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In this paper, the growth of optimized vertically aligned multi-walled carbon nanotube (VA-MWCNT) forests by LPCVD method for use in a large-area absorber in infrared detectors is presented. The effect of synthesis temperature (500−700 °C) and time (1−10 min) on the optical absorption coefficient in the infrared (2−20 μm) is investigated by FT-IR measurement at various incident angles (15-80°). The structural properties of VA-MWCNT are characterized by SEM, TEM and Raman spectroscopy. Spectral measurements show an increasing absorption with the height of the forest that results at increased synthesis time and temperature. However, the absorption coefficient decreases with increasing synthesize time and temperature, while it is also affected by other properties, such as diameter, density, alignment, and uniformity. Moreover, the reduction in absorption at oblique incident angles demonstrates the relevance of surface properties. Finally, a circular graphite waveguide system is used to model the absorption characteristics of an MWCNT forest., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Electronic Components, Technology and Materials, Electronic Instrumentation, QN/Zandbergen Lab

The resistive particulate matter sensor is a simple device that transduces the presence of soot through impedance change across inter-digital electrodes (IDEs). We investigate the information provided by impedance spectroscopy over the frequency range from 100 Hz to 10 kHz for two purposes. The first is to investigate the opportunities for an improved sensor response to particulate matter (PM), based on the additional information provided by the measurement of both the in-phase (resistive) and out-of-phase (capacitive) components of the change in impedance over this frequency range as compared to DC resistance measurement only. Secondly, the origin of the capacitive response of the device is investigated from the perspective that soot on the device is in the form of bendable dendrites that grow in three dimensions. An IDE structure with the housing acting as an additional suspended electrode for introducing a controllable vertical electric field component has been used for this purpose. The formation of dipoles, due to bending of the charged dendrites, is found to be the source of the capacitive response. Simulation of electrostatic soot deposition reinforces dendritic self-assembly mechanisms, driven by charged particle trajectories along electric field lines. Optical microscopy confirms that dendrites growing out of the substrate plane are sensitive to electric and flow forces, bending when force balances are appropriate. We also apply impedance spectroscopy under varying electric field strengths, showing that capacitive response is only observed when conditions are conducive to dendrite bending in response to the applied AC electric fields., Electronic Components, Technology and Materials, Electronic Instrumentation

The design and fabrication of wideband mid-infrared metamaterial absorbers are presented. The emphasis is put on the shape-tolerant design for using masked UV (i-line) lithography and CMOS-compatible fabrication to enable on-chip co-integration with detector and readout circuits in a MEMS foundry while maintaining wafer throughput. The CMOScompatibility implies the use of aluminum rather than the commonly used high conductivity metals. The use of masked lithography rather than e-beam lithography in the fabrication of metamaterial absorbers for the mid-infrared range between 3 and 4 μm introduces the challenge of the shape-tolerant design of the unit cell. Moreover, the sensitivity of the fabricated metamaterials to the surface roughness and exposure dose were investigated in this paper. The throughput advantage of masked lithography has been exploited in the fabrication of mid-infrared absorbers over an area of several mm2. The measurements confirm the theoretical spectral response and a 98% peak absorption at an angle close to perpendicular incidence. Measurements at different angles show that the absorption spectrum only deviates marginally from normal incidence for angles up to 30°. The combined CMOS-compatibility and masked lithography enable batch fabrication and the on-chip integration of the metamaterial absorbers with MEMS devices and sensors., Electronic Instrumentation

Thermal impedance spectroscopy has been investigated as a non-destructive technique to determine the composition of ternary mixtures of biofuels. The principle of the thermal conductivity detector has been extended for measuring both the thermal conductivity and the thermal capacity of biofuel in the range between 1 to 100 Hz, using an AC-operated polysilicon heater for injecting a sinusoidal heat flux, and another polysilicon strip at a well-defined spacing or thermopile sensors for measuring the in-phase and quadrature components of the resulting AC temperature difference., Electronic Instrumentation

Measuring the ethanol/water ratio in biofuel of high ethanol content, such as E85, is important when used in a flex-fuel engine. A capacitive probe is generally used for measuring the ethanol/gasoline ratio. However, the water content in E85 biofuel cannot be disregarded or considered constant and full composition measurement of biofuel is required. Electric impedance spectroscopy with a customized coaxial probe operating in the 10 kHz to 1 MHz frequency range was investigated. An in-depth investigation of the electrical impedance domain has led to the conclusion that additional information is required to unambiguously determine the composition of the ternary biofuel mixture. Among the different options of measurement domains and techniques, optical absorption spectroscopy in the UV spectral range between 230 and 300 nm was found to be the most appropriate. The typical absorbance in the UV range is highly dominated by gasoline, while ethanol and water are almost transparent. This approach is experimentally validated using actual fuels., Electronic Components, Technology and Materials, Electronic Instrumentation

