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Proceedings Paper

Silicon-photonic interferometric biosensor using active phase demodulation
Author(s): Y. Marin; V. Toccafondo; P. Velha; S. Scarano; S. Tirelli; A. Nottola; Y. Jeong; H. P. Jeon; M. Minunni; F. Di Pasquale ; C. J. Oton
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Paper Abstract

Silicon photonics is becoming a consolidated technology, mainly in the telecom/datacom sector, but with a great potential in the chemical and biomedical sensor market too, mainly due to its CMOS compatibility, which allows massfabrication of huge numbers of miniaturized devices at a very low cost per chip. Integrated photonic sensors, typically based on resonators, interferometers, or periodic structures, are easy to multiplex as the light is confined in optical waveguides.

In this work, we present a silicon-photonic sensor capable of measuring refractive index and chemical binding of biomolecules on the surface, using a low-cost phase interrogation scheme. The sensor consists of a pair of balanced Mach-Zehnder interferometers with interaction lengths of 2.5 mm and 22 mm, wound to a sensing area of only 500 μm x500 μm. The phase interrogation is performed with a fixed laser and an active phase demodulation approach based on a phase generated carrier (PGC) technique using a phase demodulator integrated within the chip. No laser tuning is required, and the technique can extract the univocal phase value with no sensitivity fading. The detection only requires a photo-receiver per interferometer, analog-to-digital conversion, and simple processing performed in real-time. We present repeatable and linear refractive index measurements, with a detection limit down to 4.7·10-7 RIU. We also present sensing results on a chemically-functionalized sample, where anti-BSA to BSA (bovine serum albumin) binding curves are clearly visible for concentrations down to 5 ppm. Considering the advantages of silicon photonics, this device has great potential over several applications in the chemical/biochemical sensing industry.

Paper Details

Date Published: 20 February 2018
PDF: 9 pages
Proc. SPIE 10510, Frontiers in Biological Detection: From Nanosensors to Systems X, 1051005 (20 February 2018); doi: 10.1117/12.2287803
Show Author Affiliations
Y. Marin, Scuola Superiore Sant'Anna (Italy)
V. Toccafondo, Consorzio Nazionale Interuniversitario per le Telecomunicazioni (Italy)
P. Velha, Scuola Superiore Sant'Anna (Italy)
S. Scarano, Univ. degli Studi di Firenze (Italy)
S. Tirelli, Scuola Superiore Sant'Anna (Italy)
Consorzio Nazionale Interuniversitario per le Telecomunicazioni (Italy)
A. Nottola, Scuola Superiore Sant'Anna (Italy)
Consorzio Nazionale Interuniversitario per le Telecomunicazioni (Italy)
Y. Jeong, Korean Institute of Science and Technology - Europe (Germany)
H. P. Jeon, Korean Institute of Science and Technology - Europe (Germany)
M. Minunni, Univ. degli Studi di Firenze (Italy)
F. Di Pasquale , Scuola Superiore Sant'Anna (Italy)
C. J. Oton, Scuola Superiore Sant'Anna (Italy)


Published in SPIE Proceedings Vol. 10510:
Frontiers in Biological Detection: From Nanosensors to Systems X
Amos Danielli; Benjamin L. Miller; Sharon M. Weiss, Editor(s)

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