The present invention provides a sensing device for detecting an analyte containing a non-metallic element such as F. A working sensor has a 3D array of voids each having a void internal wall. The void internal walls have cavities each having a cavity internal wall made from a material containing the non-metallic element. A binding of the analytes to the cavities induces a detectable variation of the optical property of the 3D array of voids. The invention exhibits numerous technical merits such as high sensitivity, high specificity, fast detection, ease of operation, low power consumption, zero chemical release, and low operation cost, among others.