A lab-on-a-chip (LOC) device for detecting target nucleic acid sequences in a fluid, the LOC device having electrochemiluminescent (ECL), resonance energy transfer probes for hybridization with the target nucleic acid sequences, each of the probes containing a sequence complementary to the target nucleic acid sequence, and an ECL luminophore for emitting photons when in an excited state, a functional moiety for quenching photon emission from the ECL luminophore by resonant energy transfer, electrodes for receiving an electrical pulse to excite the ECL luminophores, hybridization chambers containing the probes for hybridization with the targets, at least one of the heaters and a pair of the electrodes, and, a reagent reservoir containing a reagent for addition to the fluid, wherein, the hybridization chambers each have a volume less than 900,000 cubic microns and the reagent reservoir has a volume less than 1,000,000,000 cubic microns.