Micro Heat Engine/Refrigerator


WSU inventors have developed micro-transducers with piezoelectric properties for converting energy in one form to useful energy in another form. Piezoelectric thin films have been used for years as power transducers in micro-electro-mechanical systems (MEMS) and micro-electronic devices. Piezoelectric films are an attractive option for power transduction because of the relative ease with which such devices can be produced using conventional micro-machining methods.

This WSU invention details the design and fabrication of a micro sized heat engine as alternate portable power supply (e.g. replace conventional batteries). Our micro-sized heat engines have promising potentials in multitude of applications: micro energy sources, waste heat recovery, fluid control, propulsion, cooling systems for electronics and people, and a variety of other applications.

This piezoelectric micro-transducer can be operated either as a micro-heat engine, converting thermal energy into electrical energy, or as a micro-heat pump, consuming electrical energy to transfer thermal energy from a low-temperature heat source to a high-temperature heat sink. It can also be used to convert the kinetic energy of an oscillating or vibrating body on which the micro-transducer is placed into useful electrical energy. Further, this invention has unique features enabling cooling applications of MEMS and micro-electronics.

Applications and Advantages

§   Provides miniaturize, highly flexible, and mobile power supplying device for micro-electro-mechanical systems (MEMS) and micro-electronics

§   Performance (i.e. power density) exceeds conventional battery 

IP Status 

US Patent (7,325,914; 7,453,187)

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Scott Steiger
Associate Director
Washington State University
(509) 335-7065
Reference No: 0512-OC


Kelvin Lynn
Robert Richards
David Bahr
Cecilia Richards

Key Words