Patent ID: 7386199

Claim:
A method of sensing photons emanating from a channel portion defined in a fluidic structure, the channel portion extending a length in a longitudinal direction and having, at each position along its length, a respective cross section; in each position's cross section, the channel portion having a boundary along most of which it is surrounded by material with higher refractive index than a fluid in the channel portion would have; the fluidic structure including an end component at an end of the channel portion, the end component including a light-transmissive portion; the fluidic structure further including a light-transmissive component that extends in the longitudinal direction along at least part of the channel portion's boundary and beyond the end component to a projection of the channel portion; the method comprising: with fluid in the channel portion, propagating light in the longitudinal direction through the channel portion so that, in cross sections along a part of the length, more than approximately 10% of light intensity from the propagated light occurs in the fluid; the act of propagating light including: providing light from a source outside the channel portion through the light-transmissive component beyond the end component, through the projection of the channel portion, and through the light-transmissive portion of the end component; the light from the source entering the channel portion in a direction oblique to the longitudinal direction; and photosensing photons emanating from the channel portion in response to the propagated light.