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Polyimide-based capacitive humidity sensor

 
: Boudaden, Jamila; Steinmaßl, Matthias; Endres, Hanns-Erik; Drost, Andreas; Eisele, Ignaz; Kutter, Christoph; Müller-Buschbaum, Peter

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Volltext urn:nbn:de:0011-n-4972981 (4.5 MByte PDF)
MD5 Fingerprint: 333fa2f88b037396e9ec9551d6c94b59
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Erstellt am: 26.6.2018


Sensors. Online journal 18 (2018), Nr.5, Art. 1516, 15 S.
http://www.mdpi.com/journal/sensors
ISSN: 1424-8220
ISSN: 1424-8239
ISSN: 1424-3210
Englisch
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer EMFT ()
capacitive sensor; humidity sensor; fourier transform; infrared spectroscopy; humidity sensor; polyimide; surface morphology

Abstract
The development of humidity sensors with simple transduction principles attracts considerable interest by both scientific researchers and industrial companies. Capacitive humidity sensors, based on polyimide sensing material with different thickness and surface morphologies, are prepared. The surface morphology of the sensing layer is varied from flat to rough and then to nanostructure called nanograss by using an oxygen plasma etch process. The relative humidity (RH) sensor selectively responds to the presence of water vapor by a capacitance change. The interaction between polyimide and water molecules is studied by FTIR spectroscopy. The complete characterization of the prepared capacitive humidity sensor performance is realized using a gas mixing setup and an evaluation kit. A linear correlation is found between the measured capacitance and the RH level in the range of 5 to 85%. The morphology of the humidity sensing layer is revealed as an important parameter influencing the sensor performance. It is proved that a nanograss-like structure is the most effective for detecting RH, due to its rapid response and recovery times, which are comparable to or even better than the ones of commercial polymer-based sensors. This work demonstrates the readiness of the developed RH sensor technology for industrialization.

: http://publica.fraunhofer.de/dokumente/N-497298.html