Abstract:
This study reports the fabrication of non-invasive nitric oxide optical sensor. The sensor composes of light emitting diode with a wavelength at 525 nm, photo diode having sensitivity in the range of 400 to 1100 nm, measuring circuit that could transfer data to personal computer for analyzing and displaying result in real time. For preliminary test, the system was used to measure a standard nitric oxide derivative solution concentration of 0.125-1.000 mM in transmission mode. It was found that a linear correlation between the nitric oxide optical sensor and the conventional spectrophotometer (UV-Vis Spectrophotometer; UV-3101PC, Shimada, Japan) was obtained with the coefficient of determination (R2) of 0.9753. Further studied was done in human fingertip with reflection mode, the changes of nitric oxide level were observed after using upper-arm occlusion technique (n=25 subjects). It demonstrates the feasibility of non-invasive detection of nitric oxide levels in blood vessels. Moreover, the data were compared with skin perfusion rate test (n=5 subjects) with blood perfusion monitors (PeriFlux System 5000, PERIMED AB, Sweden). It was found that the data from the fabricated sensor and perfusion rate have increased both when release upper-arm occlusion (R=0.6994)