Electrically readable indicators

The focuses on "electrically readable indicator" sub-projects have been on the development of printable conductive wiring and electrical thin film indicators. The research work conducted in the first project involved ink-jet printing of conductive wiring using nanoparticle ink, the development of a wireless humidity sensor with polyvinyl alcohol acting as the sensing element and the fabrication and measurement of oxygen deficient titanium dioxide thin-films for room-temperature oxygen sensors. Printing and curing multiple layers led to high enough conductivity for printing functioning RF-coils. A reduction in Q-value of approximately 15% was witnessed between 50% and 100% relative humidity for the wireless humidity sensor and the TiO2-? oxygen sensors showed ~15% relative change in conductivity at room temperature when illuminated with UV. The research under the subtitle 'Electrical thin film indicators' (2005-2006) was focused on studying such oxygen sensitive materials that involved a change of conductivity rather than a change of color as a function of oxygen exposure. The studied materials were both reactive metallic thin films and organic based thin films and their suitability for food packages was a prerequisite for the utilization. In the beginning of the project a literature survey was made to find out which metals would be the best candidates for oxygen detectors (Ylilammi 2005).