Organic electrochemical neurons and synapses with ion mediated spiking

Harikesh, Padinhare Cholakkal; Yang, Chi‐Yuan; Tu, Deyu; Gerasimov, Jennifer Y.; Dar, Abdul Manan; Armada‐Moreira, Adam; Massetti, Matteo; Kroon, Renee; Bliman, David; Olsson, Roger; Stavrinidou, Eleni; Berggren, Magnus; Fabiano, Simone

doi:10.1038/s41467-022-28483-6

Cited by 136 publications

(156 citation statements)

References 45 publications

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“…The long-term operation of floating gate memory devices requires the quasi-permanent charge trapping capability. − Thus advanced dielectric polymers applied in memory devices should be electrical insulating with a large number of bulk traps for charge storage. − This requirement is highly consistent with that of the artificial synapse, which electrically emulates the human brain for next-generation neuromorphic computing. − During operation, the OFET gate serves as a presynaptic terminal to trigger an electric information pulse, while charge trapping/detrapping in dielectric polymers determines the training/learning processes and, consequently, results in varied conductance of semiconductors as the postsynapse response. , Compared with the conventional two-terminal artificial synapse device, OFET synapses enable programing (through the gate) and reading (through the semiconducting channel) processes to decouple, in which the information transmission and training/learning are simultaneously achieved . Thus, in order to improve the performance of nonvolatile memories and artificial synapses, the requirements for dielectric polymers are fundamentally similar, namely, excellent charge trapping capability for enhancing electret intensity and rapid trapping–detrapping modulation characteristic for fast writing–erasing processes …”

Section: Introductionmentioning

confidence: 99%

Side-Chain Engineering of Polystyrene Dielectrics Toward High-Performance Photon Memories and Artificial Synapses

et al. 2022

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The emerging applications of organic field-effect transistors (OFETs), such as photon memories and artificial synapses, require polymer dielectrics with superior charge trapping properties. Despite the introduction of high-k and fluorinated polymers in the performance optimization of OFETs, there is still a lack of widely recognized acknowledgment between molecular structures and charge trapping characteristics, as well as no general principles in designing polymeric dielectrics for electronic memory devices. Here, we propose a series of fluorinated polystyrene isomers through side-chain engineering, namely, ortho-(o-), meta-(m-), and para-fluorinated polystyrene (p-FPS). The gradually enlarged intramolecular charge separation of o-, m-, and p-FPS enhances molecular electrostatic potential, which promotes polarization and charge trapping performances, resulting in an enlarged dielectric constant, as well as more deep traps toward stable electret. Subsequently, largely improved photon memory and artificial synapse performances of p-FPS-based OFETs further suggest the dominating role of dielectric side-chain structures on memory and synapse performances, leading to a recommendation of low-k (ε r < 5) dielectric polymers with enhanced electrostatic potential for OFET-based memory devices and bionic nervous systems.

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Section: Introductionmentioning

confidence: 99%

Side-Chain Engineering of Polystyrene Dielectrics Toward High-Performance Photon Memories and Artificial Synapses

et al. 2022

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“…[ 12–15 ] In particular, organic conjugated polymer as core components of organic synaptic devices have been widely implemented. Several types of conjugated polymers have been developed, including poly(3,4‐ethylendioxythiophene) ( PEDOT) , [ 16 ] poly(3‐hexylthiophen‐2,5‐diyl ( P 3 HT ), [ 17 ] glycolated polythiophene ( P(g 4 2T‐T ), [ 18 ] etc., and their synaptic performance has been demonstrated to be comparable with biological synapses, thus highly promising in processing biological signals.…”

Section: Introductionmentioning

confidence: 99%

Donor Engineering Tuning the Analog Switching Range and Operational Stability of Organic Synaptic Transistors for Neuromorphic Systems

Zhao

Shen

et al. 2022

Adv Funct Materials

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Organic artificial synapses are becoming the most desirable format for neuromorphic computing due to their highly tunable resistive states. However, repressively low analog switching range, inferior memory retention, and operational instability greatly hinder the further development of organic synapses. Herein, two donor-acceptor copolymers consisting of electrondeficient isoindigo coupled with variable donating moieties for three-terminal organic synaptic transistors (TOSTs) are reported. It is found that the synaptic function and device stability of TOSTs are significantly improved by enhancing the electron-donating strength of donor units. Polymer alkylated isoindigo-bisethylenedioxythiophene exhibits high analog switching range of 170 ×, two orders of magnitude higher than that of normal organic neuromorphic devices. They also demonstrate excellent memory retention of over 5 × 10 3 s, low switching energy of 13 fJ, and ultrahigh operational stability with 99% of its original current after 100 000 write-read events in air. Furthermore, the high viability of strong donor strategy is showcased by demonstrating flexible TOSTs with stable synaptic function after repeated mechanical bending as well as organic synapses capable of simulating image information processing. Overall, this work highlights the advantages of the strong donor functionalization strategy to boost the synaptic performance and device stability of TOSTs.

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“…Implementing artificial synapses and somas from the same materials and technologies eases many fabrications constraints. To the best of our knowledge, despite some organic demonstrations to date [29,[41][42][43], all implemented artificial synaptic circuits have relied on inorganic materials.…”

Section: Introductionmentioning

confidence: 99%

An organic synaptic circuit: toward flexible and biocompatible organic neuromorphic processing

Hosseini¹,

Yang²,

Prendergast³

et al. 2022

Neuromorph. Comput. Eng.

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In the nervous system synapses play a critical role in computation. In neuromorphic systems, biologically inspired hardware implementations of spiking neural networks, electronic synaptic circuits pass signals between silicon neurons by integrating pre-synaptic voltage pulses and converting them into post-synaptic currents, which are scaled by the synaptic weight parameter. The overwhelming majority of neuromorphic systems are implemented using inorganic, mainly silicon, technology. As such, they are physically rigid, require expensive fabrication equipment and high fabrication temperatures, are limited to small-area fabrication, and are difficult to interface with biological tissue. Organic electronics are based on electronic properties of carbon-based molecules and polymers and offer benefits including physical flexibility, low cost, low temperature, and large-area fabrication, as well as biocompatibility, all unavailable to inorganic electronics. Here, we demonstrate an organic differential-pair integrator synaptic circuit, a biologically realistic synapse model, implemented using physically flexible complementary organic electronics. The synapse is shown to convert input voltage spikes into output current traces with biologically realistic time scales. We characterize circuit's responses based on various synaptic parameters, including gain and weighting voltages, time-constant, synaptic capacitance, and circuit response due to inputs of different frequencies. Time constants comparable to those of biological synapses and the neurons are critical in processing real-world sensory signals such as speech, or bio-signals measured from the body. For processing even slower signals, e.g., on behavioral time scales, we demonstrate time constants in excess of two seconds, while biologically plausible time constants are achieved by deploying smaller synaptic capacitors. We measure the circuit synaptic response to input voltage spikes and present the circuit response properties using custom-made circuit simulations, which are in good agreement with the measured behavior.

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Organic electrochemical neurons and synapses with ion mediated spiking

Cited by 136 publications

References 45 publications

Side-Chain Engineering of Polystyrene Dielectrics Toward High-Performance Photon Memories and Artificial Synapses

Side-Chain Engineering of Polystyrene Dielectrics Toward High-Performance Photon Memories and Artificial Synapses

Donor Engineering Tuning the Analog Switching Range and Operational Stability of Organic Synaptic Transistors for Neuromorphic Systems

An organic synaptic circuit: toward flexible and biocompatible organic neuromorphic processing

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