Liquid Metal / Block Copolymer Multilayer Composite for Stretchable Moisture Encapsulation

Abstract

An encapsulation barrier is required for proper application of electronic devices since gas and moisture have a direct influence on their stability and reliability. While flexible moisture barriers have already been developed and demonstrated a low range permeability, stretchable barriers for stretchable electronic devices are still challenging. This study suggests an organic-inorganic multilayer structure as a moisture barrier for stretchable devices. The multilayer encapsulation barrier consists of an alternation between poly(styrene-b-isobutylene-b-styrene) copolymer (SiBS) and Eutectic-GaIn liquid metal (LM) with 4 μm and less than 2 μm thickness, respectively. The barrier has a water evaporation rate of 0.0125 mg/h and is stretchable up to 50% uniaxial strain (). The formation of thin oxide layer on LM surface reduces the moisture penetration, which improves the barrier property, while preserving the stretchability of polymeric substrates. In addition, we demonstrate a humidity-insensitive ionic-gel based temperature sensor using the multilayer moisture barrier.