Measurement of ion concentration in the solution without reference electrodes using a terahertz chemical microscopy

In recent years, early diagnosis is important to improve quality of our life. To realize the early diagnosis, measurement of ions in bloods with small volumes is one of an excellent option. In our group, a terahertz chemical microscopy (TCM) has been developed to measure ions in the small volume of solutions (1,2). TCM measures the electric potential change of ion selective membranes on a sensing plate. Generally, this kind of ion measurement method using the ion selective membranes requires a reference electrode inserted in the sample solutions, which limit the minimum volume of the sample solutions.