Real-time, label-free detection of nucleic acid amplification in droplets using impedance spectroscopy and solid-phase substrate

A system for detecting presence of nucleic acid amplification in a series of droplets comprising:

• a fluidic channel providing a plurality of test droplets of known sizes a set of detection electrodes disposed in contact with the fluidic channel;
• an AC power supply operable to apply electrical powers across the set of detection electrodes at a plurality of known frequencies;
• an impedance measurement device operable to measure electrical impedance of each of said series of test droplets;
• and
• a processor operable to compare measured electrical impedance of each of said series of test droplets with corresponding reference electrical impedances,
• wherein the corresponding reference electrical impedances are obtained by measuring a reference droplet at said plurality of known frequencies respectively, and
• wherein the corresponding reference droplet is of substantially the same size as the testing droplets and contains known amplified nucleic acid or known non-amplified nucleic acid.

A method for detecting presence of nucleic acid amplification in a test droplet comprising:

• providing a set of detection electrode within a fluidic channel,
• providing said test droplet in vicinity of said set of electrodes through the fluidic channel;
• applying high frequency power across said set of detection electrodes at four different frequencies in sequence;
• measuring electrical impedances of the test droplet at said four frequencies by differential impedance measurements across said detection electrodes;
• comparing the measured electrical impedances with corresponding reference electrical impedances obtained by measuring a reference droplet at said four different frequencies respectively, wherein the reference droplet is of substantially the same size as the testing droplet and contains known amplified nucleic acid or known unamplified nucleic acid;
• determining the presence of amplified nucleic acid in the test droplet based on the comparison.