Wearable Power Harvesting System

• US 20160261031A1
• Filed: 03/10/2015
• Published: 09/08/2016
• Est. Priority Date: 03/10/2014
• Status: Active Grant

• Current Assignee: Drexel University
• Original Assignee: Drexel University
• Inventors: Jost, Kristy A., Le, Michael N., Fisher, Jonathan W., Watt, Stephen J., Cook, Andrea C., Dion, Genevieve, Dandekar, Kapil R., Gogotsi, Yury, Patron, Damiano
• Granted Patent: US 9,972,894 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/248 provided with an AC/DC converting device, e.g. rectennas
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

A wearable power harvesting system includes a knitted fabric rectenna including an antenna adapted to receive radio-frequency energy within a desired frequency band and a rectifier circuit that converts received radio-frequency energy into a DC current and voltage. A knitted fabric load/storage unit stores DC power from the rectifier circuit. The power harvesting system is adapted to harvest the radio-frequency energy within the desired frequency band, which may include WLAN frequencies such as the standard 2.4 GHz and 5 GHz WLAN standard frequencies.

Claims

1. A wearable power harvesting system comprising:

a knitted fabric rectenna including an antenna adapted to receive radio-frequency energy within a desired frequency band;

a rectifier circuit that converts received radio-frequency energy into a DC current and voltage; and

a knitted fabric load/storage unit that stores DC power from said rectifier circuit.

2. The system of claim 1, wherein the antenna of the rectenna comprises a compact wideband folded dipole antenna.

3. The system of claim 2, wherein the antenna comprises a single layer and includes a non-conductive fabric surrounded by a conductive fabric.

4. The system of claim 3, wherein the non-conductive fabric forms a “

T-shape”

within the conductive fabric.

5. The system of claim 1, further comprising a knitted pocket that stores circuitry including a Schottky diode and surface-mount inductance (L) and capacitance (C) components that match an impedance of the antenna to the Schottky diode.

6. The system of claim 5, wherein the circuitry is connected to the knitted fabric by silver paint covered by a coating of a liquid epoxy adapted to provide an electrical connection between the circuitry and the fabric.

7. The system of claim 5, wherein the circuitry contains tabs that extend into pockets of the conductive fabric to provide a compression fit.

8. The system of claim 5, further comprising a clasp adapted to hold the conductive elements of the circuitry in contact with the conductive fabric.

9. The system of claim 5, further comprising conductive yarn threaded through a circuit board containing the circuitry so as to connect the circuit board to the fabric.

10. The system of claim 1, wherein the rectenna is included in an array of interconnected rectennas in which a DC power output of each rectenna is combined for storage in the load/storage unit.

11. The system of claim 10, wherein each rectenna is spaced from each other rectenna so as to achieve a directive radiation pattern and to substantially eliminate coupling between each rectenna.

12. The system of claim 1, wherein the desired frequency band is 2.4 GHz or 5 GHz.

13. The system of claim 1, wherein the knitted fabric load/storage unit comprises a knitted supercapacitor.

14. The system of claim 13, wherein the rectenna includes a shorting capacitor and rectifying diode at an output port to transfer power to the supercapacitor.

15. The system of claim 13, wherein the knitted supercapacitor is interdigitated.