Flexible Hemispherical Strain Sensor with 3D Hollow Structure for Collision Perception

Flexible sensors have been widely used in the fields of tactile sensing, pressure feedback and safety monitoring, but manufacturing their three-dimensional conductive structures is still a challenge. In this study, a simple and low-cost embedded three-dimensional (3D) printing is proposed for the preparation of flexible hemispherical strain sensors (FHSSs) with integrated 3D hollow structures. Based on multi-material embedded 3D printing process, base ink is first printed in a support bath to build a hollow hemispherical silicone-shell substrate, followed by direct embedding of sensing ink in the uncured silicone-shell to print conductive sensing paths. It is synchronously cured and formed to achieve seamless integration of the FHSS conductive layer and functional layer, constructing an all-in-one structure with reliable stability. FHSSs exhibit good sensitivity response characteristics at different pressing depths and speeds, and have good stability after more than 1000 repeated pressing stimuli. Moreover, in conjunction with the control and recognition of the homemade circuit, an information processing strategy is proposed to build collision detection platform that successfully achieves real-time and intuitive collision perception and detection using FHSSs. This study not only provides an effective manufacturing method for developing flexible strain sensors, but also has important application potential in the human-computer interaction.