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

Abstract

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 lowpressure 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 humanmachine interactive interfaces.

Flexible Waterproof Piezoresistive Pressure Sensors with Wide Linear Working Range Based on Conductive Fabrics

“…Flexible pressure sensor, especially the piezoresistive sensor, is widely employed in electronic skin [1][2][3][4], healthcare monitoring [5][6][7][8], and human-machine interactions (HMI) [9][10][11]. To expand the feasibility of the piezoresistive sensor for diversified practical applications, they should have a linear pressure-sensing capability within large dynamic sensing ranges to constantly maintain their high sensitivity from lowpressure (< 10 kPa) to high-pressure region (> 100 kPa, even near 1 MPa) [12][13][14].…”

Mechanical Pressure Characterization of CNT-Graphene Composite Material

“…The opposite trend can be observed with respect to wt% of graphene: Sample fabricated with 80 wt% of graphene (CNT20) > Sample fabricated with 60 wt% of graphene (CNT40) > Sample fabricated with 40 wt% of graphene (CNT60) > Sample fabricated with 20 wt% of graphene (CNT80). It can be attributed by two factors; (1) the electrical conductivity of CNTs is higher than the electrical conductivity of graphene nanopowder (2) the density of CNTs is lower than the density of graphene nanopowder [ 18 , 19 , 20 ]. As the amount of CNTs content in CNT-graphene composites increase from 20 to 80 wt%, the conductivity of the corresponding composite increase, which leads to a reduction in the resistance of the samples.…”

Flexible Piezoresistive Tactile Sensor Based on Polymeric Nanocomposites with Grid-Type Microstructure

“…Linear Conversion of Voltage Signal Output-Since the proposed tactile sensor has a variable piezoresistive output that is inversely proportional to the static normal force, impedance matching can be connected in series with the sensor through a voltage divider circuit to convert the signal. A linear output was observed and the mathematical expression used for converting the signal into the output voltage V out is shown in Equation (1), where R 1 is the variable resistance output of the sensor, R 2 is the impedance matching connected to the voltage divider circuit, and V in is the DC voltage source input of 5 V [21,22].…”