Tough and Strain-Sensitive Organohydrogels Based on MXene and PEDOT/PSS and Their Effects on Mechanical Properties and Strain-Sensing Performance

Abstract

Conductive hydrogels have shown promising application prospects in the field of flexible sensors, but they often suffer from poor mechanical properties, low sensitivity, and lack of frost resistance. Herein, we report a tough, highly sensitive, and antifreeze strain sensor assembled from a conductive organohydrogel composed of a dual-cross-linked polyacrylamide and poly(vinyl alcohol) (PVA) network, as well as MXene nanosheets as nanofillers and poly(3,4-ethylenedioxythiophene)doped poly(styrenesulfonate) (PEDOT/PSS) as the main conducting component (PPMP-OH organohydrogel). The tensile strength and toughness of PPMP-OH had been greatly enhanced by MXene nanosheets due to the mechanical reinforcement of MXene nanosheets, as well as various strong noncovalent interactions formed in the organohydrogels. The PPM 1 P-OH organohydrogels showed a tensile strength of 1.48 MPa at 772% and a toughness of 5.59 MJ/m 3 . Moreover, the conductivity and strain-sensing performance of PPMP-OH were significantly improved by PEDOT/PSS, which can form hydrogen bonds with PVA and electrostatic interactions with MXene. This was greatly beneficial for constructing a uniformly distributed and stable 3D conductive network and helped to obtain strain-dependent resistance of PPMP-OH. The strain sensors assembled from PPMP 1 -OH exhibited a high sensitivity of 5.16, a wide range of detectable strains up to 500%, and a short response time of 122 ms, which can effectively detect various physiological activities of the human body with high stability. In addition, the corresponding pressure sensor array also showed high sensitivity in identifying pressure magnitude and position.

MXene-Based Skin-Like Hydrogel Sensor and Machine Learning-Assisted Handwriting Recognition

“…In the second stage, with the increase of strain, the length of hydrogel continues to increase, the width narrows, the distance between MXene nanosheets further increases, and the resistance also further increases. In the last stage, as the tensile strain continues to increase, the hydrogels become long and thin and the MXene nanosheets gradually separate from each other, severely disrupting the electron transfer path between the MXene nanosheets, resulting in a significant increase in resistance. ,, In Figure B, the Δ R / R 0 value increases with increasing strain and decreases immediately after release in a short time (0.24 s) at 0.5% strain, validating the ability to respond in a timely manner to external stimuli. In Figure C,D, PMAA@MXene-based strain sensor can be used to distinguish between large strains (50, 100, 150, and 200%) and small strains (0.5, 1, 3, and 4%).…”

Sensitive Wearable Strain Sensor Based on a Self-Doped Conductive Hydrogel

“…Conductive hydrogels provide electronic or ionic conductivity with structural and mechanical properties similar to those of human tissues and have been widely used for developing wearable electronic devices and bioelectronics. − Conventional hydrogels are limited by their inadequate electrical conductivity, necessitating the addition of conductive additives. The most used active substances to fabricate these hydrogels include conductive polymers such as polypyrrole (PPy), polyaniline (PANI), poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS); , carbon materials (e.g., graphene, carbon nanotubes); metal nanoparticles (e.g., gold, silver, copper); and MXene nanosheets. − Kim et al developed a high-performance hydrogel flexible strain sensor using PVA and PEDOT:PSS, exhibiting self-healing properties, low hysteresis, over 150% elongation at break, and a rapid response time of 0.88 s . Zeng et al incorporated PEDOT:PSS into mechanically robust PVA/PAA to fabricate multifunctional conductive hydrogels, exhibiting high gauge factors (GFs) ranging from 2.21 to 3.82 .…”