Flexible solid-state illumination devices

A solid-state illumination device, comprising:

• a first flexible sheet defined by a first broad-area surface and an opposing second broad-area surface that is parallel to the first broad-area surface;
• a plurality of rigid substrates distributed over at least a substantial portion of the area of the first flexible sheet according to a two-dimensional pattern and bonded to the first broad-area surface with a good thermal contact;
• a plurality of LED sources mounted to the plurality of rigid substrates with a good thermal contact;
• and
• a second flexible sheet defined by a third broad-area surface and an opposing fourth broad-area surface that is generally parallel to the third broad-area surface;
• wherein the first flexible sheet includes at least one layer of a rigid material having a Young's modulus of at least 1 GPa, wherein the second flexible sheet is formed from an optically transmissive material having a Young's modulus less than 10 MPa and an elastic range of at least 50%, and wherein the second flexible sheet is disposed in contact with the first flexible sheet so as to form a layered, flexible sheet-form structure hermetically encapsulating at least the plurality of LED sources.