title: Three-dimensional Mach-Zehnder interferometer in a microfluidic chip for spatially-resolved label-free detection.
abstract: Ultrafast laser writing of waveguides in glasses is a very flexible and simple method for direct on-chip integration of photonic devices. In this work we present a monolithic optofluidic device in fused silica providing label-free and spatially-resolved sensing in a microfluidic channel. A Mach-Zehnder interferometer is inscribed with the sensing arm orthogonally crossing the microfluidic channel and the reference arm passing over it. The interferometer is integrated either with a microchannel fabricated by femtosecond laser technology or into a commercial lab-on-chip for capillary electrophoresis. The device layout, made possible by the unique three-dimensional capabilities of the technique, enables label-free sensing of samples flowing in the microchannel with spatial resolution of about 10 microm and limit of detection down to 10(-4) RIU.
authors.affiliation: Istituto di Fotonica e Nanotecnologie-CNR, Dipartimento di Fisica-Politecnico di Milano, Piazza L. da Vinci, 32, 20133, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Crespi
authors.forename: Yu
authors.initials: Y
authors.lastname: Gu
authors.forename: Bongkot
authors.initials: B
authors.lastname: Ngamsom
authors.forename: Hugo J W M
authors.initials: HJ
authors.lastname: Hoekstra
authors.forename: Chaitanya
authors.initials: C
authors.lastname: Dongre
authors.forename: Markus
authors.initials: M
authors.lastname: Pollnau
authors.forename: Roberta
authors.initials: R
authors.lastname: Ramponi
authors.forename: Hans H
authors.initials: HH
authors.lastname: van den Vlekkert
authors.forename: Paul
authors.initials: P
authors.lastname: Watts
authors.forename: Giulio
authors.initials: G
authors.lastname: Cerullo
authors.forename: Roberto
authors.initials: R
authors.lastname: Osellame