Conductance-stable liquid metal sheath-core microfibers for stretchy smart fabrics and self-powered sensing

Abstract

Highly conductive and stretchy fibers are crucial components for smart fabrics and wearable electronics. However, most of the existing fiber conductors are strain sensitive with deteriorated conductance upon stretching, and thus, a compromised strategy via introducing merely geometric distortion of conductive path is often used for stable conductance. Here, we report a coaxial wet-spinning process for continuously fabricating intrinsically stretchable, highly conductive yet conductance-stable, liquid metal sheath-core microfibers. The microfiber can be stretched up to 1170%, and upon fully activating the conductive path, a very high conductivity of 4.35 × 104 S/m and resistance change of only 4% at 200% strain are realized, arising from both stretch-induced channel opening and stretching out of tortuous serpentine conductive path of the percolating liquid metal network. Moreover, the microfibers can be easily woven into an everyday glove or fabric, acting as excellent joule heaters, electrothermochromic displays, and self-powered wearable sensors to monitor human activities.

Electrically Conductive Textile Materials—Application in Flexible Sensors and Antennas

“…Piezoresistive properties are desirable in strain sensor applications because they allow measurement of the response to strain through the corresponding variation of resistivity. However, such variation becomes a challenge when consistent conductivity is needed in stretchable structures [45,46].…”

“…Similarly, Lu et al [135] electrodeposited nickel-aluminum layered double hydroxide (Ni-Al LDH) onto cotton fabrics and reported a superior conductivity of 143 S/cm. Another recent innovation in developing stretchable and highly conductive textile structures was reported by Zheng et al [46]. The researchers aimed to circumvent the potential for deterioration of conductivity in e-textiles due to mechanical strain and used a coaxial wet spinning process to generate liquid metal sheath-core microfibers with a conductivity of 435 S/cm that remains stable within a 4% range at strains of up to 200% [46].…”

“…Another recent innovation in developing stretchable and highly conductive textile structures was reported by Zheng et al [46]. The researchers aimed to circumvent the potential for deterioration of conductivity in e-textiles due to mechanical strain and used a coaxial wet spinning process to generate liquid metal sheath-core microfibers with a conductivity of 435 S/cm that remains stable within a 4% range at strains of up to 200% [46]. The liquid metal core used in this research consists of eutectic gallium indium (EGaIn) alloy, which is liquid at room temperature, and offers high electrical conductivity (3.4 × 10 4 S/cm) that is maintained under mechanical deformation [46,143].…”

“…The researchers aimed to circumvent the potential for deterioration of conductivity in e-textiles due to mechanical strain and used a coaxial wet spinning process to generate liquid metal sheath-core microfibers with a conductivity of 435 S/cm that remains stable within a 4% range at strains of up to 200% [46]. The liquid metal core used in this research consists of eutectic gallium indium (EGaIn) alloy, which is liquid at room temperature, and offers high electrical conductivity (3.4 × 10 4 S/cm) that is maintained under mechanical deformation [46,143]. Poly(vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene)/poly(ethylene glycol) diacrylate (PVDF-HFP-TFE/PEGDA) was used as the solution in the sheath channel of the coaxial spinneret [46].…”

“…The liquid metal core used in this research consists of eutectic gallium indium (EGaIn) alloy, which is liquid at room temperature, and offers high electrical conductivity (3.4 × 10 4 S/cm) that is maintained under mechanical deformation [46,143]. Poly(vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene)/poly(ethylene glycol) diacrylate (PVDF-HFP-TFE/PEGDA) was used as the solution in the sheath channel of the coaxial spinneret [46].…”