Fig 1

Spinning process of silkworms and the hierarchical structure of natural silk fibers. (a) Structure of a silk gland in a silkworm. It can be divided into three parts according to the evolution of silk protein during spinning: anterior gland, middle gland, and posterior gland 21. (b) Hierarchical micro/nanostructure of natural silk fiber. (c) Hydrophobic repeat segments and hydrophilic non-repeat segments are alternately arranged in a heavy chain, and sealed with N-terminal segments and C-terminal segments. (d, e) Structure of β-crystallites (d) and the antiparallel structure of β-sheet (e) 19. (a) Adapted with permission from Ref. 21, Copyright 2017, Nature Publishing Group. (b–e) Adapted with permission from Ref. 19, Copyright 2019, American Chemical Society."

Table 1

Comparison of mechanical and electrical properties between silk-based fibers and other polymer-based conductive fibers."

Fig 2

Silk-based fibers and textiles for sensing devices. (a) Graphene/silk fiber prepared by dry-Meyer-rod-coating for stress sensor 80. (b) Silk-CNT hybrid fibers prepared by wetting spinning and post drawing for pressure and electric response humidity sensing 72. (c) Carbonized silk textile for wearable strain sensor 65. (d) Multifunctional and wearable sweat analysis patch based on silk fabric-derived N doped carbon textile 87. (e) In-situ grown carbon nanotubes on carbonized silk textile for wearable airflow sensor 4. (f) Carbonized silk nanofiber membrane for detecting spatial distribution of pressure 91. (a) Adapted with permission from Ref. 80, Copyright 2016, American Chemical Society. (b) Adapted with permission from Ref. 72, Copyright 2020, Wiley-VCH. (c) Adapted with permission from Ref. 65, Copyright 2016, Wiley-VCH. (d) Adapted with permission from Ref. 87, Copyright 2019, AAAS. (e) Adapted with permission from Ref. 4, Copyright 2020, Wiley-VCH. (f) Adapted with permission from Ref. 91, Copyright 2017, American Chemical Society."

Fig 3

Silk-based fibers and textiles for actuators and optical devices. (a, b) Schematic illustration of the manufacturing process of the silk-based microactuator (a) and photographs of smart textile woven from tensile silk yarn (b), which had different weaving denseness 93. (c) Images of silk yarns weaved into air-conditioning textiles in wet/dry state 95. (d) Genes Structure of Fluorescence silk and wedding dress produced by the colored fluorescent silks 99. (e) Photographs of colored silk cocoons and fibers under room light and UV irradiation 101. (f) Schematic of direct-write assembly of silk waveguides in both straight and curvy patterns, and the setup used to image and analyze the transverse face of the silk waveguides. Optical images of printed silk waveguide and straight and wavy silk waveguides guiding light from a laser source 110. (a, b) Adapted with permission from Ref. 93, Copyright 2019, Wiley-VCH. (c) Adapted with permission from Ref. 95, Copyright 2020, Springer Nature. (d) Adapted with permission from Ref. 99, Copyright 2013, Wiley-VCH. (e) Adapted with permission from Ref. 101, Copyright 2011, Wiley-VCH. (f) Adapted with permission from Ref. 110, Copyright 2009, Wiley-VCH."

Fig 4

Silk-based materials used as energy storage devices. (a) Preparation of flexible and conductive hollow graphene fibers templated by silk fiber and the fabrication of the all-solid supercapacitor 126. (b) PEDOT conductive polymer coated on the Au@silk fiber for fiber-shaped microsupercapacitors 127. (c) Schematic of fabrication of graphitic N-doped porous carbon nanosheets derived from silk 133. (d) Silk-derived defect-rich and N-doped nanocarbon electrocatalyst for flexible and rechargeable Zn-Air Batteries 66. (e) Isolated metal single-site catalysts embedded in N-doped carbon nanosheets derived from silk fiber for catalyzing the oxidation of benzene to phenol with hydrogen peroxide at room temperature 134. (a) Adapted with permission from Ref. 126, Copyright 2017, the Royal Society of Chemistry. (b) Adapted with permission from Ref. 127, Copyright 2016, American Chemical Society. (c) Adapted with permission from Ref. 133, Copyright 2018, the Royal Society of Chemistry. (d) Adapted with permission from Ref. 66, Copyright 2019, American Chemical Society. (e) Adapted with permission from Ref. 134, Copyright 2018, Nature Publishing Group."

Fig 5

Application of silk in other flexible and wearable fields. (a) Colorless silk/CuS hybrid fabric with spontaneous heating property under sunlight 143. (b) Silk fibers with aligned lamellar pores for thermal stealth textile 142. (c) Silk-sheathed CNT (CNT@Silk) wire for textile electronics 145. (d) CNTs ink mediated by sericin for printed electronics 146. (e) Silicon electronics on silk as a path to bioresorbable, implantable devices 148. (f) Self-healable multifunctional electronic tattoos by incorporating graphene with SF/Ca2+ films for multifunctional sensors 152. (a) Adapted with permission from Ref. 143, Copyright 2020, American Chemical Society. (b) Adapted with permission from Ref. 142, Copyright 2018, Wiley-VCH. (c) Adapted with permission from Ref. 145, Copyright 2018, American Chemical Society. (d) Adapted with permission from Ref. 146, Copyright 2020, Wiley-VCH. (e) Adapted with permission from Ref. 148, Copyright 2009, American Institute of Physics. (f) Adapted with permission from Ref. 152, Copyright 2019, Wiley-VCH."