All-Printed MXene-Based Springs for Concurrent Bidirectional Hand Motion Capture.

Accurately capturing hand movements remains a challenge because the skin undergoes stretching, compression and bending at the same time, yet most flexible sensors respond only to tension. Achieving high sensitivity and a wide range often means making the sensor thick, which causes the sensing layer to shift under complex deformations and distorts the signal. Here, we address this by placing the strain-accommodating space within a plane parallel to the strain direction. Using a MXene/polyurethane ink with glycerol as a molecular bridge, we create a dense hydrogen-bonding network that enables high-resolution printing of a planar spring architecture. The resulting all-printed sensor achieves a gauge factor of 83.7 across a linear bidirectional range of ±60% strain. With just two sensors, we track and decode complex wrist motions with ±10° accuracy. When attached to finger joints, they enable real-time, dexterous control of a virtual hand. This work provides an alternative approach for skin strain capture through synergistic innovation in materials and architecture.