Highly Resistive Biomembranes Coupled to Organic Transistors enable Ion-Channel Mediated Neuromorphic Synapses

Organic electrochemical transistors (OECTs) functionalized with lipid membranes could enable new hybrid synapses for sensing and neuromorphic computing in biological media. However, prior attempts to pair these components resulted in low quality membranes formed on the OECT surface. We present a new method for forming a highly-resistive phospholipid bilayer coupled to a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) OECT that avoids the disruptive effects of the rough polymer surface. Transistor coupled droplet bilayers (TCDBs) formed from diphytanoyl phosphatidylcholine lipids exhibit an average specific resistance that is 1000X higher than values reported for solid-supported lipid membranes assembled on PEDOT:PSS. High membrane resistance and the addition of voltage-activated ionophores enable us to demonstrate that selective ion transport and spontaneous membrane resealing in response to dynamic gate voltage imparts selective programming and memory-storage capability to an OECT without chemical modification of the PEDOT:PSS. These capabilities enable paired-pulse facilitation and depression with writing speeds and memory retentions that are both >10X higher than previously reported with membrane-coated OECTs. The high resistance of the TCDB establishes a basis for hybrid biomolecular synapses that can integrate stimuli-responsive membranes and organic electronics for future applications in sensing, signal processing, and neuromorphic computing at the edge of biology.