DEPOSITION OF LAYER BY LAYER ZnO&Gr ON FABRICS SUBSTRATE FOR WEARABLE CO GAS SENSOR BY CHEMICAL BATH DEPOSITION METHODE

• Main Author: UTARI - NIM : 23316007, LISTYA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/28624
• Institution: Institut Teknologi Bandung

<p align="justify">The mine industry has a higher risk of workplace fatalities, especially underground mining. Narrow work space, poor lighting, limited ventilation system and harmful gases, that can cause disasters in underground mines. NO2, H2S, CH4, CO2 dan CO are common dangerous gas found in underground mines. Carbon monoxide (CO) is a colorless, odorless, and toxic gas produced by incomplete combustion or explosion of substance containing carbon. CO gas sources in underground mine comes from the afterdamp of a gas or coal dust explosion, machine emissions, coal oxidation, or gas trapped during coal formation. Gas sensors have been developed as wearable electronic system on flexible substrates. Gas sensor applications on flexible substrates make it more efficient, lighter, and easier to use on mine workers. Fabrics as a flexible substrate has been applied to wearable electronic system in the form of e-textile. E-textile fabrication was carried by modifying the fabric structure using functional materials. <br /> <br /> In this study, wearable gas sensor was fabricated by ZnO and graphene layer growth on fabric substrate. Graphene was coated on the surface of cotton fabric by “dip and dry” method under sonication for 2 hours. ZnO grown on graphene layer was synthesized using a two-step synthesis process. The first step was the growth of ZnO seed layer by “dip and dry” method using Zn(NO3)2.6H2O as a precursor. The second step was the formation of ZnO crystals by chemical bath deposition methode performed at 80oC for 6 hours. ZnO and Gr compositions ratio in this atudy are 1:0, 2:1, 1:1, 1:2, dan 0:1. Material characterizations method in this study are X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and CO gas performance testing. XRD results shows a high crystallinity of ZnO that form on cotton fabric. SEM results shows that graphene flakes seems covered the surface of cotton fibers, and ZnO growth on graphene layer with hexagonal nanorod structure. EDS mapping image indicated that ZnO has grown homogenously on fabric surface. <br /> <br /> ZnO growth above the graphene layer can reduce working temperature of sensor and enhanced the conductivity of ZnO film. The resistance of ZnO cotton fabric sample can not be measured due to the high resistance of ZnO at temperature under 100oC. Sample performance against CO gas was tested at room temperature with CO gas concentrations from 10-90 ppm. The highest response was 51.39% from Z0G1 samples at room temperature on 90 ppm of CO. The highest respon of Z2G1 and Z1G1 samples occurs on 90 ppm of CO gas. While Z1G2 samples has a highest respon on 90 ppm of CO gas, due to saturation. The highest performance of ZnO and graphene on fabric sample was Z1G1 sample. The optimum respon of each sample at room temperature are 36.18%, 41.08%, 30.05%, and 51.39% for Z2G1, Z1G1, Z1G2 and Z0G1 sample. Z0G1 sample has a fast respon and recovery time. The respon time of heterostructure layer sample was around 400-500 s. The recovery time of heterostructure layer sample was faster with the increasing graphene concentration. The selectivity sensor was tested toward 50 ppm of acetone, ethanol, methanol, and NO. Gas testing results indicated that wearable gas sensor more selective toward CO than acetone, ethanol, methanol, and NO.<p align="justify">