Texturing Behavior-Empowered PANI-Wrapping C-Fe2O3 Hierarchical Microarchitectures for Wearable Ammonia and Pressure Sensing.

Simultaneously monitoring ammonia (NH3) leakage and human motion is desirable for safeguarding astronauts' safety in spacecraft equipped with NH3-driven propulsion, in which stable and selective NH3 sensing combined with reliable pressure detection is highly required. However, little is reported on a sensing material that synergistically presents the required NH3 and pressure sensing. Here, wearable NH3 and pressure sensing has been developed using PANI-wrapping carbon-intermixed Fe2O3 hierarchical microarchitectures (PANI@C-Fe2O3 HMAs), which have been synthesized by employing fern-shaped C-Fe2O3 HMAs with trunk/branches as structural precursors, followed by conformal PANI-wrapping. Beneficially, PANI@C-Fe2O3 HMAs present a wide detection range of 0.1 ppm-10 v/v%, 167-day-long stability and high selectivity toward NH3. Further, a pressure sensor prototype has been constructed by laminating PET tapes onto the HMAs-integrated flexible electrode, revealing an excellent pressure-dependent response and machine-learning-assisted human-motion recognition. Such superior dual sensing is attributed to the texturing behavior, in which conformal texturing of PANI along the hierarchical surface of C-Fe2O3 HMAs establishes heterojunctions with a built-in electric field to amplify resistance modulation, while fern-shaped HMAs with trunk/branches provide abundant active interfaces and electron transport pathways. Practically, a wearable dual-sensing device that integrates flexible NH3 and pressure sensor prototypes has been built with reliable dual-sensing responses.