Integrated Optical Mach-Zehnder Interferometer Based on Organic-Inorganic Hybrids for Photonics-on-a-Chip Biosensing Applications

authors	Bastos, AR; Vicente, CMS; Oliveira-Silva, R; Silva, NJO; Tacao, M; da Costa, JP; Lima, M; Andre, PS; Ferreira, RAS
nationality	International
journal	SENSORS
author keywords	photonic; integrated optics; sol-gel; biosensors; E. coli; organic-inorganic hybrid
keywords	ESCHERICHIA-COLI; REFRACTIVE-INDEX; LABEL-FREE; FIBER TECHNOLOGY; BACTERIAL-GROWTH; PERSPECTIVE; PERFORMANCE; CELL
abstract	The development of portable low-cost integrated optics-based biosensors for photonics-on-a-chip devices for real-time diagnosis are of great interest, offering significant advantages over current analytical methods. We report the fabrication and characterization of an optical sensor based on a Mach-Zehnder interferometer to monitor the growing concentration of bacteria in a liquid medium. The device pattern was imprinted on transparent self-patternable organic-inorganic di-ureasil hybrid films by direct UV-laser, reducing the complexity and cost production compared with lithographic techniques or three-dimensional (3D) patterning using femtosecond lasers. The sensor performance was evaluated using, as an illustrative example, E. coli cell growth in an aqueous medium. The measured sensitivity (2 x 10(-4) RIU) and limit of detection (LOD = 2 x 10(-4)) are among the best values known for low-refractive index contrast sensors. Furthermore, the di-ureasil hybrid used to produce this biosensor has additional advantages, such as mechanical flexibility, thermal stability, and low insertion losses due to fiber-device refractive index mismatch (similar to 1.49). Therefore, the proposed sensor constitutes a direct, compact, fast, and cost-effective solution for monitoring the concentration of lived-cells.
publisher	MDPI
issn	1424-8220
year published	2018
volume	18
issue	3
digital object identifier (doi)	10.3390/s18030840
web of science category	Chemistry, Analytical; Electrochemistry; Instruments & Instrumentation
subject category	Chemistry; Electrochemistry; Instruments & Instrumentation
unique article identifier	WOS:000428805300161