Large-Area, Crosstalk-Free, Flexible Tactile Sensor Matrix Pixelated by Mesh Layers

Abstract

Tactile sensor arrays have attracted considerable attention for their use in diverse applications, such as advanced robotics and interactive human–machine interfaces. However, conventional tactile sensor arrays suffer from electrical crosstalk caused by current leakages between the tactile cells. The approaches that have been proposed thus far to overcome this issue require complex rectifier circuits or a serial fabrication process. This article reports a flexible tactile sensor array fabricated through a batch process using a mesh. A carbon nanotube–polydimethylsiloxane composite is used to form an array of sensing cells in the mesh through a simple “dip-coating” process and is cured into a concave shape. The contact area between the electrode and the composite changes significantly under pressure, resulting in an excellent sensitivity (5.61 kPa–1) over a wide range of pressure up to 600 kPa. The mesh separates the composite into the arranged sensing cells to prevent the electrical connection between adjacent cells and simultaneously connects each cell mechanically. Additionally, the sensor shows superior durability compared with previously reported tactile sensors because the mesh acts as a support beam. Furthermore, the tactile sensor array is successfully utilized as a Braille reader via information processing based on machine learning.

Recent Development of Flexible Tactile Sensors and Their Applications

“…One of the other ways to increase the flexibility of the piezocapacitive sensor is to increase the number of pixels. Bae et al introduced a flexible tactile sensor matrix pixelated using mesh layers ( Figure 3 b) [ 72 ]. The sensor matrix is uniformly patterned and electrically isolated between pixels using carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS) composite materials.…”

“… ( a ) Tactile sensor made from dielectric rose petal layer between two leaf electrodes [ 69 ]. ( b ) A proposed sensor utilizing fiberglass mesh [ 72 ]. ( c ) Pyramid microstructure PDMS films for piezocapacitance [ 73 ].…”

Review of Robot Skin: A Potential Enabler for Safe Collaboration, Immersive Teleoperation, and Affective Interaction of Future Collaborative Robots

“…As shown in Figure 6, many functional materials are being used in force-or pressure-sensitive skin, such as piezoresistive materials [104]- [108], piezoelectric materials [109]- [112], piezocapacitive materials [113]- [116], triboelectric materials [117]- [120], iontronic materials [121]- [126], magnetic materials [127]- [130], biomimetic materials [131]- [134], and fiber-optic materials [135]- [137]. Table III summarizes the pressure-sensitive robot skin based on the above functional materials.…”

Optical tactile sensor using scattering inside sol–gel-derived flexible macroporous monoliths

“…[1][2][3] One widely used sensor utilizes wires stretched in a mesh-like pattern to detect resistance in a membrane. [4][5][6] Low-cost sheet-type sensors are used for pressure sensing in applications other than robotics. In material chemistry, materials whose conductivity changes with deformation have been extensively developed.…”