Verification of rfid activation using variable capacitance structure

A method for verifying activation of an RF tag having an activation indicator component and an activatable environmental exposure indicator, the activation indicator component configured to change a capacitance of a variable capacitance structure of the RF tag responsive to an activation action, and the activatable environmental exposure indicator configured to change the capacitance of the variable capacitance structure of the RF tag responsive to a predetermined environmental exposure occurring subsequent to the activation action, the method comprising;

• providing a media process path including a first process point and a second process point, the second process point downstream of the first process point;
• providing, at the first process point, the RF tag;
• interrogating, at the first process point, the RF tag with an interrogation signal in a predetermined radiofrequency range;
• confirming, at the first process point, that the RF tag emits a first response signal responsive to the interrogation signal based on a capacitance of the variable capacitance structure;
• applying, at the second process point, the activation action to the RF tag;
• interrogating, at the second process point, the RF tag with an interrogation signal in a predetermined radiofrequency range;
• and
• confirming the activatable environmental exposure indicator has been activated, at the second process point, based on the RF tag emitting a second response signal responsive to the interrogation signal based on a change in capacitance of activation indicator component configured to change.

A method of forming an RF tag, the method comprising:

• defining a variable capacitance structure electrically coupled to an integrated circuit of the RF tag;
• forming an activation indicator component that is configured to interact with the variable capacitance structure, the activation indicator component including an unactivated state and an activated state, a transition from the unactivated state to the activated state changing a capacitance value of the variable capacitance structure from a first capacitance value to a second capacitance value;
• and
• forming an activatable environmental exposure indicator that is configured to interact with the variable capacitance structure, the activation indicator component including an unexposed state and an exposed state, a transition from the unexposed state to the exposed state changing the capacitance value of the variable capacitance structure from the second capacitance value to a third capacitance value.