Patent ID: 7183055

Claim:
Apparatus for detection of nucleotide hybridization comprising: (a) cell walls defining a cell for holding a sample fluid; (b) at least one working electrode mounted with an electrode surface in the cell, the electrode surface being configured for attachment to nucleotides; (c) a counter-electrode mounted in the cell at a position spaced from the working electrode and positioned to be in contact with sample fluid in the cell; (d) a first frequency signal generator connected via a directional coupler to the working electrode to apply a signal at a first frequency thereto; (e) a second frequency signal generator connected to the counter-electrode to provide a signal to the counter-electrode at a frequency lower than the first frequency signal applied to the working electrode; (f) a mixer connected via the directional coupler to the working electrode, the mixer adapted to receive a signal reflected from the working electrode and connected to the first frequency signal generator, the mixer providing an output signal that is the mix of the first frequency signal from the first frequency signal generator and the signal received through the directional coupler from the working electrode; and (g) a signal detector adapted to receive the output signal from the mixer and to detect modulation of the first frequency signal by the second frequency signal thereby indicating hybridization.