Flexible piezoresistive sensor matrix based on a carbon nanotube PDMS composite for dynamic pressure distribution measurement

Abstract

Abstract. A highly flexible, piezoresistive sensor matrix based on a carbon nanotube (CNT) polymer composite is developed for pressure distribution measurement applications. With an overall height of about 400 µm, the sensors can measure pressure directly, without any deformation elements, such as a cantilever or a deformation membrane. The measurement range is from 2.5 to 640 kPa. Both the position and the pressure of the applied load can be measured and visualized as a resistance change. The relative resistance measurement deviation of the data acquisition system is lower than 3 % for the resistance range of 610Ω to 380 kΩ. This corresponds to a systematic deviation of pressure measurement of less than 3 % in the measurement range. Besides the measurement of pressure, different sizes of loads can be detected as well. The developed fast and compact measurement system allows dynamic pressure measurement, such as gait analysis when used in an insole application.

Dynamic Interface Pressure Monitoring System for the Morphological Pressure Mapping of Intermittent Pneumatic Compression Therapy

“…A vibratory shaker and a Keithley digital multimeters system (Figure 3a) were used to characterize the reliability of the soft sensor. Referring to the IPC working time and existing literature on soft sensors [29,30,31,32,33,34,35,36,37,38,39,40,41,42,43], the R sensor was measured under the pressure exerted by a 0.5 kg weight when the vibratory shaker was set at a constant frequency of 1 Hz. The produced electrical signals were collected by the digital multimeters at a sampling period of 10 ms. Figure 3b presents the resistance variation of the soft sensor within 60 s. The response time of the resistance depends on both loading/unloading frequencies of the weight and the sampling periods of the digital multimeters in the test.…”

“…Flexible piezoresistive sensors comprising conformable substrates and compliant conductive materials are capable of detecting the applied pressure or mechanical force through changing current or resistance. Some advanced materials are used to fabricate highly flexible and stretchable strain sensors, including silicon nanomembranes [29], silver nanoparticle ink [30], thin films of carbon nanotubes [31,32], graphene films [33,34], 3,4-ethylenedioxythiophene/styrenesulfonate [35], and polydimethylsiloxane (PDMS) based electrically conductive composites such as carbon black [36], graphite [37], carbon nanotubes [38,39], and metallic nanoparticles [40]. In which, PDMS based graphite sensors can detect up to 100% stretch deformation with 50 gauge factors under a strain [36].…”

Review on Conductive Polymer/CNTs Nanocomposites Based Flexible and Stretchable Strain and Pressure Sensors

“…With an optimized dispersion procedure, CNTs can be effectively and homogeneous distributed in PDMS matrix at a lower concentration of 1 wt.% to achieve sensitivities as high as 46.8%/N in the range 0–1 N with a minimum sensing of 1 g weight and a maximum sensing range of 180 N (~18 kg) [ 37 ]. Figure 11 shows the piezoresistive [ 105 ] and piezocapacitive [ 37 ] behavior of the CNT-PDMS pressure sensor. A detailed performance comparison is presented in Table 3 .…”

“…A more dynamic arrangement of pressure sensors in matrix layout is shown in Figure 12 a as a potential grasping application to calibrate the grasping force of robot fingers with the ability present pressure distribution in a real time visual interface. A similar 4 × 4 matrix layout concept is shown in Figure 12 b, with the aim to serve as a mattress for decubitus monitoring in bedridden patients with a minimum weight resolution of 20 g [ 105 ]. The soft nature of the polymer leads to thin sensor structures that are flexible enough to detect physiological signals like movement of muscles caused by a gesture and pulse when attached to the human body as shown in Figure 12 c This enables detection of gestures that can be potentially translated into a machine-readable signal to facilitate human-machine interface for robot control and telemanipulation.…”

Working Principle and Performance of a Scalable Gravimetric System for the Monitoring of Access to Public Places

“…Different sensor types are employed: the more common and recent proposals, that can be found in the literature, involve capacitive sensors [ 16 ] and piezoresistive Polymer Thick Films (PTFs) [ 8 , 9 , 10 , 11 , 14 ]. A more advanced piezoresistive carbon nanotube polymer sensor matrix is presented in [ 20 ]. The authors introduce a smart sensing floor based on triboelectricity in [ 4 ].…”