Gradient nanofiber aerogels for extreme cryogenic and thermal environments

Striking a balance between sensitivity and detection range while ensuring stability under extreme temperatures remains a formidable challenge in the design of flexible pressure sensors. To address this issue, we draw inspiration from the multi-gradient architectures of nature and propose a bottom-up self-assembly strategy. By leveraging a meticulously orchestrated multi-step approach that encompasses electrospinning, sequential freezing, and thermal imidization, we successfully fabricate a polyimide nanofiber/carbon nanotube dual-gradient aerogel with a dynamic stiffness transition from flexible to rigid states. Experimental results highlight notable properties of the dual-gradient aerogel, which exhibits an ultralow density (0.023 g cm^-3), efficient thermal insulation (28 mW m^-1 K^-1), and reliable compressibility and fatigue resistance. Moreover, it establishes a favorable equilibrium between sensitivity (156 MPa^-1) and an extensive detection range (223 kPa). Notably, the combination of thermal resilience (-196 °C to 533.30 °C) and mechanical stability enables performance that is comparable to, or in some aspects surpasses, that of conventional flexible sensing materials. This dual-gradient aerogel provides both effective thermal insulation and high-precision physiological monitoring under extreme conditions, offering integrated thermal protection and real-time astronaut health assessment in spacesuits.