Sensing of the dynamic concentration field at the solid/liquid interface using a Mach-Zehnder interferometer

A Mach-Zehnder interferometer is employed to study the dynamic concentration field within diffusion layer in transparent liquid solutions at the solid/liquid interface. The method is applied to investigate the electrodeposition of nickel in 0.20 mol dm−3 NiSO4 solution. Interferograms of an object wave through an experimental cell containing diffusing solutions are recorded continually by a CMOS image sensor and displayed on a monitor in real time. The two-dimensional concentration change of the solution at the solid/liquid interface is determined according to the interference fringes. Software is developed to obtain the dynamic concentration field automatically. The calculated results match well with theory values. Its ease of fabrication offers the attractive applications in chemical and biological sensing.