Micro-nano-fabrication of green functional materials by multiphase microfluidics for environmental and energy applications

Multiphase microfluidic has emerged as a powerful platform to produce novel materials with tailor-designed functionalities,as microfluidic fabrication provides precise controls over the size,component,and structure of resultant materials.Recently,functional materials with well-defined micro-/nanostructures fabricated by microfluidics find important applications as environmental and energy materials.This review first illustrated in detail how different structures or shapes of droplet and jet templates are formed by typical configurations of microfluidic channel networks and multiphase flow systems.Subsequently,recent progresses on several representative energy and environmental applications,such as water purification,water collecting and energy storage,were overviewed.Finally,it is envisioned that integrating microfluidics and other novel materials will play increasing important role in contributing environmental remediation and energy storage in near future.

Instability-Driven 3D bioprinting for engineering composite bio-inks

Extrusion-based 3D bioprinting techniques are revolutionizing bioengineering by facilitating the creation of com-plex 3D microstructures.This review offers a thorough overview of extrusion-based 3D bioprinting methods,par-ticularly highlighting the innovative electric-assisted coil-write 3D bioprinting technology.The review begins by explicating the fundamental principles underlying various extrusion-based 3D bioprinting technologies.It covers the printing equipment composition,suitable materials for 3D bioprinting,and the latest breakthroughs in tech-nology.A critical aspect of this review is the in-depth comparison of the strengths and weaknesses associated with each 3D bioprinting approach.The electro-microfluidic extrusion method and the electric-assisted coil-write 3D bioprinting technology are highlighted.This advanced technology successfully overcomes the limitations of conventional extrusion-based methods,notably in the precise printing of intricately curved line structures with high resolution and speed.This method ingeniously integrates mechanical motion for creating microscale features with electrical coiling for sub-micron details,thus achieving remarkable printing speeds and structural complex-ity.This review concludes by exploring the potential applications and future advancements of this state-of-the-art technology.It underscores the ability of electric-assisted coil-write 3D bioprinting to develop pioneering materials and micro-devices for a variety of technological sectors,highlighting its transformative impact in bioengineering.

Regulation of extracellular bioactive cations in bone tissue microenvironment induces favorable osteoimmune conditions to accelerate in situ bone regeneration

The design of orthopedic biomaterials has gradually shifted from“immune-friendly”to“immunomodulatory,”in which the biomaterials are able to modulate the inflammatory response via macrophage polarization in a local immune microenvironment that favors osteogenesis and implant-to-bone osseointegration.Despite the well-known effects of bioactive metallic ions on osteogenesis,how extracellular metallic ions manipulate immune cells in bone tissue microenvironments toward osteogenesis and subsequent bone formation has rarely been studied.Herein,we investigate the osteoimmunomodulatory effect of an extracellular bioactive cation(Mg^(2+))in the bone tissue microenvironment using custom-made poly lactic-co-glycolic acid(PLGA)/MgO-alendronate microspheres that endow controllable release of magnesium ions.The results suggest that the Mg^(2+)-controlled tissue microenvironment can effectively induce macrophage polarization from the M0 to M2 phenotype via the enhancement of anti-inflammatory(IL-10)and pro-osteogenic(BMP-2 and TGF-β1)cytokines production.It also generates a favorable osteoimmune microenvironment that facilitates the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells.The in vivo results further verify that a large amount of bony tissue,with comparable bone mineral density and mechanical properties,has been generated at an early post-surgical stage in rat intramedullary bone defect models.This study demonstrates that the concept of in situ immunomodulated osteogenesis can be realized in a controlled magnesium tissue microenvironment.

Bone-inspired(GNEC/HAPAAm)hydrogel with fatigue-resistance for use in underwater robots and highly piezoresistive sensors

A novel bone-inspired fatigue-resistant hydrogel with excellent mechanical and piezoresistive properties was developed,and it exhibited great potential as a load and strain sensor for underwater robotics and daily monitoring.The hydrogel was created by using the high edge density and aspect ratio of graphene nanosheet-embedded carbon(GNEC)nanomaterials to form a three-dimensional conductive network and prevent the expansion of microcracks in the hydrogel system.Multiscale progressive enhancement of the organic hydrogels(micrometer scale)was realized with inorganic graphene nanosheets(nanometer scale).The graphene nanocrystals inside the GNEC film exhibited good electron transport properties,and the increased distances between the graphene nanocrystals inside the GNEC film caused by external forces increased the resistance,so the hydrogel was highly sensitive and suitable for connection to a loop for sensing applications.The hydrogels obtained in this work exhibited excellent mechanical properties,such as tensile properties(strain up to 1685%)and strengths(stresses up to 171 kPa),that make them suitable for use as elastic retraction devices in robotics and provide high sensitivities(150 ms)for daily human monitoring.

