Highly sensitive flexible three-axis tactile sensors based on the interface contact resistance of microstructured graphene

Abstract

The lack of high-performance tactile sensors, especially for pressure/force, is a huge obstacle for the widespread application of intelligent robots. Current pressure sensors are often operated in the high range of pressure and normal direction, showing a little ability in the low range of pressure and three-axis direction simultaneously. Herein, a highly sensitive flexible tactile sensor with three-axis force sensing capacity is presented by combining microstructured polydimethylsiloxane (PDMS) arrays and a reduced graphene oxide (rGO) film. The deformation of microstructured rGO/PDMS results in a change in the contact area between the rGO film and electrode, leading to a high sensitivity of -1.71 kPa-1 in the low range pressure of 0-225 Pa with a fast response time of 6 ms at a large feature size of 100 μm. To realize three-axis sensing, a sensing unit was built up, which was composed of the adjacent four parts of patterns and electrodes underneath a bump. A mechanical model of the exerted spatial force was established to calculate each axis force component via the deformation of the rGO/PDMS pattern. The experimental results show that the current difference between the adjacent two parts has a strong relationship with the applied force. As a proof of concept, we have demonstrated a 3 × 3 array sensor for arbitrary force sensing. Our tactile sensor would be used in transmitting information from a gentle spatial force and would exhibit broad applications as e-skin in integrated robots.

Multilevel Microstructured Flexible Pressure Sensors with Ultrahigh Sensitivity and Ultrawide Pressure Range for Versatile Electronic Skins

“…After curing, the positive PDMS (pPDMS) was peeled off from the nPDMS mold. Subsequently, the LBL assembly method was used to fabricate a uniform graphene oxide (GO) film on the as‐prepared pPDMS. The commercial GO (Figure S2, Supporting Information) was used as the graphene film precursor.…”

“…The commercial GO (Figure S2, Supporting Information) was used as the graphene film precursor. After that, GO film was reduced by the hydrazine vapor under 90 °C for 3 h. With the increase of the LBL assembly cycles, the multilayer GO film will become thicker, and the resistance of the obtained rGO film will reduce . For suitable resistance (within the measurement range of our source meter) and efficiency, we repeated ten cycles to fabricate such a rGO/PDMS film.…”

“…In this work, the irregular commercial sandpaper was adopted as the template to fabricate the multilevel microstructured (MM) PDMS and the reduced graphene oxide (rGO) coated via layer‐by‐layer (LBL) assembly method was used as the sensing materials. The pressure sensor was assembled with a microstructured PDMS and flexible interdigitated electrodes.…”

A Novel Strategy for Preparing Stretchable and Reliable Biphasic Liquid Metal

“…Stretchable conductive pattern, the foundation of flexible electronics, [1,2] demanding in concurrent of high conductivity, stretchability, long-term stability, and reliable mechanical performance, shows great potential applications in tactile electronics, [3,4] lithographic circuit, [5,6] soft bioelectronics, 3D printing of electrodes, [7,8] etc. In the previous study, a variety developing intrinsically stretchable conductive material compared to the pure metals, metal/elastomers (as described in Figure 1a), which possesses the advantage of both pure liquid and solid materials.…”

“…However, these materials with high Young's modulus possess poor stretchability and frangibility, and are prone to crack under stretching or bending environments, resulting in loss of electric conductivity. [15,16] Unlike these traditional conductive rigid materials, the emerging galliumbased liquid metals with advantages of low Young's moduli (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) and in principle infinitely deformable have attracted great attention as an ideal candidate for fabricating stretchable conductive pattern. ), which is enabled to slightly elongate but it is also limited.…”