WO₃ thick films were successfully prepared on glass substrates using the screen-printing technique, employing WO₃ nanoparticles synthesized via the sol–gel method using sodium tungstate dihydrate (Na₂WO₄·2H₂O) as the tungsten precursor salt. The sol–gel route enabled controlled hydrolysis and condensation, resulting in homogeneous and nanocrystalline WO₃ powder. The synthesized nanoparticles were mixed with an appropriate organic binder such as ethyl cellulose and butyl carbitol acetate to form a thixotropic paste, which was subsequently screen-printed onto glass substrates. The gas sensing performance of the WO₃ thick film was systematically evaluated toward LPG, CO₂, ethanol, NO₂ and H₂S over an operating temperature range of 40–200 °C. The sensor exhibited a maximum response of 81.29% to LPG at an optimal operating temperature of 160 °C for 500 ppm, demonstrating excellent selectivity toward LPG compared to other tested gases. The sensor response increased with LPG concentration from 100 to 500 ppm, indicating good concentration-dependent behaviour. The WO₃ films displayed a fast response time of 11 s and a recovery time of 53 s. The results confirm that sol–gel derived WO₃ thick films synthesized using sodium tungstate precursor are promising candidates for reliable LPG gas sensing applications.

Keywords: WO₃ Thick Films; Sol–Gel Synthesis; Screen Printing; LPG Gas Sensor; Gas Sensing Performance;