3D printable and stretchable PVA‐PAAm dual network hydrogel with conductivities for wearable sensors

Abstract

Conductive hydrogel has broad potential applications in wearable sensors and flexible electronic devices. However, due to the complicated and restrictive mold‐casting process, the manufacture of hydrogel‐based sensors is still facing great challenges. In this paper, we adopt direct inkjet printing (DIW) technology to fabricate three‐dimensional structures of chemically and physically cross‐linked hydrogels by integrating fumed silica as a rheological modifier into crosslinked poly(vinyl alcohol)/poly(acrylamide) (PVA/PAAm) network. Fumed silica not only enables hydrogels with excellent rheological properties, but also provides more hydrogen bond crosslinking sites, further improving mechanical properties. Meanwhile, calcium chloride (CaCl2) is supplemented to construct conductive channels in the hydrogel, which powers the hydrogel with good conductivity and strain sensitivity. The sensor assembled from 3D printed hydrogel shows cycle stability and accurate recognition ability in detecting mechanical deformation and various human movements (for example knee bending and frown). This work extends the application of 3D printing hydrogel in the field of wearable devices.

A Guide to Printed Stretchable Conductors

“…Adding fillers like fumed silica particles help in rheological modifications for better print resolution. Further, functional groups on the fumed silica particles can become additional cross-linking sites, thus, improving the mechanical strength of the hydrogels . The effects of fumed silica particles (labeled as SiO 2 in Figure c) leading to additional cross-linking sites and improved print resolution are shown in Figure c.…”

“…Reproduced with permission. 188 Copyright 2022, Wiley-VCH. d) Starting with the monomer EDOT instead of the polymer PEDOT can lead to improved structural integrity as seen from the reduced spreading the printed filaments (left to right).…”

“…c) Poly­(acrylamide) (PAAm)- co -poly­(vinyl alcohol) hydrogels extrusion printed with varying fraction of fumed silica particles that act as a rheological modifier. Reproduced with permission . Copyright 2022, Wiley-VCH.…”

Material Extrusion Filament Width and Height Prediction via Design of Experiment and Machine Learning

“…This processing method shows good material compatibility, simple operation, and an economical equipment cost [13][14][15]. It has also been widely applied in the processing of flexible robots [16,17], wearable sensors [18,19], tissue engineering [20,21], electronic components [22,23], and food materials [24,25], exhibiting its huge application potential across diverse domains.…”