Integrated 3D Hydrogel Waveguide Out-Coupler by Step-and-Repeat Thermal Nanoimprint Lithography: A Promising Sensor Device for Water and pH
by
Achille Francone 1,*
, Timothy Kehoe 1,†, Isabel Obieta 2, Virginia Saez-Martinez 2,‡, Leire Bilbao 2, Ali Z. Khokhar 3,§, Nikolaj Gadegaard 3, Claudia Delgado Simao 1,‖, Nikolaos Kehagias 1 and Clivia M. Sotomayor Torres 1,4
Achille Francone 1,*, Timothy Kehoe 1,†, Isabel Obieta 2, Virginia Saez-Martinez 2,‡, Leire Bilbao 2, Ali Z. Khokhar 3,§, Nikolaj Gadegaard 3, Claudia Delgado Simao 1,‖, Nikolaos Kehagias 1 and Clivia M. Sotomayor Torres 1,4
1
Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
2
Tecnalia Research & Innovation, Mikeletegi 2, E-20009 San Sebastián, Spain
3
Division of Biomedical Engineering, University Glasgow, Rankine Building, Glasgow G12 8LT, UK
4
Institucio Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
*
Author to whom correspondence should be addressed.
†
Current address: Visum Ltd., NexusUCD, Belfied Office Park, Dublin 4, Ireland.
‡
Current address: I + Med S.Coop., Technological Park of Alava, Albert Einstein St. 15, 01510 Miñano, Alava, Spain.
§
Current address: Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK.
‖
Current address: Eurecat, Centre Tecnològic de Catalunya, Functional Printing & Embedded Systems Unit, Avinguda Ernest Lluch 36, 08302 Mataró, Spain.
Sensors 2018, 18(10), 3240; https://doi.org/10.3390/s18103240
Received: 8 August 2018 / Revised: 14 September 2018 / Accepted: 20 September 2018 / Published: 26 September 2018
(This article belongs to the Section Physical Sensors)
Hydrogel materials offer many advantages for chemical and biological sensoring due to their response to a small change in their environment with a related change in volume. Several designs have been outlined in the literature in the specific field of hydrogel-based optical sensors, reporting a large number of steps for their fabrication. In this work we present a three-dimensional, hydrogel-based sensor the structure of which is fabricated in a single step using thermal nanoimprint lithography. The sensor is based on a waveguide with a grating readout section. A specific hydrogel formulation, based on a combination of PEGDMA (Poly(Ethylene Glycol DiMethAcrylate)), NIPAAm (N-IsoPropylAcrylAmide), and AA (Acrylic Acid), was developed. This stimulus-responsive hydrogel is sensitive to pH and to water. Moreover, the hydrogel has been modified to be suitable for fabrication by thermal nanoimprint lithography. Once stimulated, the hydrogel-based sensor changes its topography, which is characterised physically by AFM and SEM, and optically using a specific optical set-up.
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Keywords:
hydrogel; waveguide; thermal nanoimprint lithography; water sensor; pH sensor
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MDPI and ACS Style
Francone, A.; Kehoe, T.; Obieta, I.; Saez-Martinez, V.; Bilbao, L.; Khokhar, A.Z.; Gadegaard, N.; Simao, C.D.; Kehagias, N.; Sotomayor Torres, C.M. Integrated 3D Hydrogel Waveguide Out-Coupler by Step-and-Repeat Thermal Nanoimprint Lithography: A Promising Sensor Device for Water and pH. Sensors 2018, 18, 3240.
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