US Patent No. 9,067,207


Patent No. 9,067,207
Issue Date June 30, 2015
Title Optical Approach For Microfluidic Dna Electrophoresis Detection
Inventorship H. Randall Bell, Arlington, VA (US)
John W Pettit, Derwood, MD (US)
James P Landers, Charlottesville, VA (US)
Joan M Bienvenue, Fredericksburg, VA (US)
Daniel J Marchiarullo, North Haledon, NJ (US)
Brian E Root, Charlottesville, VA (US)
Orion N Scott, Charlottesville, VA (US)

Claim of US Patent No. 9,067,207

1. A DNA analyzer, comprising:
an interface for coupling a microfluidic chip to the DNA analyzer, wherein the microfluidic chip includes:
a first domain configured for polymerase chain reaction (PCR) amplification of DNA fragments, the DNA fragments being tagged
with fluorescent labels; and

a second domain fluidically coupled to the first domain to receive the DNA fragments, the second domain having a separation
channel for electrophoretic separation of the DNA fragments; and

a detection module configured to be optically coupled with the microfluidic chip that includes:
a laser source configured to generate a laser beam;
a set of optical elements configured to direct the laser beam to the separation channel to excite the fluorescent labels to
emit fluorescence while the DNA fragments migrate in the separation channel, and to collect the emitted fluorescence into
an optical signal, the set of optical elements including an objective lens configured to be aligned with the separation channel
to direct the laser beam to the separation channel and to collect the emitted fluorescence from the separation channel;

a motor configured to align the objective lens to the separation channel:
a filter module configured to filter the optical signal to allow a first portion of the optical signal having a first wavelength
to pass;

a photo-detector configured to generate an electrical detection signal in response to the filtered optical signal;
a modulation signal generator coupled to the filter module, the modulation signal generator being configured to generate a
modulation signal having a modulation frequency, and a reference signal having the modulation frequency, the modulation signal
being used by the filter module to modulate the filtered optical signal; and

a phase-sensitive detector configured to receive the reference signal and the electrical detection signal corresponding to
the modulated filtered optical signal, and demodulate the electrical detection signal based on the reference signal to remove
noise due to the photo-detector.