Fabrication of Low Cost Flexible Carbon Nanotube Coated Fabric for Special Applications

Abstract

A low-cost smart fabric is a need of today’s era for different applications such as electromagnetic interference (EMI) shielding, chemical gas sensing, and wearable heaters. Electromagnetic interference (EMI) shielding involves the reflection and/or absorption of electromagnetic (EM) radiation by a material. The presently available EMI shielding materials have poor flexibility, are not economical, and have difficulty achieving good shielding efficiency over the wide bandwidth. It is necessary to develop lightweight, cost-effective, biodegradable EMI shielding material which can be used as an enclosure for electronic devices and systems to reduce EMI. Furthermore, the corrosive gas carbon monoxide (CO) is hazardous to human life since it is odorless and colorless, making it difficult for humans to detect it. Semiconducting metal oxides, a conventional sensing material require a temperature of 150–600°C for operation, resulting in excessive power consumption and safety issues despite having good sensing capabilities on quartz and ceramic substrates. It is essential to develop low-cost, biodegradable, user-friendly, and highly sensitive CO gas sensors operating at room temperature. In addition, recently there has been an increase in the popularity of lightweight, portable, and wearable electronic devices. Traditional heating materials (electrical heating belts, heating mats) require high voltage and localized heating at the resistive wires. It is required to develop flexible, and wearable heating material by a simple processing technique, which can work at a low voltage. Consequently, the present study aimed to address these issues by using carbon nanotubes (CNTs) coated fabric as an EMI shielding material, gas sensor, and wearable heater. The current study concentrates on fabricating low-cost multi-walled carbon nanotubes coated cotton fabric for reducing electromagnetic interference and detecting carbon monoxide (CO) gas at room temperature. In addition, testing of the electrothermal performance of fabricated multi-walled carbon nanotubes coated cotton fabric in terms of applied voltage and heating rate to evaluate their ability as a wearable heater and overcome the limitations of conventional heating materials. A dip and drying method is used to fabricate a lightweight, inexpensive, andbiodegradable cotton fabric with multi-walled carbon nanotube coating. The cotton fabric with multi-walled carbon nanotube coating (CMC) samples are fabricated by varying the concentration of multiwalled carbon nanotubes (MWCNTs). The merits of MWCNTs coating on the cotton fabric were evaluated using field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and surface resistivity. The Fourier transform infrared (FTIR) spectroscopy result supports the bonding between MWCNTs and cotton fabric. Surface resistivity decreases as increasing the weight percentage (wt%) of MWCNTs in the CMC sample. Moreover, the influence of multi- walled carbon nanotubes (MWCNTs) wt% on transmission, reflection, and absorption properties, which leads to an estimation of electromagnetic interference (EMI) shielding was studied. The significant increase of 98.9% of EMI shielding for the highest MWCNTs weight percentage (22.23 wt%) was attributed due to the well-interconnected network of MWCNTs. The shielding mechanism in the high wt% MWCNTs samples is dominated by both reflection and absorption properties. Furthermore, the fabricated cotton fabric with multi-walled carbon nanotube coating (CMC) sensors are tested for a range of CO concentrations from 25 to 100 ppm at room temperature, and they exhibited good gas response with superior uniformity and repeatability. The fabricated CMC sensors are suitable for low-cost smart textile applications. Also, the electrothermal performance of CMC samples are investigated based on the applied voltage and the rate of heating to evaluate their ability as a heater. The fabricated samples can operate at 10-40 V and generate temperature from 30-80°C for the optimum weight percentage (22.23 wt%) of MWCNTs in the cotton fabric. The heating rate and steady-state temperature were found to be similar, a linear connection between current and voltage values was seen throughout the CMC sample with considerable variance in resistance values. The fabricated CMC samples give the latest design option for applications like wearable electronics.