Energy absorption of muscle-inspired hierarchical structure: Experimental investigation

Tsang, Hing‐Ho; Tse, Kwong Ming; Chan, Kit‐Ying; Lu, Guoxing; Lau, Alan Kin Tak

doi:10.1016/j.compstruct.2019.111250

Cited by 51 publications

(20 citation statements)

References 24 publications

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“…In sectors such as orthopedics and the medical field, the elasticity and the biocompatibility of TPU are especially useful for biomedical research [ 19 , 24 , 25 ]. An example of this can be the research focused on the development of fully customized soles and insoles for footwear, which aims to provide a greater degree of adaptation to the particular morphological and anthropomorphic needs of the user [ 14 , 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of 3D-Printed TPU Properties for the Design of Elastic Products

2021

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The design of products with elastic properties is a paradigm for design engineers because the properties of the material define the correct functionality of the product. Fused filament fabrication (FFF) allows for the printing of products in thermoplastic polyurethanes (TPU). Therefore, it offers the ability to design elastic products with the freedom of forms that this technology allows and also with greater variation of elastic properties than with a conventional process. The internal structures and the variation in thickness that can be used facilitate the design of products with different elastic realities, producing variations in the elasticity of the product with the same material. This work studies the influence of the variation of internal density as a function of basic geometries in order to quantify the difference in elasticity produced on a product when it is designed. Likewise, a case study was carried out with the creation of a fully elastic computer keyboard printed in 3D. The specimens were subjected to compression to characterize the behavior of the structures. The tests showed that the elasticity varies depending on the orientation and geometry, with the highest compressive strength observed in the vertical orientation with 80% lightening. In addition, the internal lightening increases the elasticity progressively but not uniformly with respect to the solid geometry, and also the flat faces favour the reduction in elasticity. This study classifies the behavior of TPU with the aim of being applied to the design and manufacture of products with specific properties. In this work, a totally flexible and functional keyboard was designed, obtaining elasticity values that validate the study carried out.

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Section: Introductionmentioning

confidence: 99%

Influence of 3D-Printed TPU Properties for the Design of Elastic Products

2021

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“…Each category presents different chemical compositions and therefore produces parts with different properties. In spite of this variety of chemical alternatives, the fabrication of elastic parts from TPE has been mainly carried out using TPUs for applications such as biomedical products [ 29 , 30 , 31 , 32 ], sport equipment [ 33 ] or engineering parts [ 21 , 34 , 35 ]. More importantly, most of the studies employ commercial TPU materials without a clear understanding of the chemical structure of the material and therefore, the material contribution in the final properties of the printed part, i.e., the role of the materials chemistry has been until now neglected.…”

Section: Introductionmentioning

confidence: 99%

3D Printing of Thermoplastic Elastomers: Role of the Chemical Composition and Printing Parameters in the Production of Parts with Controlled Energy Absorption and Damping Capacity

et al. 2021

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Additive manufacturing (AM) is a disruptive technology that enables one to manufacture complex structures reducing both time and manufacturing cost. Among the materials commonly used for AM, thermoplastic elastomers (TPE) are of high interest due to their energy absorption capacity, energy efficiency, cushion factor or damping capacity. Previous investigations have exclusively focused on the optimization of the printing parameters of commercial TPE filaments and the structures to analyse the mechanical properties of the 3D printed parts. In the present paper, the chemical, thermal and mechanical properties for a wide range of commercial thermoplastic polyurethanes (TPU) filaments were investigated. For this purpose, TGA, DSC, 1H-NMR and filament tensile strength experiments were carried out in order to determine the materials characteristics. In addition, compression tests have been carried out to tailor the mechanical properties depending on the 3D printing parameters such as: infill density (10, 20, 50, 80 and 100%) and infill pattern (gyroid, honeycomb and grid). The compression tests were also employed to calculate the specific energy absorption (SEA) and specific damping capacity (SDC) of the materials in order to establish the role of the chemical composition and the geometrical characteristics (infill density and type of infill pattern) on the final properties of the printed part. As a result, optimal SEA and SDC performances were obtained for a honeycomb pattern at a 50% of infill density.

