section and 700 m height have been obtained. They present high aspect ratio (>100) and very good vertical profile (88-90 • ). Hoya SD-2 and Corning Pyrex #7740 glass wafers have been processed with similar results. Different cleaning procedures have been tested to improve the anodic bondability of the samples after sawing. Machined glass columns have also been structured by commercial sand blasting technique and the results are also compared to the sawed samples. The glass wafers with machined columns have been anodically bonded to silicon. Anodic bonding characterisation of glass columns of different sections is also presented. Pull tests confirmed the good bondability of the glass columns.
Comparative performance of static-mode ferrous MEMS gradiometers fabricated by a three-step DRIE process
Journal of Micromechanics and Microengineering, 2010
Page 1. Comparative performance of static-mode ferrous MEMS gradiometers fabricated by a three-st... more Page 1. Comparative performance of static-mode ferrous MEMS gradiometers fabricated by a three-step DRIE process This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2010 J. Micromech. Microeng. 20 075006 ...
Biomaterials, 2017
Remote microactuators are of great interest in biology and medicine as minimally-invasive tools f... more Remote microactuators are of great interest in biology and medicine as minimally-invasive tools for cellular stimulation. Remote actuation can be achieved by active magnetostrictive transducers which are capable of changing shape in response to external magnetic fields thereby creating controlled displacements. Among the magnetostrictive materials, Galfenol, the multifaceted iron-based smart material, offers high magnetostriction with robust mechanical properties. In order to explore these capabilities for biomedical applications, it is necessary to study the feasibility of material miniaturization in standard fabrication processes as well as evaluate the biocompatibility. Here we develop a technology to fabricate, release, and suspend Galfenol-based microparticles, without affecting the integrity of the material. The morphology, composition and magnetic properties of the material itself are characterized. The direct cytotoxicity of Galfenol is evaluated in vitro using human macroph...
IEEE Transactions on Nanotechnology, 2015
This work presents a sensor composed of a differential arrangement of coils capable of measuring ... more This work presents a sensor composed of a differential arrangement of coils capable of measuring nanometric metallic film thickness. Experimental results achieved aluminium thickness measurements as low as 20 nm with a sensitivity of 3.8 mV/nm. This makes this sensor a flexible, nondestructive and cheap alternative for metallic thickness measurement down to nanometric scale.
2009 Spanish Conference on Electron Devices, 2009
This paper shows the technology development of microneedles electrodes for living cell applicatio... more This paper shows the technology development of microneedles electrodes for living cell applications. The study (6) (b)
SPIE Proceedings, 2007
Deflection of a microcantilever caused by any kind of biochemical reaction occurring on its surfa... more Deflection of a microcantilever caused by any kind of biochemical reaction occurring on its surface can be detected with subangstrom resolution if an appropriate detection technique is exploited. This kind of transducers has become widely used in biological research since a few years ago. Usually, for the readout of the nanomechanical response of the micro beams to bio-specific interactions, a technique similar to one used in the atomic force microscopy is employed. The optical read-out method has some disadvantages, such as low degree of integration and difficulties in work with arrays of cantilevers. In the technique presented in this work the cantilever itself is an optical waveguide butt-coupled with another one. The device is fabricated as an array of 20 waveguide cantilever channels which allows for higher integration level. The analysis of the capabilities of the device, the problems associated with the design and the fabrication of the device, the choice of the material and the technology for the fabrication of very flat cantilevers have been successfully addressed. The characterisation of the device was done, showing that the resolution of the device is comparable with the one using the optical lever read-out. Results of the simulations and experimental data on the optical cantilevers coated with an absorbent material will be presented. The choice of the appropriate thickness of the absorbent material on the cantilever surface allows for acceptable losses, for single mode behaviour and adjustment of the initial displacement of the cantilever.
Sensors and Actuators A: Physical, 2010
A system of two solid microlenses with uncoupled optical properties is presented. This structure ... more A system of two solid microlenses with uncoupled optical properties is presented. This structure has been designed in order to have one lens as a reference, while the other one can be mechanically tuneable. The reference lens presents a diameter of 2 m and it is placed in the optical axis of the mechanically tuneable lens, which has a diameter of 10 m. The proposed microoptical structure has been fabricated in poly(dimethilsiloxane) (PDMS) merging deep reactive ion etching, SU-8 and soft lithography, with a low-cost (mass-production), simple and highly repetitive technology. This device was numerically simulated prior to its fabrication, to optimize its design and improve its behaviour. In addition, an optical characterization of the fabricated devices was carried out. Both simulation and experimental results shows a good agreement, under mechanical actuation behaviour of the reference lens is invariable, while the tuneable lens become an elliptic lens and the interval of Sturm can be observed. These results provide a proof of concept of the proposed devices and validate both the design and the fabrication technology.
