Flexible capacitive three-dimensional force sensor for hand motion capture and handwriting recognition

Handwriting recognition has been widely studied as an important signal transmission method in the field of human–computer interaction. Flexible capacitive three-dimensional (3D) force sensor is widely used in this field because of its high sensitivity, large dynamic response range and good mechanical stability. However, traditional flexible capacitive 3D force sensors based on the array structure usually only sense 3D force with equivalent forward pressure rather than the decoupling of real 3D force in space. Herein, we design a flexible capacitive 3D force sensor with petal-like electrode to capture various hand movements in 3D space and further decouple 3D force to 1D force along [Formula: see text], [Formula: see text] and [Formula: see text] directions. The sensor presents a high sensitivity (1.1 kPa[Formula: see text]at the pressures below 1 kPa), a fast response (63 ms) and excellent repeatability under continuous pressure. In addition, the electrode with eight-petal structure helps simplify the decoupling process of 3D force. Through handwriting test, the sensor presents good sensing performance for hand motion capture and handwriting recognition, which is expected to be applied in the field of human–computer interaction.