Office of Technology Transfer – University of Michigan

MEMS Electrostatic Micro-Hydraulic Systems for Sensing and Actuation

Technology #5564

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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 micro-hydraulic structures for high performance sensing and actuation. Hydraulic or pneumatic structures are extensively used in systems where amplification of force, or deflection, is needed. Operation of such systems is based on uniform distribution of pressure over an incompressible liquid filling two connected chambers. And amplification of force or deflection is made possible by taking advantage of unequal surface areas of two movable pistons/membranes capping the chambers.

Design Details

The proposed design consists of two connected chambers with movable parts on each chamber, and an integrated electrode pair that forms a fluidic gap capacitor (electrostatic element) for sensing and/or actuation. Appendages are added on one or both sides of the micro-hydraulic system to convert any physical parameters to applied pressure, and implement actuation. Transducing elements convert non-electrical parameters of interest to electrical signals, or electrical signals to non-electrical signals for actuation. The design also contains electronic circuits to condition the transducer output, and to enable improved sensitivity and selectivity, or actuation performance.

Arrays of the micro-fluidic structures can be formed on the same substrate for fault tolerance, redundancy, and improved performance such as better sensitivity or wider dynamic range, or to allow for the measurement of varied parameters. Individual micro-hydraulic structures within the arrays can be made of different materials to respond to various parameters for sensing, or to generate different non-electrical signals for actuation.


  • Accelerometers
  • Flow sensors
  • Energy harvesters
  • Gyroscopes
  • Tactile imagers


  • Increased sensitivity, range, and responsiveness
  • High performance
  • Flexible design (materials and structure) allow targeting of multiple applications
  • Inherent fault tolerance and redundancy