关于举行荷兰乌特勒支大学理论物理中心终身教授René van Roij学术报告会的通知

报告题目：Neuromorphic features from microfluidic memristors of aqueous electrolytes报 告 人：René van Roij（荷兰乌特勒支大学理论物理中心终身教授）报告邀请人：周嘉嘉教授报告时间：2024年5月14 (周二) 9:00—10:00报告地址：国际校区C3-c204（线下会议）  前沿软物质学院华南软物质科学与技术高等研究院2024年5月13日 报告摘要:In this talk we will discuss recent advances in our understanding of the physics of cone-shaped microfluidic channels under static and pulsatile voltage- and pressure drops. On the basis of Poisson-Nernst-Planck-Stokes equations for transport of aqueous electrolytes through channels carrying a surface charge, we will provide a theoretical explanation for the experimentally observed diode-like current rectification of these channels in terms of salt depletion (accumulation) at steady forward (backward) electric driving [1], which also explains the observed pressure-sensitivity of the electric conductance. An extension towards an applied AC voltage predicts these channels to be tunable between diodes at low frequencies ωτ<<1, memristors (resistors with memory) at intermediate frequencies ωτ ~ 1, and Ohmic resistors at high frequency ωτ>>1, with a characteristic (memory retention) time τ proportional to the square of the channel length [2]. We predict that Hodgkin-Huxley-inspired iontronic circuits of short (fast) and long (slow) conical channels yield neuromorphic responses akin to (trains of) action potentials [2] and several other neuronic spiking modes [3]. Next, we show theoretically and experimentally that a tapered microfluidic channel filled with an aqueous nearly close-packed dispersion of colloidal charged spheres is a much stronger memristor [4]. Upon applying a train of positive (negative) voltage pulses, with pulse durations τ/8 and representing a binary “1” (“0”), we map a binary bit string on the channel conductance, which offers opportunities for reservoir computing -we give a proof of principle for the case of recognizing hand-written digits [4]. Finally, if time permits, we will also discuss recent and ongoing work on iontronic information processing. We exploit the mobility of the medium (water) by considering simultaneously applied pulsatile pressure and voltage signals to increase the bandwidth [5]. Finally, the versatile ionic nature of the charge carriers allows for Langmuir-like ionic exchange reaction kinetics on the channel surface [6]. We show that this can give rise to direct iontronic analogues of synaptic long-term potentiation and coincidence detection of electric and chemical signals [7], which are both ingredients for brain-like (Hebbian) learning.[1] W.Q. Boon, T. Veenstra, M. Dijkstra, and R. van Roij, Pressure-sensitive ion conduction in a conical channel: optimal pressure and geometry, Physics of Fluids 34, 101701 (2022).[2] T.M. Kamsma, W.Q. Boon, T. ter Rele, C. Spitoni, and R. van Roij, Iontronic NeuromorphicSignaling with Conical Microfluidic Memristors, Phys. Rev. Lett. 130, 268401 (2023).[3] T.M. Kamsma, E. A. Rossing, C. Spitoni, and R. van Roij, Advanced iontronic spiking modes with multiscale diffusive dynamics in a fluidic circuit, Neuromorph. Comput. Eng. 4 024003 (2024).[4] T.M. Kamsma, J. Kim, K. Kim, W.Q. Boon, C. Spitoni, J. Park, and R. van Roij, Brain-inspired computing with fluidic iontronic nanochannels, PNAS 121, e23202242121 (2024).[5] A. Barnaveli, T.M. Kamsma, W.Q. Boon, and R. van Roij, Pressure-gated microfluidic memristor for pulsatile information processing, arXiv 2404.15006.[6] W.Q. Boon. M. Dijkstra, and R. van Roij, Coulombic Surface-Ion Interactions Induce Nonlinear and Chemistry-Specific Charging Kinetics, Phys. Rev. Lett. 130, 058001 (2023).[7] T.M. Kamsma, M. Klop, W.Q. Boon, C. Spitoni, and R. van Roij, manuscript in preparation. 报告人简介：René van Roij，荷兰乌特勒支大学理论物理中心终身教授。van Roij教授1996年在阿姆斯特丹大学获得物理博士学位，然后在里昂高等师范学校和布里斯托尔大学从事博士后研究，2006年返回乌特勒支大学任教。van Roij教授的研究兴趣包括经典（动态）密度泛函理论，平衡和不平衡的双电层、扩散传导平流反应的纳米级传输、蓝色能量、液晶、自组装、毛细管现象。