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Poly(vinylidene fluoride- normalco -hexafluoropropylene) (PVDF/HFP)-based membranes have been prepared using tri- o -cresyl phosphate, dibutyl phthalate, propylene carbonate, or triethyl phosphate as plasticizers. Scanning electron microscopy and the gas adsorption/desorption method were used to reveal the microporous structure of the membranes. Results indicate that the boiling point and viscosity of the plasticizers are important factors during the membrane-forming process. The membrane prepared with a plasticizer of higher boiling point can achieve higher porosity, electrolyte uptake, and thus higher ionic conductivity. The pore sizes of the PVDF/HFP membranes obtained in this study are mostly below 40 nm while the average pore sizes are smaller than 20 nm. The conductivities at room temperature are higher than 10−3Scm−1. The transference numbers measured using the dc polarization method coupled with ac impedance spectra are found to be above 0.7 when 1 M LiPF6 in ethylene carbonate/γ-butyrolactone (1:1 v/v) was used as the liquid electrolyte counterpart. © 2002 The Electrochemical Society. All rights reserved.

No abstract

Despite advances in numerous artificial synaptic devices, the search for a new functionalized synaptic device remains the subject of rigorous investigation for constructing neuromorphic systems. Optical readout functionality in artificial synapses is interesting as on-chip photonic integration technology could increase bandwidth and signal transmission, stop signal interference, reduce power loss, and provide degrees of freedom that complete the photonic neuromorphic system using light rather than electrons. Here, a waveguide-integrated electrochromic artificial synaptic device in which the electrolyte-gated electrical synaptic signal is read by optical means is demonstrated. The optically readable electrochromic synaptic device successfully imitates essential synaptic functions, such as short-and long-term plasticity, excitatory and inhibitory postsynaptic potentiation, and paired-pulse facilitation. In addition, randomly accessible nonvolatile multilevel optical memories are also demonstrated based on electrolyte ion dynamics that enable electrical switching of the transparency of the electrochromic material in a nonvolatile manner. This optically readable artificial synapse approach based on photonic integration circuit technologies provides insight into an exact reading of the emulation of the biological synapse in an optical manner and is a key step toward the implementation of non-conventional photonic neuromorphic systems with tunable bio-inspired synaptic functions.

Plasmonic air-gap disk resonators with 3.5 μm diameter and a 4 nm thick, 40 nm wide air gap for a mode area of only λ0(2)/15,000 were fabricated using photolithography only. The resonant modes were clearly identified using tapered fiber coupling method at the resonant wavelengths of 1280-1620 nm. We also demonstrate the advantage of the air-gap structure by using the resonators as label-free biosensors with a sensitivity of 1.6 THz/nm.