A method using the color intensity of light to measure chemical concentrations may soon help speed the processes for developing medications, printers, and other products. A team from Purdue University created the new approach for using a light-sensitive device to measure the concentration of chemicals used in applications such as biological research and the manufacturing of consumer goods and food products. “Our concept significantly reduces the complexities associated with performing colorimetric analysis at the smaller scales necessary for research and production,” said Justin Weibel, a research associate professor in Purdue’s College of Engineering. “Our sessile-droplet approach allows for passive mixing by leveraging its intrinsic flow properties. The adjustable volume of a droplet allows for a relatively simple path to miniaturization.” Colorimetric reactions include mixing a reagent with a droplet of sample quickly enough to cause a reaction while also producing a measure of sample concentration before these aqueous samples evaporate. The method created by Purdue researchers allows for mixing to occur two orders of magnitude faster than conventional plates used for the process. “Current state-of-the art colorimetric methods require thorough mixing of the sample and the reagent, and an approximately five-minute reaction time to take the measurement,” said Aditya Chandramohan, a Purdue alumnus and senior engineer at Sandia National Laboratories. “Furthermore, miniaturization efforts require increasingly complex fabrication approaches to reduce the size of wells to accommodate lower volumes of liquid.” Colorimetry devices are used to monitor the growth of a bacterial or yeast culture, to test water quality, and to measure the concentrations of hemoglobin in blood. They can also be used to measure and monitor the color in various foods and beverages. The team worked with the Purdue Research Foundation Office of Technology Commercialization to patent the technology. The office recently moved into the Convergence Center for Innovation and Collaboration in Discovery Park District, adjacent to the Purdue campus.