Design guidelines for optimizing the sensing performance of nanoimprinted second order distributed feedback dye lasers are presented. The guidelines are verified by experiments and simulations. The lasers, fabricated by UV‐nanoimprint lithography into Pyrromethene doped Ormocomp thin films on glass, have their sensor sensitivity enhanced by a factor of up to five via the evaporation of a titanium dioxide (TiO2) waveguiding layer. The influence of the TiO2 layer thickness on the device sensitivity is analyzed with a simple model that accurately predicts experimentally measured wavelength shifts induced by varied superstrate refractive indices. The superstrate refractive index is additionally shown to determine which of the possible waveguiding modes dominates for lasing, indicating a method to flexibly select the polarization of the laser. The detection limit of the sensor system is further discussed, finding an optimum at 7.5· 10−6 RIU. Wavelength changes caused by dye bleaching must be taken into account for long‐term measurements.

<b><i>Objectives:</i></b> To develop an automated fluorescence-based caries scoring system for an intraoral scanner and to<i></i>test the performance of the system compared to state-of-the-art methods. <b><i>Methods:</i></b> Seventy-three permanent posterior teeth were scanned with a three-dimensional (3D) intraoral scanner prototype which emitted light at 415 nm. An overlay representing the fluorescence signal from the tissue was mapped onto 3D models of the teeth. Multiple examination sites (<i>n</i> = 139) on the occlusal surfaces were chosen, and their red and green fluorescence signal components were extracted. These components were used to calculate 4 mathematical functions upon which a caries scoring system for the scanner prototype could be based. Visual-tactile (International Caries Detection and Assessment System, ICDAS), radiographic (ICDAS), and histological assessments were conducted on the same examination sites. <b><i>Results:</i></b> Most index tests showed significant correlation with histology. The strongest correlation was observed for the visual-tactile examination (<i>r</i>_s = 0.80) followed by the scanner supported by the caries classification function that quantifies the overall fluorescence compared to sound surfaces (<i>r</i>_s = 0.78). Additionally, this function resulted in the highest intra-examiner reliability (κ = 0.964), and the highest sum of sensitivity (SE) and specificity (SP) (sum SE-SP: 1.60–1.84) at the 2 histological levels where the comparison with visual-tactile assessment was possible (κ = 0.886, sum SE-SP = 1.57–1.81) and at the 3 out of 4 histological levels where the comparison with radiographic assessment was possible (κ = 0.911, sum SE-SP = 1.37–1.78); the only exception was for the lesions in the outer third of dentin, where the radiographic assessment showed the highest sum SE-SP (1.78). <b><i>Conclusion:</i></b> A fluorescence-based caries scoring system was developed for the intraoral scanner showing promising performance compared to state-of-the-art caries detection methods. The intraoral scanner accompanied by an automated caries scoring system may improve objective caries detection and increase the efficiency and effectiveness of oral examinations. Furthermore, this device has the potential to support reliable monitoring of early caries lesions.

Abstract:An all-polymer photonic crystal slab sensor is presented, and shown to exhibit narrow resonant reflection with a FWHM of less than 1 nm and a sensitivity of 31 nm/RIU when sensing media with refractive indices around that of water. This results in a detection limit of 4.5 × 10 −6 RIU when measured in conjunction with a spectrometer of 12 pm/pixel resolution. The device is a two-layer structure, composed of a low refractive index polymer with a periodically modulated surface height, covered with a smooth upper-surface high refractive index inorganic-organic hybrid polymer modified with ZrO 2 -based nanoparticles. Furthermore, it is fabricated using inexpensive vacuum-less techniques involving only UV nanoreplication and polymer spin-casting, and is thus well suited for single-use biological and refractive index sensing applications.

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