Flexible Capacitive Pressure Sensor Based on Microstructured Composite Dielectric Layer for Broad Linear Range Pressure Sensing Applications

Abstract

Flexible pressure sensors have attracted a considerable amount of attention in various fields including robotics and healthcare applications, among others. However, it remains significantly challenging to design and fabricate a flexible capacitive pressure sensor with a quite broad linearity detection range due to the nonlinear stress–strain relation of the hyperelastic polymer-based dielectric material. Along these lines, in this work, a novel flexible capacitive pressure sensor with microstructured composite dielectric layer (MCDL) is demonstrated. The MCDL was prepared by enforcing a solvent-free planetary mixing and replica molding method, while the performances of the flexible capacitive pressure sensor were characterized by performing various experimental tests. More specifically, the proposed capacitive pressure sensor with 4.0 wt % cone-type MCDL could perceive external pressure loads with a broad detection range of 0–1.3 MPa, which yielded a high sensitivity value of 3.97 × 10−3 kPa−1 in a relative wide linear range of 0–600 kPa. Moreover, the developed pressure sensor exhibited excellent repeatability during the application of 1000 consecutive cycles and a fast response time of 150 ms. Finally, the developed sensor was utilized for wearable monitoring and spatial pressure distribution sensing applications, which indicates the great perspectives of our approach for potential use in the robotics and healthcare fields.

Cone‐Shaped Electrodes for Capacitive Tactile Sensors with High Sensitivity and Broad Linearity Range

“…The linear response of the realized sensors, as observed from the reported capacitive flexible tactile sensors, can be classified into three main categories: 1) introducing microstructures in the dielectric layer, 2) using a percolative elastomeric composite as the dielectric layer, and 3) designing microstructured elastic electrodes as the sensitive layer. In the case of the first strategy sensors, [18,[20][21][22][23][24][25][26] the introduction of microstructures such as gradient micro-dome architecture, [18] multi-hierarchical microstructures, [23] and foam structures, [24][25][26] has been extensively investigated to enable persistent deformation of the dielectric layer under varying pressures, consequently improving the linearity of tactile sensors. The sensors based on the second strategy compensate for the reduced sensitivity caused by mechanical saturation by increasing the dielectric constant to enhance the linearity of the sensor.…”

“…Moreover, a comparative evaluation of the proposed sensor with other reported capacitive sensors with linear response was performed, focusing on sensitivity and linear range. [18,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] The results of the comparison are shown in Figure 3h and Table S2 (Supporting Information). The majority of the reported sensors have either low sensitivity or narrow linear sensing range.…”

A Flexible Pressure Sensor with Wide Detection Range Based on Capacitive‐Piezoresistive Dual Mode Conversion for Human‐Machine Interaction

“…At present, the main solutions for improving the sensitivity of flexible sensors include constructing microstructures of elastomers, adopting new composite active materials, and manufacturing porous elastic materials. Among them, there are various microstructures that can be constructed, such as pyramid, [11][12][13][14][15][16] micropillar, [17][18][19] two-level micropillar, [20] crack, [21] fold, [22] microsphere, [23][24][25][26] fabric, [27,28] sandpaper, [29][30][31] biomimetic, [32][33][34] and other microstructures. The presence of these microstructures can greatly improve the sensitivity of sensors.…”

Highly Sensitive and Flexible Capacitive Pressure Sensors Based on Vertical Graphene and Micro-Pyramidal Dielectric Layer

“…Among these sensors, capacitive sensors with a dielectric layer sandwiched between two electrodes exhibit the advantages of a simple structure, facile manufacturing, low energy consumption, and static/dynamic detection. Therefore, flexible capacitive pressure sensors have attracted extensive attention in tactile sensing [ 16 , 17 ], environmental detection [ 18 , 19 ], and human motion monitoring [ 20 , 21 , 22 ]. High sensitivity is key to achieving high-pressure resolution, which is essential for simplifying signal processing [ 23 ].…”