Immunoassay apparatus

In apparatus for assaying a fluid sample and including a totally internally reflecting, elongated, substrate transmissive to excitation radiation from a radiation source, which radiation is capable of providing an evanescent wave for exciting fluorescence in fluorescent material disposed at least on a portion of the surface of said substrate, said substrate also being transmissive to said fluorescence, said substrate comprising a proximal end through which said excitation radiation and excited fluorescence may be transmitted, a hollow elongated enclosure spaced from and surrounding the surface of said substrate, the improvement comprising:

• mounting means couplable to said substrate and to said enclosure for mounting said substrate within said enclosure, said mounting means comprising:
• means defining a fixed interface between said mounting means and said radiation source;
• seat means for supporting said proximal end in a preselected position with respect to said interface, so that substantially all of said excitation radiation entering said proximal end at a solid angle less than or equal to a maximum acceptance angle determined in part by the refractive index of said sample undergoes total internal reflection within said substrate;
• and
• seal means for creating a barrier past which a fluid sample disposed within said enclosure cannot escape.

In apparatus for assaying a fluid sample and including a totally internally reflecting elongated substrate transmissive to radiation capable of providing an evanescent wave for exciting fluorescence in fluorescent material disposed at least on a portion of the surface of said substrate, said substrate also being transmissive to said fluorescence, and elongated means spaced from said surface of said substrate so as to define a hollow elongated enclosure surrounding said surface, and optical means couplable to said mounting means for transmitting a beam of optical radiation to an end face of said substrate, the improvement comprising:

• means coupled to said substrate and said elongated means for mounting said substrate within said enclosure and for releasably supporting both ends of said elongated substrate so that said end face is axially positionable at a fixed location with respect to said optical means and so that said elongated substrate is (a) substantially prevented from moving transversely relative to its longitudinal axis and (b) is prevented from moving in a first axial direction relative to said optical means;
• and
• wherein said optical means comprises a tapered fiber disposed in fixed spatial relationship relative to said fiber end face, said tapered fiber having an input face and an output face, said tapered fiber being transmissive to said optical radiation and being tapered smoothly so as to reduce the diameter of said tapered fiber from said input face to said output face.