3D Printable Reservoirs for Potentiometric Analysis of Solid Samples

Abstract

Potentiometric sensing is highly effective for diagnostic testing of many important ionic biomarkers. Outside of biological samples, ion-selective electrodes (ISEs) have been utilized for environmental and forensic analyses due to their high specificity and sensitivity. Unfortunately, many samples to be analyzed are solids (e.g., powders, soils, etc.), which require sample preparation steps prior to analysis. In this work, we describe the coupling of 3D printed ISEs with 3D printable hydrogels towards the ability to perform potentiometric analysis of solid samples. The hydrogel works as a sampling well, dissolving solid samples and allowing the ions to diffuse to the ISE for quantification. As a proof-of-concept demonstration we present the use of hydrogels to dissolve and transport tetrabutylammonium ions (TBA+), introduced to the hydrogel as a solid salt (TBA+Br-), through the hydrogel to the ISE. Solid sample analysis of TBA+ was achieved from 10 mM to 1 mM with a Nernstian response of 61 mV/Decade.