Fully Recyclable Liquid-Metal-Based Multi-Layer Thermally Triggered Transient Electronic Devices

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.