Flexible and Stretchable Temperature Sensors Fabricated Using Solution‐Processable Conductive Polymer Composites

Abstract

Accurate monitoring of physiological temperatures is important for the diagnosis and tracking of various medical conditions. This work presents the design, fabrication, and characterization of temperature sensors using conductive polymer composites (CPCs) patterned on both flexible and stretchable substrates through both drop coating and direct ink writing (DIW). These composites were formed using a high melting point biopolymer polyhydroxybutyrate (PHB) as the matrix and the graphenic nanomaterial reduced graphene oxide (rGO) as the nanofiller (from 3 to 12 wt%), resulting in a material that exhibits a temperature-dependent resistivity. At room temperature the composites exhibited electrical percolation behavior. Around the percolation threshold, both the carrier concentration and mobility were found to increase sharply. Sensors were fabricated by drop-coating PHB-rGO composites onto ink-jet printed silver electrodes. The temperature coefficient of resistance was determined to be 0.018 /°C for pressed rGO powders and 0.008 /°C for the 3 wt% samples (the highest responsivity of all composites). Composites were found to have good selectivity to temperature with respect to pressure and moisture. Thermal mapping was demonstrated using 6 × 7 arrays of sensing elements. Stretchable devices with a meandering pattern were fabricated using DIW, demonstrating the potential for these materials in healthcare monitoring devices.

Continuous Based Direct Ink Write for Tubular Cardiovascular Medical Devices

“…DIW has proven to be a suitable solution for printing several very promising biomedical devices due to its ability to customize the extruded material for the printing purposes [ 6 , 9 , 18 , 38 , 65 ]. The only requisite that the bioink must fulfill is the shear thinning and the rapid self-curing ability.…”

“…That technology offers a whole new range of polymeric materials in which additive manufacturing can be carried out. Employing this technique, materials like epoxy resins [ 9 , 10 ], preceramic polymers [ 7 , 11 , 12 , 13 , 14 ], natural polymers [ 3 , 15 , 16 ], or conductive composite polymers [ 17 , 18 , 19 , 20 , 21 ] can be tailored as convenience for biomedical applications. Furthermore, it is the preferred technique for printing living cells by mixing them in hydrogels due to the high survival rate [ 22 , 23 , 24 , 25 , 26 ], in addition to the biocompatible water-rich environment that simulates the extracellular matrix (ECM) [ 27 ].…”

“…DIW has the ability to build any desired shape or construction with any material that encompasses the shear thinning property. In addition, a multimaterial ink can be blended, providing characteristics of interest of both components and creating very attractive biomedical engineering devices [ 6 , 18 ]. DIW is gaining more and more presence within the cardiovascular tubular medical treatments, as the implicit viscoelastic property required to conduct the technique is ideal for the deposition of the ink on a tubular rotating bed.…”

The effects of solvent casting temperature and physical aging on polyhydroxybutyrate‐graphene nanoplatelet composites

“…The polymer used in our work is polyhydroxybutyrate (PHB), a thermoplastic produced as an energy reserve by certain strains of microbes. [53,54] PHB has several attractive properties such as biodegradability, biocompatibility and low cytotoxicity, making it a matrix of interest for applications in green biodegradable packaging, [55] tissue engineering, wearable sensors, [56] and biomedical implants. [57,58] Because of its glass transition is below room temperature (T g 2 C), PHB experiences considerable coldcrystallization and structural rearrangement, which have been shown to influence physical properties.…”

Solubility and diffusion coefficient of supercritical CO2 in polystyrene dynamic melt

“…In recent years, with the development of polymer foam and porous material theory and technology, polymer composites have been widely used in interior panels in aircraft and boats (1), gas separation material (2,3), temperature and pressure sensors (4,5), catalyst supports (6,7), lightweight devices for electromagnetic interference shielding (8), and encapsulation agents for drug release (9,10). In the preparation of polymer foams and porous materials, supercritical CO 2 is widely used due to its excellent solubility, low cost, environmental protection, and other properties.…”