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Cross-coupling among the domino coils complicates the energy flow paths and prevents the multiload constant outputs in wireless power transfer (WPT) system. To overcome this problem, the current phase of the domino coils is first analyzed so that the impedance relationship of cross-coupling in its corresponding coil loop is found. The analytical formula for computing the resonant compensation capacitance is then derived according to the current phase configuration with 90 degrees of decline gradient. It can achieve the load-independent zero phase angle and constant outputs simultaneously in a single-energy flow transmission mode. Then the domino coils are further extended to the transmission mode with multienergy flow paths that can be planned by configuring the current phase. Finally, a general capacitance calculation method is proposed for different energy flow path planning. Prototypes of seven-coil domino system and six-coil domino system are constructed. Experimental results show that seven-coil domino system with the single energy flow path achieves the constant voltage of 29.55 V and a dc–dc efficiency of 83.69%. Six-coil WPT system also has the constant outputs of 21.34 V and 32.31 V by planning the dual energy flow paths, with a dc–dc efficiency of 79.68%.

Domino-coils wireless power transfer (WPT) technology has emerged as an effective means of ensuring reliable power supply for online monitoring equipment in smart grid. Nonetheless, it encounters persistent challenges when integrating domino-coils into composite insulators, notably the issues of large coil size and low power transmission efficiency (PTE) over medium and long distances. In response, this article constructs a T equivalent model of domino-coils WPT system to deduce the optimal efficiency condition for any number of coils. Specifically, it is determined that PTE is maximized when the current ratio of nonadjacent coils equals the mutual inductance ratio of adjacent coils. Building upon this insight and considering practical constraints such as coil volume and transmission distance, an optimization model is formulated for single-layer domino-coils with uniform spacing under the optimal efficiency condition and given output power specification, which is subsequently determined using a particle swarm algorithm. Experimental validation is conducted utilizing a seven-coil system experiment platform, achieving an output power of 12.23 W and a PTE of 85.94% at a transmission distance of 50 cm. These findings demonstrate significant enhancements in PTE, coil volume reduction, and ease of integration into thin and uniformly distributed insulator.

Despite impressive advances achieved in poly(3‐alkylthiophene)s (P3ATs) and P3AT‐based block copolymers (BCPs), the investigation into their ortho‐connected systems, poly(5‐alkylthiophene)s (P5ATs) and P5AT‐based BCPs is rather limited. Moreover, the aggregation behavior of P5ATs and their BCPs remains largely less understood. Herein, we report, for the first time, the judicious design and synthesis of a family of poly(5‐butylthiophene)‐block‐poly(5‐hexylthiophene) (P5BT‐b‐P5HT) BCPs with adjustable block ratios and reveal the effects of block ratios and thermal annealing process on their aggregated structures. Moreover, the optical properties of P5BT‐b‐P5HT BCPs have been investigated, which differs greatly from P3ATs. Overall, this work offers valuable insight into the aggregation and optical properties of P5AT‐based BCPs, strengthening our fundamental understanding of ortho‐connected P5AT systems.

Leveraging the instability in bistable structures to rapidly release the stored energy is often observed in nature to improve survival and reproduction. Bistable actuators have endowed soft grippers with superior performances such as fast response and self-lock ability. However, current bistable grippers are merely determined by their structural parameters in the design processes, and their grasping modes are usually restricted. In this article, we propose a novel type of reprogrammable bistable actuators. We introduce the design, modeling, and verification of the actuators. The results show that when reprogrammed to its ultrasensitive state with a minimal energy barrier, the trigger force required to induce the fast snap-through can be reduced to less than 0.005 times of its maximum value. In this process, only a minimal energy of 0.001 mJ was needed to trigger the fast energy release of 13.1 mJ. To demonstrate the advances and uniqueness of the proposed actuator, we also prototyped multiple grippers for multimodal, fast, and ultrasensitive grasping. In the ultrasensitive state, the gripper was able to respond to the contact of the swimming fish and capture it in 0.18 s. This work broadens the frontiers of bistable actuators in the design of functional robotic grippers.

According to clinical studies, upper limb robotic suits are vital to reduce therapist fatigue and accelerate patient rehabilitation. Soft pneumatic actuators have drawn increasing attention for the development of wearable robots due to their low weight, flexibility, and high power-to-weight ratio. However, most of current actuators were designed for the flexion assistance of a specific joint, and that for joint extension requires further investigation. Furthermore, designing an actuator for diverse working scenarios remains a challenge. In this paper, we propose an all-fabric bi-directional actuator to assist the flexion and extension of the elbow, wrist, and fingers. A mathematical model is presented that predicts the deformation and guides the design of the proposed bi-directional actuator. To further validate the applicability and adaptability of the proposed actuator for different joints, we developed a 3-DOF soft robotic suit. Preliminary results show that the robotic suit can assist the motion of the elbow, wrist, and finger of the subject.

ABSTRACTCartilage tissue engineering is a promising option for repairing cartilage defects, although harvesting a large number of seeding cells remains a major challenge. Cartilage stem/progenitor cells (CSPCs) seem to be a promising cell source. Hypoxic extracellular vesicles (EVs) may play a major role in cell-cell and tissue-tissue communication. In the current study, we aimed to evaluate the effect of hypoxic adipose-derived stem cells (ADSCs)-derived EVs on CSPCs proliferation and differentiation. The characteristics of ADSCs-derived EVs were identified, and proliferation, migration, and cartilage-related gene expression of CSPCs were measured with or without the presence of hypoxic ADSCs-derived EVs. SEM, histological staining, biochemical and biomechanical analysis was performed to evaluate the effect of hypoxic ADSCs-derived EVs on CSPCs in alginate hydrogel culture. The results indicated that the majority of ADSC-derived EVs exhibited a round-shaped or cup-shaped morphology with a diameter of 40–1000 nm and expressed CD9, CD63, and CD81. CSPCs migration and proliferation were enhanced by hypoxic ADSCs-derived EVs, which also increased the expression of cartilage-related genes. The hypoxic ADSCs-derived EVs induce CSPCs to produce significantly more cartilage matrix and proteoglycan. In conclusion, hypoxic ADSCs-derived EVs improved the proliferation and chondrogenic differentiation of CSPCs for cartilage tissue engineering.

Supplemental Digital Content is available in the text.Coding Perspective for this Article is on Page 172.