3D Printing of Self‐Wiring Conductive Ink with High Stretchability and Stackability for Customized Wearable Devices

Abstract

The progress in 3D printing research has led to significant developments ranging from customized printing to rapid prototyping. However, the 3D printing of electrodes, especially stretchable electrodes for the fabrication of 3D printable electronic devices, is challenging due to the inherent weakness with respect to the printing material. A novel preparation method is reported for a 3D printable conductive ink with a self‐wiring effect during heat treatment, which pushes the silicone rubber outward and results in the accumulation of the conductors within the wire. This effect results in the formation of a polymer shell around the conductor, thus yielding conductors with larger stretchability and soft passivation characteristics. The conductive ink is prepared via the following steps: i) mixing of conductive filler, silicone rubbers, and solvent; followed by ii) soft heat treatment for soft curing and solvent evaporation. Furthermore, a capacitive sensor is fabricated using this dielectric polymer layer. As a demonstration, a mouse controller is fabricated using a capacitive sensor array prepared using the conductors developed in this study.

Interface Design for Stretchable Electronic Devices

“…The large polymer coverage at the top surface caused by the relatively small surface energy of the polymer matrix is not readily controllable. [98] Strong interfacial adhesion is critical in stretchable electronics. Applying tensile stress at the weakly bonded organic-inorganic interface creates voids and delamination due to concentrated stress.…”

“…It is because the energy transfer from the matrix to the nanomaterials takes place mainly in the central part of the fillers, and the energy transfer near the edges of the fillers is not considerable. [98] On the other aspect, the nanomaterials with a high aspect ratio are advantageous for electrical percolation. Therefore, design of a composite is up to the target property to be achieved.…”

“…Yoon et al demonstrated 3D-printed wires consisting of Ag flake and silicone rubber (Figure 16c). [98] When the printed wire was annealed at 100°C for 4 h, the Ag flake was self-concentrated in the center and the silicone rubber was at the surface of the fiber due to surface energy difference between the Ag flakes (1.2 J m −2 ) and silicon rubber (27 mJ m −2 ). This phase separation-induced wire was stretchable up to = 113% and had a moderate electrical conductivity (85.91 S cm −1 ).…”

“…Reproduced with permission. [98] Copyright 2013, Wiley-VCH. d) 3D printing of liquid metal wires to electrically connect LEDs.…”

Holocellulose Nanofibril-Assisted Intercalation and Stabilization of Ti3C2Tx MXene Inks for Multifunctional Sensing and EMI Shielding Applications

“…Nowadays, portable and flexible printed electronics is an emerging field and has extremely stimulated the design of high-performance conductive inks. − It has been claimed that conductive inks prepared through different printing technologies provide a new platform for the fabrication and development of novel intelligent packaging materials − and flexible electronic devices, such as sensors, − supercapacitors, wearable electronics, artificial skins, and batteries. , Substantial electrical components have been reported in the conductive inks on the basis of carbonaceous materials, such as graphene, − carbon nanotubes, − and metallic materials, such as silver, , copper, gold, and so on. However, conductive inks with high-resolution printing properties applied in the fields of charge storage devices are urgently needed.…”