Abstract
We describe a CMOS-based micro-system for time-resolved fluorescence lifetime analysis. It comprises a 16 × 4 array of single-photon avalanche diodes (SPADs) fabricated in 0.35 μm high-voltage CMOS technology with in-pixel time-gated photon counting circuitry and a second device incorporating an 8 × 8 AlInGaN blue micro-pixellated light-emitting diode (micro-LED) array bump-bonded to an equivalent array of LED drivers realized in a standard low-voltage 0.35 μm CMOS technology, capable of producing excitation pulses with a width of 777 ps (FWHM). This system replaces instrumentation based on lasers, photomultiplier tubes, bulk optics and discrete electronics with a PC-based micro-system. Demonstrator lifetime measurements of colloidal quantum dot and Rhodamine samples are presented.
Highlights
Fluorescence based analysis is a fundamental research technique used in the life sciences
Fluorescence lifetime analysis using micro-LED excitation was demonstrated in [25] 64 × 64 matrix-addressable LED array driven by external hardware with a pulse width of 2 ns was used to excite a sample of rhodamine-123, with the subsequent fluorescence decay being captured by a commercially available photomultiplier tube (PMT)
We describe how time domain, time-gated fluorescence lifetime analysis has been implemented on a CMOS chip
Summary
Fluorescence based analysis is a fundamental research technique used in the life sciences. Progress in miniaturization of biological and chemical analysis instrumentation is creating low-cost, robust and portable diagnostic tools capable of high-throughput, with reduced reagent quantities and analysis times. Such devices will enable point-of-care or in-the-field diagnostics. We report an integrated fluorescence lifetime analysis system capable of sub-nano second precision with the core of the instrument measuring less than 1 cm, something hitherto impossible with existing approaches. CMOS technology is key to both detection and excitation in our system providing compact, low cost, high speed electronic signal -processing circuitry for the photodetectors and vertically integrated drivers for the micro-LEDs. we demonstrate an array of pixellated fluorescence analysis sites with potential for multiplexed, high-throughput sensors, with reduced alignment tolerances. Combined with recent advances in on-chip, real-time lifetime computation [3,4] this work represents as significant step towards practical, micro-scale lifetime sensors, without the need for additional external hardware or sophisticated software post-processing
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