An ultra-sensitive and wide measuring range pressure sensor with paper-based CNT film/interdigitated structure

Flexible pressure sensors have attracted great attention due to their potential in the wearable devices market and in particular in human-machine interactive interfaces. Pressure sensors with high sensitivity, wide measurement range, and low-cost are now highly desired for such practical applications. In the present investigation, an ultrasensitive pressure sensor with wide measurement range has been successfully fabricated. Carbon nanotubes (CNTs) (uniformly sprayed on the surface of paper) comprise the sensitivity material, while lithographed interdigital electrodes comprise the substrate. Due to the synergistic effects of CNT’s high specific surface area, paper’s porous structure, interdigital electrodes’ efficient contact with CNT, our pressure sensor realizes a wide measurement range from 0 to 140 kPa and exhibits excellent stability through 15,000 cycles of testing. For the paper-based CNT film/interdigitated structure (PCI) pressure sensor, the connection area between the sensitive material and interdigital electrodes dominates in the low-pressure region, while internal change within the sensitive materials plays the leading role in the high-pressure region. Additionally, the PCI pressure sensor not only displays a high sensitivity of 2.72 kPa–1 (up to 35 kPa) but also can detect low pressures, such as that exerted by a resting mung bean (about 8 Pa). When attached to the surface of a human body, the pressure sensor can monitor physiological signals, such as wrist movement, pulse beats, or movement of throat muscles. Furthermore, the pressure sensor array can identify the spatial pressure distribution, with promising applications in human-machine interactive interfaces.