The redox characteristic of methylene blue in polyacrylate film has been investigated for applications in
monitoring time and temperature. This monitoring capability is based on a color change from colorless
to blue under exposure to air. The oxidation process is controlled by the air diffusion which is affected by
the chemical structure of the polyacrylate. The activation energy of diffusion, which was calculated by
Arrhenius equation, goes up with increasing the rigid structure of the polyacrylate. The results correlate
well with the glass transition temperature of different polyacrylates. The unique feature of the methylene
blue to change color under oxidation, can be used for the fabrication of low cost visual sensors for
monitoring time and temperature.