Carbon Nanotube Network Topology-Enhanced Iontronic Capacitive Pressure Sensor with High Linearity and Ultrahigh Sensitivity

Flexible
capacitive pressure sensors with high sensitivity over
a wide pressure range are highly anticipated in the fields of tactile
perception and physiological signal monitoring. However, despite the
introduction of microstructures on the electrolyte layer, the deformability
is still limited due to the size limitation of the microstructures,
making it difficult to significantly improve the sensitivity of iontronic
capacitive pressure sensors (ICPSs). Here, we propose an innovative
strategy of combining carbon nanotubes (CNTs) topological networks
and ionic hydrogel micropyramid array microstructures that can significantly
enhance the sensitivity of flexible ICPSs for ultrasensitive pressure
detection. Compared with other previously reported ICPSs, the sensor
developed in this work exhibits an unprecedented sensitivity (Smin > 1050 kPa–1) and a
high
linear response (R2 > 0.99) in a wide
pressure range (0.03–28 kPa) enabled by CNT percolation networks
inside the microstructred electrolyte layer. This ultrasensitive and
flexible ICPS also can effectively detect pressure from a variety
of sources, including sound waves, lightweight objects, and tiny physiological
signals, such as pulse rate and heartbeat. This work provides a general
strategy to achieve an ICPS with both broader pressure-response range
and higher sensitivity, which provides a stable and efficient way
for a low-cost, scalable sensor for sensitive tactile sensing in human–computer
interaction applications.