Flexible Microstructured Capacitive Pressure Sensors Using Laser Engraving and Graphitization from Natural Wood

Abstract

In recent years, laser engraving has received widespread attention as a convenient, efficient, and programmable method which has enabled high-quality porous graphene to be obtained from various precursors. Laser engraving is often used to fabricate the dielectric layer with a microstructure for capacitive pressure sensors; however, the usual choice of electrodes remains poorly flexible metal electrodes, which greatly limit the overall flexibility of the sensors. In this work, we propose a flexible capacitive pressure sensor made entirely of thermoplastic polyurethane (TPU) and laser-induced graphene (LIG) derived from wood. The capacitive pressure sensor consisted of a flexible LIG/TPU electrode (LTE), an LIG/TPU electrode with a microhole array, and a dielectric layer of TPU with microcone array molded from a laser-engraved hole array on wood, which provided high sensitivity (0.11 kPa−1), an ultrawide pressure detection range (20 Pa to 1.4 MPa), a fast response (~300 ms), and good stability (>4000 cycles, at 0–35 kPa). We believe that our research makes a significant contribution to the literature, because the easy availability of the materials derived from wood and the overall consistent flexibility meet the requirements of flexible electronic devices.

Flexible BaTiO3-PDMS Capacitive Pressure Sensor of High Sensitivity with Gradient Micro-Structure by Laser Engraving and Molding

“…The formation of the micro-cone exhibited a strong correlation with the laser power. The cross section intensity of the laser adhered to a Gaussian distribution, which played a significant role in the genesis of micro-cones [ 55 , 56 ]. As the laser ablation process advanced on the board, the gradual decoking resulted in a progressive decrease in the critical point’s radius, where the laser-induced ablation occurred, ultimately leading to the emergence of the micro-cone.…”

Design and Analysis of Porous Elastomeric Polymer Based on Electro-Mechanical Coupling Characteristics for Flexible Pressure Sensor

“…Therefore, it is of paramount importance to investigate the electro-mechanical response relationship between the dielectric layer and flexible sensor for sensor design. Elastomeric polymers, such as polydimethylsiloxane (PDMS) [ 13 ], poly(vinylpyrrolidone) (PVP) [ 14 ], poly(2-hydroxyethyl methacrylate) (pHEMA) [ 15 ], poly-methyl-methacrylate (PMMA) [ 16 ], polyurethane (TPU) [ 17 ], and Ecoflex [ 18 ], are commonly employed in the fabrication of dielectric layers. Nevertheless, flexible capacitive pressure sensors utilizing bulk elastomeric polymers as the dielectric layer face challenges in achieving sufficient sensitivity.…”

Bioinspired Low Hysteresis Flexible Pressure Sensor Using Nanocomposites of Multiwalled Carbon Nanotubes, Silicone Rubber, and Carbon Nanofiber for Human–Computer Interaction

“…37 Among them, carbon-based nanomaterials have been widely investigated due to their strong hardness, high chemical stability and specific surface area, and low cost. Flexible substrate materials include poly(dimethylsiloxane) (PDMS), 38 thermoplastic polyurethane (TPU), 39 Ecoflex, 40 etc. Among them, PDMS is a colorless, transparent polymer.…”