This Letter presents the fabrication and characterization of a chip-scale GaN optical device for measuring glycerol viscosity. The monolithically integrated GaN chip with a size of 1 × 1 mm² comprises a light-emitting diode (LED) and a photodiode (PD) on a transparent sapphire substrate. The glycerol droplet applied to the device acts as a medium for coupling light from the LED to the PD. When a mechanical impulse is applied, the droplet undergoes a damped vibration that depends on its viscosity, causing a change in its shape and altering the path of light propagation. The viscosity of the glycerol sample can be determined by obtaining the rate of attenuation of the measured photocurrent signals. The proposed unit offers a fast time response in microseconds and requires only a small sample volume of 5 µl. The developed device is highly suitable for the practical measurement of glycerol viscosity due to its miniaturization, low cost, and ease of operation without the need for external optical components.

中文翻译：

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用于甘油粘度测量的 GaN 集成光学器件

这封信介绍了用于测量甘油粘度的芯片级 GaN 光学器件的制造和表征。单片集成的GaN芯片尺寸为1×1mm ²，在透明蓝宝石衬底上包括发光二极管（LED）和光电二极管（PD）。施加到设备上的甘油液滴充当将光从 LED 耦合到 PD 的介质。当施加机械脉冲时，液滴会经历取决于其粘度的阻尼振动，导致其形状发生变化并改变光传播的路径。甘油样品的粘度可以通过获得测量的光电流信号的衰减率来确定。所提议的装置可提供微秒级的快速响应，并且仅需要 5 µl 的小样本量。该装置具有小型化、低成本、易于操作且无需外部光学元件等特点，非常适合甘油粘度的实际测量。