Patent ID: 6946286

Claim:
An apparatus for identifying an unknown DNA sample, said apparatus comprising: a plurality of detection nodes, each of said detection nodes operable for allowing an interaction between a known DNA sample and an unknown DNA sample, and for generating an output signal if hybridization occurs between said known DNA sample and said unknown DNA sample; and a decoder operative for receiving an input signal indicative of which of said plurality of detection nodes should be selected for processing, and for outputting control signals which operate to activate said selected detection node; wherein each of said detection nodes includes a light source and a photodetection circuit, said photodetection circuit having a conductance value which varies if hybridization occurs between the known DNA sample and the unknown DNA sample deposited in said detection node, said change in said conductance value is operative for generating said output signal, wherein each detection node further comprises: a differential amplifier for receiving a first reference voltage signal and a second reference voltage signal as input signals, and for generating said output signal, said output signal representing a difference between said first reference voltage signal and said second reference voltage signal, wherein said first reference voltage signal varies in correspondence with changes in the conductance value of said photodetection circuit, and said second reference voltage signal is a constant value; a voltage supply coupled to said photodetection circuit by a resistive element, said change in the conductance value of said photodetection circuit causing an increase in current flow through said resistive element, said first reference voltage signal varying in correspondence with changes in said current flow through said resistive element; a first pass transistor operative for coupling said voltage supply to said resistive element and said light source; and a second pass transistor operative for coupling an output of said differential amplifier to an output port of said detection node, said first pass transistor and said second pass transistor being activated by said control signals output by said decoder.