This Review covers the fundamentals of operation and scaling of elastocaloric cooling devices as well as current developments of elastocaloric shape‐memory alloy (SMA) films and the engineering of SMA film‐based cooling devices. Sputter‐deposited TiNiCuCo alloys showing ultra‐low fatigue enable unique functional properties such as tailored transformation temperature gradients. Two substantially different concepts for the development of elastocaloric cooling demonstrators are discussed. One concept relies on heat transfer by mechanical contact between the elastocaloric SMA film and solid heat sink and source elements. The second concept makes use of the heat transfer between the elastocaloric SMA film and a heat transfer fluid, including the advanced technology of active regeneration. Demonstrators based on a single SMA film reach device temperature spans of 14 K and a high specific cooling power of up to 18 W g−1. The performance characteristics are compared with other solid‐state caloric cooling technologies.

The elastocaloric effect associated with the stress-induced first order phase transformation in pseudoelastic shape memory alloy (SMA) films and foils is of special interest for cooling applications on a miniature scale enabling fast heat transfer and high cycling frequencies as well as tunable transformation temperatures. The focus is on TiNi-based materials having the potential to meet the various challenges associated with elastocaloric cooling including large adiabatic temperature change and ultra-low fatigue. The evolution of strain and temperature bands during tensile load cycling is investigated with respect to strain and strain-rate by in situ digital image correlation and infrared thermography with a spatial resolution in the order of 25 µm. Major design issues and challenges in fabrication of SMA film-based elastocaloric cooling devices are discussed including the efficiency of heat transfer as well as force recovery to enhance the coefficient of performance (COP) on the system level. Advanced demonstrators show a temperature span of 13 °C after 30 s, while the COP of the overall device reaches almost 10% of Carnot efficiency.

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Cool Review: Innovative elastocaloric cooling systems have the potential to meet the rising demand for efficient cooling and temperature control on the miniature scale, such as in microelectronic devices and lab‐on‐a‐chip systems. This Review covers fundamentals on the operation and scaling of elastocaloric cooling devices as well as current developments of elastocaloric films and engineering of corresponding devices. This cover artwork reflects this field as a whole, including fundamentals of caloric cooling, material science, and device engineering. More details can be found in the Review by Florian Bruederlin et al. on page 1588 in Issue 8, 2018 (10.1002/ente.201800137).