Fluorescence lifetime imaging for explosive detection

FLIM data obtained for a grid of organic semiconductors as they are exposed to DNT vapour. In this work a time-resolved 120 x 128 pixel single photon avalanche diode (SPAD) sensor is used in conjunction with an array of organic semiconductor films as a means of detecting the presence of explosive vapours. Using the spatial and temporal resolution of the sensor, both fluorescence intensity and fluorescence lifetime can be monitored on a pixel by pixel basis for each of the polymer films arranged in a 2 x 2 grid. This represents a significant improvement on similar systems demonstrated in the past which either offer spatial resolution without the temporal resolution required to monitor lifetime, or offer only a single bulk measurement of lifetime and intensity without spatial resolution. The potential of the sensing system is demonstrated using vapours of DNT, and differing responses for each of the four polymer films is observed. This system has clear applications as the basis of a portable chemical fingerprinting tool with applications in humanitarian demining and security. This is the basis of the paper Matheson et al. (in submission), "A handheld wide-field fluorescence lifetime imaging system based on a distally mounted SPAD array".