A novel MEMS tunable ionization sensor based on patterned freestanding Nickel nanowires and moving electrode

Walewyns, Thomas; Francis, Laurent

doi:10.1109/transducers.2011.5969195

“…The structure consists of parallel plates spaced by a few micrometers and metal nanowires added to one of the electrodes. Moreover, a split-bottom electrode is used to differentiate between the ionization field monitoring and the electrostatically-actuated gap spacing [46,47]. Such a device is aimed at gas sensing, whereas the tunable electrode spacing replaces the sensor array including several gaps required for gas mixture analysis [48].…”

Section: Miniaturized Ionization Sensor Incorporating Nanowiresmentioning

confidence: 99%

“…These devices consist of a nanomechanical lab-on-chip test platform [37][38][39][40][41][42][43] and a miniaturized ionization sensor incorporating nanowires [44][45][46][47], for which a generic sacrificial layer and a way to introduce nanostructures in MEMS structures are respectively needed.…”

Section: Introductionmentioning

confidence: 99%

Poling Field Dependence of Longitudinal and Transverse Wave Velocities, Young's Modulus, and Poisson's Ratio in Piezoelectric Ceramics

Ogawa¹,

Ishii²,

Matsumoto³

et al. 2012

Jpn. J. Appl. Phys.

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The interest of using polyimide as a sacrificial and anchoring layer is demonstrated for post-processing surface micromachining and for the incorporation of metallic nanowires into microsystems. In addition to properties like a high planarization factor, a good resistance to most non-oxidizing acids and bases, and CMOS compatibility, polyimide can also be used as a mold for nanostructures after ion track-etching. Moreover, specific polyimide grades, such as PI-2611 from HD Microsystems TM , involve a thermal expansion coefficient similar to silicon and low internal stress. The process developed in this study permits higher gaps compared to the state-of-the-art, limits stiction problems with the substrate and is adapted to various top-layer materials. Most metals, semiconductors or ceramics will not be affected by the oxygen plasma required for polyimide etching. Released structures with vertical gaps from one to several tens of μm have been obtained, possibly using multiple layers of polyimide. Furthermore, patterned freestanding nanowires have been synthesized with diameters from 20 to 60 nm and up to 3 μm in length. These results have been applied to the fabrication of two specific devices: a generic nanomechanical testing lab-on-chip platform and a miniaturized ionization sensor.(Some figures may appear in colour only in the online journal) Polyimide (PI) is often selected for its high planarization factor, CMOS compatibility, tolerance to most chemical products used in microfabrication, and chemical resistance up to high temperatures. Moreover, depending on its formulation, PI can be spin-coated with thicknesses as high as several tens of μm and as low as 200 nm by diluting the precursor solution in its solvant [8]. A large range of possible gaps is thus allowed between a top movable clamped-clamped membrane or beam and a fixed bottom electrode lying on the substrate. New formulations of PI show additional interesting properties such as a thermal expansion coefficient similar to silicon (Si),

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“…Detection of molecules can be achieved by extracting changes from interfacial capacitance, and there were traditional microelectromechanical system sensors which performed this process [12, 13]. DC voltages are always loaded to these high‐cost sensors while the particle enrichment is not significant enough.…”

Section: Mechanisms and Methodsmentioning

confidence: 99%

Rapid and sensitive detection of formaldehyde based on AC electrokinetic effects

Zhang

¹

,

Liu

²

,

Wang

³

et al. 2018

Micro & Nano Letters

4

0

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Formaldehyde is a toxic water-soluble organic matter. Its detection methods and detection limit have been attracting more attentions. An AC electrokinetic (ACEK)-enhanced capacitive sensing method for rapid detection of trace formaldehyde in liquid is presented using commercial microelectrode chips. By this method, a detection limit is achieved as low as 0.01 ppm (μg/ml) within a 60 s response time. It is proved that the trace amount of formaldehyde in common solvents can also be effectively detected. As a complement, the capacitance change rate dependence on testing voltage and frequency is investigated. Compared to other existing detection methods, this ACEK-based capacitive method is a low cost, high sensitive and fast detection means, which shows a great application prospect in industry and research such as food safety and specimen cleaning.

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“…Following a first section on the materials and methods associated with the fabrication procedures, the high potential of the proposed manufacturing process in the fabrication of innovative MEMS devices will be highlighted through two dedicated devices which have been redesigned owing to the new progress made in PI-based microprocessing. These devices consist of a nanomechanical lab-on-chip test platform [37][38][39][40][41][42][43] and a miniaturized ionization sensor incorporating nanowires [44][45][46][47], for which a generic sacrificial layer and a way to introduce nanostructures in MEMS structures are respectively needed.…”

Section: Introductionmentioning

confidence: 99%

Polyimide as a versatile enabling material for microsystems fabrication: surface micromachining and electrodeposited nanowires integration

Walewyns

¹

,

Reckinger

²

,

Ryelandt

³

et al. 2013

J. Micromech. Microeng.

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The interest of using polyimide as a sacrificial and anchoring layer is demonstrated for post-processing surface micromachining and for the incorporation of metallic nanowires into microsystems. In addition to properties like a high planarization factor, a good resistance to most non-oxidizing acids and bases, and CMOS compatibility, polyimide can also be used as a mold for nanostructures after ion track-etching. Moreover, specific polyimide grades, such as PI-2611 from HD Microsystems™, involve a thermal expansion coefficient similar to silicon and low internal stress. The process developed in this study permits higher gaps compared to the state-of-the-art, limits stiction problems with the substrate and is adapted to various top-layer materials. Most metals, semiconductors or ceramics will not be affected by the oxygen plasma required for polyimide etching. Released structures with vertical gaps from one to several tens of μm have been obtained, possibly using multiple layers of polyimide. Furthermore, patterned freestanding nanowires have been synthesized with diameters from 20 to 60 nm and up to 3 μm in length. These results have been applied to the fabrication of two specific devices: a generic nanomechanical testing lab-on-chip platform and a miniaturized ionization sensor.

show abstract

A novel MEMS tunable ionization sensor based on patterned freestanding Nickel nanowires and moving electrode

Cited by 8 publications

References 7 publications

Poling Field Dependence of Longitudinal and Transverse Wave Velocities, Young's Modulus, and Poisson's Ratio in Piezoelectric Ceramics

Poling Field Dependence of Longitudinal and Transverse Wave Velocities, Young's Modulus, and Poisson's Ratio in Piezoelectric Ceramics

Rapid and sensitive detection of formaldehyde based on AC electrokinetic effects

Polyimide as a versatile enabling material for microsystems fabrication: surface micromachining and electrodeposited nanowires integration

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