Journal of Micromechanics and Microengineering, 2004
In the last decade research in chips for DNA amplification through the polymerase chain reaction ... more In the last decade research in chips for DNA amplification through the polymerase chain reaction (PCR) has been relatively abundant, but has taken very diverse approaches, leaving little common ground for a straightforward comparison of results. Here we report the development of a line of PCR chips that is fully compatible with complementary-metal-oxidesemiconductor (CMOS) technology and its revealing use as a general platform to test and compare a wide range of experimental parameters involved in PCR-chip design and operation. Peltier-heated and polysilicon thin-film driven PCR chips have been produced and directly compared in terms of efficiency, speed and power consumption, showing that thin-film systems run faster and more efficiently than Peltier-based ones, but yield inferior PCR products. Serpentine-like chamber designs have also been compared with standard rectangular designs and with the here reported rhomboidal chamber shape, showing that serpentine-like chambers do not have detrimental effects in PCR efficiency when using non-flow-through schemes, and that chamber design has a strong impact on sample insertion/extraction yields. With an accurate temperature control (±0.2 • C) we have optimized reaction kinetics to yield sound PCR amplifications of 25 µl mixtures in 20 min and 24.4 s cycle times, confirming that a titrated amount of bovine albumin serum (BSA, 2.5 µg µl −1) is essential to counteract polymerase adsorption at chip walls. The reported use of a CMOS-compatible technological process paves the way for an easy adaption to foundry requirements and for a scalable integration of electro-optic detection and control circuitry.
Journal of Lightwave Technology, 2006
This study presents a novel generic multipurpose probe based on an array of 20 waveguide channels... more This study presents a novel generic multipurpose probe based on an array of 20 waveguide channels with microcantilevers acting as optical waveguides operated in the visible range. The principle of operation is based on the sensitivity of energy transfer between two butt-coupled waveguides to their misalignment with respect to each other. The technique can be considered an alternative to the known methods used for the readout of the nanomechanical response of microcantilevers to the external force exerted on them. The cantilever displacement can be detected with a resolution of 18 fm/ √ Hz. The limit is generally defined by the shot noise of a conventional photodetector used for the readout of the output signal. Real-time parallel monitoring of several channels can be realized. In contrast to devices based on the atomic force microscope detection principle, no preliminary alignment or adjustment, except for light coupling, is required. The detection of the cantilever deflection at subnanometer range was demonstrated experimentally.
Human Reproduction, 2013
study question: Is the attachment of biofunctionalized polysilicon barcodes to the outer surface ... more study question: Is the attachment of biofunctionalized polysilicon barcodes to the outer surface of the zona pellucida an effective approach for the direct tagging and identification of human oocytes and embryos during assisted reproduction technologies (ARTs)? summary answer: The direct tagging system based on lectin-biofunctionalized polysilicon barcodes of micrometric dimensions is simple, safe and highly efficient, allowing the identification of human oocytes and embryos during the various procedures typically conducted during an assisted reproduction cycle. what is known already: Measures to prevent mismatching errors (mix-ups) of the reproductive samples are currently in place in fertility clinics, but none of them are totally effective and several mix-up cases have been reported worldwide. Using a mouse model, our group has previously developed an effective direct embryo tagging system which does not interfere with the in vitro and in vivo development of the tagged embryos. This system has now been tested in human oocytes and embryos. study design, size, duration: Fresh immature and mature fertilization-failed oocytes (n ¼ 21) and cryopreserved day 1 embryos produced by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) (n ¼ 205) were donated by patients (n ¼ 76) undergoing ARTs. In vitro development rates, embryo quality and post-vitrification survival were compared between tagged (n ¼ 106) and non-tagged (control) embryos (n ¼ 99). Barcode retention and identification rates were also calculated, both for embryos and for oocytes subjected to a simulated ICSI and parthenogenetic activation. Experiments were conducted from January 2012 to January 2013. participants/materials, setting, methods: Barcodes were fabricated in polysilicon and biofunctionalizated with wheat germ agglutinin lectin. Embryos were tagged with 10 barcodes and cultured in vitro until the blastocyst stage, when they were either differentially