Office of Technology Transfer – University of Michigan

Electromagnetic Energy Transducer for Energy Harvesting or Mechanical Actuation

Technology #5959

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

Researchers at the University of Michigan have developed an electromagnetic transducer for converting kinetic energy to electrical energy, or electrical energy to mechanical displacement. The transducer is targeted towards operation under harsh conditions such as high centrifugal acceleration, high axial and radial static displacements, and tilting movements. The transducer can be embedded in various systems (such as car suspensions, helicopter lead-lag dampers, rail tracks, and bridges which are exposed to dynamic forces) as an energy harvester system and sensor simultaneously; in this configuration, the transducer can harness environmental vibration energy and monitor the health of the host system. Alternatively, the transducer can be used as an electromechanical actuator to provide mechanical (static or dynamic) displacement according to the injected current

Design Details

The electromagnetic energy transducer for energy harvesting or mechanical actuation developed at the University of Michigan consists of two concentric frames (e.g., cylindrical, cuboid etc.) open at least at one end, with one frame inserted partially or completely into the other. The first frame consists of at least one concentric series of stacked-up magnets, and the second frame consists of at least one set of air-core coils that can move in parallel to the central axis of the magnet frame. When the transducer is used as an energy harvester, the relative motion between the two frames causes electrical voltage to be induced in the coils. In the electromagnetic actuator configuration, the injected electrical current in the coils interacts with the magnetic field created by the magnets, thereby generating electromagnetic force which moves the coils with respect to the magnets


  • Energy harvesting
  • Mechanical actuation


  • Operation under harsh conditions
  • Simultaneous operation as energy harvester and sensor
  • Self-powered operation