Moreover, pH measurements were also conducted using CV in both artificial and real saliva, as displayed in Fig. . The overlays of the CV scans acquired at the bare Au electrodes immersed in artificial saliva across the pH range from 5 to 9 were presented in Fig. . The sensor IDEs were subjected to a scanning range from -0.4 to 0.8 V. In each case, three repeated scans were conducted to ascertain reproducibility. Notably, the gold oxide reduction potential minima were again observed to move anodically with a decrease in pH. However, the shape of the CVs were different in saliva environment due to its high viscosity, leading to deviations in the redox peak, including peak intensity, position, and shape . The calibration plot demonstrated a good linearity of R 2 = 0.955 with a sensitivity of -166 mV.pH -1 which is shown in Fig. . Then, pH was also measured in the eight different calf saliva samples and the CVs followed the same trend as the artificial saliva (Fig. ). To provide clarity, the glucose and pH values in the eight saliva samples are detailed in Table , with a comprehensive analysis provided in Table . It is evident that the pH and glucose values (with pH control on) for calves 1 to 6 were consistent and fell within the physiological range (Contreras-Aguilar et al., 2021; Reid and Huffman, 1949), while calf 7 & 8 exhibited distinct readings, affirming the effective and efficient performance of the proposed sensor in detecting pH and glucose concentrations in saliva for determination of BRD and diarrhoea. Furthermore, a comparative analysis of sensing performance between this work and previously reported enzymatic-based glucose sensors is presented in Table .