What is provided includes a porous sol-gel material whose intrinsic pH is lower than 1 and comprising at least one probe molecule chosen from the group consisting of croconic acid, p-dimethyl-aminobenzaldehyde, p-dimethyl aminocinnamaldehyde, p-methoxybenzaldehyde and 4-methoxy-1-naphtaldehyde. A plurality of inputoutput pins are provided for interfacing with external signals. Each of the first and second shield sections has open slots situated between the shield sections. In another embodiment, the microcavity and active components are made from the same substrate such as the same silicon wafer.