Publication: Fabrication and characterization of natural surfactant assisted carbon nanotubes-based flexible printed strain sensor
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Date
2022-03-01
Authors
Kamarudin, Siti Fatimah
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Abstract
Printed strain sensors have been explored in real-world applications for more than two decades due to low cost and simple fabrication processes. The utilization of natural materials combined with a ‘green’ approach in developing the sensor devices are gaining popularity among researchers to reduce the environmental impact and enable advanced health monitoring applications. The main aim of this study is to develop a carbon nanotube-based strain sensor composed mainly of natural materials. In this study, water-based multi-walled carbon nanotubes (MWCNTs) conductive inks were synthesized through a surfactant-functionalization method. The dispersion efficiency of various surfactants such as gum Arabic (GA), alkali lignin (AL), polyvinylpyrrolidone (PVP) and pluronic F-127 (PL) in promoting long-term stability to the MWCNTs inks were investigated. Next, a flexible starch/polyvinyl alcohol (SP) blend film with the addition of glucose and urea as binary plasticizer was developed by solution casting method. The SP films were then used as a substrate for the inkjet printing of MWCNTs ink to fabricate flexible printed strains sensors. The dispersion analysis showed that the highest MWCNTs stability of 66.1% and 59.5% was achieved with the help of 5 and 8 mg mL-1 of GA and PVP, respectively. SP blend film with glucose: urea weight ratio of 75:25 exhibited the highest flexibility and stretchability
with elongation at break of ~198%. MWCNTs inks printed on the SP film produced higher sheet resistance but with better printing quality compared to those on PVA film (control). A strain sensor made by GA/MWCNTs@SP showed a good stretchability up to 55% and high sensitivity at strain, ɛ<10%. Small hysteresis was obtained for ɛ<20% and excellent stability in the electrical response was observed when the sensor was subjected to a cyclic stretching. In addition, the sensor also exhibited a good and reproducible signals in response to the continuous bending and relaxing of finger, hand and elbow. Overall, although GA/MWCNTs@SP sensor showed lower electro mechanical performance compared with the previous works, with a proper modification in the sensor design, the sensor could become a great alternative in replacing conventional sensors.