Inkjet-printed Ag electrodes on paper for high sensitivity impedance measurements

Abstract

Paper electrodes, fabricated by a standard office inkjet printer, show a high sensitivity enhancement for impedance measurement. Low-cost electrodes were fabricated by a standard office inkjet printer with commercial silver ink on glossy paper. Compared to conventional thin-film metal thermal evaporated gold electrodes, the paper-based ones show a two-order enhanced sensitivity for impedance measurement over a low frequency range. The high surface roughness of paper electrodes increases the effective area of the electrolyte–electrode double layer capacitance, and therefore reduces the measured impedance at low frequency range. A passivation layer on the top of the paper electrodes is used to mimic the behaviour of the double layer capacitance. The surface roughness was characterized by optical microscopy and atomic force microscopy. Finite element analysis and impedance equivalent model analysis were also performed for different thin-film electrode devices.