Multilayer wearable device

A multilayer wearable device configured to be attached to a subject, the multilayer wearable device comprising:

• a single continuous substrate folded to form multiple layers, the substrate comprising a first portion and a second portion, the first portion having a first side and a second, opposite side, and the second portion having a first side and a second, opposite side;
• wherein the first side of the first portion is configured to be attached to the subject and the second portion is arranged on top of the first portion such that the first side of the second portion faces the second side of the first portion;
• a first electrical component arranged on the first portion of the substrate and configured to sense a physiological parameter of the subject;
• a second electrical component arranged on the second portion of the substrate;
• and
• a gel layer arranged between the first portion and the second portion,
• wherein the first portion is porous to an active pharmaceutical ingredient such that the active pharmaceutical ingredient is able to transmit through the first portion to the subject.