A medical needle shield apparatus is provided that includes a needle hub having an outer needle cannula extending therefrom. A pad interlayer insulating layer is disposed on a semiconductor substrate of an active region. A signal processor processes the electrical signal vector to compensate the impairments of the optical channel. The surface regions are subsequently wetted using a liquid solder free of flux in a contactless dosed manner. The feasibility of modulation-based sensing was demonstrated using mixtures of 6-carboxyfluorescein and Ru2,232 as a pH sensor and of the calcium probe Fluo-3 and Ru2,232 as a calcium sensor. The originating system receives acknowledgment message from the terminating system in response to the set up messages.