We present a rigorous electromagnetic theory of the electromagnetic power emitted by a dipole located in the vicinity of
a multilayer stack. We applied this formalism to a luminescent molecule attached to a CMOS photodiode surface and
report light collection efficiency larger than 80% toward the CMOS silicon substrate. We applied this result to the
development of a low-cost, simple, portable device based on CMOS photodiodes technology for the detection and
quantification of biological targets through light detection, presenting high sensitivity, multiplex ability, and fast data
processing. The key feature of our approach is to perform the analytical test directly on the CMOS sensor surface,
improving dramatically the optical detection of the molecule emitted light into the high refractive index semiconductor
CMOS material. Based on adequate surface chemistry modifications, probe spotting and micro-fluidics, we performed
proof-of-concept bio-assays directed against typical immuno-markers (TNF-α and IFN-γ). We compared the developed
CMOS chip with a commercial micro-plate reader and found similar intrinsic sensitivities in the pg/ml range.
|