Laser‐Ablated Liquid Metal Interdigital Electrodes for a Normal Force‐Decoupled Capacitive Flexible Tensile Strain Sensor

ABSTRACT Flexible tensile strain sensors employing liquid metal interdigital electrodes (LMIEs) effectively suppress normal force interference, holding significant promise for wearable electronics, soft robotics, and health monitoring. However, conventional fabrication of LMIEs relies on complex and costly micro‐electro‐mechanical system (MEMS) or femtosecond laser processes. To overcome this limitation, this paper presents a laser‐ablated LMIEs for a compressive force‐decoupled capacitive flexible tensile strain sensor (CFTSS). Utilizing a low‐cost, high‐efficiency laser ablation, the interdigital electrodes of oxidized liquid metal (oLM) are directly patterned onto a soft substrate. The mechanism of laser‐selective removal of the oLM is analyzed, and morphological changes pre‐ and post‐ablation are experimentally characterized. Furthermore, to improve selective removal of oLM, this paper introduces an enhanced method incorporating horizontal tangential airflow. Through the combination of theoretical modeling and experimental validation, the model of the sensor is established. And the normal force suppression mechanism is elucidated. Through optimizing the geometric parameters of the IEs, the sensor achieves a tensile force sensitivity 2.9 × 10 ⁷ times higher than its normal force sensitivity, presenting excellent resistance to normal force interference. Additionally, the application of the sensor in human motion monitoring and human‐computer interaction are demonstrated.