Organic dendritic fibers: novel interfaces for bioelectronics and biohybrid computing

The human brain exhibits remarkable computational capabilities, inspiring research in both neuromorphic computing and bioelectronic neural interfaces, trying to harness its full potential. Organic mixed ionic-electronic conductors (OMIECs) such as poly(3,4-ethylenedioxythiophene) (PEDOT) have been extensively studied for their role in extracellular neural recording and stimulation, benefiting from their high biocompatibility, porosity, and electrical properties. In parallel, dendritic PEDOT fibers have emerged as promising candidates for neuromorphic computing due to their ability to replicate key synaptic functionalities and to be scaled into networks capable of performing complex computations within reservoir computing systems. Furthermore, optically responsive organic semiconductors such as poly(3-hexylthiophene) (P3HT) have gained interest for neural interfacing, enabling optical stimulation without genetic modifications. Despite advances in these fields, bioelectronic neural interfaces and neuromorphic computing have only been explored independently. The integration of these two domains into a unified platform remains an open challenge. Beyond this, the development of dendritic fibers that combine both neuromorphic and optoelectronic functionalities represents a promising direction for further advancing both domains. Here, a preliminary step toward the convergence of these fields is proposed, with the fabrication of a unified platform based on dendritic OMIEC fibers. Specifically, PEDOT-based fibers were intended to support synaptic-like behavior within the structure, while P3HT was integrated to introduce optical responsiveness. The fabrication process was optimized to ensure compatibility with neural cell cultures, establishing conditions for stable growth and interaction with the polymeric structures. Experimental results confirm the feasibility of generating photovoltage within the dendritic fibers with measured peaks of 50\,mV, compatible with the standards of cellular stimulation. This also highlights their potential for optically driven neuromorphic processes. Additionally, cell viability assessments indicate that the proposed system supports neural cell adhesion and proliferation, reinforcing its suitability for biohybrid applications. These findings pave the way for an organic, biocompatible platform, with the possibility of further functionalization, bridging biological and artificial neural networks. By integrating neuromorphic processing with optically addressable bioelectronic interfaces, this work opens new perspectives for advanced brain-inspired computing and neural interfacing.