Condition sensor for medical device package

A package in which a medical device is stored, the package comprising

• an outer shell providing a vapor barrier between an interior space inside the outer shell and an exterior environment;
• a medical device positioned in the interior space inside the outer shell;
• the medical device including a liquid-containing element that is subject to drying out as liquid from the liquid-containing element vaporizes and travels from the interior space to the external environment;
• a condition sensor comprising two metallic elements,
• each of the two metallic elements being composed of different metals, with each of the different metals selected so that the two metallic elements form an anode and a cathode of an electrochemical cell,
• each of the two metallic elements being in electrical contact with a conductive water-containing element, so that the water-containing element forms the electrolyte of the electrochemical cell, and
• an electrically conductive path extending from each of the metallic elements to a location wherein the electrochemical potential formed between the metallic elements can be measured to provide an indication of the degree to which the conductive water-containing element has dried out,
• wherein the medical device stored in the package further comprises at least one electrode, and wherein the electrode includes a metallic layer in electrical contact with a conductive liquid-containing layer through which electrical current is delivered to a patient when the electrode has been applied to a patient, the conductive liquid-containing layer being subject to drying out as liquid from the liquid-containing layer vaporizes and travels from the interior space to the external environment, and
• wherein the two metallic elements and water-containing element of the condition sensor are separate from and not shared with the liquid containing element and electrode of the medical device, and
• wherein the condition sensor provides an indication of whether the liquid-containing element of the medical device has dried out sufficiently that the electrode of the medical device should not be used.