Fig. 1 Schematic of a typical water-triggered shape memory process. F s and F d denote the elastic deformation gradient of sparse and dense phases, respectively; F f denotes the frozen deformation gradient. More

Fig. 2 Relationship between the dense volume fraction ϕ d and normalized chemical potential μ ^ ; μ ^ r denotes the reference normalized chemical potential at the phase transformation center More

Fig. 3 Schematics of three types of shape memory cycles of water-trigger shape memory effects, including free-recovery process, fixed-recovery process 1, and fixed-recovery process 2 More

Fig. 4 General schematics of the stress-stretch-normalized chemical potential ( σ − λ − μ ^ ) relationship for ( a ) free-recovery process, ( b ) fixed-recovery process 1, and ( c ) fixed-recovery process 2 More

Fig. 5 Validation of the accuracy of the FEM implementation by comparing with analytical results in different processes: ( a ) stress–chemical potential relationship in the constraint-dehydrating process; ( b ) stretch–chemical potential relationship in the free-recovery process; ( c ) stress–chem... More

Fig. 6 Schematic of a self-bending bilayer structure More

Fig. 7 Comparison of simulation and experimental results of a self-bending bilayer structure. Simulated results: ( a ) and ( b ); experimental results: ( c ) and ( d ). The bilayer structure (( a ) and ( c )) will bend itself into an arch (( c ) and ( d )) when hydrating. The scale bar is 1.0 cm. More

Fig. 8 Simulated and experimental results of a gripper structure during the shape memory cycle for water-triggered SMH, ( a )—( d ) simulated results; ( e )—( f ) experimental results. ( a ) and ( e ) initial shape at high water content; ( b ) and ( f ) programed shape at high water content; ( c )... More

Fig. 1 Strain sensor based on the ISSFS: ( a ) exploded view of the strain sensor, ( b ) bending and twisting of a fabricated strain sensor, ( c ) FEA and experimental results shown in the top view for an ISSFS in the initial state and stretched by 30% applied strain (inset: enlarged view of maxim... More

Fig. 2 Theoretical analysis of the ISSFS: ( a ) Mechanical model of the ISSFS under stretch. ( b ) Effects of dimensionless parameters R / w 1 on the elastic range. ( c ) Effects of dimensionless parameters θ on the elastic range. ( d ) Effects of dimensionless parameters L 1 / w 1 on the... More

Fig. 3 Mechanical and electrical characterization of the strain sensors based on the ISSFS: ( a ) Relative resistance change of the sensor versus the applied strain under five consecutive loading–unloading cycles. ( b ) Change of the dimensionless output voltage under 0.5%-stepped applied strain (... More

Fig. 4 ( a ) Optical image of a strain sensor with the TSS. ( b ) The maximal principal strain distribution of part of the ISSFS and the TSS. ( c ) Relative resistance changes of the ISSFS and the TSS versus the applied strain under five consecutive loading–unloading cycles with 5% applied strain.... More

Fig. 5 ( a ) Illustration of the potential sensing locations and corresponding motions in human body. ( b ) Electrical signals of the repetitive motion of the neck. ( c ) Electrical signals of respiration at two different frequencies. ( d ) Electrical signals of the extension and bending of the kn... More