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“…In a word, to achieve the in vivo chronic detection of chemicals, the electrode materials of biosensors need to be flexible enough to minimize the inflammatory response and have high specific surface areas to incorporate functional materials efficiently. Actually, biological tissues such as muscle possess a hierarchically assembled architecture, the nanoscale fibrils are assembled into microfibrils and then into larger fibers to achieve high flexibility. , To this end, we discovered that if this architecture is assembled from one-dimensional conductive nanomaterials, it is possible to obtain flexible electrodes with high specific surface areas . Then, flexible biosensors could be fabricated by loading functional materials stably in such electrodes for chronic monitoring of chemicals in vivo .…”

Section: Introductionmentioning

confidence: 99%

Implantable Fiber Biosensors Based on Carbon Nanotubes

Feng¹,

Chen²,

Sun³

et al. 2021

Acc. Mater. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Implantable biosensors represent a rapidly developing direction with a wide range of applications in biotechnology and life science. For example, the detection of neurotransmitters in the brain has attracted a lot of attention because of their essential effects for neural activity. The in vivo acute detection of chemicals has been developed for decades, but there are few reports about in vivo chronic monitoring of chemicals probably due to two reasons. First, it is difficult to form stable interfaces between biosensors and tissues. Specifically, most of implantable biosensors are based on stiff electrode materials such as carbon fibers, whose moduli are several orders of magnitude higher than these of soft biological tissues. The mechanical mismatch between them will cause severe inflammatory response during chronic applications. Although some flexible neural probes with mesh geometry consisting of polymer and metal and polymer composite fibers have been employed in chronic electrophysiological recording, they are rarely employed for chronic monitoring of chemicals. Second, electrode deteriorations associated with degradation and fouling of functional materials make chemical recognitions difficult in dynamic environment. Generally, biosensors usually need to be modified with several functional materials including a recognition layer in order to identify specific chemicals from various untargeted chemicals. Although nanomaterials with high surface areas are reported to enhance the loading and immobilization of recognition layers so as to improve the sensitivity of biosensors, nanostructured and soft microelectrodes with high specific surface areas are rarely employed for longterm monitoring of chemicals in vivo.In this Account, we highlight our efforts toward flexible and miniaturized implantable fiber biosensors based on carbon nanotube (CNT) fibers for stable interfaces in vivo. We first summarize the assembly structure of CNT fiber electrodes and their mechanical, electrical, electrochemical, and biocompatible properties. Then we present a family of fiber biosensors by modifying CNT fibers with different recognition materials to detect multiple chemicals in vivo. After that, all-in-one fiber organic electrochemical transistors are described with higher sensitivity and lower detection limit, aiming to detect chemicals with low concentrations and trace changes in the deep brain. Finally, considering that soft implantable biosensors are difficult to be implanted without assistance, we introduce a neural probe with alterable moduli for direct implantation into the mouse brain and forming a stable interface with brain tissues. All three kinds of fiber biosensors are soft with mechanical properties matching biological tissues, remaining stable under deformation and showing high biocompatibility for long-term in vivo applications. Finally, a brief summary of challenges and outlooks in this field is presented.

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Energy absorption of muscle-inspired hierarchical structure: Experimental investigation

Cited by 51 publications

References 24 publications

Influence of 3D-Printed TPU Properties for the Design of Elastic Products

Influence of 3D-Printed TPU Properties for the Design of Elastic Products

3D Printing of Thermoplastic Elastomers: Role of the Chemical Composition and Printing Parameters in the Production of Parts with Controlled Energy Absorption and Damping Capacity

Implantable Fiber Biosensors Based on Carbon Nanotubes

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