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The emergent transient electronics that can be destroyed or degraded harmlessly under an environmental stimulus are attracting extensive attentions toward eco‐friendly electronic devices and confidential communication applications. However, currently available transient electronics are limited by the poor recyclability of components, which fails to meet the ever‐increasing demands of advanced electronic devices. Here, this work reports a fully recyclable transient electronic device based on a multi‐layered architecture, comprising a liquid metal (LM) as the conductor and a NaOH solution‐embedded paraffin composite (NPC) as the degradation agent. Upon thermally triggered by the bottom heater, the middle‐layer LM circuit and the top NPC layer melt, releasing the aqueous alkali to destroy the circuit at a quick transient rate (46 ± 4 s). Afterward, both the free LM and paraffin are recycled at extremely high efficiencies, that is, 98% for LM owing to the self‐aggregation and fluidic nature, 95% for paraffin arising from the low melting point and good recoverability. The successful integration of transience and recycling abilities dramatically improves the feasibility of transient electronics in real applications, as further demonstrated in a radio‐frequency transmission device and a remote destructible memristor, which hold great promises for confidential data storage devices and next‐generation electronics. [ABSTRACT FROM AUTHOR]

Transient electronics, arising electronic devices with dissolvable or degradable features on demand, is still at an early stage of development due to the limited choices of materials and strategies. Herein, a facile fabrication method for transient circuits by the combination of room‐temperature liquid metals (RTLMs) as the electronic circuit and water‐soluble poly(vinyl alcohol) (PVA) as the packaging material is reported. The as‐made transient circuits exhibit remarkable durability and stable electric performance upon bending and twisting, while possessing short transience times, owing to the excellent solubility of PVA substrates and the intrinsic flexibility of RTLM patterns. Moreover, the RTLM‐based transient circuit shows an extremely high recycling efficiency, up to 96% of the employed RTLM can be recovered. As such, the economic and environmental viability of transient electronics increases substantially. To validate this concept, the surface patterning of RTLMs with complicated shapes is demonstrated, and a transient antenna is subsequently applied for passive near‐field communication tag and a transient capacitive touch sensor. The application of the RTLM‐based transient circuit for sequentially turning off an array of light‐emitting‐diode lamps is also demonstrated. The present RTLM‐based PVA‐encapsulated circuits substantially expand the scope of transient electronics toward flexible and recyclable transient systems. Flexible and recyclable transient circuits are fabricated by employing room‐temperature liquid metals as the electronic circuit and water‐soluble poly(vinyl alcohol) as the packaging material. The as‐made transient circuits are successfully applied to various electronic devices, including near‐field communication, capacitive touch sensors, and transient circuits to allow sequentially turning off an array of light‐emitting‐diode lamps. [ABSTRACT FROM AUTHOR]