Studies on hysteresis reduction in thermally carbonized porous silicon humidity sensor

Björkqvist, M.; Paski, J.; Salonen, Jarno; Lehto, V.‐P.

doi:10.1109/jsen.2006.874029

Cited by 68 publications

(34 citation statements)

References 9 publications

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“…As a result, the porous structure contains periodical bottle necks, which significantly slow down gas desorption thereby increasing recovery time of the sensor. Hysteresis reduction and improvement in recovery time could be accomplished by employing refreshing methods such as heating the sensor [21].…”

Section: Sensor Responsivitymentioning

confidence: 99%

Electro-optical porous silicon gas sensor with enhanced selectivity

Jalkanen

Tuura

Mäkilä

et al. 2010

Sensors and Actuators B: Chemical

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Section: Sensor Responsivitymentioning

confidence: 99%

Electro-optical porous silicon gas sensor with enhanced selectivity

Jalkanen

Tuura

Mäkilä

et al. 2010

Sensors and Actuators B: Chemical

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“…[ 22 ] Although less well-defi ned than the hydrosilylation route, the "hydrocarbonized" porous fi lm is environmentally stable [ 23 ] and its chemical sensing capabilities have been demonstrated. [24][25][26][27] In this work, we prepare porous Si rugate refl ectors with the different chemical modifi cations described above, and quantify the optical refl ectivity response of the photonic crystals to hydrophilic (isopropanol) and hydrophobic (heptane) analytes. The stability of each sensor type is quantifi ed for a period of 15 days.…”

Section: Introductionmentioning

confidence: 99%

Porous Silicon‐Based Optical Microsensors for Volatile Organic Analytes: Effect of Surface Chemistry on Stability and Specificity

Ruminski

King

Salonen

et al. 2010

Adv Funct Materials

100

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Sensing of the volatile organic compounds (VOCs) isopropyl alcohol (IPA) and heptane in air using sub-millimeter porous silicon-based sensor elements is demonstrated in the concentration range 50-800 ppm. The sensor elements are prepared as one-dimensional photonic crystals (rugate fi lters) by programmed electrochemical etch of p + + silicon, and analyte sensing is achieved by measurement of the wavelength shift of the photonic resonance. The sensors are studied as a function of surface chemistry: ozone oxidation, thermal oxidation, hydrosilylation (1-dodecene), electrochemical methylation, reaction with dicholorodimethylsilane and thermal carbonization with acetylene. The thermally oxidized and the dichlorodimethylsilane-modifi ed materials show the greatest stability under atmospheric conditions. Optical microsensors are prepared by attachment of the porous Si layer to the distal end of optical fi bers. The acetylated porous Si microsensor displays a greater response to heptane than to IPA, whereas the other chemical modifi cations display a greater response to IPA than to heptane. The thermal oxide sensor displays a strong response to water vapor, while the acetylated material shows a relatively weak response. The results suggest that a combination of optical fi ber sensors with different surface chemistries can be used to classify VOC analytes. Application of the miniature sensors to the detection of VOC breakthrough in a full-scale activated carbon respirator cartridge simulator is demonstrated.

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“…The results of the thermal annealing were not significant with regards to stabilization, but coarsening of the PSi structure during the annealing in inert ambient conditions was an interesting observation. This enables the modification of the pore size distribution after the anodization, which was an exploitable finding regarding drug delivery applications [48][49][50]. While some results of the chemical derivations of the PSi surface with organic compounds and formation of Si C bonds were already reported previously [51][52][53][54][55], the reports by the group of Buriak finally confirmed the advantages of Si C bond in the stabilization [55][56][57].…”

Section: Chemical Surface Modificationsmentioning

confidence: 80%

“…Instead, the acetylene flow has to be stopped immediately before the temperature treatment. Due to the high treatment temperatures, the formed surface contains non-stoichiometric Si C species but it is completely hydrogen free and thus, hydrophilic [49]. The thermally carbonized surface has been found to be very stable in chemically harsh environments and even in HF and KOH solutions [95].…”

Section: Stabilization With Si C Bondsmentioning

confidence: 99%