Detection of heavy metal ions using screen printed wireless LC sensor

This paper reports on the successful development of a fully printed wireless LC sensor for the detection of toxic heavy metal ions. The LC sensor, consisting of inductors and interdigitated electrodes (IDE) in planar form, was screen printed on flexible polyethylene-terephthalate (PET) substrate with silver (Ag) ink as metallization layer. Palladium nanoparticles (Pd NP) were drop casted onto the IDEs as sensing layer. The resonant frequency of the LC sensor was remotely monitored by measuring the reflection coefficient (S₁₁) of a detection coil (planar inductor). The change in resonant frequency of the LC sensor towards varying concentrations of mercury (Hg²⁺) and lead (Pb²⁺) ions, revealed micro molar detection levels. The response of the printed wireless LC sensor is analyzed and presented.