Real-Time and Low-Cost Sensing Technique Based on Photonic Bandgap Structures

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.36.002707. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] A technique for the development of low-cost and high-sensitivity photonic biosensing devices is proposed and experimentally demonstrated. In this technique, a photonic bandgap structure is used as transducer, but its readout is performed by simply using a broadband source, an optical filter, and a power meter, without the need of obtaining the transmission spectrum of the structure; thus, a really low-cost system and real-time results are achieved. Experimental results show that it is possible to detect very low refractive index variations, achieving a detection limit below 2 x 10(-6) refractive index units using this low-cost measuring technique. (C) 2011 Optical Society of America[This work was funded by the Spanish Ministerio de Ciencia e Innovacion (MICINN) under contracts TEC2008-06333, JCI-009-5805, and TEC2008-05490. Support by the Universidad Politecnica de Valencia through program PAID-06-09 and the Conselleria d'Educacio through program GV-2010-031 is acknowledged.García Castelló, J.; Toccafondo, V.; Pérez Millán, P.; Sánchez Losilla, N.; Cruz, JL.; Andres, MV.; García-Rupérez, J. (2011). Real-Time and Low-Cost Sensing Technique Based on Photonic Bandgap Structures. Optics Letters. 36(14):2707-2709. https://doi.org/10.1364/OL.36.002707S270727093614Fan, X., White, I. M., Shopova, S. I., Zhu, H., Suter, J. D., & Sun, Y. (2008). Sensitive optical biosensors for unlabeled targets: A review. Analytica Chimica Acta, 620(1-2), 8-26. doi:10.1016/j.aca.2008.05.022Homola, J., Yee, S. S., & Gauglitz, G. (1999). Surface plasmon resonance sensors: review. Sensors and Actuators B: Chemical, 54(1-2), 3-15. doi:10.1016/s0925-4005(98)00321-9Kersey, A. D., Davis, M. A., Patrick, H. J., LeBlanc, M., Koo, K. P., Askins, C. G., … Friebele, E. J. (1997). Fiber grating sensors. Journal of Lightwave Technology, 15(8), 1442-1463. doi:10.1109/50.618377De Vos, K., Bartolozzi, I., Schacht, E., Bienstman, P., & Baets, R. (2007). Silicon-on-Insulator microring resonator for sensitive and label-free biosensing. Optics Express, 15(12), 7610. doi:10.1364/oe.15.007610Iqbal, M., Gleeson, M. A., Spaugh, B., Tybor, F., Gunn, W. G., Hochberg, M., … Gunn, L. C. (2010). Label-Free Biosensor Arrays Based on Silicon Ring Resonators and High-Speed Optical Scanning Instrumentation. IEEE Journal of Selected Topics in Quantum Electronics, 16(3), 654-661. doi:10.1109/jstqe.2009.2032510Xu, D.-X., Vachon, M., Densmore, A., Ma, R., Delâge, A., Janz, S., … Schmid, J. H. (2010). Label-free biosensor array based on silicon-on-insulator ring resonators addressed using a WDM approach. Optics Letters, 35(16), 2771. doi:10.1364/ol.35.002771Skivesen, N., Têtu, A., Kristensen, M., Kjems, J., Frandsen, L. H., & Borel, P. I. (2007). Photonic-crystal waveguide biosensor. Optics Express, 15(6), 3169. doi:10.1364/oe.15.003169Lee, M. R., & Fauchet, P. M. (2007). Nanoscale microcavity sensor for single particle detection. Optics Letters, 32(22), 3284. doi:10.1364/ol.32.003284García-Rupérez, J., Toccafondo, V., Bañuls, M. J., Castelló, J. G., Griol, A., Peransi-Llopis, S., & Maquieira, Á. (2010). Label-free antibody detection using band edge fringes in SOI planar photonic crystal waveguides in the slow-light regime. Optics Express, 18(23), 24276. doi:10.1364/oe.18.024276Toccafondo, V., García-Rupérez, J., Bañuls, M. J., Griol, A., Castelló, J. G., Peransi-Llopis, S., & Maquieira, A. (2010). Single-strand DNA detection using a planar photonic-crystal-waveguide-based sensor. Optics Letters, 35(21), 3673. doi:10.1364/ol.35.003673Luff, B. J., Wilson, R., Schiffrin, D. J., Harris, R. D., & Wilkinson, J. S. (1996). Integrated-optical directional coupler biosensor. Optics Letters, 21(8), 618. doi:10.1364/ol.21.000618Sepúlveda, B., Río, J. S. del, Moreno, M., Blanco, F. J., Mayora, K., Domínguez, C., & Lechuga, L. M. (2006). Optical biosensor microsystems based on the integration of highly sensitive Mach–Zehnder interferometer devices. Journal of Optics A: Pure and Applied Optics, 8(7), S561-S566. doi:10.1088/1464-4258/8/7/s41Densmore, A., Vachon, M., Xu, D.-X., Janz, S., Ma, R., Li, Y.-H., … Schmid, J. H. (2009). Silicon photonic wire biosensor array for multiplexed real-time and label-free molecular detection. Optics Letters, 34(23), 3598. doi:10.1364/ol.34.003598Povinelli, M. L., Johnson, S. G., & Joannopoulos, J. D. (2005). Slow-light, band-edge waveguides for tunable time delays. Optics Express, 13(18), 7145. doi:10.1364/opex.13.007145Garcia, J., Sanchis, P., Martinez, A., & Marti, J. (2008). 1D periodic structures for slow-wave induced non-linearity enhancement. Optics Express, 16(5), 3146. doi:10.1364/oe.16.003146Pérez-Millán, P., Torres-Peiró, S., Cruz, J. L., & Andrés, M. V. (2008). Fabrication of chirped fiber Bragg gratings by simple combination of stretching movements. Optical Fiber Technology, 14(1), 49-53. doi:10.1016/j.yofte.2007.07.00