stained with propidium iodide and Hoechst or vitrified using the Cryotop method. Embryo quality was also analyzed by embryo grading and timelapse monitoring. Injected oocytes were parthenogenetically activated using ionomycin and 6-dimethylaminopurine. main results and the role of chance: Blastocyst development rates of tagged (27/58) and non-tagged embryos (24/51) were equivalent, and no significant differences in the timing of key morphokinetic parameters and the number of inner cell mass cells were detected between the two groups (tagged: 24.7 + 2.5; non-tagged: 22.3 + 1.9), indicating that preimplantation embryo potential and quality are not affected by the barcodes. Similarly, re-expansion rates of vitrified-warmed tagged (19/21) and non-tagged (16/19) blastocysts were similar. Global identification rates of 96.9 and 89.5% were obtained in fresh (mean barcode retention: 9.22 + 0.13) and vitrified-warmed (mean barcode retention: 7.79 + 0.35) tagged embryos, respectively, when simulating an automatic barcode reading process, though these rates were increased to 100% just by rotating the embryos during barcode reading. Only one of the oocytes lost one barcode during intracytoplasmic injection (100% identification rate) and all oocytes retained all the barcodes after parthenogenetic activation.
Internalization and cytotoxicity analysis of silicon-based microparticles in macrophages and embryos
Biomedical Microdevices, 2010
Microchips can be fabricated, using semiconductor technologies, at microscopic level to be introd... more Microchips can be fabricated, using semiconductor technologies, at microscopic level to be introduced into living cells for monitoring of intracellular parameters at a single cell level. As a first step towards intracellular chips development, silicon and polysilicon microparticles of controlled shape and dimensions were fabricated and introduced into human macrophages and mouse embryos by phagocytosis and microinjection, respectively. Microparticles showed to be non-cytotoxic for macrophages and were found to be localized mainly inside early endosomes, in tight association with endosomal membrane, and more rarely in acidic compartments. Embryos with microinjected microparticles developed normally to the blastocyst stage, confirming the non-cytotoxic effect of the particles. In view of these results silicon and polysilicon microparticles can serve as the frame for future intracellular chips development and this technology opens the possibility of real complex devices to be used as sensors or actuators inside living cells.
Bioconjugate Chemistry, 2012
Cell tracking is an emergent area in nanobiotechnology, promising the study of individual cells o... more Cell tracking is an emergent area in nanobiotechnology, promising the study of individual cells or the identification of populations of cultured cells. In our approach, microtools designed for extracellular tagging are prepared, because using biofunctionalized polysilicon barcodes to tag cell membranes externally avoids the inconveniences of cell internalization. The crucial covalent biofunctionalization process determining the ultimate functionality was studied in order to find the optimum conditions to link a biomolecule to a polysilicon barcode surface using a self-assembled monolayer (SAM) as the connector. Specifically, a lectin (wheat germ agglutinin, WGA) was used because of its capacity to recognize some specific carbohydrates present on the surface of most mammalian cells. Self-assembled monolayers were prepared on polysilicon surfaces including aldehyde groups as terminal functions to study the suitability of their covalent chemical bonding to WGA. Some parameters, such as the polysilicon surface roughness or the concentration of WGA, proved to be crucial for successful biofunctionalization and bioactivity. The SAMs were characterized by contact angle measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS), and atomic force microscopy (AFM). The biofunctionalization step was also characterized by fluorescence microscopy and, in the case of barcodes, by adhesion experiments to the zona pellucida of mouse embryos. These experiments showed high barcode retention rates after 96 h of culture as well as high embryo viability to the blastocyst stage, indicating the robustness of the biofunctionalization and, therefore, the potential of these new microtools to be used for cell tagging.
Advanced materials (Deerfield Beach, Fla.), Jan 9, 2015
A novel suspended planar-array chips technology is described, which effectively allows molecular ... more A novel suspended planar-array chips technology is described, which effectively allows molecular multiplexing using a single suspended chip to analyze extraordinarily small volumes. The suspended chips are fabricated by combining silicon-based technology and polymer-pen lithography, obtaining increased molecular pattern flexibility, and improving miniaturization and parallel production. The chip miniaturization is so dramatic that it permits the intracellular analysis of living cells.
