Suction cups are commonly used as adhering and grasping devices. This study proposes a methodology to expand the applicability of suction cups. A suction cup is developed with a soft pad which consists of stretchable electrodes and insulating layers that bond to the bottom of the main body of the suction cup. When the stretchable electrodes generate an electrostatic attraction between the electrodes and the object, the pad deforms, filling the gaps between the pad and the object. Due to the soft pad, the amount of incoming air is significantly reduced compared to a normal suction cup. Experiments reveal the effect of these features. Applying a high voltage to the stretchable electrodes increases the holding success ratio of the suction cup in the normal direction for smooth and rough surfaces due to the stretchable electrodes. Measuring the negative pressure inside the suction cup confirms that the electrostatic force maintains the adhesion force on both smooth and rough surfaces. Thus, the electrostatic force and stretchability of the soft pad greatly increase the adhesion force of the suction cup. Furthermore, the electrostatic force prevents a slip of the suction cup, which improves the performance of the suction cup.
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