The present invention relates to a liquid crystal device for detecting interactions between a surface and an analyte. Specifically it provides a device for detecting interactions between a surface and an analyte, said device comprising a first substrate having an active surface supporting one or more first analyte(s), a second substrate, and a liquid crystal disposed on the active surface between the first substrate and second substrate, wherein the liquid crystal has a cross-section of varying thickness, wherein the cross-section of the liquid crystal has a first thickness and second thickness that is different to the first thickness, whereby the interaction between the active surface and the first analyte causes the orientation of the liquid crystal to change at a first critical thickness that is between the first and second thicknesses of the liquid crystal.