Neuromorphic device architectures with global connectivity through electrolyte gating

Abstract

Information processing in the brain takes place in a network of neurons that are connected with each other by an immense number of synapses. At the same time, neurons are immersed in a common electrochemical environment, and global parameters such as concentrations of various hormones regulate the overall network function. This computational paradigm of global regulation, also known as homeoplasticity, has important implications in the overall behaviour of large neural ensembles and is barely addressed in neuromorphic device architectures. Here, we demonstrate the global control of an array of organic devices based on poly(3,4ethylenedioxythiophene):poly(styrene sulf) that are immersed in an electrolyte, a behaviour that resembles homeoplasticity phenomena of the neural environment. We use this effect to produce behaviour that is reminiscent of the coupling between local activity and global oscillations in the biological neural networks. We further show that the electrolyte establishes complex connections between individual devices, and leverage these connections to implement coincidence detection. These results demonstrate that electrolyte gating offers significant advantages for the realization of networks of neuromorphic devices of higher complexity and with minimal hardwired connectivity.

Bridging Biological and Artificial Neural Networks with Emerging Neuromorphic Devices: Fundamentals, Progress, and Challenges

“…[242] Several mechanisms have been proposed underlying homeostatic plasticity (Figure 10d) including but not restricted to synaptic scaling, shift of excitation and inhibition ratio, sliding threshold for LTP and LTD, and changes in neuronal excitability. [244] Synaptic scaling refers to the fact that synaptic strengths can make compensatory changes to restore average AP firing rate in response to prolonged decreased or increased activity. [244] Synaptic scaling refers to the fact that synaptic strengths can make compensatory changes to restore average AP firing rate in response to prolonged decreased or increased activity.…”

Mechanisms for Enhanced State Retention and Stability in Redox‐Gated Organic Neuromorphic Devices

“…[6] However, these algorithms have proven to be computationally intensive, requiring >100 graphics processing such as poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), due to the low voltages required to modulate the material's conductance. [32][33][34][35][36] When implemented in a three-terminal architecture as an NVRM, PEDOT:PSS devices show exceptionally low switching energies (10 pJ for a 100 µm 2 device) in addition to linear and symmetric conductance response required for "blind" weight update (i.e., not involving a read). [32][33][34][35][36] When implemented in a three-terminal architecture as an NVRM, PEDOT:PSS devices show exceptionally low switching energies (10 pJ for a 100 µm 2 device) in addition to linear and symmetric conductance response required for "blind" weight update (i.e., not involving a read).…”

Selective UV‐Gating Organic Memtransistors with Modulable Levels of Synaptic Plasticity

“…[4,8] However, there are two often-overlooked aspects in synaptic electronics. [12][13][14] From these perspectives, the synaptic applications of memristors are limited by their two-terminal and passive nature, and an additional degree of control is essential to achieve "memtransistors" with highly modulable strength of the memristive characteristics. [9][10][11] As a simple example schematically illustrated in Figure 1a, biological synapses at different stages (Mature and Newborn) may have enormous variations in the amount of neurotransmitters released from the presynaptic neurons and/or receptors located on the postsynaptic neurons, [11] thus generating different levels of synaptic plasticity.…”