Direct-ink-write printing of hydrogels using dilute inks

Abstract

Summary Direct-ink-write (DIW) printing has been used in myriad applications. Existing DIW printing relies on inks of specific rheology to compromise with printing process, imposing restrictions on the choice of printable materials. Reported ink viscosity ranges from 10 −1 to 10 3 Pa·s. Here we report a method to enable DIW printing that is compatible with dilute ink (10 −3 Pa·s) by manipulating the interactions between ink and substrate. By exemplifying hydrogel printing, we build a printing system and show that dilute ink of appropriate surface energy, once extruded, can spontaneously wet and reside within the region of higher surface energy on a substrate of lower surface energy, while resisting gravity and maintaining shape before solidification. We demonstrate the diversity for printing various materials on various substrates and three deployments immediately enabled by the proposed method. The method expands the range of printable materials for DIW printing and the toolbox for additive manufacturing.

Ethanol‐Induced Ni2+‐Intercalated Cobalt Organic Frameworks on Vanadium Pentoxide for Synergistically Enhancing the Performance of 3D‐Printed Micro‐Supercapacitors

“…[ 26,27 ] Similar to traditional supercapacitors, the charge storage performance of MSCs is highly dependent on the inherent characteristics of the electrode materials, charge storage mechanisms, and configuration of the MSCs. [ 28,29 ] In symmetrical MSCs that use the same material in two electrodes, the voltage window is limited because of water splitting. Asymmetric MSCs with customized 3D configurations can overcome this limitation and improve energy storage performance.…”

“…[26,27] Similar to traditional supercapacitors, the charge storage performance of MSCs is highly dependent on the inherent characteristics of the electrode materials, charge storage mechanisms, and configuration of the MSCs. [28,29] In symmetrical MSCs that use the same material in two electrodes, the voltage window…”

Direct ink writing of a graphene/CNT/silicone composite strain sensor with a near-zero temperature coefficient of resistance

“…24 Compared with conventional preparation methods including complicated and lengthy microfabrication steps in cleanrooms and mold-casting techniques, the DIW technique has great potential in the field of wearable electronics due to its low processing cost and broad selection of functional materials. 25,26 Meanwhile, compared with well-developed film/ foam-like devices, the fiber-shaped strain sensors developed by the DIW technique have the advantages of excellent flexibility, weavability, portability and suitable conformability onto uneven surfaces. [27][28][29] Consequently, in this study, we will develop a robust and highly stretchable GNP/CNT/silicone elastomer (GCE) fiber with small or near-zero TCR by a facile DIW technique.…”

Manipulation of cross-linking in PEDOT:PSS hydrogels for biointerfacing

“…As IL concentration increased, viscosity of the pre-gel mixture increased ranging from 0.03–0.11 Pa s (Table S1, ESI†). These viscosity values indicate that PEDOT:PSS-IL mixtures are anticipated to be compatible with solution-based processing techniques such as extrusion-based 18,28 and inkjet 29,30 printing and dip coating 31 which utilize solutions of viscosities that range from 0.1–1000 Pa s, 0.001 to 0.04 Pa s, and 0.05 to 0.5 Pa s respectively. However, the gelation kinetics of the mixture must be carefully considered.…”