Giant room-temperature electrical switching effects in water-in-oil emulsions

Thermally-triggered electrical switching materials are of urgent demand for developing novel temperature sensors , overheat protection circuits, thermal controllers, battery management systems against overheating, etc. Here, we report a water-in-oil emulsion system with giant electrical switching ratios at room temperature prepared by a simple and efficient method. The temperature-sensitive phase transition process of alkanes as the oil phase causes the formation and collapse of conductive paths in the emulsion, resulting in electrical switching ratios of up to 6 orders of magnitude. The emulsions have good thermal cycle stability, and the switching ratio remains essentially unchanged after 100 cycles. The switching temperature can be easily adjusted by using alkanes of various chain lengths. In addition, the similar electrical switching effect is observed in four emulsions containing different neutral salts, ensuring the tunability and versatility of the system. The electrical switching emulsions offer a promising avenue to developing future high-performance, energy-saving, and low-cost electrical switching systems.