P3.6 - Multifunctional T/RH-Sensitive Thick-Film Structures for Environmental Sensors
- SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
- Proceedings SENSOR 2011
- P3 - Temperature / Humidity
- H. Klym, I. Hadzaman, O. Shpotyuk - Lviv Scientific Research Institute of Materials of SRC “Carat” (Ukraine), M. Brunner - Fachhochschule Köln (Germany)
- 744 - 748
The problem of simultaneous temperature and relative humidity T/RH control consists in principally different sensitivities of monitored solid-state system to thermally- and moistureactivated environmentally-induced processes.
Functional spine-type ceramics are known to be widely used for T and RH measurement. The main aim of this work is to develop integrated multilayer T/RH-sensitive thick-film structures for multifunctional sensor application.
To prepare multifunctional T/RH-sensitive sensor elements, we used Cu0.1Ni0.1Mn1.2Co1.6O4 –based compound with p+-type of electrical conductivity, p-conductive Cu0.1Ni0.8Mn1.9Co0.2O4 compounds and insulating (i-type) MgAl2O4 compound.
Pastes for screen-printing were prepared by mixing powders of basic bulk ceramics with ecological glass powders (without PbO), inorganic binder Bi2O3 and organic vehicle.
The T-sensitive thick films and their mixed p+-p structures based on NiMn2O4-CuMn2O4-MnCo2O4 ceramic system possess good linear electrophysical characteristics in the region from 298 to 358 K. The values of temperature constant B were 3589, 3630 and 3615 K for p-, p+- conductive thick films and p+-p sensor structure, respectively. The RH-sensitive i-type MgAl2O4 thick films possess linear dependence of electrical resistance from RH without hysteresis in the range of RH 40-99 %.
By using spinel-type ceramics of mixed Mn-Co-Ni system with RuO2 additives, the T-sensitive elements prepared in thick-film performance attain additionally a better RH sensitivity. Despite improved long-term stability and good T-sensitive properties with character material B constant value, such thick-film elements possess only small RH sensitivity. This disadvantage occurred, because of relatively poor intrinsic pore topology proper to semiconducting mixed transition-metal manganited in contrast to insulating aluminates with the same spinel-type structure.
So, separate T- and RH-sensitive thick-film elements based on spinel-type NiMn2O4- CuMn2O4-MnCo2O4 manganites, p+-p structures and insulating i-type magnesium aluminate MgAl2O4 can be used to produce T/RH-sensitive thick-film sensor structures for ecological environment monitoring and control.