On the basis of lactic acid detection discussed above, a sweat pH sensor based on Y-TCPP/DBCZ PVA composite gel film was designed, as shown in Figure 5. In order to ensure the repeatability of the experiment, artificial sweat was selected as the test sample to avoid the difference in pH. Artificial sweat with pH=4.7 was selected as the base sample. 50 μL different proportions of sweat were applied to the film and dried, it is found that when the proportion of sweat was higher than 3%, the intensity fluorescence and phosphorescence have changed dramatically (Figure 5a). We also investigated the effect of coating amount on the luminescence of the composite gel films, the higher of the amount of the sweat applied at, the lower of the fluorescence intensity, and the stronger of the phosphorescence intensity. However, due to the different sizes and shapes of sweat stains after drying, the differences are not obvious (Figure 5b). The response time to sweat is also a topic that needs to be explored, and we found that the 10 μL sweat droplets on the film show little change in the first four minutes, also remain basically unchanged after 12 minutes (Figure 5c). Finally, the influence of artificial sweat with different pH on the luminescence of coincidence membranes was explored in order to expand the application of coincidence membranes in health diagnosis. The higher the pH value, the smaller the change in luminescence intensity (Figure 5d). From the above results, a sweat pH sensor has successfully constructed based on Y-TCPP/DBCZ PVA composite gel film. This composite material has application prospects in body fluid detection and health examination.