Layer-by-layer modification effects on a nanopore's inner surface of polycarbonate track-etched membranes

The control of the morphology, as well as the physical and chemical properties, of nanopores is a key issue for many applications. Reducing pore size is important in nanopore-based sensing applications as it helps to increase sensitivity. Changes of other physical properties such as surface net charge can also modify transport selectivity of the pores. We have studied how polyelectrolyte layer-by-layer (LBL) surface modification can be used to change the characteristics of nanoporous membranes. Studies were performed with a custom made three-dimensional multilayer microfluidic device able to fit membrane samples. The device allowed us to efficiently control LBL film deposition over blank low-cost commercially available polycarbonate track-etched (PCTE) membranes. We have demonstrated pore diameter reduction and deposition of the layers inside the pores through confocal and SEM images. Posterior impedance measurement studies served to evaluate experimentally the effect of the LBL deposition on the net inner nanopore surface charge and diameter. Measurements using direct current (DC) and alternative current (AC) voltages have demonstrated contrasted behaviors depending on the number and parity of deposited opposite charge layers. PCTE membranes are originally negatively charged and results evidenced higher impedance increases for paired charge LBL depositions. Impedance decreased when an unpaired positive layer was added. These results showed a different influence on the overall ion motility due to the effect of different surface charges. Results have been fit into a model that suggested a strong dependence of nanopores' impedance module to surface charge on conductive buffers, such as Phosphate Buffer Saline (PBS), even on relatively large nanopores. In AC significant differences between paired and unpaired charged LBL depositions tended to disappear as the total number of layers increased.Peer ReviewedPostprint (published version

μ-Si strain gauge array on flexible substrate for dynamic pressure measurement

All tests and devices have been performed on the NanoRennes platform with the support of the CNRS French national research agency and the project CPER Sophie/STIC&Onde. Artificial Wrist was realized at Cherry Biotech Rennes.International audienceLow Temperature μ-Si layers have been deposited by Inductively Coupled Plasma Chemical Vapour Deposition (ICP-CVD) to produce strain gauges. These strain gauges performed on 25 μm thick flexible Kapton Polyimide (PI) were investigated in terms of Gauge Factor but also in dynamic mode through a homemade pneumatic test bench. Best strain gauge design has been identified and subsequently used to perform a 25 sensor array which was also tested using pulses and more complex signals. A simulation of blood pressure monitoring was performed to demonstrate the value of the technology

Metallic nanostructures based on blu-ray discs for multiplexed plasmonic biodetection

Resumen del trabajo presentado al VIII International Congress on Analytical Nanoscience and Nanotechnology, celebrado en Barcelona (España) del 3 al 5 de julio de 2017.Nanostructure-based plasmonic biosensors have quickly positioned themselves as interesting candidates for the design of portable optical biosensor platforms considering the potential benefits they can offer in miniaturization, multiplexing, real-time and label-free detection. We have developed a simple integrated nanoplasmonic sensor taking advantage of the periodic nanostructured array of commercial Blu-ray discs. Sensors with different metallic film layers (50 and 100 nm) were fabricated and optically characterized by varying the oblique-angle of the incident light in optical reflectance measurements. We observed an enhancement in sensitivity and a narrowing of the resonant linewidths as the light incidence angle was increased, which could be related to the generation of Fano resonant modes. The new sensors achieve a figure of merit (FOM) up to 35 RIU-1 and a competitive bulk limit of detection (LOD) of 6.34×10-6 RIU. Based on these structures, a single-channel sensor in a 1cm2 integrated chip has been designed an incorporated in a compact biosensor prototype. The label-free biosensing capability of the new sensor has been assessed by evaluating the presence of specific antibodies against the GTF2b protein, a tumor-associate antigen (TAA) related to colorectal cancer. We have achieved a LOD in the pM order and have evaluated the feasibility of directly measuring biological samples such as human serum. The design has been transferred and adapted to a multiplexed prototype incorporating a sensor chip with four integrated channels. The optical and the sensing performance have been evaluated. We have assessed bulk sensitivity and attempted real-time biosensing measurements, obtaining good reproducibility between the channels.Peer reviewe

A label-free nanostructured plasmonic biosensor based on Blu-ray discs with integrated microfluidics for sensitive biodetection

Nanostructure-based plasmonic biosensors have quickly positioned themselves as interesting candidates for the design of portable optical biosensor platforms considering the potential benefits they can offer in integration, miniaturization, multiplexing, and real-time label-free detection. We have developed a simple integrated nanoplasmonic sensor taking advantage of the periodic nanostructured array of commercial Blu-ray discs. Sensors with two gold film thicknesses (50 and 100 nm) were fabricated and optically characterized by varying the oblique-angle of the incident light in optical reflectance measurements. Contrary to the use normal light incidence previously reported with other optical discs, we observed an enhancement in sensitivity and a narrowing of the resonant linewidths as the light incidence angle was increased, which could be related to the generation of Fano resonant modes. The new sensors achieve a figure of merit (FOM) up to 35 RIU and a competitive bulk limit of detection (LOD) of 6.3×10 RIU. These values significantly improve previously reported results obtained with normal light incidence reflectance measurements using similar structures. The sensor has been combined with versatile, simple, ease to-fabricate microfluidics. The integrated chip is only 1 cm (including a PDMS flow cell with a 50 µm height microfluidic channel fabricated with double-sided adhesive tape) and all the optical components are mounted on a 10 cm×10 cm portable prototype, illustrating its facile miniaturization, integration and potential portability. Finally, to assess the label-free biosensing capability of the new sensor, we have evaluated the presence of specific antibodies against the GTF2b protein, a tumor-associate antigen (TAA) related to colorectal cancer. We have achieved a LOD in the pM order and have assessed the feasibility of directly measuring biological samples such as human serum.GL acknowledges financial support from CONACYT 225362 scholarship. We acknowledge the financial support from COLONTEST project (RETOS-COLABORACIÓN Subprogram, RTC-2014-1518-1) and from PreDICT project (Programa estatal de investigación, desarrollo e innovación orientada a los Retos de la Sociedad, TEC2016-78515-R). The NanoB2A is a consolidated research group (Grup de Recerca) of the Generalitat de Catalunya and has support from the Departament d’Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya (2014 SGR 624). ICN2 is the recipient of Grant SEV-2013-0295 from the “Severo Ochoa Centers of Excellence” Program of Spanish MINECO. The authors thank Miguel Berenguel Alonso and Prof. Julián Alonso Chamarro from the Group of Sensors and Biosensors (Department of Chemistry, Autonomous University of Barcelona) for their technical support in this work.Peer Reviewe

Simultaneous impedance and fluorescence detection of proteins in a cyclo olefin polymer chip containing a column with an ordered pillar array with integrated gold microelectrodes

In this work, we report the detection of proteins by means of simultaneous fluorescence and impedance measurements in a cyclo olefin polymer (COP) chip containing an ordered pillar array column, used for reversed-phase liquid chromatography, with integrated microband gold electrodes at the end of the channel