Lauren Adegoke

3D printing technologies can address many sustainability aspects of creating new materials, such as reduced waste and on demand production, which reduces the carbon footprint of transport and storage. Additionally, creating bio-based resins for 3D printing is a viable way of improving the sustainability of polymeric materials. Coupled with this, by using dynamic covalent chemistry (DCC), we can provide materials with smart properties like self-healing or reprocessability to either extend their usable lifetime or provide an alternative to the materials ending up in a landfill. Here, we report a series of completely bio-based aromatic resins for digital light projection (DLP) printing. By incorporating β-hydroxyesters and a zinc catalyst, the polymer networks can participate in transesterification reactions to provide self-healing capabilities or reprocessability. The self-healing abilities of these materials were characterized using optical microscopy, and the reprocessability using a hot-press. Additionally, by subjecting the printed thermosets to thermal annealing, considerable changes in the mechanical performance were observed leading to more than a 2000% increase in the Young’s modulus. The thermal behavior after annealing was also studied and a discussion on the effect of the structural differences between the aromatic monomers is proposed. These resin formulations address two of the key goals of sustainable materials: using renewable resources and obtaining recyclable materials while remaining competitive through their mechanical performance and compatibility with 3D printing technologies.

Medical science technology has improved tremendously over the decades with the invention of robotic surgery, gene editing, immune therapy, etc. However, scientists are now recognizing the significance of ‘biological circuits’ i.e., bodily innate electrical systems for the healthy functioning of the body or for any disease conditions. Therefore, the current trend in the medical field is to understand the role of these biological circuits and exploit their advantages for therapeutic purposes. Bioelectronics, devised with these aims, work by resetting, stimulating, or blocking the electrical pathways. Bioelectronics are also used to monitor the biological cues to assess the homeostasis of the body. In a way, they bridge the gap between drug-based interventions and medical devices. With this in mind, scientists are now working towards developing flexible and stretchable miniaturized bioelectronics that can easily conform to the tissue topology, are non-toxic, elicit no immune reaction, and address the issues that drugs are unable to solve. Since the bioelectronic devices that come in contact with the body or body organs need to establish an unobstructed interface with the respective site, it is crucial that those bioelectronics are not only flexible but also stretchable for constant monitoring of the biological signals. Understanding the challenges of fabricating soft stretchable devices, we review several flexible and stretchable materials used as substrate, stretchable electrical conduits and encapsulation, design modifications for stretchability, fabrication techniques, methods of signal transmission and monitoring, and the power sources for these stretchable bioelectronics. Ultimately, these bioelectronic devices can be used for wide range of applications from skin bioelectronics and biosensing devices, to neural implants for diagnostic or therapeutic purposes.