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

Abstract

Many practical applications require flexible high-sensitivity pressure sensors. However, such sensors are difficult to achieve using conventional materials. Engineering the morphology of the electrodes and the topography of the dielectrics has been demonstrated to be effective in boosting the sensing performance of capacitive pressure sensors. In this study, a flexible capacitive pressure sensor with high sensitivity was fabricated by using three-dimensional vertical graphene (VG) as the electrode and micro-pyramidal polydimethylsiloxane (PDMS) as the dielectric layer. The engineering of the VG morphology, size, and interval of the micro-pyramids in the PDMS dielectric layer significantly boosted the sensor sensitivity. As a result, the sensors demonstrated an exceptional sensitivity of up to 6.04 kPa−1 in the pressure range of 0–1 kPa, and 0.69 kPa−1 under 1–10 kPa. Finite element analysis revealed that the micro-pyramid structure in the dielectric layer generated a significant deformation effect under pressure, thereby ameliorating the sensing properties. Finally, the sensor was used to monitor finger joint movement, knee motion, facial expression, and pressure distribution. The results indicate that the sensor exhibits great potential in various applications, including human motion detection and human-machine interaction.

Rapid-Response and Highly Sensitive Piezocapacitive Pressure Sensor Based on Micro Buckling Periodic Layers for Wearable Applications

“…The high sensitivity along with the fast response may benefit from the face-to-face placement of the two different micro buckling structures. The sensitivity and response are superior to those of the newly reported vertical graphene/micropyramidal PDMS piezocapacitive pressure sensor, 34 the reported capacitive sensor using a porous micropillar PDMS as the dielectric layer (∼20 ms), 44 and the spinosum capacitive pressure sensor based on CNT/ PDMS nanocomposites (∼20 ms). 45 The high sensitivity can be attributed to the micro pyramid structure of the dielectric layer and the air gap between the wrinkle structure and the pyramid structure.…”

“…Hence, the deformation mechanism and the geometry morphology of the dielectric layer, sandwiched between two conductive electrodes, are very promising for the sensor's sensitivity and response. To enhance the sensitivity and response, dielectric layers with various microstructures such as pyramid, 34 micropillar, 35 microtower, 36 nanofiber, 37 and porous, 38 like photolithography and chemical etching. Low-cost methods to create effective microstructures are accordingly investigated.…”

“…Hence, the deformation mechanism and the geometry morphology of the dielectric layer, sandwiched between two conductive electrodes, are very promising for the sensor’s sensitivity and response. To enhance the sensitivity and response, dielectric layers with various microstructures such as pyramid, micropillar, microtower, nanofiber, and porous, have been applied in research studies, instead of plain ones. However, the production of the sophisticated microstructure usually involves costly and multistep processes like photolithography and chemical etching.…”

Synergistic advancements in high-performance flexible capacitive pressure sensors: structural modifications, AI integration, and diverse applications

“…The most effective approach for enhancing the performance of CPSs that operate based on the parallel-plate capacitance principle involves structural modifications of the dielectric or electrodes. Accordingly, various microstructures have been incorporated, such as micro-pyramidal, 30,31 microporous, [32][33][34] micro-spherical, 35,36 micropillar array, 37,38 foam-like, 39,40 bionic, 41,42 and wrinkled 43,44 structures. These microstructures decrease the Young's modulus of the dielectric material, thereby enhancing its deformability.…”

Template‐free Formation of Hybrid Dielectric for Flexible Capacitive Sensors with Wide‐Pressure‐Range Linear Detection

“…[18,19,24] Specifically, various microstructures, such as micro-cones, micro-pyramids, micro-domes, micro-cilia, wrinkled and porous structures and have been proven as an effective way to enhance the stretchability of sensors. [25][26][27][28][29][30][31][32] In our previous work, a hair-like micro-cilla array as the dielectric layer was demonstrated for the flexible capacitive pressure sensor with a high sensitivity of 0.28 kPa −1 at low pressure (0-10 kPa). But the sensitivity drops sharply at 0.02 kPa −1 under 50-200 kPa.…”