Flexible planar dual-mode capacitive sensor based on interdigital electrodes with vertical conductive ridges for human-computer interaction

Abstract

Flexible planar capacitive sensor have been widely applied in human-computer interaction and wearable systems due to their excellent tactile detection capabilities. Proximity perception as a complementary approach, enhances the overall perception range and provides new possibilities for applications. However, at present, the dual-mode cooperative operation mechanism and the improvement strategy of tactile sensitivity and proximity perception performance still need to be further improved. This paper employs laser-induced graphene (LIG) technology to significantly enhance the sensor's dual-mode collaborative sensing capabilities by incorporating vertical conductive ridges into conventional interdigital electrodes. These ridges partition the traditional capacitive region into multiple parallel independent units, effectively increasing the sensing area and thereby improving tactile sensitivity. Simultaneously, the dielectric layer utilizes a sandpaper microstructure doped with barium titanate (BaTiO₃) particles, further enhancing sensitivity while broadening the sensor's operational range. Additionally, the introduction of vertical conductive ridges combined with porous electrodes fabricated by LIG technology substantially increases the number of effective edges, strengthening the fringe effect and consequently improving proximity sensing performance. The experimental results demonstrate that the sensor exhibits high sensitivity (0.5938 kPa⁻¹, ≤1 kPa), broad detection range (0.5–500 kPa), fast response time (160 ms), excellent mechanical stability (5000 cycles), and reliable proximity sensing capability (60 mm). The sensor has been successfully applied to space pressure distribution array sensing, smart home lamp continuous dimming and human motion monitoring, and has broad prospects in the field of intelligent wearable and human-computer interaction.