Wandermur, Gisele, et al. Biosensors and Bioelectronics, 2014, 54, 661-666.
This work developed a biosensor based on plastic optical fiber (POF) for rapid detection of Escherichia coli.
Principles and production of POF-based sensors
· The refraction index (RI)-based biological sensor works by measuring the index of refraction of a medium and saline initially, and then detecting an increase in the RI as bacteria attach to the surface of the functionalized probe. The sensor measures the averaged RI, which continues to rise until it reaches the RI of the bacteria (1.39), indicating that the bacteria are completely covering the probe's sensitive part.
· All POF probes were created using a straightforward, specially designed machine with a U-shaped matrix that was operated manually. The process started by inserting the original fiber into the machine slot and then using a hot air blower gun to soften it for approximately 5 seconds. Once softened, the machine handle was pushed to force the fiber into the U-shaped mold. After allowing the fiber to solidify, the ends were cut in another mold to ensure uniform size for all probes.
· The technology was used to produce four POF probes of each fiber type, including POF Probe 1 - Multimode (MM), Step Index (SI) POF. This telecommunication POF has a pure polymethyl methacrylate (PMMA) core and a doped low-refractive-index fluoropolymer cladding with a core diameter of 980 mm and a cladding thickness of 10 mm. POF Probe 2: Pure PMMA unclad fiber with a diameter of 0.45 mm. POF Probe 3: Pure PMMA unclad fiber with a diameter of 1 mm. POF Probe 4: Essentially the same material as POF Probe 1, but with a taper.
