The measurement of bending direction and bending angles is essential in the multiaxial servo-controlled system, especially for collaborative robots. However, most flexible sensors developed for bending measurements cannot distinguish bending directions due to their sensitivity to both positive and negative bending. Also, these sensors usually exhibit simultaneous response to normal pressure, which results in additional calibration. Here, a unidirectional-sensitive flexible capacitive sensor is proposed. A simple asymmetric pyramidal microstructure was designed to create uneven responses to positive and negative bending and minimum response to normal pressure based on the fringe effect. The fabricated sensor shows a relative capacitance change of nearly 0.9 in the sensitive direction and only 0.05 in the other direction as the sensor bends from flat to the curvature radius of 10 mm. Also, the sensor shows negligible sensitivity even under a normal pressure force as high as 16 N, either in planar or bending condition.

弯曲方向和弯曲角度的测量在多轴伺服控制系统中至关重要，特别是对于协作机器人而言。但是，大多数为弯曲测量而开发的柔性传感器由于对正弯曲和负弯曲均敏感，因此无法区分弯曲方向。而且，这些传感器通常对正常压力表现出同时响应，从而导致额外的校准。在此，提出了一种单向敏感的柔性电容传感器。设计了一个简单的不对称金字塔形微结构，以基于条纹效应创建对正向和负向弯曲的不均匀响应以及对法向压力的最小响应。制成的传感器在敏感方向上的相对电容变化接近0.9，而只有0。当传感器从平面弯曲到10 mm的曲率半径时，在另一个方向上为05。而且，即使在平面或弯曲条件下，即使在高达16 N的法向压力下，传感器的灵敏度也可忽略不计。