Xylan‑Assisted construction of anisotropic aerogel for pressure sensor

Abstract

Currently, aerogels are promising for wearable pressure sensors due to their superior flexibility and high sensitivity. However, uniform dispersion of conductive solid filler is a critical step in the preparation process. Herein, xylan with good amphiphilicity was obtained by hydroxypropylsulfonation under mild reaction conditions, which is accepted as a dispersant for multi-walled carbon nanotubes (MWCNTs) in water. The hydroxypropylsulfonated xylan (HSX) exhibited a satisfactory dispersion efficiency reached to 97.8 %. After standing for 20 days, there are still 76 % of MWCNTs stabilized in the dispersion. Then, the ultralight, flexible and superstable anisotropic aerogels were prepared by freeze-casting technology. The obtained aerogel reveals excellent mechanical performance, with a great compressibility (undergoing a strain of 70 %) and elasticity (91.8 % height retention after 100 cycles at a strain of 20 %). As a proof of concept, the HSX/MWCNTs aerogel is utilized to construct a pressure sensor, which exhibit high sensitivity (S = 2.17 kPa−1) and impressive responsiveness to human motions. This work demonstrates a promising flexible electronic material for wearable electronics, electronic skin, and human motion monitoring.