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Ultrasensitive interferometric on-chip microscopy of transparent objects Ultrasensitive interferometric on-chip microscopy of transparent objects

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Date added: 07/24/2016
Date modified: 07/24/2016
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Light microscopes can detect objects through several physical processes, such as scattering, absorption, and reflection. In transparent objects, these mechanisms are often too weak, and interference effects are more suitable to observe the tiny refractive index variations that produce phase shifts. We propose an on-chip microscope design that exploits birefringence in an unconventional geometry. It makes use of two sheared and quasi-overlapped illuminating beams experiencing relative phase shifts when going through the object, and a complementary metal-oxide-semiconductor image sensor array to record the resulting interference pattern. Unlike conventional microscopes, the beams are unfocused, leading to a very large field of view (20 mm2) and detection volume (more than 0.5 cm3), at the expense of lateral resolution. The high axial sensitivity (<1 nm) achieved using a novel phase-shifting interferometric operation makes the proposed device ideal for examining transparent substrates and reading microarrays of biomarkers. This is demonstrated by detecting nanometer-thick surface modulations on glass and single and double protein layers.

http://advances.sciencemag.org/content/2/6/e1600077.full

RAIS: A new platform for diagnosing infectious diseases RAIS: A new platform for diagnosing infectious diseases

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Date added: 07/23/2016
Date modified: 07/23/2016
Filesize: 260 Bytes
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Publication by ICFO in Electro Optics Magazine, June 2016 (http://www.electrooptics.com/news/news_story.php?news_id=2553)

Phase-sensitive plasmonic biosensor using a portable and large field-of-view interferometric... Phase-sensitive plasmonic biosensor using a portable and large field-of-view interferometric...

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Date added: 03/26/2018
Date modified: 03/26/2018
Filesize: 2.75 MB
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"Phase-sensitive plasmonic biosensor using a portable and large field-of-view interferometric microarray imager"

Nanophotonics, and more specifically plasmonics, provides a rich toolbox for biomolecular sensing, since the engineered metasurfaces can enhance light–matter interactions to unprecedented levels. So far, biosensing associated with high-quality factor plasmonic resonances has almost exclusively relied on detection of spectral shifts and their associated intensity changes. However, the phase response of the plasmonic resonances have rarely been exploited, mainly because this requires a more sophisticated optical arrangement. Here we present a new phase-sensitive platform for high-throughput and label-free biosensing enhanced by plasmonics. It employs specifically designed Au nanohole arrays and a large field-of-view interferometric lens-free imaging reader operating in a collinear optical path configuration. This unique combination allows the detection of atomically thin (angstrom-level) topographical features over large areas, enabling simultaneous reading of thousands of microarray elements. As the plasmonic chips are fabricated using scalable techniques and the imaging reader is built with low-cost off-the-shelf consumer electronic and optical components, the proposed platform is ideal for point-of-care ultrasensitive biomarker detection from small sample volumes. Our research opens new horizons for on-site disease diagnostics and remote health monitoring.

Infrared Plasmonic Biosensor for Real-Time and Label-Free Monitoring of Lipid Membranes Infrared Plasmonic Biosensor for Real-Time and Label-Free Monitoring of Lipid Membranes

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Date added: 01/22/2016
Date modified: 07/25/2016
Filesize: 260 Bytes
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In this work, we present an infrared plasmonic biosensor for chemical-specific detection and monitoring of biomimetic lipid membranes in a label-free and real-time fashion. Lipid membranes constitute the primary biological interface mediating cell signaling and interaction with drugs and pathogens. By exploiting the plasmonic field enhancement in the vicinity of engineered and surface-modified nanoantennas, the proposed biosensor is able to capture the vibrational fingerprints of lipid molecules and monitor in real time the formation kinetics of planar biomimetic membranes in aqueous environments. Furthermore, we show that this plasmonic biosensor features high-field enhancement extending over tens of nanometers away from the surface, matching the size of typical bioassays while preserving high sensitivity.