Surface acoustic waves drive interfacial fragmentation in porous fibrous solids

Surface acoustic waves provide a surface-confined route for activating dry, compliant porous solids, but their coupling through direct solid-solid contact remains poorly understood. Here, we use compressed plant-derived fiber networks as a model system. Compared with conductive heating and combustion, surface acoustic wave excitation generates stable particulate plumes at approximately 150°C–210°C with only 8%–9% mass loss. Particle-size measurements reveal a reproducible fine-particle mode of 1–2.5 μm and, at stronger excitation, an additional coarse fraction near 35 μm. Post-treatment microscopy shows pronounced fiber network disruption and interfacial debris, while in situ microscopy captures interfacial restructuring and discrete fiber fracture during excitation. These observations show that bulk temperature alone cannot account for the release behavior and support an interface-confined acousto-thermo-mechanical response in which acoustothermal dissipation and contact-mediated mechanical excitation jointly promote localized fragmentation and particulate detachment.