A new type of sheet porous structures with functionally gradients based on triply periodic minimal surfaces (TPMS) is proposed for designing bone scaffolds. The graded structures were generated by constructing branched features with different number of sheets. The design of the structure was formulated mathematically and five types of porous structure with different structural features were used for investigation. The relative density (RD) and surface area to volume (SA/V) ratio of the samples were analyzed using a slice-based approach to confirm their relationships with design parameters. All samples were additively manufactured using selective laser melting (SLM), and their physical morphologies were observed and compared with the designed models. Compression tests were adopted to study the mechanical properties of the proposed structure from the obtained stress–strain curves. The results reveal that the proposed branched-sheet structures could enhance and diversify the physical and mechanical properties, indicating that it is a potential method to tune the biomechanical properties of porous scaffolds for bone tissue engineering (TE).

Liquid metal droplets immersed in an alkaline electrolyte undergo various deformations and movements after a driving voltage is applied. However, interference with the electrolyte severely restricts further applications. In this study, a novel approach using the Marangoni effect is introduced to control the actuation of the liquid metal and overcome existing limitations. First, the linear movement of the liquid metal droplets on various substrates, including paper and cloth saturated with an NaOH solution and glass wetted with an NaOH solution, is characterized. The reciprocating movement can be precisely controlled by modulating the amplitude and the frequency of the driving voltage. In addition, the liquid metal droplet can move along an NaOH solution path with complex shapes and have a self-correction ability to move along the desired route. Finally, the unique actuation of the liquid metal droplet based on the Marangoni effect is applied to electronic switches and microvalves. The experimental results show that the liquid metal droplets using the Marangoni effect open new avenues for soft actuators.

The rapid development of stretchable electronics made by circuits, microchips, and encapsulation elastomers has caused the production of a large amount of electronic waste (e‐waste). The degradation of elastomers can highly minimize the negative effects of e‐wastes. However, chemicals that included acid, alkali, and organics were repeatedly used during the recycling process, which were environmentally unfriendly. Here, a water‐modulation‐degradation‐reconstruction (WDR) polyvinylpyrrolidone (PVP)‐honey composite (PHC) polymer‐gel was developed and could be regarded as encapsulation elastomers to realize a fully recyclable water‐degradable stretchable (WS) electronics with multi‐functions. The stretchability of the PHC polymer‐gel could be modulated by the change of its water retention. The Chip‐integrated liquid metal (LM) circuits encapsulated with the modulated PHC encapsulation elastomer could withstand a strain value of ~3000%. Moreover, we developed a WS biomedical sensor composed of PHC encapsulation elastomer, LM circuits, and microchips, which could be fully recycled by biodegrading it in water to reconstruct a new one. As before, the reconstructed WS biomedical sensor could still simultaneously realize the combination of ultra‐stretchability, recycling, self‐healing, self‐adhesive, and self‐conformal abilities. The results revealed that this study exercises a profound influence on the rational design of multi‐functional WS electronics.

Stretchable electronics have the unique capability of 3D (three dimensional) deformation, overcoming the brittleness of traditional inorganic electronics. However, during large deformations, different scale strains between the rigid and stretchable components lead to mismatch, causing interconnect failures. Therefore, the development of the rigidity‐programmable substrate with effective strain shielding capabilities has become a research hotspot. Furthermore, the exponential growth in electronic density presents challenges in the circuit design of stretchable electronics. The urgent need is to develop highly integrated stretchable electronic systems. In this study, a highly integrated stretchable pulse sensor with effective strain shielding capabilities using hybrid 3D printing technology is developed, which comprises electronic chips, a rigidity‐programmable substrate/encapsulation layer printed by using PSC (polydimethylsiloxane/silica‐nanoparticles composite)‐based ink, and LM (liquid metal)‐based 3D circuits. First, the PSC‐based ink is optimized to enhance the strain shielding effectiveness of the rigidity‐programmable substrate. Meanwhile, 3D printing parameters are optimized to achieve high printing precision with minimum line widths below 100 µm. The resulting stretchable pulse sensor demonstrated good mechanical and electrical stability under complex 3D deformations, including bending, twisting, and stretching. The PSC region strain of the sensor is only ≈2% when the global strain is up to ≈65%, which exhibited effective strain shielding capabilities.