Ultrasoft,sensitive fiber-like sensor by assembly of bacterial cellulose(BC)nanofibrils and BC molecules for biocompatible strain sensing

The development of implantable bioelectronics is driven by emerging applications including continuous health monitoring and human-machine interfacing.The mechanical mismatch between implanted bioelectronics and tissues not only compromises device accuracy,but also causes interference with tissues undesirably.To address this issue,it is necessary to develop ultrasoft and biocompatible fiber strain sensor with proper stretchability and sensitivity.Here,we fabricate a bacterial cellulose-based sensing fiber which possesses the stretchability and elastic modulus(~102 kPa)close to those of soft tissues.In addition,such fiber has high sensitivity to tiny tensile force/strain(8.8×10^(−3)N/2.5%)and low cell cytotoxicity.These excellent properties make the bacterial cellulose(BC)-based sensing fiber an excellent candidate of implantable bioelectric devices for monitoring subtle motions of organs.We demonstrate this by applying it for continuous monitoring of human pulse and bullfrog heartbeats.The(BC/oxBC)@PANI(ox=oxidized and PANI=polyaniline)fibers can further be woven into an array sensor and serve more complex sensing functions,such as multipoint force perception and shape recognition as demonstrated.

Digital light processing 3D printing for microfluidic chips with enhanced resolution via dosing-and zoning-controlled vat photopolymerization

Conventional manufacturing techniques to fabricate microfluidic chips,such as soft lithography and hot embossing process,have limitations that include difficulty in preparing multiple-layered structures,cost-and labor-consuming fabrication process,and low productivity.Digital light processing(DLP)technology has recently emerged as a costefficient microfabrication approach for the 3D printing of microfluidic chips;however,the fabrication resolution for microchannels is still limited to sub-100 microns at best.Here,we developed an innovative DLP printing strategy for high resolution and scalable microchannel fabrication by dosing-and zoning-controlled vat photopolymerization(DZC-VPP).Specifically,we proposed a modified mathematical model to precisely predict the accumulated UV irradiance for resin photopolymerization,thereby providing guidance for the fabrication of microchannels with enhanced resolution.By fine-tuning the printing parameters,including optical irradiance,exposure time,projection region,and step distance,we can precisely tailor the penetration irradiance stemming from the photopolymerization of the neighboring resin layers,thereby preventing channel blockage due to UV overexposure or compromised bonding stability owing to insufficient resin curing.Remarkably,this strategy can allow the preparation of microchannels with cross-sectional dimensions of 20μm×20μm using a commercial printer with a pixel size of 10μm×10μm;this is significantly higher resolution than previous reports.In addition,this method can enable the scalable and biocompatible fabrication of microfluidic drop-maker units that can be used for cell encapsulation.In general,the current DZC-VPP method can enable major advances in precise and scalable microchannel fabrication and represents a significant step forward for widespread applications of microfluidics-based techniques in biomedical fields.

Gas marbles: ultra-long-lasting and ultra-robust bubbles formed by particle stabilization

Bubbles and foams are ubiquitous in daily life and industrial processes.Studying their dynamic behaviors is of key importance for foam manufacturing processes in food packaging,cosmetics and pharmaceuticals.Bare bubbles are inherently fragile and transient;enhancing their robustness and shelf lives is an ongoing challenge.Their rupture can be attributed to liquid evaporation,thin film drainage and the nuclei of environmental dust.Inspired by particle-stabilized interfaces in Pickering emulsions,armored bubbles and liquid marble,bubbles are protected by an enclosed particle-entrapping liquid thin film,and the resultant soft object is termed gas marble.The gas marble exhibits mechanical strength orders of magnitude higher than that of soap bubbles when subjected to overpressure and underpressure,owing to the compact particle monolayer straddling the surface liquid film.By using a water-absorbent glycerol solution,the resulting gas marble can persist for 465 d in normal atmospheric settings.This particle-stabilizing approach not only has practical implications for foam manufacturing processes but also can inspire the new design and fabrication of functional biomaterials and biomedicines.

Turning liquid metals into elastic ropes

Liquid metals are a class of metals that are fluids at room temperature. They have surface tension, that is approximately an order of magnitude higher than that of water, owing to the high surface energy of metals. The ultra-high surface tension creates a stream of liquid metal droplets to minimize surface energy, and therefore, creating other shapes is difficult. Enormous efforts have been made to manipulate liquid metals into various shapes and patterns, and are driven by emerging opportunities for soft.