Smart Phone Camera Used to Determine Ion Concentration in Saliva Based on Fluorescence Level

The use of saliva sampling as a noninvasive way for drug analysis as well as the monitoring systems within the body has become increasingly important in recent research. Because of the growing interest in saliva, this project proposes a way to analyze sodium ion concentration in a saliva solution based on its fluorescence level when in the presence of a sodium indicator dye and recorded with a smartphone camera. The dyed sample was placed in a specially designed housing to exclude all ambient light from the images. A source light of known wavelength was used to excite the fluorescent dye and the smartphone camera images recorded the emission light wavelengths. After analysis of the images using ImageJ, it was possible to create a model to determine the level of fluorescence based on sodium ion concentration. The smartphone camera image model was compared to readings from a standard fluorescence plate recorder to test the accuracy of the model. The study found that the model was accurate within 5 % as compared to the fluorescence plate recorder. Based on the results, it was concluded that the method and resulting model proposed in this study is a valid was to analyze saliva or other solutions for their sodium ion concentration via images recorded by a smartphone camera.