A method of forming a polymer matrix array includes applying an aqueous solution into wells of a well array. The aqueous solution includes polymer precursors. The method further includes applying an immiscible fluid over the well array to isolate the aqueous solution within the wells of the well array and polymerizing the polymer precursors isolated in the wells of the well array to form the polymer matrix array. An apparatus includes a sensor array, a well array corresponding to the sensor array, and an array of polymer matrices disposed in the well array.