The test device comprises a substantially opaque light reflecting matrix having a refractive index significantly different from {HEAD ~ the refractive index} of {TAIL ~ blood} 
of
The test device comprises a substantially opaque light reflecting matrix having a refractive index significantly different from { HEAD ~ the refractive index } of { TAIL ~ blood }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL