Small‐Sized Deformable Shear Sensor Array for Direct Monitoring of Quantitative Shear Distribution

Abstract

Wang et al. fabricated a 100 × 100 pressure sensor matrix with a resolution of 100 dpi that could detect a wide pressure range. [32] You et al. made a flexible pressure sensor array of 100 pixels cm −2 without having electrical crosstalks between the pixels. [33] Kim et al. have demonstrated a carbonbased piezocapacitive pressure sensor array which could perceive a low pressure (0.4 Pa). [34] Li et al. fabricated a 4 × 4 matrix of supercapacitive pressure sensors using the ion-electronic interface and showed a high pressure-to-capacitance sensitivity (114 nF kPa -1 ). [35] In contrast to the intensive studies on the pressure sensors, shear sensors have been rarely investigated. It is because of the structural complexity of the shear sensor required for detecting different horizontal shear directions and the angles to the normal direction. Another technological difficulty in shear sensor fabrication is the need for deformability requested to prevent the slip of an object.So far, tactile shear force recognition has proceeded in three approaches; i) fabrication of a unit shear sensor, ii) profiling relative strain distribution by analyzing strain distribution obtained from a strain sensor array, and iii) direct mapping of shear forces by using a shear sensor array. The unit sensors are relatively large and designed to detect the shear forces applied from four directions. Viry et al. made a three-axial force sensor by using fluorosilicone and air gap between top and bottom electrodes. [36] Although the sensor could quantitatively measure shear forces, it could not provide the shear force distribution over a large area. Hua et al. implemented a 10 × 10 strain sensor array showing the shear force distribution through the piezoresistive sensor network. [37] Unfortunately, the quantitative value of shear force was difficult to obtain through the strain distribution approach. A shear sensor array is expected to simultaneously provide the shear force distribution and the quantitative force values. Cheng et al. fabricated a shear sensor array based on capacitance change upon air gap deformation. [38] Because of the small capacitance of the air gap, this type of capacitive sensor requires a large sensing area to obtain reliable sensing signals, thus fabrication of a miniaturized array sensor is difficult through this approach.In this work, we propose a deformable shear sensor array (3 × 3) in 27 mm × 27 mm, in which each sensor can An array of shear sensors is essential in tactile sensation as well as the pressure sensors. Surprisingly, however, the shear sensor array is rarely investigated mainly due to the structural complexity to measure the horizontal forces from various directions and also due to the mechanical softness required for preventing the slip of an object. Here, an array of small shear sensors that can recognize both shear force and shear rotational angle is fabricated. All the device components are made of deformable materials to acquire the softness of the sensor. This work presents a novel design for the sm...

An Angle‐Sensitive Microcolumn‐Based Capacitive Shear Force Sensor for Robot Grasping

“…In addition, the performance of our sensor is compared with previously reported shear force sensors, as shown in Table S1 (Supporting Information). [11,21,30,31,[37][38][39][40][41] The results indicate that the sensitivity and linearity of our sensor are superior. Although some sensors using ion gel materials exhibit higher sensitivity, their detection range is narrower.…”

“…However, most of the reported shear force sensors focus on detecting the magnitude of the force using various methods, including porous dielectric layers, [10,42] construct design of sensors, [30,43] and others. Although some sensor arrays with specific configurations have been successful in capturing detailed information about the direction of the shear force, [18,21] their applications and mass production are limited due to the increased complexity of sensor design and fabrication.…”

“…Sensors that convert shear force into electrical signals are based on different principles, including piezoelectric, [17] piezoresistive, [18,19] and capacitive mechanisms. [20,21] In particular, capacitive sensors have drawn attention due to their simple structure, low power consumption, and temperature stability. [22] The widely used strategy to enhance the performance of capacitive sensors is to modify the dielectric layer.…”

Shear-Pressure Decoupling and Accurate Perception of Shear Directions in Ionic Sensors by Analyzing the Frequency-Dependent Ionic Behavior

“…Previous studies on shear sensors have employed two approaches to perceive the direction of the shear force: configuring the electrodes for each direction − or utilizing a sensor array to detect the force distribution. − However, perceiving the exact direction with a high angle resolution of the shear force is a great challenge. For shear sensors with four electrodes positioned at an interval of 90°, the typical approach was a two-layered structure. , In the two-layered structure, the upper electrode responds to the direction of the shear force, resulting in a corresponding electrical signal change between the upper and lower electrodes.…”

An ionic pressure sensor array with digitizable sensitivity

“…Tactile sensation is one of the most important ways for the human body to perceive the external world, which includes stimuli such as pressure [1,2], strain [3,4], torsion [5,6], shear force [7,8], and touch [9,10]. Among them, pressure is a critical stimulus in tactile perception.…”