Pressure Sensors: Ultralight Biomass‐Derived Carbonaceous Nanofibrous Aerogels with Superelasticity and High Pressure‐Sensitivity (Adv. Mater. 43/2016)

Abstract

A sustainable strategy was demonstrated for creating superelastic carbonaceous nanofibrous aerogels (CNFAs) with an ordered honeycomb-like structure using a novel biomass konjac glucomannan (KGM) and flexible SiO 2 nanofibers. The SiO 2 nanofibers were first dispersed in water to form a homogeneous nanofiber dispersion, then the KGM powder and sodium hydroxide were added to the dispersion with further stirring. After degassing in a vacuum oven, the dispersion was freeze-dried into KGM/SiO 2 nanofiber composite aerogels (KNFAs). To introduce further elastic bonding in the aerogels, the as-prepared KNFAs were heated at 90°C to fully deacetylate the KGM, then carbonized at 850°C to form carbonaceous nanofibrous networks consisting of SiO2/carbon core?shell nanofibers, which had a final carbon content of about 40 wt%, corresponding to a C/Si molar ratio of 10:1. The acetyl groups are connected to the saccharide units at the C-6 position with an occurrence of approximately 1 acetyl group per 19 sugar units. In contrast to the brittle feature of common biomass-derived carbonaceous aerogels, the CNFAs exhibited robust mechanical properties with a structure allowing for large deformations without cracks. These results indicate that the tiny differences in human pulses can be detected by the CNFA-based pressure sensor, implying its potential use as a scalable diagnostic device to monitor human pulse signs in real-time with high accuracy.