光遗传(Optogenetics)结合光学和遗传学手段, 可以精确地控制特定神经元的活动, 为神经科学的研究提供了强有力的手段。光电极在光遗传研究中起着关键的作用, 它可以将光导入到动物体内, 并通过电极记录神经元在光调控下的活动。为了减小体积、增加功能, 依托高密度集成硅微电极和裸光纤, 设计并制备了一种植入部分横截面尺寸不超过0.1mm2、包含2个平行的给光通道和32个记录点的光电极器件。与传统的单光通道电极相比, 两个通道可以更灵活地配置不同的激发波长, 对不同位点的神经元同时进行激活或抑制。32通道的硅电极与传统的金属丝电极相比, 集成度更高, 能够以更高的空间分辨率记录神经元在激发前后的活动情况。

An implantable optrode with micro-thermal detectors was designed to investigate the availability and safety of INS using high repetition rates. Optical auditory brainstem responses (oABRs) were recorded in normal-hearing guinea pigs, and the energy thresholds, pulse durations, and amplitudes evoked by the varied stimulus repetitions were analyzed. Stable oABRs could be evoked through INS even as the repetition rate of stimulation reached 19 kHz. The energy threshold of oABRs was elevated, the amplitudes decreased as pulse durations increased and repetition rates were higher, and the latencies were delayed as the pulse durations increased. The temperature variation curves on the site of stimulation significantly increased as the pulse duration increased to 400 μs. INS elevated the temperature around the stimulus site area via thermal accumulation during radiation, especially when higher repetition stimuli were used. Our results demonstrate that high repetition infrared stimulations can safely evoke stable and available oABRs in normalhearing guinea pigs.

光电极是研究光遗传学不可或缺的工具之一。 波长为460nm的蓝光可以对ChR2神经蛋白产生刺激, 而波长为580nm的黄光可以刺激NpHR神经蛋白, 对生物体的反应产生抑制。目前, 蓝光波段的光电极具有很高的功率密度, 可以满足光遗传学的研究, 而黄光波段半导体发光器件的发光效率较低, 因此对黄光波段的光电极研究较少。在蓝宝石衬底蓝光光电极研制的基础上, 通过激发黄色荧光粉和量子点两种形式获得黄光, 并通过沉积SiO2/TiO2分布式布拉格反射镜(DBR)有效滤除了蓝光波段的激发光, 最后通过沉积Ag金属反射镜增强黄光信号, 制备出荧光粉基和量子点基黄光光电极。与荧光粉基黄光光电极相比, 量子点基黄光光电极具有更高的功率密度、更窄的光谱半宽和更薄的厚度。在1~10mA的注入电流下, 量子点基黄光光电极的功率密度为4.46~15.37mW/mm2, 满足刺激NpHR神经蛋白的要求。

Optical fiber optrodes are attractive sensing devices due to their ability to perform point measurement in remote locations. Mostly, they are oriented to biochemical sensing, quite often supported by fluorescent and spectroscopic techniques, but with the refractometric approach considered as well when the objective is of high measurement performance, particularly when the focus is on enhancing the measurand resolution. In this work, we address this subject, proposing and analyzing the characteristics of a fiber optic optrode relying on plasmonic interaction. A linearly tapered optical fiber tip is covered by a double overlay: the inner one - a silver thin film and over it - a dielectric layer, with this combination allowing to achieve, at a specific wavelength range, surface plasmonic resonance (SPR) interaction sensitive to the refractive index of the surrounding medium. Typically, the interrogation of the SPR sensing structures is performed, considering spectroscopic techniques, but in principle, a far better performance can be obtained, considering the reading of the phase of the light at a specific wavelength located within the spectral plasmonic resonance. This is the approach which is studied here in the context of the proposed optical fiber optrode configuration. The analysis performed shows the combination of a silver inner layer with a dielectric titanium oxide layer with tuned thicknesses enables sensitive phase reading and allows the operation of the fiber optic optrode sensor in the third telecommunication wavelength window.