Stretchable electronic patch having a foldable circuit layer

1. An electronic patch, comprising:

a substrate comprising:

a first flat portion;

a second flat portion; and

an undulated ribbon that connects the first flat portion and the second flat portion, wherein the undulated ribbon is undulated in a direction perpendicular to the first flat substrate or the second flat substrate, wherein the undulated ribbon is above and below the first flat substrate and the second flat substrate;

a first conductive circuit on the first flat portion of the substrate;

a second conductive circuit on the second flat portion of the substrate;

a third conductive circuit on the undulated ribbon, wherein the third conductive circuit is connected with the first conductive circuit and the second conductive circuit; and

an elastic layer that encloses the substrate, the first conductive circuit, the second conductive circuit, and the third conductive circuit.

2. The electronic patch of claim 1 , wherein the undulated ribbon is configured to unfold and elongate in responses a user's movement when the electronic patch is worn by the user.

3. The electronic patch of claim 1 , wherein the undulated ribbon has serpentine or zigzag shape that includes turns, folds, or loops out of a plane of the first flat substrate or the second flat substrate.

4. The electronic patch of claim 1 , wherein the first flat portion and the second flat portion of the substrate are parallel to each other.

5. The electronic patch of claim 1 , further comprising:

multiple undulated ribbons that are connected the first flat portion and the second flat portion, wherein the multiple undulated ribbons define at least one opening therein.

6. The electronic patch of claim 1 , wherein the elastic layer comprises an elastomeric material or a viscoelastic polymeric material.

7. The electronic patch of claim 1 , wherein the undulated ribbon is formed by a flexible material.

8. The electronic patch of claim 1 , further comprising:

one or more semiconductor chips on the first flat portion, the second flat portion, or a combination thereof, wherein the one or more semiconductor chips are in connection with the first conductive circuit and the second conductive circuit.

9. The electronic patch of claim 8 , wherein the one or more semiconductor chips in conjunction with the first conductive circuit or the second conductive circuit are configured to wirelessly communicate with an external device.

10. The electronic patch of claim 8 , wherein at least one of the first conductive circuit or the second conductive circuit includes an antenna circuit configured to receive or transmit wireless signals.

11. The electronic patch of claim 8 , wherein the one or more semiconductor chips in conjunction with the first conductive circuit or the second conductive circuit are configured to wirelessly communicate with an external device based on near field communication (NFC), Wi-Fi, Bluetooth, or RFID wireless communication standard.

12. The electronic patch of claim 1 , further comprising:

an adhesive layer under the elastic layer and configured to adhere to a user's skin.

13. The electronic patch of claim 1 , further comprising:

one or more sensors, actuators, or chemical delivery devices in connection with the first conductive circuit and the second conductive circuit.

14. The electronic patch of claim 1 , wherein at least one of the first conductive circuit or the second conductive circuit comprises one or more electronic components selected from the group consisting of capacitors, inductors, resistors, metal pads, diodes, transistors, and amplifiers.

15. A method for fabricating an electronic patch, comprising:

pressing a flat substrate by a pair of molds, wherein the flat substrate comprises a first flat portion, a second flat portion, and a flat middle portion, wherein the molds have undulated contours corresponding to the middle portion, wherein the flat substrate comprises a first conductive circuit on the first flat portion of the substrate, a second conductive circuit on the second flat portion of the substrate, a third conductive circuit on the flat middle portion of the substrate;

transforming the flat middle portion of the substrate into an undulated ribbon that is undulated in a direction perpendicular to the first flat substrate or the second flat substrate, wherein the undulated ribbon is above and below the first flat portion and the second flat portion; and

forming an electronic patch by enclosing the first flat portion, the second flat portion, the undulated ribbon, the first conductive circuit, the second conductive circuit, and the third conductive circuit in an elastic layer.

16. The method of claim 15 , wherein the third conductive circuit is connected with the first conductive circuit and the second conductive circuit.

17. The method of claim 15 , wherein the flat substrate includes one or more semiconductor chips on the first flat portion, the second flat portion, or both the first flat portion and the second flat portion, wherein the one or more semiconductor chips are in connection with the first conductive circuit and the second conductive circuit.

18. The method of claim 17 , wherein the molds comprise recesses configured to provide spaces to clear the one or more semiconductor chips during the step of pressing, wherein the recesses in the molds are registered to the first flat portion and the second flat portion.

19. The method of claim 15 , wherein the electronic patch includes multiple undulated ribbons that are connected the first flat portion and the second flat portion, wherein the multiple undulated ribbons define at least one opening therein.