Magnetically actuated microvalve for disposable drug infusor
2007 International Conference on Thermal, Mechanical and Multi-Physics Simulation Experiments in Microelectronics and Micro-Systems. EuroSime 2007, 2007
Abstract A magnetic microfluidic valve has been analyzed to improve its performance. Operation re... more Abstract A magnetic microfluidic valve has been analyzed to improve its performance. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co-Ni on a V-shaped cantilever beam. The deflection caused by the magnetic forces opens or closes the fluid flow. The microvalve performance has been optimized by means of finite element analysis. The FEA model has been experimentally validated using confocal microscopy and used to improve the magnetic circuit. Then, a fluidic cell has been built ...
Reproductive BioMedicine Online, 2015
The increasing number of patients undergoing assisted reproductive technology (ART) treatments an... more The increasing number of patients undergoing assisted reproductive technology (ART) treatments and of cycles performed in fertility centres has led to some traceability errors. Although the incidence of mismatching errors is extremely low, any error is unacceptable, therefore different strategies have been developed to further minimize these errors, such as manual double witnessing or electronic witnessing systems. More recently, our group developed a direct tagging method consisting of attaching microbarcodes directly to the zona pellucida of human oocytes/embryos. Here, this method is taken a step further by using these microbarcodes to tag human semen samples, demonstrating that the barcodes are not toxic and do not interfere in the selection of motile spermatozoa nor in the cryopreservation of the sperm samples. In addition, when this tagging system was applied to an animal model (rabbit), pregnancy rate and kitten viability were not affected.
Design, fabrication and characterization of an externally actuated ON/OFF microvalve
Sensors and Actuators a-Physical, 2008
A magnetic microfluidic valve has been designed, fabricated and tested. Operation relies on the u... more A magnetic microfluidic valve has been designed, fabricated and tested. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co–Ni (soft magnetic material) on a V-shaped cantilever beam. The deflection caused by the magnetic forces opens or closes the fluid flow. The microvalve performance has been optimized by means of finite element analysis (FEA). The FEA model has been experimentally validated using confocal microscopy and used to improve the magnetic circuit. Then, a fluidic cell ...
Design and characterization of a magnetic digital flow regulator
Sensors and Actuators a-Physical, 2010
Design, fabrication and testing of a novel micromachined “quasi-digital” microflow regulator for ... more Design, fabrication and testing of a novel micromachined “quasi-digital” microflow regulator for integrated microfluidic systems. Operation relies on the use of a permanent magnet which interacts with an electrodeposited layer of Co–Ni on an array of V-shaped cantilever beams under a constant pressure. Each valve actuates as an on–off fluidic switch, opening or closing its corresponding microchannel. The flow can be adjusted to a set of different values (digital) by changing the position of the magnet. The microflow regulator has been ...
Nanomagnet fabrication on FBAR for magnetic sensor applications
2009 IEEE International Ultrasonics Symposium, 2009
Abstract We report a focused-ion-beam-assisted technique intended for ultra-small, hard magnet f... more Abstract We report a focused-ion-beam-assisted technique intended for ultra-small, hard magnet fabrication and placement on thin-film bulk acoustic resonators (FBAR). Reduced-size NdFeB magnets were extracted from a macroscopic quarry and bonded to the surface of FBARs ...
Small, 2010
Figure 3. CFDA-derivatized ICCs interact with the cell cytoplasm. D. discoideum (A, C) and HeLa c... more Figure 3. CFDA-derivatized ICCs interact with the cell cytoplasm. D. discoideum (A, C) and HeLa cells (B, D) show intracellular ICCs with green fluorescence (yellow arrow). Extracellular ICCs do not display fluorescence and appear as white dots (black arrow) (A, B). Zoom of D. discoideum (C) and HeLa cells (D) showing functionalized ICCs. Images are maximal confocal projections taken with CLSM. Bar ¼ 10 mm.
