This PDF file contains the front matter associated with SPIE Proceedings Volume 12145, including the Title Page, Copyright information, Table of Contents, and Committee Page.

In this work, we report on a polymer toolkit for fabrication of hydrogel microstructures by means of one- and two-photon crosslinking process. Using home-built and commercial multi-photon lithography setups, we show the ability to prepare hydrogel structures attached to a solid substrate from developed copolymer or terpolymer layers. These polymers bear a photo-active benzophenone or anthraquinone moieties and additional groups enabling their chemical post-modification with biofunctional molecules. The crosslinked polymer networks can swell in water forming hydrogel structures with a geometry controlled by the UV or two-photon crosslinking imposed by a focused beam scanned over the substrate. In conjunction with post-modification, these micro-structured materials may serve in biosensing and other emerging applications such as responsive hydrogel-based miniature actuators supporting microfluidic devices and micromachines.

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.

Optical sensors based on a plasmonic multilayer stack, such as metal-insulator-metal (MIM), have attracted considerable attention over the past decades owing to their high resolution and high performance compared to conventional surface plasmon resonance (CSPR) sensors for bulk sensing (BS) applications. In this paper we show that CSPR is better than MIM sensors for thin film sensing, i.e. when a dielectric sensing layer (SL) is deposited on the outermost metal layer of the structure. We demonstrate that the deposition of a thin film SL on the top of the outermost-layer of an optimized multilayer structure, i.e. MIM, strongly decreases the evanescent electric field and the field enhancement at metal-SL interface and decreases the sensor’s sensitivity for MIM versus CSPR. By considering the theoretical and experimental results we demonstrated that CSPR is more suitable than MIM for thin films sensing applications.

We report on the utilization of an antifouling brush biointerface at the surface of surface plasmon resonance (SPR) optical probe for real-world biosensor applications. This biointerface architecture provides the advantage of resistance to fouling when contacted with complex biological fluids, it can be postmodified with functional biomolecular species for affinity biosensor applications, and allows for combined optical and electronic-based biosensing. The SPR optical probe carrying the thin gold film and antifouling polymer brush architecture is successfully implemented as a gate electrode in electrolyte-gated field effect transistor (EG-FET) readout and as a working electrode in cyclic voltammetry (CV). The poly (carboxybetaine acrylamide) (pCBAA) brush was synthesized by the ‘grafting from’ approach with a thickness matching the evanescent field of surface plasmons. When contacted with water, the film partially swells yielding a thickness of about 100 nm and resistance to fouling from undiluted blood plasma as documented by SPR measurements. In addition, its open structure enables shuttling of charge through the polymer coating and it offers means to investigate this biointerface with combined SPR and FET/CV methods. Such a platform is attractive for the investigation of complex processes on affinity biosensors and provide important leads in design of rapid direct readout of sensitive bioassays with both optical and electronic means.

In this work, we report a new approach for fabricating a high sensitivity lysozyme biosensing. The aforementioned device consists of an optimized Fabry-Perot micro-cavity (FPC) fabricated onto cleaved end of a standard single mode fibre (SMF). The sensitive part of our device is the external face of the FPC, which was ad-hoc functionalized in order to provide high selectivity and high sensitivity. From the experimental test carried out, we have found that our sensor has a sensitivity higher than others reported so far, to the best of our knowledge. In addition, the platform introduced here can operate over a broad wavelength which makes it adaptable to different sensing targets. In addition, our sensor offers several advantages such as repeatability of fabrication, wide operating range and small size and weight, which benefit its sensing applications.

Plasmonic optical fiber Bragg gratings offer a large range of opportunities in many biosensing applications by providing well-suited solutions for continuous and accurate monitoring. One of the most preferred configurations relies on surface plasmon resonance (SPR) implemented on tilted fiber Bragg grating (TFBG) by covering it with a very thin metal sheath (mostly gold), responsible for a drastic sensitivity improvement. When bioreceptors are immobilized onto the sensitive area, a plasmonic TFBG-based sensor leads to a highly sensitive and specific biosensor. Nevertheless, all possibilities using such a versatile platform were not totally investigated yet. Indeed, in addition to generate a plasmonic effect, the gold layer can also serve as a working electrode in an electrochemical set-up. By applying an electric field, it is possible to attract and detect molecules in solution. In this work, we developed the technique in the frame of the detection of the HER2 (Human Epidermal Growth Factor Receptor-2) protein, a relevant biomarker in breast cancer diagnosis. For that purpose, we biofunctionalized the probe using anti-HER2 aptamers with a high affinity to HER2 before performing a specific electrophoresis on gold-coated gratings. Results show a significant improvement in the sensitivity in comparison with the common non-electrochemical approach. The strength of this new sensing method is based on the ability to tweeze and detect targeted biomarkers with the same sensor. This method opens the way to more robust and reliable biosensing measurements with enhanced sensitivity.