Hydrogel-assisted microfluidic spinning of stretchable fibers via fluidic and interfacial self-adaptation

Stretchable polymeric fibers have significant impact, although their production requires rigorous environmental methods and resource consumption. The process is challenging for elastic polymers with reduced spinnability and ...

Guoxu Zhao and a team of scientists in medical engineering, materials science , and life sciences in China, have presented a hydrogel-assisted microfluidic spinning method to address such challenges, which they accomplished by encapsulating pre-polymers within long, protective, and sacrificial hydrogel fibers. The research has been published in the journal Science Advances . They designed simple apparatuses and regulated the fluidic and interfacial self-adaptations of oil/water flows to successfully produce fibers with a widely regulated diameter, notable length, and high quality. The method allowed for easy, effective, reshaping of helical fibers for exceptional stretchability, and mechanical regulation.

The fibers have potential applications as textile components and optoelectronic devices. The method provides a powerful path to mass-produce high quality stretchable fibers. Stretchable polymers Intrinsically stretchable fibers have widespread applications when compared with non-stretchable fibers, where stretchable fibers can retain their functions under mechanical dynamics to realize specific uses. Stretchable polymers can be incorporated to develop biomaterials and bioelectronics with increasing attention obtained for their capacity to conform with human bodies .

HAMS method. (A) Schematic of the hydrogel-assisted microfluidic spinning (HAMS) platform. (B) Schematic showing the formation of an SOP/hydrogel core/shell fiber via fluidic (flow speed equalization) and interfacial (interface deformation and stabilization) self-adaptations. The width and direction of gray arrows indicate the flow speeds of the SOP, sodium alginate solution, and CaCl2 solution. (C) Schematics showing the fabrication strategies and some application demonstrations of SOP-based fibers. (D to F) Photographs of (D) an as-spun SYLGARD 184 PDMS/hydrogel fiber, (E) a core/shell fiber after the curing of core flow, and (F) a SYLGARD 184 PDMS fiber after removing the hydrogel shell (scale bars, 1 mm). (G) Photographs of continuous SYLGARD 184 PDMS fibers with different diameters (D) and long lengths (L) (scale bar, 2 cm). (H) Scanning electron microscopy (SEM) images of these two fibers (scale bar, 1 mm). (I) High-magnification SEM images on the surface of a SYLGARD 184 PDMS fiber (scale bar, 20 μm). (J) Photographs on the sections of these two fibers (scale bar, 1 mm). Science Advances, doi:10.1126/sciadv.adj5407 Read more

Fiber spinning mechanisms of HAMS method. (A to C) Formation of PDMSliq spheres under different Qcore/Qshell (scale bars, 1 mm). (D) Phase-field numerical results showing the interfacial deformation and fluid flow field of core (PDMSliq) and shell flows under different Qcore/Qshell at different times (t) after starting the extrusion of core flows (scale bar, 1 mm). (E) Schematics showing the potential mechanisms in spinning PDMSliq/hydrogel fibers. (F and G) Photographs of as-spun PDMSthi core/shell fibers at different Qcore/Qshell, where the schematics show the potential spinning mechanisms (scale bars, 1 mm). Credit: Science Advances, doi:10.1126/sciadv.adj5407 Read more

Reshaping-production of helical fibers via HAMS method. (A) Schematic showing the reshaping production of helical fibers. Inset is an as-wrapped fiber on steel rod (scale bar, 1 mm). (B) Three helical PDMSthi fibers fabricated from different as-spun fibers (inner needle: 12, 16, and 24 gauge from top to bottom) and rods (diameter: 4, 2, and 0.5 mm from top to bottom; scale bar, 5 mm). (C) Photographs showing the excellent stretchability of a microscaled helical PDMSthi fiber (inner needle of 27 gauge and rod diameter of 0.5 mm; scale bar, 5 mm). (D and E) Schematics and photographs showing the influences of Tshell, Drod, H, and Deg on the structure of helical PDMSthi fibers (scale bars, 1 mm). (F) Photographs of four helical PDMSthi fibers with distinct fiber diameters and helix diameters (scale bar, 1 mm). (G) Tensile curves, statistical tensile strengths, and elongations at break (dots with SDs), of helical PDMSthi fibers fabricated by using different rods. (H) Tensile curves of the four helical PDMSthi fibers in (F). (I) Schematics showing the potential mechanisms in reshaping helical structures. Science Advances, doi:10.1126/sciadv.adj5407 Read more

Application demonstrations of stretchable fibers fabricated via HAMS method. (A) Photographs showing the magnetically driven elongation of a magnetic-modified helical PDMSthi fiber within a vessel-like channel [a polyvinyl chloride (PVC) tube as model] to reach a target (a magnet as model) and its spring back after removing the magnetic field (scale bar, 5 mm). (B) Photograph of a 1-m-long PDMSliq fiber in transmitting red, green, and blue lights (scale bar, 2 cm). (C) Photograph of this PDMSliq fiber in transmitting red light under bending (scale bar, 2 cm). (D) Influence of PDMSliq fiber length on its light transmission in transmitting red, green, and blue lights. (E) Light transmission of a PDMSliq fiber during a 1000-times 100%-strain cyclical stretching process. (F to I) Monitoring of (F) finger bending, (G) finger pressing, (H) finger pressing–inputted Morse information, and (I) wrist pulses based on the light transmission of a PDMSliq fiber. The average pattern shows the systolic peak (PS), tidal wave (PT), and diastolic peak (PD) of wrist pulses. (J) SEM images of straight and helical CNT/PDMSliq fibers. (K) Resistance variation (△R/R0) curves and tensile curves of straight and helical CNT/PDMSliq fibers during a stretching-until-break process. (L) △R/R0 curves of a straight CNT/PDMSliq fiber during cyclical stretching processes with different strains. (M) Monitoring of finger bending using a straight CNT/PDMSliq fiber. (N) Wirelessly monitoring of finger bending by combining a CNT/PDMSliq fiber with a Bluetooth unit and phone application, and (O) the wirelessly monitoring result on finger bending. Credit: Science Advances, doi:10.1126/sciadv.adj5407 Read more