Progress in Organ Bioprinting for Regenerative Medicine

Organ damage or failure arising from injury,disease,and aging poses challenges due to the body’s limited regenerative capabilities.Organ transplantation presents the issues of donor shortages and immune rejection risks,necessitating innovative solutions.The three-dimensional(3D)bioprinting of organs on demand offers promise in tissue engineering and regenerative medicine.In this review,we explore the state-of-the-art bioprinting technologies,with a focus on bioink and cell type selections.We follow with discussions on advances in the bioprinting of solid organs,such as the heart,liver,kidney,and pancreas,highlighting the importance of vascularization and cell integration.Finally,we provide insights into key challenges and future directions in the context of the clinical translation of bioprinted organs and their large-scale production.

Frontiers of 3D Printing/Additive Manufacturing: from Human Organs to Aircraft Fabrication

It has been more than three decades since stereolithography began to emerge in various forms of additive manufacturing and 3D printing. Today these technologies are proliferating worldwide in various forms of advanced manufacturing. The largest segment of the 3D printing market today involves various polymer component fabrications, particularly complex structures not attainable by other manufacturing methods.Conventional printer head systems have also been adapted to selectively print various speciated human cells and special molecules in attempts to construct human organs, beginning with skin and various tissue patches. These efforts are discussed along with metal and alloy fabrication of a variety of implant and bone replacement components by creating powder layers, which are selectively melted into complex forms（such as foams and other open-cellular structures） using laser and electron beams directed by CAD software. Efforts to create a ＂living implant＂ by bone ingrowth and eventual vascularization within these implants will be discussed briefly. Novel printer heads for direct metal droplet deposition as in other 3D printing systems are briefly described since these concepts will allow for the eventual fabrication of very large and complex products, including automotive and aerospace structures and components.

Interfacial engineering of printable bottom back metal electrodes for full-solution processed flexible organic solar cells

Printing of metal bottom back electrodes of flexible organic solar cells（FOSCs） at low temperature is of great significance to realize the full-solution fabrication technology. However, this has been difficult to achieve because often the interfacial properties of those printed electrodes, including conductivity, roughness, work function,optical and mechanical flexibility, cannot meet the device requirement at the same time. In this work, we fabricate printed Ag and Cu bottom back cathodes by a low-temperature solution technique named polymer-assisted metal deposition（PAMD） on flexible PET substrates. Branched polyethylenimine（PEI） and ZnO thin films are used as the interface modification layers（IMLs） of these cathodes. Detailed experimental studies on the electrical, mechanical, and morphological properties, and simulation study on the optical properties of these IMLs are carried out to understand and optimize the interface of printed cathodes. We demonstrate that the highest power conversion efficiency over 3.0% can be achieved from a full-solution processed OFSC with the device structure being PAMDAg/PEI/P3 HT：PC61BM/PH1000. This device also acquires remarkable stability upon repeating bending tests.

Microfibrillated Cellulose Based Ink for Eco-Sustainable Screen Printed Flexible Electrodes in Lithium Ion Batteries

Free organic solvent ink containing graphite, carboxymethyl cellulose and microfibrillated cellulose as active material, dispersing and binder, respectively, has been formulated to produce flexible and eco- sustainable electrodes for lithium ion batteries. Content ratio of components and dispersion protocol were tailored in order to have theological properties suitable for a large and cheap manufacturing process as well as screen printing. The bio-sourced printed electrodes exhibit a high porosity value of 70% that limits the electrochemical performances. However, the calendering process enhances electrode performances by increasing the reversible capacity from 85 until 315 mAh/g and reducing porosity to an optimal value of 34%. Moreover the introduction of 2% w/w of monofluoro-ethylene carbonate in the electrolyte reduced their reversible capacity loss of 11% in the printed electrode.