Biocompatible Silk/Polymer Energy Harvesters Using Stretched Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) Nanofibers

Abstract

Abstract:Energy harvested from human body movement can produce continuous, stable energy to portable electronics and implanted medical devices. The energy harvesters need to be light, small, inexpensive, and highly portable. Here we report a novel biocompatible device made of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers on flexible substrates. The nanofibers are prepared with electrospinning followed by a stretching process. This results in aligned nanofibers with diameter control. The assembled device demonstrates high mechanical-to-electrical conversion performance, with stretched PVDF-HFP nanofibers outperforming regular electrospun samples by more than 10 times. Fourier transform infrared spectroscopy (FTIR) reveals that the stretched nanofibers have a higher β phase content, which is the critical polymorph that enables piezoelectricity in polyvinylidene fluoride (PVDF). Polydimethylsiloxane (PDMS) is initially selected as the substrate material for its low cost, high flexibility, and rapid prototyping capability. Bombyx Mori silkworm silk fibroin (SF) and its composites are investigated as promising alternatives due to their high strength, toughness, and biocompatibility. A composite of silk with 20% glycerol demonstrates higher strength and larger ultimate strain than PDMS. With the integration of stretched electrospun PVDF-HFP nanofibers and flexible substrates, this pilot study shows a new pathway for the fabrication of biocompatible, skin-mountable energy devices.

Fabrication and application of biocompatible nanogenerators

“…OPEN ACCESS Niu et al, 2020;Najjar et al, 2017;Saravanakumar et al, 2015;Sun et al, 2020a;Sun et al, 2020b;Wang et al, 2017). In addition to serving as a power source, biocompatible nanogenerators can also be used as a sensor, such as a pressure sensor or chemical sensor (Khandelwal et al, 2019;Kim et al, 2018b;Qian et al, 2019;Saravanakumar et al, 2015 (Saravanakumar et al, 2015).…”

“…In vitro applications of biocompatible nanogenerators require the precursor materials to be nontoxic and biocompatible. As mentioned earlier, cellulose (He et al, 2018;Kim et al, 2017b;Wang et al, 2017), silk protein (Jiang et al, 2019;Karan et al, 2018;Liu et al, 2017;Niu et al, 2020;Najjar et al, 2017), chitin (Li et al, 2019b), peptide (Yuan et al, 2019;Nguyen et al, 2016;, and biocompatible polymers have been widely explored for constructing nanogenerators for health monitoring devices or e-skin applications (Rao et al, 2020;Peng et al, 2020). Khatua et al developed a robust PENG based on biocompatible and biodegradable spider silk (Figure 10A).…”

Protein-Based Fiber Materials in Medicine: A Review

“…Silk fibroin obtained from the Bombyx mori silkworm is one of the most commonly used biomaterials due to its availability and low cost [ 29 , 79 ]. It has been shown to exhibit excellent biocompatibility, bioactivity, biodegradability, tunability, mechanical stability, and low immunogenicity, allowing silk-based fibers to be used to create tissue engineering scaffolds that allow for bone [ 82 , 83 , 84 , 85 ], cartilage [ 86 ], heart valve [ 87 ], and nerve [ 88 ] regeneration. The oxygen and water vapor permeability of silk also encourages its use in wound healing [ 25 , 89 ].…”

Thermal Conductivity of Protein-Based Materials: A Review

“…Silk is a well-known natural fiber produced by silkworms or spiders. Silk has been well studied in the past decades due to its outstanding mechanical durability, stable chemical properties and good biocompatibility [28,29]. It can be classified into wild silk and domestic silk according to the growth environment of the insects.…”