A method for detecting a target nucleic acid molecule in a sample with a sensor comprising a first electrode and a second electrode coupled to a sensor surface in a spaced apart arrangement and a plurality of capture probes coupled to the sensor surface between the first electrode and the second electrode, the method comprising: performing nucleic acid molecule amplification via polymerase chain reaction using a first primer having a 5'-tail and comprising an internal replication block configured to stop a polymerase action short of the 5'-tail, and a second primer being complimentary to a region of the target nucleic acid molecule and having no 5'-tail, wherein the PCR forms a plurality of double-stranded amplicons with a single-strand 5'-tail, wherein each double stranded amplicon comprises a first strand including an internal target sequence, wherein the first strand further comprises the 5'-tail, and a second strand with no tail; applying the plurality of double-stranded amplicons formed by the PCR to the sensor surface; hybridizing the plurality of double-stranded amplicons to the plurality of capture probe sequences, wherein the single-strand 5'-tails of the plurality of double-stranded amplicons bind to the plurality of capture probe sequences; converting the plurality of double-stranded amplicons to a plurality of single strand molecules using a 5'-3' exonuclease with specificity for double-stranded DNA to expose the target sequence of the first strand, wherein the 5'-tails of the plurality of single-strand molecules remain bound to the plurality of capture probe sequences and an opposing 3' end is unbound; hybridizing a catalyst cluster to the internal target sequence of each of the plurality of single strand molecules; contacting the plurality of single strand molecules having a catalyst cluster bound thereon with a metal or metal alloy, wherein the metal or metal alloy binds to the catalyst cluster to form a conductive metal film between the first electrode and the second electrode; and determining if an electrical current can be carried between the electrodes, the electrical current between the electrodes indicating presence of the target nucleic acid molecule in the sample. performing nucleic acid molecule amplification via polymerase chain reaction using a first primer having a 5'-tail and comprising an internal replication block configured to stop a polymerase action short of the 5'-tail, and a second primer being complimentary to a region of the target nucleic acid molecule and having no 5'-tail, wherein the PCR forms a plurality of double-stranded amplicons with a single-strand 5'-tail, wherein each double stranded amplicon comprises a first strand including an internal target sequence, wherein the first strand further comprises the 5'-tail, and a second strand with no tail; applying the plurality of double-stranded amplicons formed by the PCR to the sensor surface; hybridizing the plurality of double-stranded amplicons to the plurality of capture probe sequences, wherein the single-strand 5'-tails of the plurality of double-stranded amplicons bind to the plurality of capture probe sequences; converting the plurality of double-stranded amplicons to a plurality of single strand molecules using a 5'-3' exonuclease with specificity for double-stranded DNA to expose the target sequence of the first strand, wherein the 5'-tails of the plurality of single-strand molecules remain bound to the plurality of capture probe sequences and an opposing 3' end is unbound; hybridizing a catalyst cluster to the internal target sequence of each of the plurality of single strand molecules; contacting the plurality of single strand molecules having a catalyst cluster bound thereon with a metal or metal alloy, wherein the metal or metal alloy binds to the catalyst cluster to form a conductive metal film between the first electrode and the second electrode; and determining if an electrical current can be carried between the electrodes, the electrical current between the electrodes indicating presence of the target nucleic acid molecule in the sample.