In situ MEMS gradiometer with nanometer-resolution optical detection system
Sensors and Actuators A: Physical, 2010
Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurement... more Mechanically resonant ferromagnetic MEMS sensors intended for magnetic field gradient measurements are presented. Suspended quad-beams with proof mass have been designed to improve their sensitivity and to simplify the detection. Fabricated devices exhibit the compact size of current MEMS technologies and are built within a simple deep-reactive-ion etching-based process. Nanometer-resolution detection based on optical interferometry and signal processing techniques have
Sensors and Actuators A: Physical, 2003
The paper is focused on the structuring of glass wafers to obtain high aspect ratio glass columns... more The paper is focused on the structuring of glass wafers to obtain high aspect ratio glass columns with high vertical profile for Micro Electro Mechanical Systems (MEMS). The technique proposed is to pattern columns by mechanical sawing. The sawing parameters have been optimised to achieve a high yield. Different dimensions of the column have been tested and glass columns down to 150 m × 150 m of cross-section and 700 m height have been obtained. They present high aspect ratio (>100) and very good vertical profile (88-90 • ). Hoya SD-2 and Corning Pyrex #7740 glass wafers have been processed with similar results. Different cleaning procedures have been tested to improve the anodic bondability of the samples after sawing. Machined glass columns have also been structured by commercial sand blasting technique and the results are also compared to the sawed samples. The glass wafers with machined columns have been anodically bonded to silicon. Anodic bonding characterisation of glass columns of different sections is also presented. Pull tests confirmed the good bondability of the glass columns.
Comparative performance of static-mode ferrous MEMS gradiometers fabricated by a three-step DRIE process
Journal of Micromechanics and Microengineering, 2010
Page 1. Comparative performance of static-mode ferrous MEMS gradiometers fabricated by a three-st... more Page 1. Comparative performance of static-mode ferrous MEMS gradiometers fabricated by a three-step DRIE process This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2010 J. Micromech. Microeng. 20 075006 ...
Biomaterials, 2017
Remote microactuators are of great interest in biology and medicine as minimally-invasive tools f... more Remote microactuators are of great interest in biology and medicine as minimally-invasive tools for cellular stimulation. Remote actuation can be achieved by active magnetostrictive transducers which are capable of changing shape in response to external magnetic fields thereby creating controlled displacements. Among the magnetostrictive materials, Galfenol, the multifaceted iron-based smart material, offers high magnetostriction with robust mechanical properties. In order to explore these capabilities for biomedical applications, it is necessary to study the feasibility of material miniaturization in standard fabrication processes as well as evaluate the biocompatibility. Here we develop a technology to fabricate, release, and suspend Galfenol-based microparticles, without affecting the integrity of the material. The morphology, composition and magnetic properties of the material itself are characterized. The direct cytotoxicity of Galfenol is evaluated in vitro using human macroph...
IEEE Transactions on Nanotechnology, 2015
This work presents a sensor composed of a differential arrangement of coils capable of measuring ... more This work presents a sensor composed of a differential arrangement of coils capable of measuring nanometric metallic film thickness. Experimental results achieved aluminium thickness measurements as low as 20 nm with a sensitivity of 3.8 mV/nm. This makes this sensor a flexible, nondestructive and cheap alternative for metallic thickness measurement down to nanometric scale.
2009 Spanish Conference on Electron Devices, 2009
This paper shows the technology development of microneedles electrodes for living cell applicatio... more This paper shows the technology development of microneedles electrodes for living cell applications. The study (6) (b)
SPIE Proceedings, 2007
Deflection of a microcantilever caused by any kind of biochemical reaction occurring on its surfa... more Deflection of a microcantilever caused by any kind of biochemical reaction occurring on its surface can be detected with subangstrom resolution if an appropriate detection technique is exploited. This kind of transducers has become widely used in biological research since a few years ago. Usually, for the readout of the nanomechanical response of the micro beams to bio-specific interactions, a technique similar to one used in the atomic force microscopy is employed. The optical read-out method has some disadvantages, such as low degree of integration and difficulties in work with arrays of cantilevers. In the technique presented in this work the cantilever itself is an optical waveguide butt-coupled with another one. The device is fabricated as an array of 20 waveguide cantilever channels which allows for higher integration level. The analysis of the capabilities of the device, the problems associated with the design and the fabrication of the device, the choice of the material and the technology for the fabrication of very flat cantilevers have been successfully addressed. The characterisation of the device was done, showing that the resolution of the device is comparable with the one using the optical lever read-out. Results of the simulations and experimental data on the optical cantilevers coated with an absorbent material will be presented. The choice of the appropriate thickness of the absorbent material on the cantilever surface allows for acceptable losses, for single mode behaviour and adjustment of the initial displacement of the cantilever.
Sensors and Actuators A: Physical, 2010
A system of two solid microlenses with uncoupled optical properties is presented. This structure ... more A system of two solid microlenses with uncoupled optical properties is presented. This structure has been designed in order to have one lens as a reference, while the other one can be mechanically tuneable. The reference lens presents a diameter of 2 m and it is placed in the optical axis of the mechanically tuneable lens, which has a diameter of 10 m. The proposed microoptical structure has been fabricated in poly(dimethilsiloxane) (PDMS) merging deep reactive ion etching, SU-8 and soft lithography, with a low-cost (mass-production), simple and highly repetitive technology. This device was numerically simulated prior to its fabrication, to optimize its design and improve its behaviour. In addition, an optical characterization of the fabricated devices was carried out. Both simulation and experimental results shows a good agreement, under mechanical actuation behaviour of the reference lens is invariable, while the tuneable lens become an elliptic lens and the interval of Sturm can be observed. These results provide a proof of concept of the proposed devices and validate both the design and the fabrication technology.
Journal of Micromechanics and Microengineering, 2004
In the last decade research in chips for DNA amplification through the polymerase chain reaction ... more In the last decade research in chips for DNA amplification through the polymerase chain reaction (PCR) has been relatively abundant, but has taken very diverse approaches, leaving little common ground for a straightforward comparison of results. Here we report the development of a line of PCR chips that is fully compatible with complementary-metal-oxidesemiconductor (CMOS) technology and its revealing use as a general platform to test and compare a wide range of experimental parameters involved in PCR-chip design and operation. Peltier-heated and polysilicon thin-film driven PCR chips have been produced and directly compared in terms of efficiency, speed and power consumption, showing that thin-film systems run faster and more efficiently than Peltier-based ones, but yield inferior PCR products. Serpentine-like chamber designs have also been compared with standard rectangular designs and with the here reported rhomboidal chamber shape, showing that serpentine-like chambers do not have detrimental effects in PCR efficiency when using non-flow-through schemes, and that chamber design has a strong impact on sample insertion/extraction yields. With an accurate temperature control (±0.2 • C) we have optimized reaction kinetics to yield sound PCR amplifications of 25 µl mixtures in 20 min and 24.4 s cycle times, confirming that a titrated amount of bovine albumin serum (BSA, 2.5 µg µl −1) is essential to counteract polymerase adsorption at chip walls. The reported use of a CMOS-compatible technological process paves the way for an easy adaption to foundry requirements and for a scalable integration of electro-optic detection and control circuitry.
Journal of Lightwave Technology, 2006
This study presents a novel generic multipurpose probe based on an array of 20 waveguide channels... more This study presents a novel generic multipurpose probe based on an array of 20 waveguide channels with microcantilevers acting as optical waveguides operated in the visible range. The principle of operation is based on the sensitivity of energy transfer between two butt-coupled waveguides to their misalignment with respect to each other. The technique can be considered an alternative to the known methods used for the readout of the nanomechanical response of microcantilevers to the external force exerted on them. The cantilever displacement can be detected with a resolution of 18 fm/ √ Hz. The limit is generally defined by the shot noise of a conventional photodetector used for the readout of the output signal. Real-time parallel monitoring of several channels can be realized. In contrast to devices based on the atomic force microscope detection principle, no preliminary alignment or adjustment, except for light coupling, is required. The detection of the cantilever deflection at subnanometer range was demonstrated experimentally.
Human Reproduction, 2013
study question: Is the attachment of biofunctionalized polysilicon barcodes to the outer surface ... more study question: Is the attachment of biofunctionalized polysilicon barcodes to the outer surface of the zona pellucida an effective approach for the direct tagging and identification of human oocytes and embryos during assisted reproduction technologies (ARTs)? summary answer: The direct tagging system based on lectin-biofunctionalized polysilicon barcodes of micrometric dimensions is simple, safe and highly efficient, allowing the identification of human oocytes and embryos during the various procedures typically conducted during an assisted reproduction cycle. what is known already: Measures to prevent mismatching errors (mix-ups) of the reproductive samples are currently in place in fertility clinics, but none of them are totally effective and several mix-up cases have been reported worldwide. Using a mouse model, our group has previously developed an effective direct embryo tagging system which does not interfere with the in vitro and in vivo development of the tagged embryos. This system has now been tested in human oocytes and embryos. study design, size, duration: Fresh immature and mature fertilization-failed oocytes (n ¼ 21) and cryopreserved day 1 embryos produced by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) (n ¼ 205) were donated by patients (n ¼ 76) undergoing ARTs. In vitro development rates, embryo quality and post-vitrification survival were compared between tagged (n ¼ 106) and non-tagged (control) embryos (n ¼ 99). Barcode retention and identification rates were also calculated, both for embryos and for oocytes subjected to a simulated ICSI and parthenogenetic activation. Experiments were conducted from January 2012 to January 2013. participants/materials, setting, methods: Barcodes were fabricated in polysilicon and biofunctionalizated with wheat germ agglutinin lectin. Embryos were tagged with 10 barcodes and cultured in vitro until the blastocyst stage, when they were either differentially stained with propidium iodide and Hoechst or vitrified using the Cryotop method. Embryo quality was also analyzed by embryo grading and timelapse monitoring. Injected oocytes were parthenogenetically activated using ionomycin and 6-dimethylaminopurine. main results and the role of chance: Blastocyst development rates of tagged (27/58) and non-tagged embryos (24/51) were equivalent, and no significant differences in the timing of key morphokinetic parameters and the number of inner cell mass cells were detected between the two groups (tagged: 24.7 + 2.5; non-tagged: 22.3 + 1.9), indicating that preimplantation embryo potential and quality are not affected by the barcodes. Similarly, re-expansion rates of vitrified-warmed tagged (19/21) and non-tagged (16/19) blastocysts were similar. Global identification rates of 96.9 and 89.5% were obtained in fresh (mean barcode retention: 9.22 + 0.13) and vitrified-warmed (mean barcode retention: 7.79 + 0.35) tagged embryos, respectively, when simulating an automatic barcode reading process, though these rates were increased to 100% just by rotating the embryos during barcode reading. Only one of the oocytes lost one barcode during intracytoplasmic injection (100% identification rate) and all oocytes retained all the barcodes after parthenogenetic activation.
Internalization and cytotoxicity analysis of silicon-based microparticles in macrophages and embryos
Biomedical Microdevices, 2010
Microchips can be fabricated, using semiconductor technologies, at microscopic level to be introd... more Microchips can be fabricated, using semiconductor technologies, at microscopic level to be introduced into living cells for monitoring of intracellular parameters at a single cell level. As a first step towards intracellular chips development, silicon and polysilicon microparticles of controlled shape and dimensions were fabricated and introduced into human macrophages and mouse embryos by phagocytosis and microinjection, respectively. Microparticles showed to be non-cytotoxic for macrophages and were found to be localized mainly inside early endosomes, in tight association with endosomal membrane, and more rarely in acidic compartments. Embryos with microinjected microparticles developed normally to the blastocyst stage, confirming the non-cytotoxic effect of the particles. In view of these results silicon and polysilicon microparticles can serve as the frame for future intracellular chips development and this technology opens the possibility of real complex devices to be used as sensors or actuators inside living cells.
Bioconjugate Chemistry, 2012
Cell tracking is an emergent area in nanobiotechnology, promising the study of individual cells o... more Cell tracking is an emergent area in nanobiotechnology, promising the study of individual cells or the identification of populations of cultured cells. In our approach, microtools designed for extracellular tagging are prepared, because using biofunctionalized polysilicon barcodes to tag cell membranes externally avoids the inconveniences of cell internalization. The crucial covalent biofunctionalization process determining the ultimate functionality was studied in order to find the optimum conditions to link a biomolecule to a polysilicon barcode surface using a self-assembled monolayer (SAM) as the connector. Specifically, a lectin (wheat germ agglutinin, WGA) was used because of its capacity to recognize some specific carbohydrates present on the surface of most mammalian cells. Self-assembled monolayers were prepared on polysilicon surfaces including aldehyde groups as terminal functions to study the suitability of their covalent chemical bonding to WGA. Some parameters, such as the polysilicon surface roughness or the concentration of WGA, proved to be crucial for successful biofunctionalization and bioactivity. The SAMs were characterized by contact angle measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS), and atomic force microscopy (AFM). The biofunctionalization step was also characterized by fluorescence microscopy and, in the case of barcodes, by adhesion experiments to the zona pellucida of mouse embryos. These experiments showed high barcode retention rates after 96 h of culture as well as high embryo viability to the blastocyst stage, indicating the robustness of the biofunctionalization and, therefore, the potential of these new microtools to be used for cell tagging.