Triboelectric nanogenerator
The present disclosure relates to a novel triboelectric nanogenerator comprising a novel polyvinyl alcohol (PVA)-based biocompatible polymer. The novel polyvinyl alcohol-based biocompatible polymer comprises a blending product of a mixture comprising a polyvinyl alcohol, a gelatin, and an optional salt. The polyvinyl alcohol-based biocompatible polymer is a substantially transparent film.
1 . A triboelectric nanogenerator comprising:
a polyvinyl alcohol (PVA)-based biocompatible polymer, wherein the polyvinyl alcohol-based biocompatible polymer comprises a blending product of a mixture comprising a polyvinyl alcohol, a gelatin, and a salt, wherein the gelatin is provided in an amount effective to disrupt PVA crystalline domains;
a friction layer including a material more negative in a triboelectric series than the PVA-based biocompatible polymer; and
metal electrodes coupling the polyvinyl alcohol (PVA)-based biocompatible polymer and the friction layer, and when the polyvinyl alcohol (PVA)-based biocompatible polymer is brought into contact with the friction layer, the difference from triboelectric polarities on the polyvinyl alcohol (PVA)-based biocompatible polymer and the friction layer leads to electrons flowing between the polyvinyl alcohol (PVA)-based biocompatible polymer and the friction layer;
wherein a concentration of the gelatin and the salt are provided to tune both interfacial polarization and ionic polarization so as to increase a dielectric constant of the PVA blend relative to pure PVA.
2 . The triboelectric nanogenerator of claim 1 , wherein the polyvinyl alcohol (PVA)-based biocompatible polymer comprises a blending product of a mixture comprising the polyvinyl alcohol, the gelatin, and the salt, wherein the salt comprises NaCl, KCl, or a combination thereof, and wherein the weight percentage of the salt is 0.5-1.3 wt. % of the total weight of the polyvinyl alcohol (PVA)-based biocompatible polymer, and the salt forms complexes with hydroxyl groups of PVA that reduce hydrogen-bond density and increase dipolar reorientation mobility.
3 . The triboelectric nanogenerator of claim 1 , wherein the polyvinyl alcohol (PVA)-based biocompatible polymer comprises 1-20 wt. % of the gelatin.
4 . The triboelectric nanogenerator of claim 1 , wherein the polyvinyl alcohol (PVA)-based biocompatible polymer is a substantially transparent film.
5 . The triboelectric nanogenerator of claim 1 , wherein the molecular weight of the polyvinyl alcohol is 100,000 to 250,000, and the molecular weight of the gelatin is 10,000 to 150,000.
6 . The triboelectric nanogenerator of claim 1 , wherein the polyvinyl alcohol (PVA)-based biocompatible polymer is a neutral material with pH range of 6.5-7.5.
7 . The triboelectric nanogenerator of claim 6 , wherein the polyvinyl alcohol (PVA)-based biocompatible polymer is a neutral material with pH value of about 7.
8 . The triboelectric nanogenerator of claim 1 , wherein the polyvinyl alcohol (PVA)-based biocompatible polymer has a dielectric constant range of 8-20.
9 . The triboelectric nanogenerator of claim 1 , wherein the friction layer comprises polyimide, polytetrafluoroethylene, polydimethylsiloxane, polyvinyl chloride, polypropylene (PP), or a metal.
10 . The triboelectric nanogenerator of claim 1 , wherein the PVA blend is processed to yield a crystalline grain size smaller than that of pure PVA, thereby increasing interfacial polarization area.
11 . The triboelectric nanogenerator of claim 1 , wherein a coil size of the PVA blend is adjusted by controlling at least one of:
gelatin loading to produce a maximum coil size at an intermediate concentration;
pH to maximize coil size at about pH 7; and
cation type and concentration to control chain entanglement density.
12 . The triboelectric nanogenerator of claim 1 , wherein the triboelectric nanogenerator is adhered to skin and generates output signals in response to imperceptible skin deformations, the signals being processed to produce cardiovascular diagnostic indices.