Table 1 Comparison of responsive materials applied in TFAs
TFA type | Responsive materials | Favorable material properties | Fabrication processes |
|---|---|---|---|
Thermo-driven | • PDMS • Shape memory alloys • Graphene • MXene | • High thermal stability • High flexibility • High ductility • High thermal expansion coefficient | • Casting • Molding • Direct bonding • PVD/CVD |
Electro-driven | • Conductive carbon materials • Dielectric elastomers • Ionic polymer-metal composites | • High electrical conductivity • High dielectric constant • High thermal stability • Fast response | • Lamination • Electrospinning • Casting • Molding |
Light-driven | • Graphene • Carbon nanotubes (CNTs) • Liquid crystal elastomers (LCEs) • Azobenzene-based polymer | • High photothermal conversion efficiency • Photo-reactivity • Wavelength selectivity • High light transmittance | • Vacuum filtration • Casting • Coating • Self-assembly |
Humidity-driven | • Graphene oxide • Carbon nanotubes (CNTs) • MXene • Cellulose • Sodium alginate | • High hygroscopic stability • High flexibility • High hygroscopic expansion coefficient • Water diffusivity | • Vacuum filtration • Hot pressing • Chemical cross-linking |
Chemical-driven | • Polyacrylate • Polyamino acids • PVDF | • High pH or chemical vapor sensitivity • Reversibility • High chemical stability | • Casting • Electrospinning • Chemical cross-linking |
