Advanced Materials Technologies
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2024
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IF 6.4
Yunlong Gao,Shikun Lin,Chuanwei Liang,Siqi Qiu,Chengyun Long,Yingjun Wang,Yunquan Li,Yuan-Fang Zhang
Soft robots have excellent spatial adaptability and high flexibility, but they are limited by the low stiffness of their constituent materials when faced with high-load tasks. In recent years, there have been many works on the development of stiffness-tunable soft actuators by introducing variable stiffness materials into soft actuators, but the existing solutions usually suffer from the problems of slow response, complex structure, and the need of many auxiliary devices to support the completion of the stiffness tuning cycle. This paper proposes a tendon-driven stiffness-tunable soft actuator that addresses these issues. Benefiting from the bidirectional temperature control of thermoelectric modules and the excellent in-plane thermal conductivity of graphene, the actuator is capable of achieving the heating and cooling process by transferring the heat flow through the graphene structure into and out of the shape-memory polymer (SMP) layer of the tendon-driven actuator. This enables stiffness tuning via a single device, reducing the dependence on complex external cooling systems. The use of tendon-driven actuators further eliminates the complex bellow structure of conventional pneumatic actuators and dramatically reduces the size and manufacturing difficulty of individual actuators. Finally, the high load capacity and shape adaptability of the actuator are demonstrated by a gripper equipped with three actuators, which successfully grips objects of various shapes and weights, ranging from less than 10 g to up to 1.6 kg.
研究领域:
机器人学
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材料科学
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DOI
高影响因子
ADVANCED MATERIALS
·
2021
·Vol. 34
·期 10
·2107857
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IF 30.849
Dawei Zhao,Bo Pang,Ying Zhu,Wanke Cheng,Kaiyue Cao,Dongdong Ye,Chuanling Si,Guangwen Xu,Chaoji Chen,Haipeng Yu
In nature, stiffness-changing behavior is essential for living organisms, which, however, is challenging to achieve in synthetic materials. Here, a stiffness-changing smart material, through developing interchangeable supramolecular configurations inspired from the dermis of the sea cucumber, which shows extreme, switchable mechanical properties, is reported. In the hydrated state, the material, possessing a stretched, double-stranded supramolecular network, showcases a soft-gel behavior with a low stiffness and high pliability. Upon the stimulation of ethanol to transform into the coiled supramolecular configuration, it self-adjusts to a hard state with nearly 500-times enhanced stiffness from 0.51 to 243.6 MPa, outstanding load-bearing capability (over 35 000 times its own weight), and excellent puncture/impact resistance with a specific impact strength of ≈116 kJ m −2 (g cm −3 ) −1 (higher than some metals and alloys such as aluminum, and even comparable to the commercially available protective materials such as D3O and Kevlar). Moreover, this material demonstrates reconfiguration-dependent self-healing behavior and designable formability, holding great promise in advanced engineering fields that require both high-strength durability and good formability. This work may open up a new perspective for the development of self-regulating materials from supramolecular-scale configuration regulation.
研究领域:
材料科学
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生物仿生学
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超分子化学
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DOI
高影响因子
Acta Biomaterialia
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2021
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IF 8.947
Yuan Liu,Yingxin Li,Guilan Xue,Wenxiong Cao,Zhanlin Zhang,Chaomin Wang,Xiaohong Li
Geometry and mechanical property have emerged as important parameters in designing nanocarriers, in addition to their size, surface charge, and hydrophilicity . However, inconsistent and even contradictory demands regarding the shape and stiffness of nanoparticles have been noted in blood circulation, tumor accumulation, and tumor cell internalization . Herein, CaCO 3 nanorods (NRs) with an aspect ratio of around 2.4 are assembled with hyaluronic acid (HA) hydrogel layers to prepare CaCO 3 @HA NRs. The rod geometry enables lower recognition by macrophages and higher extravasation into tumor tissues than the spherical counterpart. In response to the slightly acidic tumor matrix, the acid-labile removal of CaCO 3 templates achieves shape switching into spherical HA nanocapsules (NCs). The shape switchable CaCO 3 @HA NRs show significantly higher uptake and cytotoxicities to 4T1 cells than CaCO 3 [email protected] NRs with silica layers on CaCO 3 cores to inhibit shape switching. In addition, HA NCs with 2 − 8 layers of HA hydrogels exhibit stiffness from 1.85 to 12.3 N/m, and the assembly of 4 layers shows 2- to 3-fold higher cellular uptake than those of other NCs. The shape shift satisfies long-term blood circulation of NRs, and the resulting stiffness-adjustable NCs promote tissue infiltration and intracellular accommodation, resulting in a 4-fold higher drug accumulation in tumors. The CaCO 3 @HA NR treatment significantly suppresses tumor growth; prolongs animal survival; inhibits lung metastasis; and eliminates systemic toxicities to blood, liver, kidney, and heart tissues. This study achieves a comprehensive understanding of the shape and stiffness effects and demonstrates a hierarchical targeting strategy to address the multiple delivery barriers for chemotherapeutic agents. Statement of significance The different barriers involved in the drug delivery pathway have inconsistent and even contradictory demands on the shape and stiffness of nanoparticles. In the current study, in situ switching of nanorods (NRs) into spherical nanocapsules (NCs) in tumor tissues is proposed to address these dilemmas. The NR shape ensures long-term blood circulation and high tumor tissue accumulation , while the in situ switching into NCs promotes tissue infiltration and cellular internalization. NCs with different numbers of hydrogel layers also provide a robust system wherein NC stiffness is controlled as a single variable to study stiffness-dependent cellular behaviors. Thus, this straightforward design offers a comprehensive understanding of how the shape and stiffness of nanocarriers affect their biological pathways.
研究领域:
纳米技术
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药学
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生物医学工程
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癌症研究
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产品关联
DOI
PubMed
高影响因子
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