Additive manufacturing (AM) is a current technology undergoing rapid development that is utilized in a wide variety of applications. In the field of biological and bioinspired materials, additive ...manufacturing is being used to generate intricate prototypes to expand our understanding of the fundamental structure–property relationships that govern nature's spectacular mechanical performance. Herein, recent advances in the use of AM for improving the understanding of the structure–property relationship in biological materials and for the production of bioinspired materials are reviewed. There are four essential components to this work: a) extracting defining characteristics of biological designs, b) designing 3D‐printed prototypes, c) performing mechanical testing on 3D‐printed prototypes to understand fundamental mechanisms at hand, and d) optimizing design for tailorable performance. It is intended to highlight how the various types of additive manufacturing methods are utilized, to unravel novel discoveries in the field of biological materials. Since AM processing techniques have surpassed antiquated limitations, especially with respect to spatial scales, there has been a surge in their demand as an integral tool for research. In conclusion, current challenges and the technical perspective for further development of bioinspired materials using AM are discussed.
How a diverse range of additive manufacturing (AM) techniques is used to develop bioinspired structures to better understand the governing mechanisms of biological materials is highlighted. AM can generate intricate structures, such as layered, hierarchical, suture, articulated, helical, cellular, shape morphing, and structured surfaces. Mechanical testing of these prototypes reveals the contribution of the structure to their properties and performance.
Recently, electronic skin and smart textiles have attracted considerable attention. Flexible sensors, as a kind of indispensable components of flexible electronics, have been extensively studied. ...However, wearable airflow sensors capable of monitoring the environment airflow in real time are rarely reported. Herein, by mimicking the spider's fluff, an ultrasensitive and flexible all‐textile airflow sensor based on fabric with in situ grown carbon nanotubes (CNTs) is developed. The fabric decorated with fluffy‐like CNTs possesses exceptionally large contact area, endowing the airflow sensor with superior properties including ultralow detection limit (≈0.05 m s−1), multiangle airflow differential response (0°–90°), and fast response time (≈1.3 s). Besides, the fluffy fabric airflow sensor can be combined with a pristine fabric airflow sensor to realize highly sensitive detection in a wide airflow range (0.05–7.0 m s−1). Its potential applications including transmitting information according to Morse code by blowing the sensors, monitoring increasing and decreasing airflow velocity, and alerting blind people walking outside about potential hazard induced by nearby fast‐moving objects are demonstrated. Furthermore, the airflow sensor can be directly integrated into clothing as stylish designs without sacrificing comfortness. It is believed that the ultrasensitive all‐textile airflow sensor holds great promise for applications in smart textiles and wearable electronics.
Inspired by the spider's fluffy hair, an ultrasensitive and flexible all‐textile airflow sensor is fabricated based on a fluffy fabric with in situ grown hair‐like carbon nanotubes on a silk fabric. The airflow sensor shows high sensitivity, ultralow detection limit, multi‐angle airflow detection capability, fast response, and wide detection range, promising wide potential applications in wearable electronics.
A simplified prototype device of high‐performance all‐solid‐state supercapacitors (ASSSs) based on 3D nitrogen and boron co‐doped monolithic graphene aerogels (BN‐GAs) is demonstrated for the first ...time. The resulting ASSSs show high specific capacitance, good rate capability, and enhanced energy density or power density.
Novel β‐NaGdF4/Na(Gd,Yb)F4:Er/NaYF4:Yb/NaNdF4:Yb core/shell 1/shell 2/shell 3 (C/S1/S2/S3) multi‐shell nanocrystals (NCs) have been synthesized and used as probes for in vivo imaging. They can be ...excited by near‐infrared (800 nm) radiation and emit short‐wavelength infrared (SWIR, 1525 nm) radiation. Excitation at 800 nm falls into the “biological transparency window”, which features low absorption by water and low heat generation and is considered to be the ideal excitation wavelength with the least impact on biological tissues. After coating with phospholipids, the water‐soluble NCs showed good biocompatibility and low toxicity. With efficient SWIR emission at 1525 nm, the probe is detectable in tissues at depths of up to 18 mm with a low detection threshold concentration (5 nM for the stomach of nude mice and 100 nM for the stomach of SD rats). These results highlight the potential of the probe for the in vivo monitoring of areas that are otherwise difficult to analyze.
A multi‐shell nanocrystal was synthesized and used as an effective probe for in vivo imaging. With emission in the short‐wavelength infrared region at 1525 nm, the probe is detectable in tissues at depths of up to 18 mm with a low detection threshold.
