Applying Neurodynamic Behavior of Mott Memristors for Auditory Sensing

Tímea Nóra Török^a^,^b, Roland Kövecs^a, László Pósa^a^,^b, Ferenc Braun^b, György Molnár^b, Nguyen Quoc Khánh^b, András Halbritter^a^,^c, János Volk^b

^aDepartment of Physics, Institute of Physics, Budapest University of Technology and Economics, Muegyetem rkp. 3, H-1111 Budapest, Hungary

^bInstitute of Technical Physics and Materials Science, HUN-REN Centre for Energy Research, Konkoly-Thege M. út 29-33, 1121 Budapest, Hungary.

^cHUN-REN-BME Condensed Matter Research Group, Műegyetem rkp. 3., H-1111 Budapest, Hungary.

Proceedings of Neuronics Conference (Neuronics)

València, Spain, 2024 February 21st - 23rd

Organizers: Sabina Spiga and Juan Bisquert

Oral, László Pósa, presentation 017
DOI: https://doi.org/10.29363/nanoge.neuronics.2024.017
Publication date: 18th December 2023

Neurodynamic behavior of artificial neuron circuits made of Mott memristors [1] provide versatile opportunities to utilize them for artificial sensing [2,3]. In these realizations, usually a sensor is connected to an artificial neuron or oscillator circuit to generate a spiking output encoding the stimulus, which is later carried to a spiking neural network for further processing. By directly conducting such signals encoding stimuli into the nervous system, an artificial sensory input can be created. We explore possibilities to realize an auditory sensing circuit aiming future applications in cochlear implants, motivated by small size and energy-efficient spike generation capabilities of VO₂ oscillator circuits. The sensory part of the circuit can be realized with micro-electromechanical systems (MEMS), also applicable as bio-inspired acoustic sensors [4,5].

In this work, a MEMS cantilever is connected to a VO₂ nanogap Mott memristor [6] -based oscillator circuit, capable of neural spike emission. The MEMS cantilever can realize frequency selective sensing of sound waves due to its sharp resonance. Electrical signal of the cantilever serves as an input for the VO₂ oscillator circuit after proper conditioning. The cantilever is excited with mechanical stimuli in the range of ~10 nm, which is realistic in the human ear [7]. As a result, the oscillator emits a train of spikes with a well-defined frequency, which can be tuned to the desired frequency domain of typical spiking rates in the nervous system [8], via the proper selection of passive elements in the oscillator. By the addition of further passive elements to the oscillator, the spiking waveform can be brought to a bipolar form. This is a beneficial property, since electric signals carried into the nervous system should have bipolar characteristics to exclude the possibility of charge accumulation near the end of the implanted electrodes [9]. Due to the internal dynamics of the oscillator part, the frequency of oscillation encodes the amplitude of the stimulus – similarly to processes of natural hearing [10]. The proposed circuit serves as a proof-of-concept demonstration of a Mott memristor-based auditory sensing unit for future cochlear implants.

References:

[1] Yi, W., Tsang, K.K., Lam, S.K. et al. Biological plausibility and stochasticity in scalable VO2 active memristor neurons. Nature Communications. 2018, 9, 4661.

[2] Zhang, X., Zhuo, Y., Luo, Q. et al. An artificial spiking afferent nerve based on Mott memristors for neurorobotics. Nature Communications. 2020, 11, 51.

[3] Yuan, R., Duan, Q., Tiw, P.J. et al. A calibratable sensory neuron based on epitaxial VO2 for spike-based neuromorphic multisensory system. Nature Communications. 2022, 13, 3973.

[4] Lenk, C., Hövel, P., Ved, K. et al. Neuromorphic acoustic sensing using an adaptive microelectromechanical cochlea with integrated feedback. Nature Electronics. 2023, 6, 370–380.

[5] Lenk, C., Ved, K., Durstewitz, S., Ivanov, T., Ziegler, M., Hövel, P. Bio-inspired, Neuromorphic Acoustic Sensing. In: Bio-Inspired Information Pathways, edited by Ziegler, M., Mussenbrock, T., Kohlstedt, H. Springer International Publishing. 2024, 287–315.

[6] Pósa, L., Hornung, P., Török, T. N., Schmid, S. W., Arjmandabasi, S., Molnár, G., ... & Volk, J. Interplay of Thermal and Electronic Effects in the Mott Transition of Nanosized VO2 Phase Change Memory Devices. ACS Applied Nano Materials. 2023, 6 (11), 9137-9147.

[7] Javel, E., Grant, IL., Kroll, K. In vivo characterization of piezoelectric transducers for implantable hearing aids. Otology & Neurotology. 2003, 24(5), 784-95.

[8] Pérez-González, D., Malmierca, M. S. Adaptation in the auditory system: an overview. Frontiers in Integrative Neuroscience. 2014, 8, 19.

[9] Navntoft, C.A., Marozeau, J., Barkat, T.R. Ramped pulse shapes are more efficient for cochlear implant stimulation in an animal model. Scientific Reports. 2020, 10, 3288.

[10] Westerman LA, Smith RL. Conservation of adapting components in auditory-nerve responses. The Journal of the Acoustical Society of America. 1987, 81(3) 680-691.

Acknowledgements:

Project no. 963575 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2020 funding scheme. Project TKP2021-NVA-03 was also supported by the National Research, Development and Innovation Office.

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