Dual Optical Signal-based Intraocular Pressure-sensing Principle Using Pressure-sensitive Mechanoluminescent ZnS:Cu/PDMS Soft Composite

Novel cementitious materials with mechanoluminescence for the application of visible stress monitoring and recording

The development of real-time and accurate visual stress detection is crucial for the field of building engineering. Herein, a new strategy is explored for the development of novel cementitious materials by hierarchical aggregation smart luminescent material and resin-based material. The cementitious material with such layered structure is inherently capable of visualization of stress monitoring and recording by converting the stress to visible light. The specimen fabricated by the novel cementitious material could repetitively emit green visible light under excitation of a mechanical pulse for 10 cycles, suggesting that the cementitious material shows highly reproducible performance. Moreover, the numerical simulations and analysis for the models of stress indicate that the luminescent time is synchronous with the stress and the emission intensity is proportional to the value of stress. To the best of our knowledge, this is the first study that the cementitious material realizes visible stress monitoring and recording, which supplies new insights for exploring modern multi-functional building materials.

A detailed methodology to model the Non Contact Tonometry: a Fluid Structure Interaction study

Understanding the corneal mechanical properties has great importance in the study of corneal pathologies and the prediction of refractive surgery outcomes. Non-Contact Tonometry (NCT) is a non-invasive diagnostic tool intended to characterize the corneal tissue response in vivo by applying a defined air-pulse. The biomarkers inferred from this test can only be considered as indicators of the global biomechanical behaviour rather than the intrinsic biomechanical properties of the corneal tissue. A possibility to isolate the mechanical response of the corneal tissue is the use of an inverse finite element method, which is based on accurate and reliable modelling. Since a detailed methodology is still missing in the literature, this paper aims to construct a high-fidelity finite-element model of an idealized 3D eye for in silico NCT. A fluid-structure interaction (FSI) simulation is developed to virtually apply a defined air-pulse to a 3D idealized eye model comprising cornea, limbus, sclera, lens and humors. Then, a sensitivity analysis is performed to examine the influence of the intraocular pressure (IOP) and the structural material parameters on three biomarkers associated with corneal deformation. The analysis reveals the requirements for the in silico study linked to the correct reproduction of three main aspects: the air pressure over the cornea, the biomechanical properties of the tissues, and the IOP. The adoption of an FSI simulation is crucial to capture the correct air pressure profile over the cornea as a consequence of the air-jet. Regarding the parts of the eye, an anisotropic material should be used for the cornea. An important component is the sclera: the stiffer the sclera, the lower the corneal deformation due to the air-puff. Finally, the fluid-like behavior of the humors should be considered in order to account for the correct variation of the IOP during the test which will, otherwise, remain constant. The development of a strong FSI tool amenable to model coupled structures and fluids provides the basis to find the biomechanical properties of the corneal tissue in vivo.

Recent progress on wearable point-of-care devices for ocular systems

The eye is a complex sensory organ that contains abundant information for specific diseases and pathological responses. It has emerged as a facile biological interface for wearable healthcare platforms because of its excellent accessibility. Recent advances in electronic devices have led to the extensive research of point-of-care (POC) systems for diagnosing and monitoring diseases by detecting the biomarkers within the eye. Among these systems, contact lenses, which make direct contact with the ocular surfaces, have been utilized as one of the promising candidates for non-invasive POC testing of various diseases. The continuous and long-term measurement from the sensor allows the patients to manage their symptoms in an effective and convenient way. Herein, we review the progress of contact lens sensors in terms of the materials, methodologies, device designs, and target biomarkers. The anatomical structure and biological mechanisms of the eye are also discussed to provide a comprehensive understanding of the principles of contact lens sensors. Intraocular pressure and glucose, which are the representative biomarkers found in the eyes, can be measured with the biosensors integrated with contact lenses for the diagnosis of glaucoma and diabetes. Furthermore, contact lens sensors for various general pathologies as well as other ocular diseases are also considered, thereby providing the prospects for further developments of smart contact lenses as a future POC system.