Sensor elements CO sensor 3 Carbon monoxide 3 Carbon monoxide sensor 3 Colloidal protection method 3 Humidity change 3 Humidity resistance 3 Loading 3 Loading methods 3 Nanoparticles 3 Palladium 3 Pd loading 3 Pd loadings 3 Pd nanoparticles 3 Protection methods 3 Sensing layers 3 Silicon 3 SnO2 3 Sols 3 colloidal protection method 3 humidity resistance 3 6G-IoT 2 6g-IoT 2 Acetone 2 Benchmarking 2 Constrained optimization 2 Convolution 2 Convolutional neural network 2 Data handling 2 Electronic nose 2