Miniaturized reflectance devices for chemical sensing

This effort seeks to evaluate the potential of the TAOS TCS3200 RGB sensor chip in a reflectance configuration for use in target detection based on color changes in porphyrin indicators using alcohols as model targets. The chip was evaluated as provided by Parallax, Inc as a component of the TCS3200-DB which includes white LEDs, collimator lens, and standoffs for optimization of sensing distance. Nonlinearity in the response of the daughter board to color standards was observed. Signal noise levels were determined to be less than 1% within a given measurement and measurement-to-measurement variations of ~9% were observed. The device proved effective for detection of the color change in several porphyrins upon target exposure and for monitoring the time dependence of changes following exposure. An array of six porphyrins was used for demonstration of differential changes in response to specific targets. Proof-of-concept use of the porphyrin indicators onboard two types of unmanned aerial vehicles (UAVs) is described.