We report on the results of a combinatorial approach for the optimization of materials for use in fluorescent sensing of metal ions, primarily alkali ions. The sensor materials studied are composed of a hydrogel containing an emulsion of a lipophilic plasticizer, the latter incorporating an ion carrier and a polarity-sensitive dye that acts as a fluorescent reporter probe. The carriers were varied, and the response of all sensor materials to 24 electrolyte solutions was studied using a microtiterplate format, the sensor layers being deposited on the bottom of the wells. The method is shown to enable fast screening of ion carrier-based sensors with respect to sensor composition, response time, signal change, and selectivity.