Single strip solid contact ion selective electrodes on a pencil-drawn electrode substrate

A simple and low-cost approach for the preparation of ion-selective electrodes (ISEs) is proposed as a favorable alternative to traditional paper-based electrodes. This involved the application of graphite from a simple household pencil via mechanical abrasion onto a modified acetate sheet. The resulting electrodes exhibited excellent sensing properties towards all tested ions, including a wide dynamic response range, fast response time and satisfactory long-term stability. The same methodology was used to produce stable and functional reference electrodes. These electrodes were then combined with other graphite-based ISEs to yield single strip solid-contact electrodes for simultaneous detection of cations and anions in aqueous solutions. The described approach, which is analogous to simply drawing on paper, opens new avenues for the development of sensing devices using very cheap and easily accessible components.