Paper-Based Ion-Selective Potentiometric Sensors

Abstract

A new approach to develop ultra low-cost, robust, rugged, and disposable potentiometric sensors is presented. A suspension of carbon nanotubes in a water-surfactant mixture (carbon nanotubes ink) is applied on conventional filter papers to turn them into conductive papers, which are then used as a substrate to build ion-selective electrodes. The electrodes are made by drop casting a membrane on a small circular area of the conductive paper. In this way, the carbon nanotubes act as both electric conductors and ion-to-electron transducers of the potentiometric signal. Electrodes for sensing K(+), NH(4)(+), and pH were built and tested using this approach, and the results were compared with classical solid-state ion selective electrodes using carbon nanotubes as transducers and glassy carbon as a substrate. In all cases, the analytical performance (sensitivity, linear ranges, limits of detection, selectivity, etc.) of these disposable paper electrodes was similar to that obtained for the more conventional type of ion-selective-electrodes. This opens new avenues for very low-cost platforms for generation of chemical information.

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

“…Importantly, the unbiased selectivity coefficients of NH 4 + -and NO 3 --selective ISEs obtained with the separate solution method closely match those reported for other electrodes based on the solid contact (see Supporting information Table S1 and S2). 6,[58][59][60] This indicates that graphite can be successfully employed as a conductive substrate for the preparation of ISEs without having any significant influence on their potentiometric response characteristics. …”

“…[1][2][3][4][5][6][7][8][9][10] This versatile character can be attributed to their excellent electrical conductivity, high tensile strength and ability to function simultaneously as recognition element and transducer (transduction via the formation of electrical double layer).…”

Integrated paper-based electroanalytical devices for determination of dopamine extracted from striatum of rat

“…Paper-based analytical devices only required low sample volumes as low as several micro liters, which might be especially useful for biological assays with limited samples. Besides, PADs effectively combined the advantages (passive transport of fluid via capillary wicking, compatibility with biological samples, wide variety of functional group to immobilize protein, disposability, portability, low-cost and easy-fabrication) of cellulose-based paper with conventional and complex electroanalytical sensors [10][11][12][13][14][15][16]. To date, analytical methods, such as electrochemiluminescence (ECL) [17,18], photoelectrochemistry [19,20], chemiluminescence [9], colorimetry [21] and electrochemistry [22][23][24], have been integrated with PADs.…”

Carbon Nanotubes-Based Potentiometric Bio-Sensors for Determination of Urea

“…Carbon nanotubes can be applied on the glassy carbon surface and then covered by an ion-selective membrane [7][8][9]. Alternatively, carbon nanotubes can be also useful to prepare (nominally) disposable sensors, where CNTs are used both as a transducer and as an electrical lead [12][13][14]. The latter concept is especially attractive to develop further in order to obtain disposable potentiometric biosensors.…”