Fiber-Optic Biosensor to Detect pH and Glucose

In this paper, we propose fast, highly sensitive, and wide-dynamic-range fiber-optic probe-type biosensors to detect pH and glucose. The operation principle of the proposed biosensors is based on the Fabry-Perot interferometry technique. Three pH-sensitive dyes (methyl orange, methyl red, and thymol blue) and three solvatochromic dyes (Nile red, rhodamine-B, and 4-amino-N-methylphthalimide) were individually mixed with polymers to obtain five pHand three glucose-sensitive sensing membranes. These membranes were subsequently deposited on eight gold nanoparticles coated on fiber-optic probes to obtain five pH and three glucose fiber-optic probe sensors. To ascertain the effectiveness of the sensors, various concentrations of pH buffer solutions and glucose solutions were tested. The proposed fiber-optic pH and glucose probe sensors showed sensitivities of 1.95 nm/pH and 3.25 nm/mM, respectively, with high-sensing stability with the relative standard deviation about 2.5%. The proposed sensors offer a linear sensing ability over wide ranges of pH (2-12) and glucose (1 μM-1 M) with an R
²
value of approximately 0.996. The response and recovery times of the proposed sensors were approximately 8 and 9 s, respectively. Finally in this paper, we compared the performance of the proposed fiber-optic probe sensors with that of other pH and glucose sensors and determined that the proposed sensors achieve better sensing performance.