Multifunctional PLLA/HOFs/MXene Composite Piezoelectric Fabrics with Self-Powering and Unidirectional Moisture Wicking for Flexible Wearable Electronics

Piezoelectric fabrics are urgently required by flexible wearable electronics applications for their advantages, such as high sensitivity, wearer comfort, and environmental compatibility. However, existing piezoelectric materials are often limited by poor comfort and a lack of multifunctionality, making it difficult to reconcile sweat management on the skin-contacting side with efficient mechanical energy harvesting. Herein, a biodegradable poly( l -lactic acid) (PLLA) matrix integrated with MXene and hydrogen-bonded organic frameworks (HOFs) was employed to fabricate a PLLA/Mxene/HOFs self-powered nanofiber membrane, serving as the basis for a flexible piezoelectric fabric (PHMF) sensor with unidirectional moisture-guiding functionality. The integration of HOFs and MXene into electrospun PLLA nanofibers through hydrogen-bonding interactions elevated the glass transition and melting temperatures. The PHMF sensor exhibited a tensile strength of 5.61 MPa, and it consisted of Coolmax yarn and a hydrophobic layer and allowed sweat to move from the inner layer near the skin to the outer layer in 0.06 s. When sweat was applied to the inner layer, the moisture content of the inner layer quickly increased to 650% within 10 s before gradually decreasing to around 264%, while the moisture content of the outer layer accumulated to 470%. The PHMF sensor exhibited strong piezoelectric performance, with an open-circuit voltage of 26 V measured at 3 Hz under dry conditions, response and recovery times of 122.25 and 80.15 ms, respectively, and favorable stability after 5000 cycles. This work demonstrates the potential of eco-friendly and multifunctional PHMF sensors for flexible, wearable electronics.