A vertically integrated CMOS micro-system for time-resolved fluorescence analysis

We describe a two-chip micro-scale time-resolved fluorescence analyzer integrating excitation, detection and filtering. A new 8 × 8 array of drivers integrated in standard low-voltage 0.35 ¿m CMOS is bump-bonded to AlInGaN blue micro-pixellated light-emitting diodes (micro-LED). The array is capable of producing sample excitation pulses with a width of 777 ps (FWHM) enabling short lifetime fluorophores to be excited. The fluorescence emission is detected by a second, vertically-opposed 16 × 4 array of single-photon avalanche diodes (SPADs) fabricated in 0.35 ¿m high-voltage CMOS technology with in-pixel time-gated photon counting circuitry. This constitutes the smallest reported solid-state micro-system for fluorescence decay analysis, replacing lasers, photomultiplier tubes, bulk optics and discrete electronics. The system is demonstrated with measurements of fluorescent colloidal quantum dot and Rhodamine samples.