Organic electronic ion pumps (OEIPs) are a versatile tool for electrophoretic delivery of substances with high spatiotemporal resolution. To date, OEIPs and similar iontronic components have been fabricated using thin-film techniques, and often rely on laborious, multistep photolithographic processes. OEIPs have been demonstrated in a variety of in vitro and in vivo settings for controlling biological systems, but the thin-film form factor and limited repertoire of polyelectrolyte materials and device fabrication techniques unnecessarily constrain the possibilities for miniaturization and extremely localized substance delivery, e.g., the greater range of pharmaceutical compounds, on the scale of a single cell. Here, we demonstrate an entirely new OEIP form factor based on capillary fibers that include hyperbranched polyglycerols (dPGs) as the selective electrophoretic membrane. The dPGs enable electrophoretic channels with high concentration of fixed charges, well-controlled cross-linking, and can be realized using a simple "one-pot" fluidic manufacturing protocol. Selective electrophoretic transport of cations and anions of various sizes is demonstrated, including "large" substances difficult to transport with other OEIP technologies. We present a method for tailoring and characterizing the electrophoretic channels' fixed charge concentration in the operational state. Subsequently, we compare the experimental performance of these capillary-OEIPs to a computational model and are able to explain unexpected features in the ionic current for the transport and delivery of larger, lower mobility ionic compounds. From the model, we are able to elucidate several operational and design principles relevant for miniaturized electrophoretic drug delivery technologies in general. Overall, the compactness of the capillary-OEIP enables electrophoretic delivery devices with probe-like geometries, suitable for a variety of ionic compounds, paving the way for less-invasive implantation into biological systems and for healthcare applications.

the analog and digital domains at various scales of time and distance, [1] exhibit manyto-one-to-many connectivity, [2] implement global as well as local control of neuronal signaling, [3] and can reorganize connectivity based on necessity. [4] Taken together, these properties allow the nervous system to operate efficiently, multitask, and retain information for years at a time.Several of the computational paradigms used by the brain have been implemented in the constantly evolving technological field of neuromorphic computing. For example, architecture-based approaches include the design of systems that replicate neural spiking and complex connectivity in the form of silicon-based spiking array processors. [5] Memristor arrays have been widely implemented in neuromorphic applications, as they feature a high degree of interconnectivity, the capacity for 3D integration, and access to multiple conductance states. [6] Three-terminal devices have also been shown to exhibit behaviors mimicking synaptic plasticity at the level of a single transistor and have been assembled into networks to accomplish classification tasks. [7] Organic electrochemical transistors (OECTs) have proven to be particularly attractive for neuromorphic applications, in part due to the recent advances reported by Keene et al. to increase the density and reduce the volatility of conductance states. [8] Additionally, the low voltages required to switch between conductance states in OECTs translate into low energy consumption. [7f-i,9] Higher order effects, like functional connectivity and the incorporation of sensors and actuators into neuromorphic circuits, have also been explored. [7h,10] Heretofore reported implementations of neuromorphic analog devices and circuits have proven very effective in executing a panel of biomimetic behaviors like spatiotemporal signal processing, pattern recognition, and global regulation. [11] However, in sharp contrast to biological neuronal networks, the systems investigated to date are fundamentally static in that the interconnectivity and conductance range of each component is predetermined during fabrication. Since the wiring and rewiring of neuronal connectivity is an integral mechanism of neuroplasticity, [12] we were motivated to introduce a comparable process at an analog neuromorphic device. We thus developed the first evolvable OECT (EOECT) that is capable of in situ channel formation through electropolymerization of a conductive polymer between metal source and drain contacts in addition to short-term and long-term learning behaviors. [13] The dynamic nature of the EOECT affords additional degrees of freedom in constructing neuromorphic circuits by making Biomimicry at the hardware level is expected to overcome at least some of the challenges, including high power consumption, large footprint, twodimensionality, and limited functionality, which arise as the field of artificial intelligence matures. One of the main attributes that allow biological systems to thrive is the successful interpretation...

Interfacing electronics with neural tissue is crucial for understanding complex biological functions, but conventional bioelectronics consist of rigid electrodes fundamentally incompatible with living systems. The difference between static solid-state electronics and dynamic biological matter makes seamless integration of the two challenging. To address this incompatibility, we developed a method to dynamically create soft substrate-free conducting materials within the biological environment. We demonstrate in vivo electrode formation in zebrafish and leech models, using endogenous metabolites to trigger enzymatic polymerization of organic precursors within an injectable gel, thereby forming conducting polymer gels with long-range conductivity. This approach can be used to target specific biological substructures and is suitable for nerve stimulation, paving the way for fully integrated, in vivo–fabricated electronics within the nervous system.

Leveraging the biocatalytic machinery of living organisms for fabricating functional bioelectronic interfaces, in vivo , defines a new class of micro-biohybrids enabling the seamless integration of technology with living biological systems. Previously, we have demonstrated the in vivo polymerization of conjugated oligomers forming conductors within the structures of plants. Here, we expand this concept by reporting that Hydra , an invertebrate animal, polymerizes the conjugated oligomer ETE-S both within cells that expresses peroxidase activity and within the adhesive material that is secreted to promote underwater surface adhesion. The resulting conjugated polymer forms electronically conducting and electrochemically active μm-sized domains, which are inter-connected resulting in percolative conduction pathways extending beyond 100 μm, that are fully integrated within the Hydra tissue and the secreted mucus. Furthermore, the introduction and in vivo polymerization of ETE-S can be used as a biochemical marker to follow the dynamics of Hydra budding (reproduction) and regeneration. This work paves the way for well-defined self-organized electronics in animal tissue to modulate biological functions and in vivo biofabrication of hybrid functional materials and devices.

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