Highly Reliable Sensitive Capacitive Tactile Sensor with Spontaneous Micron‐Pyramid Structures for Electronic Skins

Abstract

In recent years, it is still challenging to develop a capacitive tactile sensor with low cost, high sensitivity, and controllable morphology. Herein, the flexible capacitive pressure sensor (FCPS) with high sensitivity is fabricated via a one-step template method to produce spontaneous micron-pyramid structured polydimethylsiloxane (PDMS) by releasing a four-way stretched PDMS film treated with ultraviolet ozone exposure. The capacitive sensor is composed of two silver nanowire electrodes coated on polyimide substrate and a patterned PDMS dielectric layer sandwiching in the middle, exhibits an ultrahigh sensitivity of 15.66 kPa −1 , an ultralow limit of detection of 0.2 Pa, a fast response time of 42.4 ms, and excellent cycling stability. The finite-elemental analysis suggests that the uniform micro-pyramid structures are vital to obtain ultrahigh sensitivity, low detection limit, and fast response. In particular, the FCPS can keep the tactile performance unchanged after 4000 repeated tests, reflecting the high robustness. In conclusion, the significant advantages of the sensor enable it to be well applied in the fields of sign language detection, spatial pressure distribution, and physiological signal monitoring, indicating that FCPS has a potential application prospect in the fields of flexible wearable electronic devices and electronic skins.

Highly sensitive flexible capacitive pressure sensor with structured elastomeric dielectric layers

“…It is worth noting that the combination of electrodes and the specific dielectric that we employ here results in significantly high sensitivity that compares well with other designs. It is worth noting that L Zhao et al achieved a remarkable sensitivity of 15 kPa −1 by integrating silver nanowires into electrodes and reducing microstructure pyramid dimensions to ∼1 µm [53].…”

“…Micro-pillars diminish the effective dielectric constant of the layer, enhance its deformability, and thus increase the device's sensitivity. The flexibility and roughness of the coated paper electrode render it more flexible and robust than the conventional ITO-coated PET film and conductive polymers [51][52][53][54][55][56][57][58]. Furthermore, the roughness of the paper electrodes enhances the adhesion between coppercoated trace paper and the dielectric.…”

Bamboo-Inspired, Environmental Friendly PDMS/Plant Fiber Composites-Based Capacitive Flexible Pressure Sensors by Origami for Human–Machine Interaction

“…For example, the fork-finger electrode structure and micronano structure can be used. 62,63 Besides, regulation of the porosity of the sensing layer may be a strategy worth considering. The elastic deformation of the sensing layer can be improved by methods such as the sacrificial template method and increasing the internal porosity of the fabric, thus enhancing the sensing performance.…”

Pressure Sensors Combining Porous Electrodes and Electrospun Nanofiber-Based Ionic Membranes

“…At present, microstructure design is widely regarded as an effective strategy to reduce Young’s modulus to improve the sensor sensitivity and range. As prepared by a microelectromechanical system (MEMS) technology pattern template, to obtain the microstructure of the dielectric layer surface, such as pyramids, cone, and column microstructure design, these designs produced by the complex and expensive sensor can only implement high sensitivity in a low-pressure area. − The porosity of the dielectric layer is improved by using sacrificial materials or by generating bubbles through a chemical reaction to significantly increase the capacitance change, thus improving the measurement range. − Due to the existence of van der Waals forces, it is easy to form local agglomeration between solid particles, and the pore size may differ by several orders of magnitude. Therefore, the pore size is highly differentiated, and the distribution within the film is uneven and random, so the measurement accuracy is low in a wide range.…”