Objective. -The main risk factor for the development of glaucoma, a retinal disease leading to blindness, is an increase in the intraocular pressure (IOP). Reducing this IOP can be obtained by eye drops but unfortunately the disease can still progress because IOP increases are painless, can fluctuate and, thus remain undetected during a visit to an ophthalmologist. The "MATEO" ANR project aims to develop sensors embedded in a contact lens for continuously IOP monitoring. Materials and methods. -Pressure sensors were produced by MEMS technology and tested with pig eyes obtained at a local slaughterhouse. Solution was injected by 50 L steps in the eye with a Hamilton syringe while IOP was monitored in parallel with a TonoVET system and an industrial pressure transducer inserted in the injection tubing system. Results. -Our first pressure sensor prototypes were generated and inserted in a lens compatible with eye application. A wireless system was developed to excite the sensor. At same time, it was recorded the data in components inserted into spectacles and a pocket recorder. In parallel, we showed that injecting a solution in the eye anterior chamber triggered an IOP increase smaller and more stable than injections in the posterior chamber. Finally, a direct correlation was observed between IOP measured on the corneal surface with the TonoVET and the pressure transducer placed close to eye injection point. Discussion. -Our results indicate that our in vitro model on pig eyes is adequate to test our new lens sensor. Finally, the pressure sensor was successfully inserted in contact lens opening the way for their in vitro and in vivo preclinical validation. RésuméObjectifs. -L'augmentation de pression intraoculaire (PIO) est le principal facteur de risque du glaucome -une pathologie cécitante. Bien qu'une réduction de la PIO puisse être obtenue par des gouttes oculaires, la maladie peut tout de même progresser car l'augmentation de PIO est indolore, fluctue dans le temps et par conséquent reste indétectable à l'examen ophtalmologique. Le projet ANR « MATEO » vise à produire des capteurs intégrés dans des lentilles de contact pour mesurer en continu la PIO. Matériels et méthodesDes capteurs de pression ont été produits par la technologie MEMS et testés sur des yeux de porc obtenus à un abattoir local. Une solution a été injectée dans l'oeil par dose de 50 L grâce à une seringue Hamilton pendant que la PIO était mesurée en parallèle avec un TonoVET et un capteur (transducteur) de pression industriel, inséré dans le dispositif d'injection.Résultats. -Nos prototypes de capteurs de pression ont été intégrés avec succès dans des lentilles compatibles avec l'oeil. Un système électronique sans fil embarqué sur une lunette a été développé pour exciter le capteur et enregistrer des données image de la PIO. Parallèlement, nous avons montré que l'injection d'une solution dans la chambre antérieure de l'oeil produit une augmentation de PIO plus faible et plus stable que les injections dans la chambre postérieure. Enfin, nous avo...
Developing electronic medical devices is challenging. Simulations or in vivo experiments are not sufficient to obtain pertinent comparisons between potential design options. This paper presents a new artificial tool allowing objective comparisons between electronic device topologies. The main idea is to build a tool which is sensitive to targeted biological parameters only. These tools are generally called phantoms. The phantom presented in this paper is dedicated to IntraOcular Pressure (IOP) Measurement devices used in glaucoma diagnosis and treatment. It is called Biomechanical Eye Emulator (BEE). The BEE emulates the main biomechanical parameters influencing the IOP measurements. Because it is not sensitive to the living context, the BEE is the most efficient tool to investigate the best sensor design. BEE specifications are defined to be as close as possible to chosen models (humans or animals). Its efficiency is shown with a case study on rabbits. The results clearly demonstrate the BEE phantoms efficacy in providing objective assessment metrics during the sensor design process.
Bioimpedance spectroscopy is a promising tool for non-invasive monitoring of tissue structure and fluids. With the objective of using it to assess muscle fatigue in vitro, we have developed a measurement bench allowing the monitoring of myoblasts cultures by bioimpedance measurements. This work presents the setup and its characterization, combining modeling and measurements. This setup relies on a microelectrodes array and a commercial impedance analyzer. Its characterization with Phosphate Buffered Saline is coherent with our simulation. The impedance increases at low frequencies after several cell cultures, due to a degradation of the microelectrode interface. Nevertheless, the measurement bench allows us to detect the presence of myoblasts covering the electrodes in a frequency range from 10 kHz to 100 kHz. The measurement bench is therefore suitable to explore the relative impedance variation as a signature of muscle fatigue.
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