Sub-50 nm positioning of organic compounds onto silicon oxide patterns fabricated by local oxidation nanolithography

We present a process to fabricate molecule-based nanostructures by merging a bottom-up interaction and a top-down nanolithography. Direct nanoscale positioning arises from the attractive electrostatic interactions between the molecules and silicon dioxide nanopatterns. Local oxidation nanolithography is used to fabricate silicon oxide domains with variable gap separations ranging from 40 nm to several microns in length. We demonstrate that an ionic tetrathiafulvalene (TTF) semiconductor can be directed from a macroscopic liquid solution (1 μM) and selectively deposited onto predefined nanoscale regions of a 1 cm2 silicon chip with an accuracy of 40 nm.This work was supported by the European Commission under contract numbers G5RD-CT-2000-00349 and NAIMO integrated project no. NMP4-CT-2004-500355. Financial support from the DGI, MEC (Spain) (contract nos. MAT2006- 03849 and CTQ2006-06333/BQU) and DGR, Catalonia (contract no. 2005SGR00591) is also acknowledged.Peer reviewe

Identification of plastic constitutive parameters at large deformations from three dimensional displacement fields

The aim of this paper is to provide a general procedure to extract the constitutive parameters of a plasticity model starting from displacement measurements and using the Virtual Fields Method. This is a classical inverse problem which has been already investigated in the literature, however several new features are developed here. First of all the procedure applies to a general three-dimensional displacement field which leads to large plastic deformations, no assumptions are made such as plane stress or plane strain although only pressure-independent plasticity is considered. Moreover the equilibrium equation is written in terms of the deviatoric stress tensor that can be directly computed from the strain field without iterations. Thanks to this, the identification routine is much faster compared to other inverse methods such as finite element updating. The proposed method can be a valid tool to study complex phenomena which involve severe plastic deformation and where the state of stress is completely triaxial, e.g. strain localization or necking occurrence. The procedure has been validated using a three dimensional displacement field obtained from a simulated experiment. The main potentialities as well as a first sensitivity study on the influence of measurement errors are illustrated

Placement and orientation of individual DNA shapes on lithographically patterned surfaces

Artificial DNA nanostructures show promise for the organization of functional materials to create nanoelectronic or nano-optical devices. DNA origami, in which a long single strand of DNA is folded into a shape using shorter 'staple strands', can display 6-nm-resolution patterns of binding sites, in principle allowing complex arrangements of carbon nanotubes, silicon nanowires, or quantum dots. However, DNA origami are synthesized in solution and uncontrolled deposition results in random arrangements; this makes it difficult to measure the properties of attached nanodevices or to integrate them with conventionally fabricated microcircuitry. Here we describe the use of electron-beam lithography and dry oxidative etching to create DNA origami-shaped binding sites on technologically useful materials, such as SiO_2 and diamond-like carbon. In buffer with ~ 100 mM MgCl_2, DNA origami bind with high selectivity and good orientation: 70–95% of sites have individual origami aligned with an angular dispersion (±1 s.d.) as low as ±10° (on diamond-like carbon) or ±20° (on SiO_2)

