Self-assembled micro-structured sensors for food safety in paper based food packaging

• Novel sensor paper was developed using micro-structured diatomaceous earth and pH sensitive dye.
• The functionality is based on pH sensitive dye to indicate spoilage of meat or fish by color change.
• Diatomaceous earth was successfully immobilized to the polyvinyl alcohol coating.
• The coating was engineered to maximize the exposure of the diatom morphology.
• The sensor paper achieved very high sensitivities for ammonia gas detection.

Natural self-assembled microstructured particles (diatomaceous earth) were used to develop a gas sensor paper with detection mechanism based on visible and distinct color changes of the sensor paper when exposed to volatile basic nitrogen compounds. The coating formulation for paper was prepared by applying diatomites, polyvinyl alcohol (PVOH), and pH sensitive dyes on acidic paper substrate. The surface coating was designed to allow a maximum gas flow through the diatomite sensors. The produced sensor paper was tested for sensitivity using different ammonia concentrations and we observed a sensitivity lower limit at 63 ppm. As a comparison, the results show comparable sensitivity levels to carbon nanotube based sensor technologies reported in literature.