Searched for: author%3A%22Wolffenbuttel%2C+R.F.%22
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Wolffenbuttel, R.F. (author), Ghaderi, M. Amir (author)
Metasurface coatings on a free-standing SiN thin film membrane are fabricated on a Si substrate using masked lithography and CMOS-compatible surface micromachining. The result is a band-limited absorber for the mid-IR, which is part of a microstructure that is attached to the substrate by long and slender suspension beams to provide thermal...
journal article 2023
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Wolffenbuttel, R.F. (author), Ghaderi, M. (author)
The use of masked UV (i-line) lithography in a MEMS foundry for CMOS-compatible fabrication of large-area metasurface-based absorbers for the mid-infrared is demonstrated. The challenges are in: (a) the limited number of acceptable metals, (b) the thickness tolerance of the layers used in the CMOS process, and (c) the imaging capabilities of...
journal article 2022
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Mirza Gheytaghi, Amir (author), Ghaderi, M. (author), Vollebregt, S. (author), Ahmadi, M. (author), Wolffenbuttel, R.F. (author), Zhang, Kouchi (author)
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...
journal article 2020
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Middelburg, L.M. (author), Ghaderi, M. (author), Visser, J.H. (author), Wolffenbuttel, R.F. (author)
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...
journal article 2020
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Middelburg, L.M. (author), Ghaderi, Mohammadamir (author), Bilby, David (author), Visser, J.H. (author), Zhang, Kouchi (author), Wolffenbuttel, R.F. (author)
Impedance spectroscopy in the frequency range 100 Hz to 10 kHz has been applied to the Inter-Digitated Electrode (IDE) structure that is conventionally operated as a resistive sensor for the measurement of Particulate Matter (PM). The measurement of both the in-phase (resistive) and out-of-phase (capacitive) components of the impedance over this...
conference paper 2020
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Middelburg, L.M. (author), Ghaderi, Mohammadamir (author), Bilby, David (author), Visser, Jaco H. (author), Zhang, Kouchi (author), Lundgren, Per (author), Enoksson, Peter (author), Wolffenbuttel, R.F. (author)
Ensuring optical transparency over a wide spectral range of a window with a view into the tailpipe of the combustion engine, while it is exposed to the harsh environment of sootcontaining exhaust gas, is an essential pre-requisite for introducing optical techniques for long-term monitoring of automotive emissions. Therefore, a regenerable...
journal article 2020
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Bonenkamp, T.B. (author), Middelburg, L.M. (author), Hosli, M.O. (author), Wolffenbuttel, R.F. (author)
Decision-making on the optimum transition pathway to an energy economy that meets agreed carbon reduction goals in the European Union (EU) by 2050 is challenging, because of the size of the infrastructural legacy, technological uncertainties, affordability and assumptions on future energy demand. This task is even more complicated in...
journal article 2020
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Costa, Adriana C. (author), Pimenta, Sara (author), Ribeiro, João F. (author), Silva, Manuel F. (author), Wolffenbuttel, R.F. (author), Dong, Tao (author), Yang, Zhaochu (author), Correia, José H. (author)
Minimally invasive medical devices can greatly benefit from Narrow Band Imaging (NBI) diagnostic capabilities, as different wavelengths allow penetration of distinct layers of the gastrointestinal tract mucosa, improving diagnostic accuracy and targeting different pathologies. An important performance parameter is the light intensity at a...
journal article 2019
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Ghaderi, M. (author), Karimi Shahmarvandi, Ehsan (author), Wolffenbuttel, R.F. (author)
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...
journal article 2018
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Ghaderi, M. (author), Karimi Shahmarvandi, Ehsan (author), Ayerden, N.P. (author), Wolffenbuttel, R.F. (author)
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...
conference paper 2017
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Ayerden, N.P. (author), Mandon, Julien (author), Harren, Frans J.M. (author), Wolffenbuttel, R.F. (author)
Increasing demand for field instruments designed to measure gas composition has strongly promoted the development of robust, miniaturized and low-cost handheld absorption spectrometers in the mid-infrared. Efforts thus far have focused on miniaturizing individual components. However, the optical absorption path that the light beam travels...
journal article 2017
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Jiang, Bo (author), Ghaderi, M. (author), Bossche, A. (author), Visser, Jaco H. (author), Wolffenbuttel, R.F. (author)
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...
conference paper 2017
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Middelburg, L.M. (author), Ghaderi, M. (author), Bossche, A. (author), Bastemeijer, J. (author), de Graaf, G. (author), Wolffenbuttel, R.F. (author), Soltis, Rick (author), Visser, Jaco (author)
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...
conference paper 2017
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Middelburg, L.M. (author), de Graaf, G. (author), Bossche, A. (author), Bastemeijer, J. (author), Ghaderi, M. (author), Wolffenbuttel, F.S. (author), Visser, J. (author), Soltis, R. (author), Wolffenbuttel, R.F. (author)
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...
journal article 2017
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Wolffenbuttel, R.F. (author), Wolffenbuttel Hosli, T.M. (author)
Apps have been used for providing additional user functionality on demand to the smartphone. Several highly promising medical apps have been introduced that rely on the build-in camera. However, some of these apps fall short of the expectations, due to the inherent limitation of the camera to operation in the visible spectral range. The more...
journal article 2016
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Costa, C.G. (author), Gomes, J.M. (author), Wolffenbuttel, R.F. (author), Correia, J.H. (author)
Medical imaging is an important part of diagnosis. The procedure should provide valuable information for diagnosis and, at the same time, should be minimally invasive for the patient. Therefore, when performing endoscopic imaging, a system with reduced dimensions is crucial. The performance of imaging systems, used in several diagnosis...
journal article 2016
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Middelburg, L.M. (author), de Graaf, G. (author), Ghaderi, M. (author), Bossche, A. (author), Bastemeijer, J. (author), Visser, J.H. (author), Soltis, R.E. (author), Wolffenbuttel, R.F. (author)
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...
journal article 2016
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Ayerden, N.P. (author), Ghaderi, M. (author), Wolffenbuttel, R.F. (author)
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...
journal article 2016
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Ayerden, N.P. (author), de Graaf, G. (author), Wolffenbuttel, R.F. (author)
A miniaturized methane (CH4) sensor based on nondispersiveinfrared absorption is realized in MEMS technology. A high level offunctional integration is achieved by using the resonance cavity of a linearvariable optical filter (LVOF) also as a gas absorption cell. For effectivedetection of methane at λ = 3.39 µm, an absorption path length of at...
journal article 2016
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Karimi Shahmarvandi, Ehsan (author), Ghaderi, M. (author), Wolffenbuttel, R.F. (author)
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...
journal article 2016
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