Researchers demonstrated a film-based elastocaloric cooling prototype driven by thermal energy rather than electromechanical motors, according to a study published in Nature Energy on Aug. 28, 2026.
The prototype pairs a 22-micrometre-thick titanium-nickel shape memory actuator film with a 26.5-micrometre-thick titanium-nickel-iron superelastic refrigerant film. Mounted on low-friction sliders and connected by a polymer element, the actuator contracts when heated above its austenite finish temperature of 60.8 degrees Celsius, mechanically pulling the refrigerant film into a stress-induced phase change that releases heat.
Measurements recorded a temperature span of 12.9 Kelvin at the refrigerant film level and 4.0 Kelvin across the assembled device under Joule-heated actuation at 86 degrees Celsius. When powered directly by an external heat source, the system maintained a device-level temperature span of 2.2 Kelvin across its operating cycle.
The thermal actuator generated a force-to-displacement ratio of 14.5 newtons per millimetre, compared to 1.1 newtons per millimetre measured on a commercial electromechanical actuator. Stand-alone testing of the actuator produced strokes between 368 and 415 micrometres with output forces exceeding 5.5 newtons, providing sufficient mechanical work to drive the refrigerant film through its full transformation plateau.
Bench tests of the cooling unit using an electromechanical drive demonstrated a maximum temperature span of 8.2 Kelvin at 2 hertz under 4.5 percent strain. Differential scanning calorimetry confirmed the superelastic refrigerant film has an austenite finish temperature of 18.5 degrees Celsius, allowing the cooling effect to operate at room temperature.
