Biomaterials- and biostructures Inspired high-performance flexible stretchable strain sensors: A review

[Display omitted] •Natural biomaterials in flexible stretchable strain sensor applications are critically reviewed.•Three strategies based on nature-inspired structural designs for enhancing the electromechanical performance are presented.•Challenges and future perspectives of biomaterials and biostructures for flexible stretchable strain sensors are discussed. Flexible stretchable strain sensors have received tremendous attention due to their excellent performance and comfort. Material selection and structural design are considered the two essential factors for driving the development of flexible stretchable strain sensors. Due to natural biomaterials with numerous superiorities (such as unique structures, diverse chemical group, biodegradability, and environmental benignity) and biostructures with delicate and rational design principles, they have become new stars in the field of flexible stretchable strain sensors. Herein, this review systematically summarizes the state-of-the-art achievements in biomaterials and biostructures for the development of high-performance flexible stretchable strain sensors. According to the structural features of flexible stretchable strain sensors, the various roles and function of biomaterials are reviewed in detail, including as active materials, flexible substrates, and functional materials. Special attention is paid to the three most representative nature-inspired structural designs and optimization for flexible stretchable strain sensors, including crack, brick-and-mortar and wrinkled structures. The main challenges and future R&D directions for biomaterials-and biostructures- inspired flexible stretchable strain sensors are discussed. This comprehensive review and outlooks will enlighten readers to better understand the current development status and future research activities in using natural biomaterials and biostructures for the fabrication of flexible stretchable strain sensors.