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Project TitleEAHS: Electrically Actuated Hydraulic Solids for Use as a Wax Motor
Track Code6760
Short Description

We present a versatile method for fabricating monolithic electrically actuated wax motors/actuators.


Wax actuators convert thermal or electrical energy into usable mechanical energy. The mechanical energy is a result of the expansion and contraction of a blend of paraffin wax that is encapsulated within the actuator. In general, wax actuators are used for applications where there is a need for highly reliable, short stroke, and high power density movements.


Hydraulic solids can generate higher forces and stresses per unit density, than any previously reported actuator material. We offer a method to synthesize a uniform monolithic material which acts as an electrically actuated hydraulic solid (EAHS). Our EAHS is composed of a blend of an elastomeric matrix, a wax, and a conductive material. The addition of a conductive material allows direct transfer of energy into the bulk material, thereby inducing thermal expansion in the microencapsulated wax, causing the entire material to expand.  This approach introduces the functionality and components of a traditional paraffin wax actuator into a highly-scalable material framework.


(Left) A phase change material such as paraffin wax is dispersed in an elastomer matrix. The matrix contains a network of conductive material which allows the elastomeric matrix to act as a heater for the phase changing microencapsulated wax.

(Right) When a voltage is applied to the bulk material, the system heats and the wax expands generating an internal pressure. This pressure causes the overall structure to expand.


Our hydraulic solid-based actuators are operable at relatively low voltages and currents, allowing for easy integration into many environments where high voltages or currents can be detrimental. The actuators can be manufactured by additive processes (3D printing) or traditional methods and are suitable for manufacture in small-scale rapid prototyping systems and large-scale commercial production facilities.


We have developed a number of prototype models and have shown that by varying the amount of hydraulic wax in the blend, the force in the resulting actuator can be controlled. One of our prototypes, a 14mm diameter 50mm long actuator, can produced 4,500 Newtons of force and an elongation of ~4%. When compared to existing actuators such as dielectric elastomer actuators (DEA) and ionic polymer–metal composites (IPMCs) our actuators produce two and five orders of magnitude more force respectively.




Using a homogenous mixture to manufacture our EAHS actuator allows the final actuator to be shaped in a number of ways including:

(A)   Cutting the monolithic block

(B)    3D printing the EAHS material on a desired substrate

(C)    Forcing the blended precursors into a mold to obtain complex shapes and morphologies.


Potential Applications

  •  Rapid prototyping of wax actuators
  • Soft Robotics
  •  Automation
  • Microfluidics
  • Soft electronics
  • Valves and O-rings for aerospace applications
  • Temperature regulation systems for greenhouses, appliances, HVAC and automotive applications
  • Highly reliable short stroke and high power density applications



  • Suitable for manufacture using 3D printing or standard manufacturing processes
  • Metal-free design usable in environments with high magnetic fields such as MRIs
  • Soft structure can be integrated into soft-robotics
  • Can operate at low voltages and currents

Keywords: Materials Fabrication, Nanoapplications, Oleochemicals & Petrochemicals, Thermal Linear Actuator, Thermostat, Wax Actuator, Wax Motor, actuators, aerospace, alternative & green energy, chemicals, composites, electrical engineering, energy, engineering, materials, materials science, nanocomposites, nanotechnology, optimization, physical sciences, polymers, robotics, synthetic methods

Tagspolymers, Oleochemicals & Petrochemicals, chemicals, physical sciences, synthetic methods, optimization, electrical engineering, actuators, robotics, energy, alternative & green energy, materials, composites, nanotechnology, Nanoapplications, nanocomposites, Materials Fabrication, aerospace, engineering, materials science, Thermal Linear Actuator, Wax Actuator, Wax Motor, Thermostat
Posted DateMar 31, 2016 4:26 PM


Jeffrey Lipton

Additional Information


  •  J. Lipton. “System and methods for fabricating actuators and electrically actuated hydraulic solid materials”. PCT Patent Application. Publication Number: WO2016187302
  • Lipton, J. I., Angle, S., Banai, R. E., Peretz, E. and Lipson, H. (2016), “Electrically Actuated Hydraulic Solids”. Adv. Eng. Mater., 18: 1710–1715. doi:10.1002/adem.201600271
  • Downloadable Videos

Licensing Contact

Carolyn A. Theodore
607 254 4514


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