Method of determining the nucleotide sequence of oligonucleotides and DNA molecules

A method for sequencing DNA, comprising:

• a) providing a primer/template system comprising a template sequence hybridized to a primer oligonucleotide and a DNA polymerase that lacks 5′ to 3′ exonuclease activity;
• b) contacting the primer/template system with a single type of deoxyribonucleotide under conditions that produce a detectable signal when the DNA polymerase incorporates a deoxyribonucleotide onto the 3′ end of the primer oligonucleotide, wherein the single type of deoxyribonucleotide is an unlabeled and unblocked deoxyribonucleotide, and wherein the contacting occurs in a reaction chamber;
• c) converting, with a device, the detectable signal into an electrical signal based on an electrical potential generated across the device by the detectable signal, wherein the converting occurs in the reaction chamber, and wherein the amplitude of the electrical signal corresponds to the number of nucleotides incorporated onto the 3′ end of the primer oligonucleotide by the DNA polymerase;
• and
• d) detecting the electrical signal generated by the detectable signal produced in the reaction chamber.