Spatially selective fixed-optics multicolor fluorescence detection system for a multichannel microfluidic device, and method for detection

A spatially selective fluorescence detection system, comprising:

• a plurality of optical fibers;
• and
• a plurality of ball lenses each mounted adjacent to an end of a respective one of the plurality of optical fibers for receiving an emitted light from one of the plurality of spatially selected volumes, each of the plurality of ball lenses having a diameter larger than a diameter of the respective one of the plurality of optical fibers
• wherein each of the plurality of ball lenses and one end of the respective one of the plurality of optical fibers being separated by a first distance, the first distance being greater than a radius of the respective one of the plurality of ball lenses so that the emitted light from the plurality of the selected volumes and received by the plurality of ball lenses converges onto the one ends of the plurality of optical fibers, wherein the first distance from each of the plurality of ball lenses to the respective one of the plurality of optical fibers is determined by positioning each of the plurality of selected volumes, each treated as a point source, relative to a respective one of the plurality of ball lenses such that a circle of transmitted light defined by an intersection of the caustic of transmitted rays and a marginal transmitted ray has a diameter equal to that of the respective one of the plurality of optical fibers.

A fluorescence detection system for detecting fluorescence of spatially selected volumes from a plurality of spatially selected volumes, comprising:

• a pair of cylindrical lenses mounted apart from each other by predetermined distance;
• a plurality of plano-convex lenses arranged in a linear array;
• a laser emitting a beam of light which passes through the pair of cylindrical lenses and the plurality of plano-convex lenses, the beam of light being split into multiple spots by the plurality of plano-convex lenses, each of the multiple spots being projected toward a different one of the plurality of spatially selected volumes;
• and
• a plurality of optical fibers, each of the plurality of optical fibers corresponding to a respective one of the plurality of spatially selected volumes;
• and a plurality of ball lenses each being positioned adjacent to one end of a respective one of the plurality of optical fibers for receiving an emitted light from the respective one of the spatially selected volumes, each of the plurality of the ball lenses having a diameter larger than a diameter of the respective one of the plurality of optical fibers, each of the plurality of ball lenses and the respective one of the plurality of optical fibers being separated by a first distance, such that the light emitted from each of the plurality of spatially selected volumes and received by the respective one of the plurality of ball lenses converges onto the one end of respective one of the plurality of optical fibers, wherein the first distance from each of the plurality of ball lenses to the respective one of the plurality of optical fibers is determined by positioning each of the plurality of selected volumes, treated as a point source, relative to the respective one of the plurality of ball lenses such that a circle of transmitted light defined by an intersection of the caustic of transmitted rays and a marginal transmitted ray has a diameter equal to that of the respective one of the plurality of optical fibers.

A fluorescence detection system for detecting fluorescence from a plurality of spatially selected volumes comprising:

• an excitation laser emitting a beam of light, the beam of light being split into multiple spots by a series of beam splitters, each of the multiple spots being projected toward a different one of the spatially selected volumes;
• a plurality of optical fibers, each of the plurality of optical fibers corresponding to a respective one of the plurality of spatially selected volumes;
• a plurality of ball lenses each being positioned adjacent to one end of a respective one of the plurality of optical fibers for receiving an emitted light from a respective one of the plurality of spatially selected volumes, each of the plurality of ball lenses and the one end of the respective one of the plurality of optical fibers being separated by a first distance, each of the plurality of ball lenses having a diameter larger than a diameter of a respective one of the plurality of optical fibers, wherein the first distance from each of the plurality of ball lenses to the respective one of the plurality of optical fibers is determined by positioning each of the plurality of selected volumes, treated as a point source, relative to a respective one of the plurality of ball lenses such that a circle of transmitted light defined by the intersection of the caustic of transmitted rays and a marginal transmitted ray has a diameter equal to that of the respective one of the plurality of optical fibers, and such that the light emitted from each of the plurality of spatially selected volumes and received by the plurality of ball lenses converges onto the respective one of the plurality of optical fibers;
• and
• a holder for mounting the plurality of ball lenses, and the plurality of optical fibers.

A method for analyzing a plurality of spatially selected volumes by fluorescence, comprising:

• positioning a plurality of ball lenses adjacent to a plurality of spatially selected volumes of a microfluidic device, each of the plurality of ball lenses corresponding to one of the plurality of spatially selected volumes;
• positioning a plurality of optical fibers, each of the plurality of optical fibers corresponding to one of the plurality of ball lenses;
• obtaining simultaneously a fluorescence spectrum from fluorescent substances in the plurality of spatially selected volumes;
• wherein each of the plurality of ball lenses and an end a respective one of the plurality of optical fibers is separated by a first distance, wherein the first distance from each of the plurality of ball lenses to the respective one of the plurality of optical fibers is determined by positioning each of the plurality of selected volumes, treated as a point source, relative to a respective one of the plurality of ball lenses such that a circle of transmitted light defined by an intersection of the caustic of transmitted rays and a marginal transmitted ray has a diameter equal to that of the respective one of the plurality of optical fibers, the first distance being in a range of 3 to 40 times the diameter the respective one of the plurality of optical fibers, so that the light emitted from each of the plurality of spatially selected volumes and received by a respective one of the plurality of ball lenses converges onto the end of the respective one of the plurality of optical fibers.