Recent progress in the development of conductive hydrogels and the application in 3D printed wearable sensors

Abstract

This paper reviewed the research progress of 3D printing in wearable sensors based on conductive hydrogels, with an emphasis on classification of conductive hydrogels, the mechanisms of wearable sensors and applications of 3D printing methods.

Direct ink writing of polyimide aerogels for battery thermal mitigation

“…Of these, DIW is particularly useful because it is inexpensive, simple to use, has minimal instrumentation requirements, and allows for high control over the feedstock composition. Although many studies have been published on the DIW of gels, [68][69][70][71][72] DIW of aerogels is rare. The major challenge of using DIW to print polymer aerogels is achieving the requisite rheology of the sol.…”

Three-dimensional printed cellulose nanofibers/carbon nanotubes/silicone rubber flexible strain sensor for wearable body monitoring

“…11 To ensure the necessary stretchability, different polymers are commonly used as flexible substrates, with popular choices including PU (polyurethane), 12,13 PDMS (polydimethylsiloxane), 14 and hydrogels. 15 PDMS is particularly favored due to its similar modulus to human tissue, chemical inertness, and non-tissue damaging properties. 16–18…”

Direct ink writing of porous shape memory polyesters

“…DIW does not necessitate added heat, extending its suitability to temperature-sensitive materials, [17][18][19] including some that can provide desirable rheological modification 20,21 as well as induced porosity. 22,23 For example, Cipriani et al created a DIW ink based on paraffin wax beads and a photocurable resin wherein the wax could be removed after printing/curing by washing with ethyl acetate, thereby generating pores. 24,25 Wei et al showcased DIW inks based on sodium chloride (NaCl) particles combined with solvent-based solutions of triblock copolycarbonates, with porosity created upon washing with water to both cure the ink and remove the salt.…”