Luminescent nanomaterials have shown promise for thermal sensing in bio-applications, yet little is known of the role of organic coatings such as supported lipid bilayers on the thermal conductivity between the nanomaterial and its environment. Additionally, since the supported lipid bilayer mimics the cell membrane, its thermal properties are fundamentally important to understand the spatial variations of temperature and heat transfer across membranes. Herein we describe a new approach that enables direct measurement of these thermal properties using a LiYF4:Er 3+ /Yb 3+ upconverting nanoparticle encapsulated within a conformal supported lipid bilayer and dispersed in water as a temperature probe yielding the temperature gradient across the bilayer. The thermal conductivity of lipid bilayer was measured as function of the temperature, being 0.20±0.02 W·m -1 ·K -1 at 300 K. For the uncapped nanoparticles dispersed in water, the temperature dependence of the thermal conductivity was also measured in the 300-314 K range as [0.63-0.69]±0.11 W·m -1 ·K -1 . Using a lumped elements model, we calculate the directional heat transfer at each of the system interfaces, namely nanoparticle-bilayer and bilayer-nanofluid, opening a new avenue to understand the membrane biophysical properties as well as the thermal properties of organic and polymer coatings.

The potential applications in disparate fields led to a rapid evolution of luminescence thermometry. In particular, luminescent thermometry based on trivalent lanthanide ions (Ln3+) has become very popular in the past decade due to the unique versatility, stability, and narrow emission band profiles covering a broad spectral range (from ultraviolet to the infrared) with relatively high emission quantum yields. Nevertheless, the reliability of Ln3+ ratiometric nanothermometry measurements is recently questioned in a few works reporting fake temperature readouts caused by experimental artifacts and even intrinsic effects. Using NaYF4:Er3+/Yb3+@NaNdF4@PAA (PAA stands for polyacrylic acid) core–shell nanoparticles, it is shown that how the primary luminescent thermometer concept can be used to correct the thermometric parameter (the intensity ratio of the Er3+ 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions) from the interference of the intruding 2H9/2 → 4I13/2 emission ensuring, thereafter, reliable temperature measurements.

Development of natural-based luminescent solar concentrators able to convert sunlight into specific wavelengths which are guided by total internal reflection to a PV device featuring reliable, sustainable and competitive energy systems.

An integrated photonic‐on‐a‐chip device based on a single organic‐inorganic di‐ureasil hybrid was fabricated for optical waveguide and temperature sensing. The device is composed by a thermal actuated Mach‐Zehnder (MZ) interferometer operating with a switching power of 0.011 W and a maximum temperature difference between branches of 0.89 ºC. The MZ interferometer is covered by a Eu3+/Tb3+ co‐doped di‐ureasil luminescent molecular thermometer with a temperature uncertainty of 0.1ºC and a spatial resolution of 13 µm. This is an uncommon example in which the same material (an organic‐inorganic hybrid) that is used to fabricate a particular device (a thermal‐actuated MZ interferometer) is also used to measure one of the device intrinsic properties (the operating temperature). The photonic‐on‐a‐chip example discussed here can be applied to sense temperature gradients with high resolution (10−3 ºC·µm−1) in chip‐scale heat engines or refrigerators, magnetic nanocontacts and energy‐harvesting machines.

The integration of photovoltaic (PV) elements in urban environments is gaining visibility due to the current interest in developing energetically self-sustainable buildings. Luminescent solar concentrators (LSCs) may be seen as a solution to convert urban elements, such as façades and windows, into energy-generation units for zero-energy buildings. Moreover, LSCs are able to reduce the mismatch between the AM1.5G spectrum and the PV cells absorption. In this work, we report optically active coatings for LSCs based on lanthanide ions (Ln3+ = Eu3+, Tb3+)-doped surface functionalized ionosilicas (ISs) embedded in poly(methyl methacrylate) (PMMA). These new visible-emitting films exhibit large Stokes-shift, enabling the production of transparent coatings with negligible self-absorption and large molar extinction coefficient and brightness values (~2 × 105 and ~104 M−1∙cm−1, respectively) analogous to that of orange/red-emitting organic dyes. LSCs showed great potential for efficient and environmentally resistant devices, with optical conversion efficiency values of ~0.27% and ~0.34%, respectively.

Visible-light communications (VLCs) based on white light-emitting diodes (LEDs) are emerging as a low-cost and energy-efficient alternative solution to wireless communications. As white emitting LEDs use a combination of a long-lived yellow emission combined with the faster response of a blue emitting LED (∼460 nm), VLC technology requires amplification of the blue component to improve the signal-to-noise ratio. We report the fabrication and characterization of planar and channel waveguides based on a blue-emitting polyfluorene conjugated polyelectrolyte, namely, poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl- alt -1,4-phenylene] (PBS-PFP) incorporated into diureasil organic–inorganic hybrids for optical amplification in VLC. Taking advantage of the diureasil host as a UV self-patternable material, direct UV laser writing was used to pattern channel waveguides with a larger refractive index (Δ n =0.09) compared to the nonexposed region, enabling confinement and guidance of the PBS-PFP emission with a maximum optical gain efficiency value of 1.62 ± 0.02 cm μJ –1 . This value is among the best figures of merit known for polymeric materials with additional advantages added by the diureasil hybrid host, namely, mechanical flexibility, thermal stability, and low insertion losses due to the nearly null refractive index contrast between the optical fiber and the amplification device, establishing the proposed approach as a promising cost-effective solution for optical amplification in VLCs.

The Internet of Things (IoT) fosters the development of smart city systems for sustainable living and increases comfort for people. One of the current challenges for sustainable buildings is the optimization of energy management. Temperature monitoring in buildings is of prime importance, as heating account for a great part of the total energy consumption. Here, a solar optical temperature sensor is presented with a thermal sensitivity of up to 1.23% °C−1 based on sustainable aqueous solutions of enhanced green fluorescent protein and C‐phycocyanin from biological feedstocks. These photonic sensors are presented under the configuration of luminescent solar concentrators widely proposed as a solution to integrate energy‐generating devices in buildings, as windows or façades. The developed mobile sensor is inserted in IoT context through the development of a self‐powered system able to measure, record, and send data to a user‐friendly website.

The development of portable low-cost integrated optics-based biosensors for photonics-on-a-chip devices for real-time diagnosis are of great interest, offering significant advantages over current analytical methods. We report the fabrication and characterization of an optical sensor based on a Mach-Zehnder interferometer to monitor the growing concentration of bacteria in a liquid medium. The device pattern was imprinted on transparent self-patternable organic-inorganic di-ureasil hybrid films by direct UV-laser, reducing the complexity and cost production compared with lithographic techniques or three-dimensional (3D) patterning using femtosecond lasers. The sensor performance was evaluated using, as an illustrative example, E. coli cell growth in an aqueous medium. The measured sensitivity (2 × 10−4 RIU) and limit of detection (LOD = 2 × 10−4) are among the best values known for low-refractive index contrast sensors. Furthermore, the di-ureasil hybrid used to produce this biosensor has additional advantages, such as mechanical flexibility, thermal stability, and low insertion losses due to fiber-device refractive index mismatch (~1.49). Therefore, the proposed sensor constitutes a direct, compact, fast, and cost-effective solution for monitoring the concentration of lived-cells.