Abstract: Methods and devices for determining a preferred composition of anions in a liquid crystal device, and methods and devices for detecting a targeted agent in a sample using such preferred compositions, are disclosed. Such methods include the steps of preparing a liquid crystal device including a liquid crystal, a metal cation, a strongly coordinating anion, and a weakly coordinating anion, contacting the liquid crystal device with a sample suspected of including the targeted agent, and observing the orientational ordering of the liquid crystal at the surface.