Metamaterial absorbers are photonic structures composed of an array of sub-wavelength metallic patterns. Results in literature are usually based on structures of nominal dimensions, despite the significant effect of fabrication tolerances on performance. This research aims to identify the main sources of uncertainty and to investigate their effect, notably that of an irregular surface quality (i.e., roughness) of the thin metallic layer and the lithography related variations in size and shape. The effect of the shape and positioning of the resonance peak was investigated and validated using mid-infrared metamaterial absorbers. This sensitivity analysis is essential to the batch fabrication of metamaterial absorbers for MEMS applications., Electronic Instrumentation, Mathematical Geodesy and Positioning

A capacitive probe is generally used in a flex-fuel engine for measuring the ethanol content in biofuel. However, the water content in biofuel of high ethanol content cannot be disregarded or considered constant and the full composition measurement of ethanol, gasoline and water in biofuel is required. Electrical impedance spectroscopy with a customized capacitive probe operating in the 10 kHz to 1 MHz frequency range is combined with optical absorption spectroscopy in the UV spectral range between 230 and 300 nm for a full composition measurement. This approach is experimentally validated using actual fuels and the results demonstrate that electrical impedance spectroscopy when supplemented with optical impedance spectroscopy can be used to fully determine the composition of the biofuel and applied for a more effective engine management. A concept for a low-cost combined measurement system in the fuel line is presented., Accepted author manuscript, Electronic Components, Technology and Materials, Electronic Instrumentation

The increasing demand for small, robust and low-cost gas sensors triggers the batch fabrication of highly selective and sensitive miniaturized devices. A linear variable optical filter (LVOF) based microspectrometer enables selectivity in a wide wavelength range, while maintaining the robustness and low cost. To achieve sensitivity in an LVOF based absorption spectrometer, a long gas cell is required. In this paper, we propose an on-chip absorption path that also serves as a gas cell, where the light beam is steered using 45° inclined mirrors. The fabrication of 45° inclined mirrors is demonstrated and optical efficiency of the system is analyzed using ray tracing., Electronic Instrumentation

The design of a metamaterial-based absorber for use in a mid-IR microspectrometer-based gas sensor is reported.The microspectrometer consists of a linear variable optical filter (LVOF) that is aligned with an array of thermopiledetectors, which is fabricated on a SiN membrane and covered with the absorber. Special emphasis was put on theCMOS compatible fabrication, which resulted in an absorber design based on aluminium disk resonators and analuminium background plane that are separated by a SiO2 layer. The fabrication process is described, and thechallenges are discussed., Electronic Instrumentation

Electronic Instrumentation

The optical absorption of water-containing bio-fuel is investigated as a parameter to determine the gasoline content of this fuel. Optical measurements reveal that gasoline shows an interesting and useful spectrum with typical absorption behavior in the UV range between 230 and 300 nm. This result indicates that significant information can be obtained to determine the gasoline concentration in bio-fuel by UV absorption spectroscopy. A concept for a low-cost measurement system in the fuel line is presented, by implementing a LVOF in combination with a wide-band light source and detector arrays., Electronic Instrumentation

A CMOS-compatible approach is presented for the fabrication of a wideband mid-IR metamaterial-based absorber on top of a Si3N4 membrane, which contains poly-Si thermopiles. The application is in IR microspectrometers that are intended for implementation in portable microsystem for use in absorption spectroscopy. Although Au is the conventional material of choice, we demonstrate by simulation that near-perfect absorption can be achieved over a wider band when using the more CMOS-compatible Al. The absorber design is based on Al disk resonators and an Al backplane, which are separated by a SiO2 layer. The fabrication process involves the deposition of Al and SiO2 layers on top of a Si3N4 membrane, lithography and a lift-off process for patterning of the top Al layer., Electronic Instrumentation

The design and CMOS-compatible fabrication of airgap-based optical filters in a surface micromachining process with sacrificial release using thevapour phase is presented. An airgap-dielectric layer combination offers a higher refractive index contrast, as compared to the conventional all-dielectriclayer based filters, which results in a higher peak reflectance and a wider bandwidth in a distributed Bragg reflector (DBR). Several DBRs and Fabry-Perot filters with multiple (low-n) airgap layers separating a stack of (high-n) layers of a dielectric material were designed for operation in the UV-visible spectrum. The fabrication was based on an Al2O3 and SiO2 system. The lateral design includes a set of anchor points and access holes. Finally, a vapour phase HF etching was used to remove the SiO2 layers and release the Al2O3 membranes. This method prevents the stiction of the membranes and provides a higher control and uniformity over the filter area., Microelectronics, Electrical Engineering, Mathematics and Computer Science

