Fully solution processed liquid metal features as highly conductive and ultrastretchable conductors

Abstract

Liquid metal represents a highly conductive and inherently deformable conductor for the development of stretchable electronics. The widespread implementations of liquid metal towards functional sensors and circuits are currently hindered by the lack of a facile and scalable patterning approach. In this study, we report a fully solution-based process to generate patterned features of the liquid metal conductor. The entire process is carried out under ambient conditions and is generally compatible with various elastomeric substrates. The as-prepared liquid metal feature exhibits high resolution (100 μm), excellent electrical conductivity (4.15 × 104S cm−1), ultrahigh stretchability (1000% tensile strain), and mechanical durability. The practical suitability is demonstrated by the heterogeneous integration of light-emitting diode (LED) chips with liquid metal interconnects for a stretchable and wearable LED array. The solution-based technique reported here is the enabler for the facile patterning of liquid metal features at low cost, which may find a broad range of applications in emerging fields of epidermal sensors, wearable heaters, advanced prosthetics, and soft robotics.

Intrinsically stretchable electronics with ultrahigh deformability to monitor dynamically moving organs

“…As shown in Fig. 2A , a nonoxidized liquid metal droplet naturally spreads and adheres to thermally evaporated Cu film with a low contact angle of 30°, which is promoted by the formation of intermetallic compounds through interfacial alloying reaction ( 43 , 44 ). In contrast, nonoxidized liquid metal exhibits a high contact angle of 130° with the pristine SEBS elastomer, suggesting the lack of affinity.…”

Liquid Metal Based Nano-Composites for Printable Stretchable Electronics

“…Well-defined pattern features for liquid metal can be directly placed on the substrate in one step by selective wetting. As shown in the process in Figure 6 b, Zhu et al adopted screen printing to define the locations and morphologies as desired pattern features on the elastomer substrate [ 35 ]. Then, they deposited a layer of polydopamine (PDA) as the self-polymerization initiating layer to realize surface functionalization, which can also subsequently facilitate deposition of Cu film as a LM-reactive wetting layer.…”

“…Reprinted with permission from Ref. [ 35 ] Copyright 2021 Springer Nature. ( c ) Unit structure of the LM-based circuit including two design strategies for reliability enhancement.…”

“…To address this concern, surface ligand modification is potential solution to enable mechanical property and chemical function enhancement of the oxide layer. The LM–ligand molecule composite systems present a stable physical status in dispersion, storage, and solution processing [ 35 ]. Printable inks composed of liquid metal nanoparticles retain unique and desirable material properties suitable for high-resolution printed electronics.…”

Hybrid patterning of metal nanowire/polymer composites based on selective photocuring-and-transfer and kirigami cutting techniques for stretchable circuit application

“…To date, stretchable LED circuits have been fabricated by three representative strategies, which are based on (1) stretchable architectures composed of metal thin-films, [47][48][49] (2) intrinsically stretchable materials (e.g., liquid metal), [50][51][52] and (3) conductive elastomer composites. 20,21 However, many of the reported stretchable LED circuits suffer from either performance degradation under strain or require a complex fabrication process.…”