Bioproduction is becoming increasingly important for the pharmaceutical industry. Real-time impurities monitoring during the purification phase could increase productivity and reduce drug cost. Here, we present a silicon photonics platform based on biofunctionalized Mach Zehnder Interferometers for this application. We demonstrate host cell proteins detection in the μg/ml range within 1 min, as well as the possibility to serially monitor up to 8 samples using a single silicon die.
Beyond the classical lock/key-recognition-based approach used in the bio-analytical field, an electronic tongue or nose device (eT/eN) is an assembly of non-specific sensors. Following a long story around the imaging of biological interactions of biomolecules by surface plasmon resonance imaging, we recently extended this approach to the non-specific interactions studies in gas phase giving rise to a new optical-nose generation. The signals resulting from the binding of VOCs on an array of bioinspired receptors can be seen as 3D continuous dynamic images or movies. Finally, complex data obtained from odors are analyzed as simple images via a specific database. This flexible and straightforward approach allowed a downscaling of the device and a new miniaturized portable and generic opto-nose, Neose, was recently launched also based on silicon integrated photonic technologies (Mach-Zehnder interferometers array). The translation of a smell into an image could be seen as a first step to open up the merging of the olfactory and visual senses.
Novel sub-wavelength silicon photonic waveguides for label-free sensors are demonstrated in this article. We use silicon-on-insulator (SOI) waveguides that consist of sub-wavelength grating (SWG) structures, where the waveguides are made of small silicon arrays (180 × 180 nm2 rectangles with 60 nm gaps). They are used to form microring and Bragg grating resonators which measure the change of refractive index by monitoring the resonant wavelength shift. Due to the high surface contact area and low optical confinement of the proposed waveguide, the sensitivity (both bulk and surface) can be significantly increased. The bulk sensitivity of 580 nm/RIU for the microring and 610 nm/RIU for the Bragg grating are better than other recently published resonator sensors. Moreover, a standard biological sandwich assay demonstrates an enhanced surface sensitivity of 2050 pm/nm for both devices. Theoretical models and experimental results are investigated, indicating the predominant losses are from the water absorption at 1550 nm and scattering by sidewall roughness.
Biosensors based on silicon photonic integrated circuits have attracted a growing interest in recent years. The use of sub-micron silicon waveguides to propagate near-infrared light allows for the drastic reduction of the optical system size, while increasing its complexity and sensitivity. Using silicon as the propagating medium also leverages the fabrication capabilities of CMOS foundries, which offer low-cost mass production. Researchers have deeply investigated photonic sensor devices, such as ring resonators, interferometers and photonic crystals, but the practical integration of silicon photonic biochips as part of a complete system has received less attention. Herein, we present a practical system-level architecture which can be employed to integrate the aforementioned photonic biosensors. We describe a system based on 1 mm2 dies that integrate germanium photodetectors and a single light coupling device. The die are embedded into a 16x16 mm2 epoxy package to enable microfluidic and electrical integration. First, we demonstrate a simple process to mimic Fan-Out Wafer-level-Packaging, which enables low-cost mass production. We then characterize the photodetectors in the photovoltaic mode, which exhibit high sensitivity at low optical power. Finally, we present a new grating coupler concept to relax the lateral alignment tolerance down to ± 50 μm at 1-dB (80%) power penalty, which should permit non-experts to use the biochips in a“plug-and-play” style. The system-level integration demonstrated in this study paves the way towards the mass production of low-cost and highly sensitive biosensors, and can facilitate their wide adoption for biomedical and agro-environmental applications.
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