The Combined Spectral Response of a MEMS Metamaterial Absorber for the Mid-IR and Its Sub-Wavelength Fabrication Residual Array of Holes

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...

Design of large-area metasurfaces for the mid-IR and suited for CMOS-compatible fabrication by masked lithography

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...

Infrared absorbance of vertically-aligned multi-walled CNT forest as a function of synthesis temperature and time

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...

Exploring the response of a resistive soot sensor to AC electric excitation

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...

Maintaining transparency of a heated MEMs membrane for enabling long-term optical measurements on soot-containing exhaust gas

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...

CMOS-compatible mid-IR metamaterial absorbers for out-of-band suppression in optical MEMS

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...

Multi-domain spectroscopy for composition measurement of water-containing bio-ethanol fuel

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...

Optical Spectroscopy for Biofuel Composition Sensing

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...

Design and fabrication of 45° inclined mirrors for wafer-level optical absorption spectroscopy

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...

CMOS-compatible fabrication of metamaterial-based absorbers for the mid-IR spectral range

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...

Implementation of CMOS-compatible Metamaterial Absorber for gas Sensing Application

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...

Surface-micromachined Bragg Reflectors Based on Multiple Airgap/SiO2 Layers for CMOS-compatible Fabry-perot Filters in the UV-visible Spectral Range

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...

Optical Filter for Providing the Required Illumination to Enable Narrow Band Imaging

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)...

A Lossy Fabry-perot Based Optical Filter for Natural Gas Analysis

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...

Fabrication, characterization, and simulation of a cantilever-based airflow sensor integrated with optical fiber

In this paper, we present the fabrication and packaging of a cantilever-based airflow sensor integrated with optical fiber. The sensor consists of a micro Fabry–Perot (FP) cavity including a fiber and a micro cantilever that is fabricated using the photolithography method. Airflow causes a small deflection of the micro cantilever and changes the...