  A complex experiment was performed to unravel the simplest particle,Higgs
Boson, and we performed a simple experiment to address a complex system. We
tested the pH response of liquid metal EGaInSn in the form of a pendant drop
and measured the sensitivity of 92.96 mV.pH-1 in the pH range from 4 to 10. We
derived a unified Nernst equation to explain high pH sensitivity and
coincidentally rediscovered Marcel Pourbaix illuminating work on the
pH-Potential Diagram. The surface potential in the sensor probe is originated
from a spontaneous electrochemical reaction purely driven by thermodynamics,
rendering to the lowest system energy possible. Our findings have a great
scientific significance, which could redefine the conventional concept of the
ion sensing mechanism in a solid-state electrochemical sensor.
