Office of Technology Transfer – University of Michigan

Focused wireless power transfer using multiple near-field plates

Technology #6853

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Anthony Grbic
Managed By
Joohee Kim
Licensing Specialist, Physical Sciences & Engineering 734-764-8202
Patent Protection
US Patent Pending
US Patent Pending

Wireless power transfer and charging is an important component in creating more independent devices, especially for medical and mobile applications. However, the technology currently has significant limits on transmission distance and transmitter/receiver size, which limits design flexibility and usability. Near-field plates have previously been shown to improve the focus of wireless power transmitters. A new approach using multiple near-field plates has now been demonstrated to further improve efficiency, working distance, and size of wireless power systems.

Multiple plates enhance magnetic field control

The new technology includes a near-field plate after the transmitter and a second plate before the receiver. Careful design of the near-field plates, a grating-like array of subwavelength structures, can allow for a greater magnetic field between the transmitter and receiver that is suppressed elsewhere, improving transmission efficiency while minimizing interference. The gains in efficiency can be translated to longer working distances, enabling more design flexibility and deeper medical implant placement. The plates can also be used to improve magnetic field control with differently sized transmitter and receiver units with less loss of power.


  • Wireless charging in consumer electronics
  • Power transfer systems for medical devices


  • Greater power transmission efficiency
  • Longer working distances at a given efficiency level
  • Flexibility in different transmitter and receiver sizes