Characterisation of polymeric materials as passivation layer for calorimetric H₂O₂ gas sensors

Abstract

Calorimetric gas sensors for monitoring the H 2 O 2 concentration at elevated temperatures in industrial sterilisation processes have been presented in previous works. These sensors are built up in form of a differential set-up of a catalytically active and passive temperature-sensitive structure. Although, various types of catalytically active dispersions have been studied, the passivation layer has to be established and therefore, chemically as well as physically characterised. In the present work, fluorinated ethylene propylene (FEP), perfluoralkoxy (PFA) and epoxy-based SU-8 photoresist as temperature-stable polymeric materials have been investigated for sensor passiva-tion in terms of their chemical inertness against H 2 O 2 , their hygroscopic properties as well as their morphology. The polymeric materials were deposited via spin-coating on the temperature-sensitive structure, wherein spin-coated FEP and PFA show slight agglomerates. However, they possess a low absorption of humidity due to their hydrophobic surface, whereas the SU-8 layer has a closed surface but shows a slightly higher absorption of water. All of them were inert against gaseous H 2 O 2 during the characterisation in H 2 O 2 atmosphere that demonstrates their suitability as passivation layer for calorimetric H 2 O 2 gas sensors.

Strategies in developing thin-film sensors for monitoring aseptic food processes: Theoretical considerations and investigations of passivation materials

“…Thin-films of the polymeric layers were fabricated by spin-coating processes onto silicon wafers for the characterization. The sensor fabrication method is described in [24]. A resulting layer thickness of about 1.5 mm could be obtained for all materials.…”

FEM-based modeling of a calorimetric gas sensor for hydrogen peroxide monitoring

“…Also, the sensor based on this measurement principle can be calibrated and measured using thermoelectric elements. This concept was implemented in the work of Kirchner et al , where a thin‐film‐based calorimetric H 2 O 2 gas sensor has been previously developed and tested.…”

“…Figure represents the sensor concept based on the work of Kirchner et al . The base of the sensor is made of a 340μm silicon (Si) substrate covered with a 500 nm silicon oxide (SiO 2 ) layer.…”

“…One part of the sensor is catalytically activated by applying a MnO 2 layer on top of it. Adapted from Kirchner et al .…”

“…In the present study, the response of the calorimetric H 2 O 2 sensor based on the work by Kirchner et al is numerically analyzed. The previously established and published numerical models are different in term of the initial physical state of the H 2 O 2 and physical quantities governed by the non‐isothermal turbulent reacting flow physics.…”