Sustainable electronic textiles towards scalable commercialization.

Textiles represent a fundamental material format that is extensively integrated into our everyday lives. The quest for more versatile and body-compatible wearable electronics has led to the rise of electronic textiles (e-textiles). By enhancing textiles with electronic functionalities, e-textiles define a new frontier of wearable platforms for human augmentation. To realize the transformational impact of wearable e-textiles, materials innovations can pave the way for effective user adoption and the creation of a sustainable circular economy. We propose a repair, recycle, replacement and reduction circular e-textile paradigm. We envisage a systematic design framework embodying material selection and biofabrication concepts that can unify environmental friendliness, market viability, supply-chain resilience and user experience quality. This framework establishes a set of actionable principles for the industrialization and commercialization of future sustainable e-textile products.

Additive manufacturing of sustainable biomaterials for biomedical applications.

Biopolymers are promising environmentally benign materials applicable in multifarious applications. They are especially favorable in implantable biomedical devices thanks to their excellent unique properties, including bioactivity, renewability, bioresorbability, biocompatibility, biodegradability and hydrophilicity. Additive manufacturing (AM) is a flexible and intricate manufacturing technology, which is widely used to fabricate biopolymer-based customized products and structures for advanced healthcare systems. Three-dimensional (3D) printing of these sustainable materials is applied in functional clinical settings including wound dressing, drug delivery systems, medical implants and tissue engineering. The present review highlights recent advancements in different types of biopolymers, such as proteins and polysaccharides, which are employed to develop different biomedical products by using extrusion, vat polymerization, laser and inkjet 3D printing techniques in addition to normal bioprinting and four-dimensional (4D) bioprinting techniques. This review also incorporates the influence of nanoparticles on the biological and mechanical performances of 3D-printed tissue scaffolds. This work also addresses current challenges as well as future developments of environmentally friendly polymeric materials manufactured through the AM techniques. Ideally, there is a need for more focused research on the adequate blending of these biodegradable biopolymers for achieving useful results in targeted biomedical areas. We envision that biopolymer-based 3D-printed composites have the potential to revolutionize the biomedical sector in the near future.

A binder jet 3D printed MXene composite for strain sensing and energy storage application.

Polymer composite materials have been proven to have numerous electrical related applications ranging from energy storage to sensing, and 3D printing is a promising technique to fabricate such materials with a high degree of freedom and low lead up time. Compared to the existing 3D printing technique for polymer materials, binder jet (BJ) printing offers unique advantages such as a fast production rate, room temperature printing of large volume objects, and the ability to print complex geometries without additional support materials. However, there is a serious lack of research in BJ printing of polymer materials. In this work we introduce a strategy to print poly(vinyl alcohol) composites with MXene-surfactant ink. By ejecting highly conductive MXene particles onto a PVOH matrix, the resulting sample achieved conductive behaviour in the order of mS m-1 with demonstrated potential for strain sensing and energy storage. This work demonstrates that BJ printing has the potential to directly fabricate polymer composite materials with different end applications.

Cost-Effective Fabrication of Uniformly Aligned Silver Nanowire Microgrid-Based Transparent Electrodes with Higher than 99% Transmittance.

Silver nanowire (Ag NW)-based transparent electrodes (TEs) are promising alternatives to indium tin oxide (ITO) for next-generation flexible optoelectronic devices. Although many different constructs of Ag NW networks and post-treatment methods have been developed for TE applications, trade-offs between optical and electrical performance still remain. Herein, aided by electrohydrodynamic (EHD) printing, we present a cost-effective strategy to fabricate aligned Ag NW microgrids in a large area with excellent uniformity, resulting in superior optoelectronic properties. Guided by the percolation theory and simulation, we demonstrated that by confining aligned Ag NWs into a microgrid arrangement, the percolation threshold can be reduced significantly and adequate electrical conducting pathways can be achieved with an optimized combination of sheet resistance and optical transparency, which surpass conventional random Ag NW networks and random aligned Ag NW networks. The resulting TEs exhibit an ultrahigh transmittance of 99.1% at a sheet resistance of 91 Ω sq-1 with extremely low nanowire usage, an areal mass density of only 8.3 mg m-2, and uniform spatial distribution. Based on this TE design, we demonstrated transparent heaters exhibiting rapid thermal response and superior uniformity in heat generation. Using UV-curable epoxy, highly flexible Ag NW-embedded TEs were fabricated with superior mechanical stabilities and low surface roughness of 2.6 nm. Bendable organic light-emitting diodes (OLEDs) are directly fabricated on these flexible Ag NW electrodes, with higher current efficiency (27.7 cd A-1) than ITO devices (24.8 cd A-1).

On-chip perivascular niche supporting stemness of patient-derived glioma cells in a serum-free, flowable culture.

Glioblastoma multiforme (GBM) is the most common and the most aggressive type of primary brain malignancy. Glioblastoma stem-like cells (GSCs) can migrate in vascular niches within or away from the tumour mass, increasing tumour resistance to treatments and contributing to relapses. To study individual GSC migration and their interactions with the perivasculature of the tumour microenvironment, there is a need to develop a human organotypic in vitro model. Herein, we demonstrated a perivascular niche-on-a-chip, in a serum-free condition with gravity-driven flow, that supported the stemness of patient-derived GSCs and foetal neural stem cells grown in a three-dimensional environment (3D). Endothelial cells from three organ origins, (i) human brain microvascular endothelial cells (hCMEC/D3), (ii) human umbilical vein endothelial cells (HUVECs) and, (iii) human lung microvascular endothelial cells (HMVEC-L) formed rounded microvessels within the extracellular-matrix integrated microfluidic chip. By optimising cell extraction protocols, systematic studies were performed to evaluate the effects of serum-free media, 3D cell cultures, and the application of gravity-driven flow on the characteristics of endothelial cells and their co-culture with GSCs. Our results showed the maintenance of adherent and tight junction markers of hCMEC/D3 in the serum-free culture and that gravity-driven flow was essential to support adequate viability of both the microvessel and the GSCs in co-culture (>80% viability at day 3). Endpoint biological assays showed upregulation of neovascularization-related genes (e.g., angiopoietins, vascular endothelial growth factor receptors) in endothelial cells co-cultured with GSCs in contrast to the neural stem cell reference that showed insignificant changes. The on-chip platform further permitted live-cell imaging of GSC - microvessel interaction, enabling quantitative analysis of GSC polarization and migration. Overall, our comparative genotypic (i.e. qPCR) and phenotypic (i.e. vessel permeability and GSC migration) studies showed that organotypic (brain cancer cells-brain endothelial microvessel) interactions differed from those within non-tissue specific vascular niches of human origin. The development and optimization of this on-chip perivascular niche, in a serum-free flowable culture, could provide the next level of complexity of an in vitro system to study the influence of glioma stem cells on brain endothelium.