Fabrication of Flexible Capacitive Pressure Sensors by Adjusting the Height of the Interdigital Electrode

Flexible pressure sensors have great application prospects in the fields of human–computer interaction and wearable electronic devices. Nowadays, the emergence of planar capacitive pressure sensors composed of an interdigital electrode has solved the problem of mechanical mismatch between the electrode layer and the dielectric layer during packaging and further realizes the miniaturization and thinness. However, there are few reports on whether adjusting the height of the interdigital electrode can improve the sensitivity of the sensor. This paper proposes a strategy based on dispensing technology to improve the performance of a capacitive pressure sensor by adjusting the height of the interdigital electrode. The results show that the optimal height of the interdigital electrode is 1.3 mm. On this basis, increasing the number of fingers of the interdigital electrode can also expand the sensitivity and detection range of the sensor. In order to further improve the performance of the sensor, we doped barium titanate with a high dielectric constant in the dielectric layer and introduced the pyramid microstructure. The test results show that our sensor has high sensitivity (0.6275 kPa^–1, ≤1 kPa), wide detection range (0.5–166 kPa), fast response time (120 ms), and good stability after 10,000 cycles. In addition, the sensor can be applied to various pressure detection scenarios such as finger pressing, human joint motion detection, and grasping object detection. Meanwhile, we also constructed a 3 × 3 pressure sensor array to identify the distribution of the spatial pressure. This work provides a solution for preparing high-performance capacitive pressure sensors using an interdigital electrode, which has great application prospects in the field of intelligent wearables.