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Integration of mid-infrared silicon-on-insulator photonics with microfluidics
Author(s): Yanli Qi; David J. Rowe; Vinita Mittal; Mehdi Banakar; Yangbo Wu; Milos Nedeljkovic; James S. Wilkinson; Goran Z. Mashanovich
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Paper Abstract

This work describes the integration of mid-infrared (MIR) silicon photonics with PDMS microfluidics to perform absorption spectroscopy of IPA-water solutions. The MIR spectral region contains strong absorption bands for many molecules, and photonic devices operating in the MIR can be used in many sensing applications. In this work a preliminary demonstration of a silicon-on-insulator (SOI) device is carried out in which the transmission spectra of different concentrations of water-IPA solutions are measured at wavelengths between 3.725 μm and 3.888 μm. A PDMS microfluidic channel is integrated with the waveguides in order to improve the repeatability of sample handing, reduce reagent volumes and prevent evaporation of the analyte. A microfluidic channel with 3000 x 100 μm cross-section and 30 mm length is bonded to a SOI chip comprising 500 nm thick rib waveguides and a 2 μm thick SiO2top cladding isolating the waveguide mode from the analyte. Trenches were patterned into the SiO2 cladding to create sensing windows of varying lengths (10 μm to 3mm) along different waveguides. The devices were used to detect an expected IPA absorption peak at 3.77 μm, and concentration as low as 3% IPA in water (by volume) was detected. Further work will focus on increasing the sensitivity of the measurement by using increased interaction lengths, reduction of noise and instability, and on the detection of drugs using transmission measurements over a broader wavelength range.

Paper Details

Date Published: 4 March 2019
PDF: 9 pages
Proc. SPIE 10923, Silicon Photonics XIV, 109230I (4 March 2019); doi: 10.1117/12.2507815
Show Author Affiliations
Yanli Qi, Univ. of Southampton (United Kingdom)
David J. Rowe, Univ. of Southampton (United Kingdom)
Vinita Mittal, Univ. of Southampton (United Kingdom)
Mehdi Banakar, Univ. of Southampton (United Kingdom)
Yangbo Wu, Univ. of Southampton (United Kingdom)
Milos Nedeljkovic, Univ. of Southampton (United Kingdom)
James S. Wilkinson, Univ. of Southampton (United Kingdom)
Goran Z. Mashanovich, Univ. of Southampton (United Kingdom)

Published in SPIE Proceedings Vol. 10923:
Silicon Photonics XIV
Graham T. Reed; Andrew P. Knights, Editor(s)

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