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Letter

Integrated Lab-on-a-Chip Optical Biosensor Using Ultrathin Silicon Waveguide SOI MMI Device

1
Institute of Biomedical Engineering (BME), University of Toronto, Toronto, ON M5S 3E2, Canada
2
Department of Chemistry and Earth Sciences, College of Arts and Sciences, Qatar University, Doha 2713, Qatar
3
School of Science and Engineering, Department of Physics, The American University in Cairo, New Cairo 11835, Egypt
*
Author to whom correspondence should be addressed.
This is paper is an extended version of the paper: Elsayed, M.; Mohamed, S.; Aljaber, A.; Swillam, M. Optical Biosensor Based on Ultrathin SOI Waveguides. In Proceedings of the Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America), Washington, DC, USA, 10–15 May 2020; paper JTu2F.8.
Sensors 2020, 20(17), 4955; https://doi.org/10.3390/s20174955
Received: 4 August 2020 / Revised: 27 August 2020 / Accepted: 28 August 2020 / Published: 1 September 2020
(This article belongs to the Section Biosensors)
Waveguides with sub-100 nm thickness offer a promising platform for sensors. We designed and analyzed multimode interference (MMI) devices using these ultrathin platforms for use as biosensors. To verify our design methodology, we compared the measured and simulated spectra of fabricated 220-nm-thick MMI devices. Designs of the MMI biosensors based on the sub-100 nm platforms have been optimized using finite difference time domain simulations. At a length of 4 mm, the 50-nm-thick MMI sensor provides a sensitivity of roughly 420 nm/RIU and with a figure of merit (FOM) definition of sensitivity/full-width-at-half-maximum, the FOM is 133. On the other hand, using a thickness of 70 nm results in a more compact design—only 2.4 mm length was required to achieve a similar FOM, 134, with a sensitivity of 330 nm/RIU. The limits of detection (LOD) were calculated to be 7.1 × 10−6 RIU and 8.6 × 10−6 RIU for the 50 nm and the 70-nm-thick sensor, respectively. The LOD for glucose sensing was calculated to be less than 10 mg dL−1 making it useful for detecting glucose in the diabetic range. The biosensor is also predicted to be able to detect layers of protein, such as biotin-streptavidin as thin as 1 nm. The ultrathin SOI waveguide platform is promising in biosensing applications using this simple MMI structure. View Full-Text
Keywords: optical biosensors; ultrathin silicon waveguides; multimode interference optical biosensors; ultrathin silicon waveguides; multimode interference
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MDPI and ACS Style

Y. Elsayed, M.; M. Sherif, S.; S. Aljaber, A.; A. Swillam, M. Integrated Lab-on-a-Chip Optical Biosensor Using Ultrathin Silicon Waveguide SOI MMI Device. Sensors 2020, 20, 4955. https://doi.org/10.3390/s20174955

AMA Style

Y. Elsayed M, M. Sherif S, S. Aljaber A, A. Swillam M. Integrated Lab-on-a-Chip Optical Biosensor Using Ultrathin Silicon Waveguide SOI MMI Device. Sensors. 2020; 20(17):4955. https://doi.org/10.3390/s20174955

Chicago/Turabian Style

Y. Elsayed, Mohamed, Sherif M. Sherif, Amina S. Aljaber, and Mohamed A. Swillam. 2020. "Integrated Lab-on-a-Chip Optical Biosensor Using Ultrathin Silicon Waveguide SOI MMI Device" Sensors 20, no. 17: 4955. https://doi.org/10.3390/s20174955

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