Intrinsically Stretchable, Transient Conductors from a Composite Material of Ag Flakes and Gelatin Hydrogel

Abstract

Transient conductors are one of the most important components in transient electronics, which attract great attention because of their environment-friendly and biocompatible characters. To meet the requirement for wearable electronics, good stretchability and mechanical durability are needed for the transient conductors. However, it remains challenging to achieve stretchability and transient behavior simultaneously because of a lack of the proper elastomer. Herein, we demonstrate the first highly stretchable and transient conductor from a composite material of Ag flakes and gelatin hydrogel. It shows a maximum stretchability of more than 100% with minimal resistance increase and a good cyclic durability of 1000 cycles of deformation at 20%. The above mentioned good mechanical properties come from the rational design of the conductor with a seamless interface between the hydrogel and Ag flakes. When the conductor is immersed in water at 60 °C, it can be quickly dissolved within 90 s, and the transient behavior can be controlled by tuning the content of the hydrogel in the conductors and dissolving temperature. These properties make the conductor a good wiring candidate for stretchable and transient electronics.

Biodegradable Molybdenum/Polybutylene Adipate Terephthalate Conductive Paste for Flexible and Stretchable Transient Electronics

“…[23][24][25][26][27][28][29][30][31][32] Combining biodegradable electronic inks and pastes with an appropriate solution process can provide a scalable, rapid, cost-effective, and safe way to fabricate a fully biodegradable and biocompatible electronic device. [23][24][25][26][27][28][29][30][31][32] For example, fully functional and biodegradable sensors (including strain and temperature sensors) along with multiple arrays of printed circuit boards and RF inductive devices have been successfully realized through ink-jet and screen-printing methods utilizing biodegradable composite paste containing water-soluble metal microparticles (e.g., Mg, Zn, Mo, W) and biodegradable polymers such as poly(ethylene oxide) (PEO), PBTPA, natural waxes, polycaprolactone (PCL), poly-l-lactic acid (PLA), poly lactic-co-glycolic acid (PLGA), polyvinylpyrrolidone (PVP), and polyvinyl alcohol (PVA). [23][24][25][26][27][28][29][30][31][32] The polymer matrix of biodegradable conductive pastes plays an important role in determining their overall mechanical properties, as well as their dissolution and swelling behavior.…”

“…[ 23–32 ] For example, fully functional and biodegradable sensors (including strain and temperature sensors) along with multiple arrays of printed circuit boards and RF inductive devices have been successfully realized through ink‐jet and screen‐printing methods utilizing biodegradable composite paste containing water‐soluble metal microparticles (e.g., Mg, Zn, Mo, W) and biodegradable polymers such as poly(ethylene oxide) (PEO), PBTPA, natural waxes, polycaprolactone (PCL), poly‐l‐lactic acid (PLA), poly lactic‐ co ‐glycolic acid (PLGA), polyvinylpyrrolidone (PVP), and polyvinyl alcohol (PVA). [ 23–32 ]…”

Stretchable Systems

“…The transistor demonstrated 50% stretchability with the decrease in mobility from 7.46 ± 1.37 to 3.57 ± 1 cm 2 V −1 s −1 [81]. In the same way, stretchable transient conductors using Ag flakes and gelatine hydrogel have been developed, as shown in Figure 2.3d [82].…”

“…(d) Schematic representing the stretchable transient conductor from Ag flakes and gelatin hydrogel composite material and the photomicrograph of composite material under stretching and releasing. Reprinted from [82]. Copyright (2020) American Chemical Society.…”

Recent Progress in Materials Chemistry to Advance Flexible Bioelectronics in Medicine

“…[367] Biologically derived structural polymers such as gelatin and collagen can be processed into films and used as substrates in bioelectronics. [369][370][371][372][373] Through the use of additives such as glycerol, citric acid, and glucose, Baumgartner et al process tough gelatin biogels that can accommodate strains of up to ε max = 300%. Conductive zinc traces were defined through laser patterning to fabricate a wearable sensor capable of moni toring a number of different parameters such as temperature, humidity, and strain.…”