Modern people are usually under a sub-health condition for a long time because of the great life pressure, the unhealthy eating habits, etc., and if this condition continues, various diseases will be caused to seriously endanger people's health. Normally, people should be in an alkaline physical condition, and if a change towards a weak acid condition can be detected in time and can be intervened by a change of diet, etc., keeping healthy would not be so hard.
At present, display devices like mobile phone terminals are widely used, and if a pH value sensing circuit can be combined with the display devices, especially with mobile phone terminals, the pH values of holders of the terminals can be sensed in real time so as to determine the physical condition of the body.