Through-Polymer Via Technology-Enabled Flexible, Lightweight, and Integrated Device for Implantable Neural Probes

Abstract In implantable electrophysiological recording systems, the headstage typically consists of neural probes interfacing with brain tissue and integrated circuit chips for signal processing. Although advancements in MEMS and CMOS technology have significantly improved these components, their connection still relies heavily on conventional printed circuit boards and sophisticated adapters. This traditional approach adds considerable weight and volume, especially as channel counts increase. To address this, we have developed a Through-Polymer Via (TPV) method, inspired by the Through-Silicon Via (TSV) technique in advanced three-dimensional packaging. This innovation enables the vertical integration of flexible probes, amplifier chips, and PCBs, culminating in the creation of a Flexible, Lightweight, and Integrated Device (FLID). The total weight of FLID is only 25% of that of conventional counterparts using adapters, which significantly enhances animal activity levels, nearly matching those of control animals without implants. Furthermore, by incorporating a platinum-iridium alloy as the top layer material for electrical contacts, the FLID demonstrates exceptional electrical performance, enabling in vivo measurements of both local field potentials and individual neuron action potentials. Our findings not only showcase the potential of the FLID in scaling up implantable neural recording systems but also mark a significant step forward in the field of neurotechnology.