Absolute Length Sensor Based on Time of Flight in Stretchable Optical Fibers
Absolute Length Sensor Based on Time of Flight in Stretchable Optical Fibers
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DOI：
10.1109/lsens.2020.3028332
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发表时间：
2020-10
影响因子：
2.8
通讯作者：
Ji-Tzuoh Lin;C. Harnett
中科院分区：
文献类型：
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作者：
Ji-Tzuoh Lin;C. Harnett
柔软和可拉伸的光纤是一种有前途的全聚合物传感器元件，用于极端的机械应变，压力，弯曲和其他变形。与电子传感器相比，传感器元件本质上是可拉伸的，并且不受电磁干扰。然而，通过跟踪透射光强度来测量变形的典型方法是类似于基于电阻的测量的积分方法;它不提供关于变形的位置或性质的信息。这封信描述了一种驱动可拉伸光纤的替代方法：连接到光纤两端的消费者光检测和测距芯片，通过光脉冲的飞行时间（TOF）测量其长度。这种方法是机器人和人机接口设备中先前声学TOF和电子时域反射仪的小型化，基于光学的版本。这种测距系统使用少量传感器收集空间信息。我们发现，TOF方法可以在总长度为1.330 mm的情况下测量1 mm以内的纤维长度（>1%的准确度）。振幅和TOF方法都对产生微弯曲的压力敏感，但方向相反。对于大于7.5 mm的弯曲半径，TOF传感器对弯曲的敏感性低于基于振幅的传感器。结果，TOF传感器准确地测量了具有小半径拐角的形状的周长，而基于幅度的传感器由于弯曲损耗而高估了周长。与早期的工作相比，TOF装置较少依赖于影响信号水平的制造变化，例如光纤-源和光纤-检测器对准。我们得出结论，振幅方法可能是最好的纯弯曲传感器，TOF传感器可以区分压力从拉伸，和TOF方法是明显更好地测量长度超过地形，如在服装尺寸和其他可穿戴应用。
Soft and stretchable optical fibers are a promising all-polymer sensor element for extreme mechanical strains, pressures, bending, and other deformations. Compared to electronic sensors, the sensor elements are intrinsically stretchable and are not subject to electromagnetic interference. However, the typical approach of measuring deformation by tracking the transmitted light intensity is an integrating approach similar to resistance-based measurements; it does not provide information about the location or the nature of the deformation. This letter describes an alternate method for driving stretchable optical fibers: a consumer light detection and ranging chip connected to both ends of the fiber to measure its length via the time-of-flight (TOF) of a light pulse. This approach is a miniaturized, optics-based version of previous acoustic TOF and electronic time-domain reflectometry in robotics and human-interface devices. Such ranging systems collect spatial information using a small number of sensors. We found that the TOF approach can measure fiber lengths to within 1 mm on an overall length of ∼330 mm (>1% accuracy). Both the amplitude and TOF methods were sensitive to pressure that created microbending but in opposite directions. For bending radii greater than 7.5 mm, the TOF sensor was less sensitive to bending than the amplitude-based sensor. As a result, the TOF sensor accurately measured the perimeter of a shape with small-radius corners, while the amplitude-based sensor overreported the perimeter because of bending losses. Compared to earlier work, the TOF devices were less dependent on manufacturing variations that affected the signal level, such as fiber- source and fiber-detector alignment. We conclude that the amplitude method may be preferable for pure bending sensors, TOF sensors can distinguish pressure from stretching, and the TOF approach is notably better at measuring lengths over topography, such as in clothing-sizing and other wearable applications.