Abstract: There is described an indicator device comprising: an indicator section comprising an indicator material that displays different visible properties in response to the presence or absence of an activating agent; an activator section comprising an activating agent that effects a change in the visible properties of the indicator material; and a barrier section comprising a barrier layer that is substantially impermeable to the activating agent, the barrier section being located between the indicator section and the activator section; wherein at least part of the barrier layer is configurable to allow the activating agent and the indicator material to come into contact with each other, thereby effecting a visible change. The device may be used to detect or report the passage of time and can be applied to perishable goods and/or associated packaging to show that packaging has been compromised and/or that the device has been compromised.

Abstract: There is disclosed an indicator composition, the application thereof to substrates, and related products. The indicator composition comprises an organic solvent soluble polymer and a redox sensitive material which displays different visible properties in the oxidized and reduced forms. The organic solvent soluble polymer can be at least partially sulfonated polystyrene. The indicator composition can be dissolved in organic solvents such as acetone, ethanol and ethyl acetate to form inks which can be used in a variety of printing processes. The indicator composition can be used to detect oxidizing agents, oxygen, water, reducing agents, UV light, temperature and the passage of time.