Capacitive tactile sensors using dielectric polymer materials
as
dielectric layers have been studied due to their high sensitivity
and flexibility with a variety of types of materials in response to
external stimuli. However, a polymer-based tactile sensor device is
limited in long-term use due to a lack of mechanical stability against
repeated external stimuli. In this study, a dynamic covalent polymer-based
carbon composite material with high sensitivity, structural stability
as well as self-healing ability was manufactured and applied as a
capacitive tactile sensor dielectric layer. A polymer chain with a
disulfide dynamic covalent bond was used as a composite matrix, and
carbon nanofibers were applied as fillers to dramatically increase
the dielectric constant of the material. The material-based capacitive
tactile sensor not only had a high response signal even at a low external
stimulus (0.5 kPa) but also had a high sensitivity (46.7 MPa–1) according to the intensity of the stimulus (0.5–17.5 kPa).
In addition, the sensor device had a short response of less than 0.2
s and a recovery time of 0.25 s to external stimuli with a stable
response signal for 5000 repetitive stimuli. Furthermore, after self-healing
deformation of the dielectric layer, the sensor device showed the
same level of sensitivity to external stimuli as before deformation
by more than 95%.