Francone, AchilleKehoe, TimothyObieta, IsabelSaez-Martinez, VirginiaBilbao, LeireKhokhar, Ali Z.Gadegaard, NikolajDelgado Simao, ClaudiaKehagias, NikolaosSotomayor Torres, Clivia M.2018-10Francone , A , Kehoe , T , Obieta , I , Saez-Martinez , V , Bilbao , L , Khokhar , A Z , Gadegaard , N , Delgado Simao , C , Kehagias , N & Sotomayor Torres , C M 2018 , ' Integrated 3D Hydrogel Waveguide Out-Coupler by Step-and-Repeat Thermal Nanoimprint Lithography: A Promising Sensor Device for Water and pH : A promising sensor device for water and pH ' , Sensors , vol. 18 , no. 10 , 3240 , pp. 3240 . https://doi.org/10.3390/s181032401424-3210researchoutputwizard: 11556/617Publisher Copyright: © 2018 by the authors. Licensee MDPI, Basel, Switzerland.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.13804560enginfo:eu-repo/semantics/openAccessjournal article10.3390/s18103240HydrogelWaveguideThermal nanoimprint lithographyWater sensorpH sensorHydrogelWaveguideThermal nanoimprint lithographyWater sensorpH sensorAnalytical ChemistryInformation SystemsBiochemistryAtomic and Molecular Physics, and OpticsInstrumentationElectrical and Electronic Engineeringhttp://www.scopus.com/inward/record.url?scp=85054544470&partnerID=8YFLogxK