Thermo-Mechanically Trained Shape Memory Alloy for Temperature Recording With Visual Readout

Economical sensing and recording of temperature are important in the transportation and management of sensitive goods such as medicine. Existing approaches measure the entire temperature profile using electronic devices running on a continuous power source. This letter presents a simple, intelligent, and battery-free solution for capturing informative temperature events using the natural thermo-mechanical state of a shape memory alloy (SMA). This approach utilizes the temperature-induced irreversible mechanical deformation of the SMA as a natural way to capture the temperature history without the need for electronic data logging. In this letter, a two-way SMA-based sensor is used to record both high and low temperature peak events. The reading utilizes a smartphone to visualize and quantify temperature-induced deformation for monitoring. Detailed design and experimental studies have been performed to validate the proposed approach.