Gallium-Carbon: A Universal Composite for Sustainable 3D Printing of Integrated Sensor-Heater-Battery Systems in Wearable and Recyclable Electronics.

This study presents a novel three-dimensional (3D) printable gallium-carbon black-styrene isoprene styrene block copolymer (Ga-CB-SIS), offering a versatile solution for the rapid fabrication of stretchable and integrated sensor-heater-battery systems in wearable and recyclable electronics. The composite exhibits sinter-free characteristics, allowing for printing on various substrates, including heat-sensitive materials. Unlike traditional conductive inks, the Ga-CB-SIS composite, composed of gallium, carbon black, and styrene isoprene block copolymers, combines electrical conductivity, stretchability, and digital printability. By introducing carbon black as a filler material, the composite achieves promising electromechanical behavior, making it suitable for low-resistance heaters, batteries, and electrical interconnects. The fabrication process involves a simultaneous mixing and ball-milling technique, resulting in a homogeneous composition with a CB/Ga ratio of 4.3%. The Ga-CB-SIS composite showcases remarkable adaptability for digital printing on various substrates. Its self-healing property and efficient recycling technique using a deep eutectic solvent contribute to an environmentally conscious approach to electronic waste, with a high gallium recovery efficiency of ∼98%. The study's innovation extends to applications, presenting a fully digitally printed stretchable Ga-CB-SIS battery integrated with strain sensors and heaters, representing a significant leap in LM-based composites. This multifunctional and sustainable Ga-CB-SIS composite emerges as a key player in the future of wearable electronics, offering integrated circuits with sensing, heating, and energy storage elements.

In vivo recordings in freely behaving mice using independent silicon probes targeting multiple brain regions.

In vivo recordings in freely behaving animals are crucial to understand the neuronal circuit basis of behavior. Although current multi-channel silicon probes provide unparalleled sampling density, the study of interacting neuronal populations requires the implantation of multiple probes across different regions of the brain. Ideally, these probes should be independently adjustable, to maximize the yield, and recoverable, to mitigate costs. In this work, we describe the implementation of a miniaturized 3D-printed headgear system for chronic in vivo recordings in mice using independently movable silicon probes targeting multiple brain regions. We successfully demonstrated the performance of the headgear by simultaneously recording the neuronal activity in the prelimbic cortex and dorsal hippocampus. The system proved to be sturdy, ensuring high-quality stable recordings and permitted reuse of the silicon probes, with no observable interference in mouse innate behaviors.