<p>With the rapid advancement of wearable smart devices, there is an increasing demand for intelligent flexible strain sensors. However, to date, traditional metallic or inorganic semiconductor strain sensors exhibit poor stretchability and sensitivity, limiting their applications in this field. Flexible elastomer-based smart sensing materials (FESSM) offer several advantages, including lightweight design and quantifiable production capabilities. These FESSM have garnered significant attention for their potential applications in robotic electronic skins and intelligent homecare systems. The materials and structural design of FESSM are continually being optimized to facilitate the development of high-performance flexible electronics. This article reviews the latest advancements in the design concepts of materials and structures for FESSM. It examines the preparation methods for various elastic substrates, such as polyurethane fibers and polydimethylsiloxane films, and explores the design of their micro-nano structures, as well as the appropriate use of conductive fillers. This review aims to provide insights and strategies for the design of high-performance FESSM.</p> Graphical abstract <p></p>