Biological neurons are electro-mechanical systems, where the generation and propagation of an action potential are coupled to the generation and transmission of an acoustic wave. Neuristors, such as VO2, characterized by insulator-metal transition (IMT) and negative differential resistance, can be engineered as self-oscillators, which are good approximations of biological neurons in the domain of electrical signals. In this study, we show that these self-oscillators are coupled electro-opto-mechanical systems, with better energy conversion coefficients than the conventional electro-mechanical or electro-optical materials. This is due to the significant contrast in the material's resistance, optical refractive index, and density across the induced temperature range in a Joule heating driven IMT. We carried out laser interferometry to measure the opto-mechanical response while simultaneously driving the devices electrically into self-oscillations of different kinds. We analyzed films of various thicknesses, engineered device geometry, and performed analytical modeling to decouple the effects of refractive index change vis-à-vis mechanical strain in the interferometry signal. We show that the effective piezoelectric coefficient (d13*) for our neuristor devices is 660 ± 20 pm/V, with a 31% internal energy conversion efficiency, making them viable alternatives to Pb-based piezoelectrics for MEMS applications. Furthermore, we show that the effective electro-optic coefficient (r13*) is ∼22 nm/V, which is much larger than that in thin-film and bulk Pockels materials.

中文翻译：

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VO2 神经电阻中的大型电光机械耦合

生物神经元是机电系统，其中动作电位的产生和传播与声波的产生和传输耦合。 VO2 等神经晶体管的特点是绝缘体-金属转变 (IMT) 和负微分电阻，可以设计为自振荡器，它非常接近电信号领域的生物神经元。在这项研究中，我们证明这些自振荡器是耦合的电光机械系统，具有比传统的机电或电光材料更好的能量转换系数。这是由于在焦耳热驱动的 IMT 中，材料的电阻、光学折射率和密度在感应温度范围内存在显着差异。我们进行了激光干涉测量来测量光机械响应，同时用电力驱动设备产生不同类型的自振荡。我们分析了各种厚度的薄膜、设计了器件几何形状，并进行了分析建模，以消除折射率变化与干涉测量信号中的机械应变的影响。我们证明，我们的神经电阻器件的有效压电系数 (d13*) 为 660 ± 20 pm/V，内部能量转换效率为 31%，使其成为 MEMS 应用中铅基压电器件的可行替代品。此外，我们还发现有效电光系数 (r13*) 约为 22 nm/V，远大于薄膜和体泡克尔斯材料。