Glass varnish-based carbon conductive ink: a new way to produce disposable electrochemical sensors

Abstract Nowadays, there is growing interest in portable and disposable electrochemical sensors due to the low-cost, simplicity, and excellent analytical performance associated with these devices. Despite recent advances, however, there remains a need to create cheap, high-performance electrode materials. Thus, this study evaluated the suitability of carbon conductive inks prepared by the mixture of glass varnish and graphite powder to produce disposable electrochemical sensors. Two different ink manufacturing processes and compositions were studied to produce different disposable electrodes, each providing high electrical conductivity and adhesion on paper and polyethylene terephthalate (PET) substrates. Electrochemical impedance spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used for the characterization of inks. The electrodes were applied for the electrochemical determination of some compounds. For the paper electrode, the electrochemical detection of dopamine was performed, ranging from 15 μmol to 100 μmol L−1, with a detection limit of 4.1 μmol L−1; the individual electrochemical detection of catechol was performed ranging from 10 μmol L−1 to 1000 μmol L−1, with a detection limit of 9.0 μmol L−1. The detection of hydroquinone was performed, ranging from 10 μmol L−1 to 1000 μmol L−1, with a detection limit of 5.3 μmol L−1. Also, the screen-printed electrode was applied for estriol electrochemical determination in the linear range from 0.1 μmol L−1 to 8.0 μmol L−1 with a detection limit of 0.08 μmol L−1. The glass varnish is an alternative to creating carbon composite electrodes, and the new devices are inexpensive and simple to prepare, with attractive analytical performance.