Variable carrier reduction in radio-over-fiber systems for increased modulation efficiencyusing a Si3N4 tunable extinction ratio ring resonator

This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.20.025478 e. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] Variable optical carrier reduction via the use of a Si3N4 ring resonator notch filter with tunable extinction ratio is demonstrated in a 10 GHz radio-over-fiber system for improving the modulation efficiency. The extinction of the filter notch is tuned with micro-heaters, by setting the Mach-Zehnder coupler of the ring. Experimental results showing a modulation depth improvement of up to 20 dB are providedThis work was supported by the NANOCAP project A-1084-RT-GC that is coordinated by the European Defence Agency (EDA) and funded by 11 contributing Members (Cyprus, France, Germany, Greece, Hungary, Italy, Norway, Poland, Slovakia, Slovenia and Spain) in the framework of the Joint Investment Programme on Innovative Concepts and Emerging Technologies (JIP-ICET).Perentos, A.; Cuesta, F.; Rodrigo, M.; Canciamilla, A.; Vidal Rodriguez, B.; Pierno, L.; Griol Barres, A.... (2012). Variable carrier reduction in radio-over-fiber systems for increased modulation efficiencyusing a Si3N4 tunable extinction ratio ring resonator. Optics Express. 20(23):25478-25488. doi:10.1364/OE.20.025478S25478254882023Lim, C., Nirmalathas, A., Bakaul, M., Gamage, P., Ka-Lun Lee, Yizhuo Yang, … Waterhouse, R. (2010). Fiber-Wireless Networks and Subsystem Technologies. Journal of Lightwave Technology, 28(4), 390-405. doi:10.1109/jlt.2009.2031423Capmany, J., & Novak, D. (2007). Microwave photonics combines two worlds. Nature Photonics, 1(6), 319-330. doi:10.1038/nphoton.2007.89Gomes, N. J., Morant, M., Alphones, A., Cabon, B., Mitchell, J. E., Lethien, C., … Iezekiel, S. (2009). Radio-over-fiber transport for the support of wireless broadband services [Invited]. Journal of Optical Networking, 8(2), 156. doi:10.1364/jon.8.000156Williams, K. J., & Esman, R. D. (1994). Stimulated Brillouin scattering for improvement of microwave fibre-optic link efficiency. Electronics Letters, 30(23), 1965-1966. doi:10.1049/el:19941344Tonda-Goldstein, S., Dolfi, D., Huignard, J.-P., Charlet, G., & Chazelas, J. (2000). Stimulated Brillouin scattering for microwave signal modulation depth increase in optical links. Electronics Letters, 36(11), 944. doi:10.1049/el:20000723Hraimel, B., Zhang, X., Pei, Y., Wu, K., Liu, T., Xu, T., & Nie, Q. (2011). Optical Single-Sideband Modulation With Tunable Optical Carrier to Sideband Ratio in Radio Over Fiber Systems. Journal of Lightwave Technology, 29(5), 775-781. doi:10.1109/jlt.2011.2108261LaGasse, M. J., Hamilton, M. C., Charczenko, W., & Thaniyavarn, S. (1994). Optical carrier filtering for high dynamic range fibre optic links. Electronics Letters, 30(25), 2157-2158. doi:10.1049/el:19941422Esman, R. D., & Williams, K. J. (1995). Wideband efficiency improvement of fiber optic systems by carrier subtraction. IEEE Photonics Technology Letters, 7(2), 218-220. doi:10.1109/68.345928Attygalle, M., Lim, C., Pendock, G. J., Nirmalathas, A., & Edvell, G. (2005). Transmission improvement in fiber wireless links using fiber Bragg gratings. IEEE Photonics Technology Letters, 17(1), 190-192. doi:10.1109/lpt.2004.836901Lim, C., Attygalle, M., Nirmalathas, A., Novak, D., & Waterhouse, R. (2006). Analysis of optical carrier-to-sideband ratio for improving transmission performance in fiber-radio links. IEEE Transactions on Microwave Theory and Techniques, 54(5), 2181-2187. doi:10.1109/tmtt.2006.872809Barwicz, T., Popovic, M. A., Watts, M. R., Rakich, P. T., Ippen, E. P., & Smith, H. I. (2006). Fabrication of add-drop filters based on