The design, fabrication and characterization of a highly integrated optical gas sensor is presented. The gas cell takes up most of the space in a microspectrometer and is the only component that has so far not been miniaturized. Using the tapered resonator cavity of a linear variable optical filter as a gas cell enables ultimate miniaturization, while maintaining robustness without any moving parts. Multiple reflections from highly reflective mirrors allow a 24-25.5 ?m long resonator cavity to also act as a gas cell with an equivalent optical absorption path length of 6 mm., Microelectronics, Electrical Engineering, Mathematics and Computer Science

Contains fulltext : 137293.pdf (publisher's version ) (Open Access), Del(5q) myelodysplastic syndromes defined by the International Prognostic Scoring System as low- or intermediate-1-risk (lower-risk) are considered to have an indolent course; however, recent data have identified a subgroup of these patients with more aggressive disease and poorer outcomes. Using deep sequencing technology, we previously demonstrated that 18% of patients with lower-risk del(5q) myelodysplastic syndromes carry TP53 mutated subclones rendering them at higher risk of progression. In this study, bone marrow biopsies from 85 patients treated with lenalidomide in the MDS-004 clinical trial were retrospectively assessed for p53 expression by immunohistochemistry in association with outcome. Strong p53 expression in >/= 1% of bone marrow progenitor cells, observed in 35% (30 of 85) of patients, was significantly associated with higher acute myeloid leukemia risk (P=0.0006), shorter overall survival (P=0.0175), and a lower cytogenetic response rate (P=0.009), but not with achievement or duration of 26-week transfusion independence response. In a multivariate analysis, p53-positive immunohistochemistry was the strongest independent predictor of transformation to acute myeloid leukemia (P=0.0035). Pyrosequencing analysis of laser-microdissected cells with strong p53 expression confirmed the TP53 mutation, whereas cells with moderate expression predominantly had wild-type p53. This study validates p53 immunohistochemistry as a strong and clinically useful predictive tool in patients with lower-risk del(5q) myelodysplastic syndromes. This study was based on data from the MDS 004 trial (clinicaltrials.gov identifier: NCT00179621).

In CMOS-compatible optical filter designs, SiO2 is often used as the low-index material, limiting the optical contrast (nHi/nLo) to about 2. Using the air as low-index material improves the optical contrast by about 50%, thus increasing the reflectivity and bandwidth at a given design complexity. The design and fabrication of a 4-layered air-dielectric distributed Bragg reflector (DBR) centered at 400 nm using surface micromachining techniques, is presented here. Fabrication is based on the deposition of poly-Si thin films and subsequent thermal oxidation. Selectively removing the Si layers, produces an air/SiO2 filter stack according to the optical design. The width of the air-gaps needed in this application is typically smaller as compared to conventional MEMS devices. The number of layers is also higher, while no electrical contact is required. The concept, the fabrication of 4-layer DBRs and preliminary measurement results are discussed in this paper., Microelectronics, Electrical Engineering, Mathematics and Computer Science

This paper presents the design, fabrication and characterization of two Fabry Perot type optical filters (415 nm and 540 nm) for enabling Narrow Band Imaging (NBI) in medical devices (MD). The two-colour illumination should satisfy a highly specific optical design, which is composed of a thin-film optical filter stack of titanium dioxide (TiO2) and silicon dioxide (SiO2) thin-films and commercially available light-emitting diodes (LEDs). The short-wavelength design is the most critical and simulations show a maximum relative optical output of 21% at 415 nm with Full-Width-Half-Maximum (FWHM) of 13 nm for a blue LED with the designed optical filter, which is confirmed by experiment. The green light simulations show a maximum relative optical output of 34% with FWHM 36 nm at 540 nm. The TiO2 and SiO2 thin films were fully characterized., Microelectronics, Electrical Engineering, Mathematics and Computer Science

A set-up for optical gas composition measurement based on absorption spectroscopy is composed of a white light source, a gas cell and a spectrometer. The Fabry-Perot optical filter is suitable for miniaturization of this system, as it is composed of only two reflectors with a transparent layer in-between. Varying the width of this optical resonator to cover the wavelength range in which the components to be analyzed have specific features, gives the absorption spectrum. The gas cell remains a separate unit in the conventional microsystem and a MEMS is the implementation of the microspectrometer. The ultimate miniaturization requires the monolithic integration of all these components. In the lossy Fabry-Perot filter that is presented in this paper, the gas cell and the microspectrometer are functionally integrated, using a gas-filled resonator in which the optical path is determined by multiple reflections in the resonator cavity itself., Microelectronics, Electrical Engineering, Mathematics and Computer Science