Finding the time for fluorescence. Its measurement and applications in life science

We summarise how developments in technology have brought fluorescence lifetime spectroscopy from being the preserve of the specialist to becoming a major tool for research across many science and engineering disciplines. We highlight the advantages which fluorescence lifetime measurements can bring, not only to underpin research, but also through application in helping to solve real-world problems. We illustrate this with recent examples in cancer and Alzheimer’s research, which are aimed at improving disease understanding, diagnosis and therapeutics

A 192×128 Time Correlated SPAD Image Sensor in 40-nm CMOS Technology

A 192 X 128 pixel single photon avalanche diode (SPAD) time-resolved single photon counting (TCSPC) image sensor is implemented in STMicroelectronics 40-nm CMOS technology. The 13% fill factor, 18.4\,\,\mu \text {m} \times 9.2\,\,\mu \text{m} pixel contains a 33-ps resolution, 135-ns full scale, 12-bit time-to-digital converter (TDC) with 0.9-LSB differential and 5.64-LSB integral nonlinearity (DNL/INL). The sensor achieves a mean 219-ps full-width half-maximum (FWHM) impulse response function (IRF) and is operable at up to 18.6 kframes/s through 64 parallelized serial outputs. Cylindrical microlenses with a concentration factor of 3.25 increase the fill factor to 42%. The median dark count rate (DCR) is 25 Hz at 1.5-V excess bias. A digital calibration scheme integrated into a column of the imager allows off-chip digital process, voltage, and temperature (PVT) compensation of every frame on the fly. Fluorescence lifetime imaging microscopy (FLIM) results are presented

TCSPC camera for real time video rate FLIM acquisition based on CMOS technology

The use of fluorescence lifetime imaging microscopy (FLIM) is appealing for the study of biomolecular interactions. Traditionally FLIM has made use of scanning techniques to image a sample with a “single-pixel” detector, while widefield approaches have mainly related to intensity-based imaging. The latter is is advantageous to study mobile samples or kinetics, usually not achievable with FLIM. Rapid fluorescence lifetime imaging is especially important in the monitoring of biological samples, eg. because of cell movement. Recent advances in CMOS technology has led to the development of imaging sensors, based on arrays of pixels, with each pixel containing a single-photon avalanche photodiode (SPAD) and its associated timing electronics, based on a time to digital converter (TDC). This enables rapid (video rate) fluorescence lifetime determination based on the time-correlated single-photon counting technique (TCSPC) to be realised independently in each pixel. Here, we incorporate a 192 x 128 pixel image sensor1, implemented in STMicroelectronics 40nm CMOS technology, in a widefield epifluorescence microscope set-up. The sensor exhibits a 13% fill-factor and each 18.4 x 9.2 μm pixel contains a TDC with a resolution 30 fps) rate. This capability is demonstrated using standard samples and FUN-1 labelled yeast2

Instrumentation for fluorescence lifetime measurement using photon counting

We describe the evolution of HORIBA Jobin Yvon IBH Ltd, and its time-correlated single-photon counting (TCSPC) products, from university research beginnings through to its present place as a market leader in fluorescence lifetime spectroscopy. The company philosophy is to ensure leading-edge research capabilities continue to be incorporated into instruments in order to meet the needs of the diverse range of customer applications, which span a multitude of scientific and engineering disciplines. We illustrate some of the range of activities of a scientific instrument company in meeting this goal and highlight by way of an exemplar the performance of the versatile DeltaFlex instrument in measuring fluorescence lifetimes. This includes resolving fluorescence lifetimes down to 5 ps, as frequently observed in energy transfer, nanoparticle metrology with sub-nanometre resolution and measuring a fluorescence lifetime in as little as 60 μs for the study of transient species and kinetics

A 192 x 128 time correlated single photon counting imager in 40nm CMOS technology

A 192 x 128 pixel single photon avalanche diode (SPAD) time-resolved single photon counting (TCPSC) image sensor is implemented in STMicroelectronics 40nm CMOS technology. The 13 % fill-factor, 18.4 x 9.2 mm pixel contains a 33 ps resolution, 135 ns full-scale, 12-bit time to digital converter (TDC) with 0.9 LSB differential and 8.7 LSB integral nonlinearity (DNL/INL). The sensor achieves a mean 219 ps fullwidth half maximum (FWHM) impulse response function (IRF) and a 5 mW core power consumption and is operable at up to 18.6 kfps. Cylindrical microlenses with a concentration factor of 3.15 increase the fill-factor to 41%. The median dark count rate (DCR) is 25 Hz at 1.5 V excess bias. Fluorescence lifetime imaging (FLIM) results are presented

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This music score was submitted for the Kaleidoscope 2020 Call for Scores, an open access collaboration with the UCLA Music Library

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This music score was submitted for the Kaleidoscope 2020 Call for Scores, an open access collaboration with the UCLA Music Library