frequency-matched microring resonators. Journal of Lightwave Technology, 24(5), 2207-2218. doi:10.1109/jlt.2006.872298Ferrari, C., Canciamilla, A., Morichetti, F., Sorel, M., & Melloni, A. (2011). Penalty-free transmission in a silicon coupled resonator optical waveguide over the full C-band. Optics Letters, 36(19), 3948. doi:10.1364/ol.36.003948Gasulla, I., Lloret, J., Sancho, J., Sales, S., & Capmany, J. (2011). Recent Breakthroughs in Microwave Photonics. IEEE Photonics Journal, 3(2), 311-315. doi:10.1109/jphot.2011.2130517Capmany, J., Gasulla, I., & Sales, S. (2011). Harnessing slow light. Nature Photonics, 5(12), 731-733. doi:10.1038/nphoton.2011.290Kopp, C., Bernabé, S., Bakir, B. B., Fedeli, J., Orobtchouk, R., Schrank, F., … Tekin, T. (2011). Silicon Photonic Circuits: On-CMOS Integration, Fiber Optical Coupling, and Packaging. IEEE Journal of Selected Topics in Quantum Electronics, 17(3), 498-509. doi:10.1109/jstqe.2010.2071855Xu, D. W., Yoon, S. F., Tong, C. Z., Zhao, L. J., Ding, Y., & Fan, W. J. (2009). High-Temperature Continuous-Wave Single-Mode Operation of 1.3-$\mu$m p-Doped InAs–GaAs Quantum-Dot VCSELs. IEEE Photonics Technology Letters, 21(17), 1211-1213. doi:10.1109/lpt.2009.2024220Green, W. M. J., Lee, R. K., DeRose, G. A., Scherer, A., & Yariv, A. (2005). Hybrid InGaAsP-InP Mach-Zehnder Racetrack Resonator for Thermooptic Switching and Coupling Control. Optics Express, 13(5), 1651. doi:10.1364/opex.13.001651Li, C., Zhou, L., & Poon, A. W. (2007). Silicon microring carrier-injection-based modulators/switches with tunable extinction ratios and OR-logic switching by using waveguide cross-coupling. Optics Express, 15(8), 5069. doi:10.1364/oe.15.005069Espinola, R. L., Tsai, M. C., Yardley, J. T., & Osgood, R. M. (2003). Fast and low-power thermooptic switch on thin silicon-on-insulator. IEEE Photonics Technology Letters, 15(10), 1366-1368. doi:10.1109/lpt.2003.818246Barwicz, T., Popovic, M. A., Rakich, P. T., Watts, M. R., Haus, H. A., Ippen, E. P., & Smith, H. I. (2004). Microring-resonator-based add-drop filters in SiN: fabrication and analysis. Optics Express, 12(7), 1437. doi:10.1364/opex.12.00143

Can environment or allergy explain international variation in prevalence of wheeze in childhood?

Asthma prevalence in children varies substantially around the world, but the contribution of known risk factors to this international variation is uncertain. The International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two studied 8–12 year old children in 30 centres worldwide with parent-completed symptom and risk factor questionnaires and aeroallergen skin prick testing. We used multilevel logistic regression modelling to investigate the effect of adjustment for individual and ecological risk factors on the between-centre variation in prevalence of recent wheeze. Adjustment for single individual-level risk factors changed the centre-level variation from a reduction of up to 8.4% (and 8.5% for atopy) to an increase of up to 6.8%. Modelling the 11 most influential environmental factors among all children simultaneously, the centre-level variation changed little overall (2.4% increase). Modelling only factors that decreased the variance, the 6 most influential factors (synthetic and feather quilt, mother’s smoking, heating stoves, dampness and foam pillows) in combination resulted in a 21% reduction in variance. Ecological (centre-level) risk factors generally explained higher proportions of the variation than did individual risk factors. Single environmental factors and aeroallergen sensitisation measured at the individual (child) level did not explain much of the between-centre variation in wheeze prevalence

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat