3D Printed Reduced Graphene Oxide/Elastomer Resin Composite with Structural Modulated Sensitivity for Flexible Strain Sensor

Abstract

High-performance flexible strain sensors with cost-effective and scalable fabrication methods are highly demanded for human-machine interfaces, soft robotics, and health monitoring. Herein, a digital light processing-based 3D printing method, which manufactures structures in a scalable and efficient layerby-layer manner, is developed to prepare a type of flexible strain sensors consisting of reduced graphene oxide/elastomer resin (RGO/ER) composite as the strain sensing element and RGO/ER composite with rhombic structure as the electrode. The RGO/ER composite as the sensing element has a sensitivity of 6.723 at a linear strain detection range from 0.01% to 40% and a high mechanical stability of more than 10 000 stretching-relaxing cycles. Furthermore, through the structural modulation, the sensitivity of the composite responding to mechanical deformation is modulated and suppressed, which can be used as the electrode for the strain sensor. The all-3D printed device with structurally modulated performance can be used for monitoring various human motions.

Lignin as a High-Value Bioaditive in 3D-DLP Printable Acrylic Resins and Polyaniline Conductive Composite

“…The data are slightly lower than those obtained for DLP 3D printed acrylic resins filled with 0.3–0.6 wt.% carbon nanotubes (10 −4 –10 −5 S cm −1 ) [ 80 , 81 , 82 ] and similar contents of PANI-HCl (10 −5 S cm −1 ) [ 31 ] or a mixture of PANI/MWCNT (10 −4 S cm −1 ) [ 32 ]. Simultaneously, the conductivity values achieved are similar or higher than those reported for printable photocurable resins using 16 wt.% (10 −6 S cm −1 ) [ 83 ] and 1 wt.% (10 −11 S cm −1 ) [ 84 ] of Ag nanoparticles or 2 wt.% reduced graphene oxide (rGO) (10 −7 S cm −1 ) [ 85 ]. By contrast, some authors have reported conductivity values of the order of 10 −2 –10 −3 S cm −1 with 6 wt.% of rGO [ 86 ] or using 20 wt.% of PEDOT [ 60 ].…”

Flexible 3D Printed Acrylic Composites based on Polyaniline/Multiwalled Carbon Nanotubes for Piezoresistive Pressure Sensors

“…The conductivity values achieved are higher than those reported for printable photocurable resins using other fillers such as nanoparticles of Ag (10 −6 –10 −11 S cm −1 ) [ 59,60 ] or reduced graphene oxide (rGO) (10 −7 S cm −1 ). [ 61 ] By contrast, some authors have reported higher conductivity [ 62 ] values in the order of 10 −2 –10 −3 S cm −1 , although using a much higher amount of fillers such as 6% of rGO [ 63 ] or 20% of PEDOT. [ 55 ] The use of high amounts of filler is not desirable considering their cost and the negative effect on the performance of the material.…”

Printed flexible mechanical sensors

“…Besides, the cost-effectiveness of screen printing makes the use of large area electronic or tactile skin in robotics possible. 122 While AJP 35,45,67,123 and DLP 38,40,42,43,124,125 have been applied for the fabrication of flexible mechanical sensors, they are less common due to various reasons. For example, although AJP is a newly developed printing technique with high resolution 91 and fast printing speed, 90 the cost of AJP is much higher in contrast to other techniques; while DLP can fabricate sophisticated 3D geometries with high resolution and rapid speed, the requirement of a photocurable resin limits the material selection.…”

“…2.1.3 Graphene-based. All graphene-based flexible strain sensors identified in the literature have a relatively large sensing range, 124,[136][137][138] as shown in Fig. 2.…”

“…For example, Qian et al DLP-printed a reduced graphene oxide (rGO)/elastomer resin (ER) composite into a flexible strain sensor. 124 Possibly due to the good tensile properties of the ER made of acrylated aliphatic epoxy (EAA) and aliphatic urethane diacrylate (AUD) and a great distribution and interactions of rGO, the sensors can sense strain up to 60%. While a single printed line of rGO/ER (the unit sensing element) exhibited a GF of 6.723 for 0-40% strain, the GFs of the printed electrodes were less than that of the printed line and varied based on the angle of the sensor's rhombic structure (Fig.…”