Stretchable Transparent Wireless Charging Coil Fabricated by Negative Transfer Printing

Area of Science:

• Materials Science
• Electrical Engineering
• Wearable Technology

Background:

• Wearable electronics (smartwatches, VR/AR smartglasses, E-textiles) offer new interaction methods but are limited by power sources, leading to short operational times and frequent charging.
• Developing efficient and integrated power solutions is crucial for the advancement and user experience of wearable devices.

Purpose of the Study:

• To demonstrate a novel stretchable and transparent wireless charging coil for wearable electronics.
• To provide a compatible power solution for soft and flexible wearable components, overcoming current power limitations.

Main Methods:

• Fabrication of a stretchable transparent wireless charging coil using negative adhesive transfer printing (NATP).
• Development of a stretchable transparent conductor using a silver nanowire (AgNW)-polyurethane acrylate (PUA) composite.
• Characterization of the conductor's electrical conductivity, transparency, and mechanical robustness under tensile strain.

Main Results:

• Achieved a 10.6 ohm/sq thin film with 84% transmittance.
• Demonstrated conductivity maintained under up to 60% tensile strain.
• Successfully transferred a maximum power of 59 mW with approximately 24% power transfer efficiency, powering a green LED wirelessly.

Conclusions:

• The developed stretchable transparent wireless charging coil offers a viable alternative power solution for wearable devices.
• The AgNW-PUA composite conductor exhibits excellent conductivity, transparency, and mechanical flexibility, suitable for integration into soft electronics.
• This technology can significantly enhance the usability and performance of next-generation wearable electronics by addressing power constraints.