There is a specialized niche for the electrohydrodynamic jetting of melts, from biomedical products to filtration and soft matter applications. The next frontier includes optics, microfluidics, ...flexible electronic devices, and soft network composites in biomaterial science and soft robotics. The recent emphasis on reproducibly direct‐writing continual molten jets has enabled a spectrum of contemporary microscale 3D objects to be fabricated. One strong suit of melt processing is the capacity for the jet to solidify rapidly into a fiber, thus fixing a particular structure into position. The ability to direct‐write complex and multiscaled architectures and structures has greatly contributed to a large number of recent studies, explicitly, toward fiber–hydrogel composites and fugitive inks, and has expanded into several biomedical applications such as cartilage, skin, periosteum, and cardiovascular tissue engineering. Following the footsteps of a publication that summarized melt electrowriting literature up to 2015, the most recent literature from then until now is reviewed to provide a continuous and comprehensive timeline that demonstrates the latest advances as well as new perspectives for this emerging technology.
The developments in melt electrospinning and melt electrowriting over the past 4 years are comprehensively reviewed to provide insight into this burgeoning field. The improvements in electrified jet control bring the technology to a stage where discrete structures can be designed to impart unique properties on such 3D‐printed products.
The cartilage and skin of animals, which are made up of more than fifty per cent water, are rather stiff (having elastic moduli of up to 100 megapascals) as well as tough and hard to break (with ...fracture energies of up to 9,000 joules per square metre). Such features make these biological materials mechanically superior to existing synthetic hydrogels. Lately, progress has been made in synthesizing tough hydrogels, with double-network hydrogels achieving the toughness of skin and inorganic-organic composites showing even better performance. However, these materials owe their toughness to high stretchability; in terms of stiffness, synthetic hydrogels cannot compete with their natural counterparts, with the best examples having elastic moduli of just 10 megapascals or less. Previously, we described the enzyme-induced precipitation and crystallization of hydrogels containing calcium carbonate, but the resulting materials were brittle. Here we report the enzyme-induced formation of amorphous calcium phosphate nanostructures that are homogenously distributed within polymer hydrogels. Our best materials have fracture energies of 1,300 joules per square metre even in their fully water-swollen state-a value superior to that of most known water-swollen synthetic materials. We are also able to modulate their stiffness up to 440 megapascals, well beyond that of cartilage and skin. Furthermore, the highly filled composite materials can be designed to be optically transparent and to retain most of their stretchability even when notched. We show that percolation drives the mechanical properties, particularly the high stiffness, of our uniformly mineralized hydrogels.
By imitating the exceptional compositions, structures, formations and functions of biological or natural materials, a myriad of biomimetic and bioinspired membranes have been designed and prepared ...using cell membrane, lotus, mussel as representative prototypes and biomineralization, bioadhesion, self-assembly as major tools. These membranes have displayed fascinating properties and outstanding performances such as multiple interactions, hierarchical organizations, multiple selective transport mechanisms, superior stability/resistance and distinct adaptability. Meanwhile, these membranes have made tremendous contributions in coping with energy and water stress, environment threats. Biomimetics focuses on the basic science by fundamentally exploring the principles of biological systems, while bioinspiration focuses on the applied engineering by technologically implementing the principles from biological systems. Biomimetics and bioinspiration, as the complementary and interchangeable strategies for sustainable innovation and development of membrane technology, have great implications in exploring membrane materials and intensifying membrane processes. This review will present a brief overview on the prototypes, preparation, application as well as perspective of biomimetic and bioinspired membranes.
We overcome two of the most daunting challenges in single-particle diffractive imaging: collecting many high-quality diffraction patterns on a small amount of sample and separating components from ...mixed samples. We demonstrate this on carboxysomes, which are polyhedral cell organelles that vary in size and facilitate up to 40% of Earth's carbon fixation. A new aerosol sample-injector allowed us to record 70,000 low-noise diffraction patterns in 12 min with the Linac Coherent Light Source running at 120 Hz. We separate different structures directly from the diffraction data and show that the size distribution is preserved during sample delivery. We automate phase retrieval and avoid reconstruction artefacts caused by missing modes. We attain the highest-resolution reconstructions on the smallest single biological objects imaged with an X-ray laser to date. These advances lay the foundations for accurate, high-throughput structure determination by flash-diffractive imaging and offer a means to study structure and structural heterogeneity in biology and elsewhere.
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