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电子皮肤[1-4]是一类仿生皮肤,可以实现人类一样的触觉感知。面向机器人触觉的柔性压力传感器能够对压力进行高灵敏度感知,吸引了国内外科研学者的广泛关注,在医学[5]、机械[6]等领域有很好的应用前景。目前面向机器人触觉的电子皮肤多考虑生物相容性等因素,不具有自供能的特性,而通过压电传感器进行力学信号和电信号的转变来实现传感功能的电子皮肤不需要外部供电,具有解决供能问题和环境友好的特点。压电传感器的核心为压电转换层,须采用具有高压电系数的材料制成。高压电系数的压电陶瓷[7-9]如锆钛酸铅、钛酸钡等因为不具有柔性,不利于设备的可穿戴性设计,因此面向机器人触觉的柔性压电材料多采用以聚偏氟乙烯 (polyvinylidene fluoride, PVDF)及其共聚物为代表的有机压电材料[10]和有机无机压电复合材料[11]。PVDF压电聚合物具有较高的压电性能和较好的柔韧性,其与三氟乙烯的共聚物聚偏氟乙烯-三氟乙烯(PVDF-TrFE)极化后具有更高的β晶含量,表现出更加优异的压电性能,在柔性压电传感器的设计制作中具备明显优势。
本文以有机PVDF-TrFE薄膜为功能层,制备了面向机器人触觉的柔性压力传感器,并通过羟基磷灰石的微量掺杂改善了薄膜的压电性能。该传感器对力的大小以及位置具有精准的感知,能够很好地应用于机器人触觉系统。
Flexible Pressure Sensor for Robotic Touch
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摘要: 机器人触觉传感器需要同时满足对受力大小进行精确感知以及对作用位置进行精准定位。该文采用等离子体原位极化工艺,在柔性电路板上制备了PVDF-TrFE压电薄膜。在PVDF-TrFE薄膜的制备中,以少量羟基磷灰石掺杂提高了PVDF的结晶性能,有利于β晶型的转化,进而提高了PVDF的压电系数,提升了PVDF对力的电学响应精度,从而提高了感知器件灵敏度。采用柔性PCB电路板制备柔性PVDF压电传感器,不仅可以对力的大小实现三维传感,而且能够对作用力的位置进行定位,从而可以应用于机器人触觉传感。Abstract: Robotic touch sensors need to satisfy both accurately sense on the force and precisely position of the force. In this paper, PVDF-TrFE piezoelectric film was fabricated on a flexible circuit board through an in-situ polarization method. The crystallinity of PVDF is improved by a small amount of hydroxyapatite doping, which is beneficial to the conversion of β crystal form, and thus increases the piezoelectric coefficients of PVDF. With the increased piezoelectric coefficient, the electrical response precision of PVDF to force is improved, and makes the PVDF-based pressure sensing device more sensible. The flexible PVDF piezoelectric sensor is fabricated by using a flexible PCB, which can not only realize three-dimensional sensing of the force level, but also locate the position of the force, so that it can be applied to the tactile sensing of the robot.
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Key words:
- hydroxyapatite /
- piezoelectric coefficient /
- piezoelectric sensor /
- robotic touch
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