Methods and devices for determining sensing device usability

A method comprising the steps of:

• providing a device comprising a first electrical pad;
• a second electrical pad;
• and a first polymer layer contacting at least a portion of said first and said second electrical pads and a second polymer layer contacting said first polymer layer and not said first and said second electrical pads;
• applying a potential across said first and said second electrical pads;
• measuring an electrical property associated with said first and said second polymer layers, wherein the measured electrical property predictably changes over time based on exposure of the device to environmental conditions;
• determining whether the measured electrical property associated with said first and said second polymer layers has exceeded a threshold level associated with a shelf-life of said device,
• when the measured electrical property has exceeded the threshold level, determining the device has been exposed to the environmental condition for a time period that exceeds the shelf-life of the device;
• and
• indicating to a user that the shelf-life of the device has been exceeded,
• wherein said electrical property comprises current, and the threshold level is at least five times greater than an initial current value associated with the first and the second polymer layers that is measured at a time of manufacture of the device.

A method comprising the steps of:

• providing a device comprising a first electrical pad;
• a second electrical pad;
• and a first polymer layer contacting at least a portion of said first and said second electrical pads and a second polymer layer contacting said first polymer layer and not said first and said second electrical pads;
• applying a potential across said first and said second electrical pads;
• measuring an electrical property associated with said first and said second polymer layers, wherein the measured electrical property predictably changes over time based on exposure of the device to environmental conditions;
• determining whether the measured electrical property associated with said first and said second polymer layers has exceeded a threshold level associated with a shelf-life of said device,
• when the measured electrical property has exceeded the threshold level, determining the device has been exposed to the environmental condition for a time period that exceeds the shelf-life of the device;
• and
• indicating to a user that the shelf-life of the device has been exceeded,
• wherein said electrical property comprises impedance, and the threshold level is at least five times greater than an initial impedance value associated with the first and the second polymer layers that is measured at a time of manufacture of the device.

A method comprising the steps of:

• providing a device comprising a first electrical pad;
• a second electrical pad;
• and a first polymer layer contacting at least a portion of said first electrical pad and a second polymer layer contacting at least a portion of said second electrical pad and at least a portion of said first polymer layer;
• applying a potential across said first and said second electrical pads;
• measuring an electrical property associated with said first and said second polymer layers, wherein the measured electrical property predictably changes over time based on exposure of the device to environmental conditions;
• determining whether the measured electrical property associated with said first and said second polymer layers has exceeded a threshold level associated with a shelf-life of said device,
• when the measured electrical property has exceeded the threshold level, determining the device has been exposed to the environmental condition for a time period that exceeds the shelf-life of the device;
• and
• indicating to a user that the shelf-life of the device has been exceeded,
• wherein said first polymer layer comprises a polymer matrix and a plasticizer,
• wherein said second polymer layer comprises a polymer matrix, a plasticizer, and an organic salt,
• wherein said first and said second polymer layers each comprise from 20 to 40 wt. % polymer matrix,
• wherein said polymer matrix in each layer comprises a polymer selected from a group consisting of polyvinyl chloride, polyurethane, polyvinylacetate, carboxylated PVC, hydroxylated PVC and polydimethyl siloxane,
• wherein said first and said second polymer layers each comprise from 60 to 80% plasticizer,
• wherein said plasticizer in each layer is selected from a group consisting of trioctyl phosphate (TOP), nitrophenyloctyl ether (NPOE), bisethylhexylsebacate (BEHS), trimethyl trimellitate (TMTT), dioctyl adipate (DOA) and diisobutyl phthalate (DIBP), and
• wherein said second polymer layer comprises from 0.1 to 10 wt. % of an organic salt.

A method comprising the steps of:

• providing a device comprising a first electrical pad;
• a second electrical pad;
• and a first polymer layer contacting at least a portion of said first electrical pad and a second polymer layer contacting at least a portion of said second electrical pad and at least a portion of said first polymer layer;
• applying a potential across said first and said second electrical pads;
• measuring an electrical property associated with said first and said second polymer layers, wherein the measured electrical property predictably changes over time based on exposure of the device to environmental conditions;
• determining whether the measured electrical property associated with said first and said second polymer layers has exceeded a threshold level associated with a shelf-life of said device,
• when the measured electrical property has exceeded the threshold level, determining the device has been exposed to the environmental condition for a time period that exceeds the shelf-life of the device;
• and
• indicating to a user that the shelf-life of the device has been exceeded,
• wherein said electrical property comprises current, and the threshold level is at least five times greater than an initial current value associated with the first and the second polymer layers that is measured at a time of manufacture of the device.

A method comprising the steps of:

• providing a device comprising a first electrical pad;
• a second electrical pad;
• and a first polymer layer contacting at least a portion of said first electrical pad and a second polymer layer contacting at least a portion of said second electrical pad and at least a portion of said first polymer layer;
• applying a potential across said first and said second electrical pads;
• measuring an electrical property associated with said first and said second polymer layers, wherein the measured electrical property predictably changes over time based on exposure of the device to environmental conditions;
• determining whether the measured electrical property associated with said first and said second polymer layers has exceeded a threshold level associated with a shelf-life of said device,
• when the measured electrical property has exceeded the threshold level, determining the device has been exposed to the environmental condition for a time period that exceeds the shelf-life of the device;
• and
• indicating to a user that the shelf-life of the device has been exceeded,
• wherein said electrical property comprises impedance, and the threshold level is at least five times greater than an initial impedance value associated with the first and the second polymer layers that is measured at a time of manufacture of the device.