Apparatus and method for measuring the signal from a fluorescing nanodrop contained by surface tension

Apparatus for the measurement of fluorescence of a fluorescently-excited sample in the form of a fluorescently-excited liquid drop contained by surface tension forces between two anvil surfaces in a substantially parallel relationship, an optical path having been established between wetted areas on each of the two surfaces, said apparatus comprising:

• first and second substantially parallel anvil surfaces, one being moveable relative to the other to any one of three positions;
• an adjustable sample loading position so selected that at least one moveable surface and the other surface are so remotely spaced that a droplet can be placed on the first surface;
• an adjustable compression position so selected that the anvil surfaces are opposed and substantially parallel and proximally spaced so that the liquid spreads upon both surfaces forming a wetted area on each;
• an adjustable sample measuring position so selected that the opposed substantially parallel surfaces are spaced apart to pull the sample into a column wherein it is contained by surface tension thereby providing an optical path for a measurement of fluorescence;
• one said anvil surface having the proximal end of a first optical fiber flush with the surface thereof within said wetted area, the distal end of said first optical fiber in active connection with a spectrometer detector;
• the other said anvil surface having the proximal end of a second optical fiber in-line with said first optical fiber flush with the surface thereof within said wetted area, the distal ends of second optical fiber having means for modifying the optical signal transmitted within said optical fiber;
• at least one means for illuminating the sample comprising a relatively collimated light such that minimal light enters the optical fibers within their transmission numeric aperture from at least one source located away from the sample containment area, said source having a stable wavelength distribution of selected extent to excite the fluorescence of target molecules in said sample.