DC-AC signal decoupling in contact-asymmetric nanofiber membranes for self-powered thermal and mechanical sensing

Reliable simultaneous thermal and mechanical sensing remains challenging for single-membrane self-powered multimodal sensors due to the difficulty of independently resolving coupled output signals. Here, we report direct current-alternating current (DC-AC) signal decoupling in a contact-asymmetric self-powered sensor based on a flexible polyacrylonitrile/polypyrrole/carbon nanotube nanofiber membrane (PPCNFM). By constructing asymmetric Al/PPCNFM and Cu/PPCNFM contacts at opposite ends of the membrane, an internal electric field is introduced to direct charge transport and regulate stimulus-dependent electrical outputs. Thermal stimulation induces a quasi-static DC baseline through thermally driven charge separation without requiring a deliberately configured hot-cold junction, whereas mechanical loading generates transient AC peaks associated with piezoelectric charge generation. The distinct DC and AC output features enable bias-free discrimination of thermal and mechanical stimuli over 30–90 °C and 0.5–3.5 N, respectively, with reduced signal crosstalk. This work establishes DC-AC signal decoupling in contact-asymmetric nanofiber membranes as a simple interfacial strategy for self-powered multimodal sensing, offering a practical route toward integrated thermal and mechanical signal recognition in flexible intelligent electronics. Download: Download high-res image (296KB) Download: Download full-size image