Effective piezoelectric activity of zinc oxide films grown by RF planar magnetron sputtering

We present a study of the effective piezoelectric activity of thin ZnO films produced by RF planar magnetron sputtering. The energetic plasma particles which bombard the substrate in the above deposition system increase the substrate temperature, thus causing a gradual variation in film structure during the beginning of the film growth. As a result, a precursor layer is formed which consists of small randomly oriented crystallites, and exhibits poor piezoelectric activity. Hence, the film thickness responsible for piezoelectric activity is generally less than the physical thickness of the film. This leads to an increase in the resonant frequency of the film. For example, a film designed to have a half-wave resonance at 288 MHz, was found to be resonant at 332 MHz. The poorly structured initial layer meant in this typical case that only 87 % of this film volume exhibited piezoelectric activity. Investigations based on the deposition conditions (substrate temperature, and deposition rate), the optical losses, SEM imaging and RF electrical behaviour are presented in this letter

Towards registration of multimodal images of vocal folds based on mutual information.

International audienceThis paper deals with mutual information-based registration of multimodal images for laser phonomicrosurgery of the vocal folds. The images to be registered are white light images (white light camera) versus fluorescence images. This work is carried out within the framework of the European project RALP which involves the use of microrobotic system for endoluminal laser phonosurgery. The designed system includes two fiber bundles connected to a high speed camera and one fiber bundle used for fluorescence image. Using the mutual information based registration method, it will be possible to represent the visible information in the fluorescence image and use it in the other image

Microsensors and image processing for single oocyte qualification: toward multiparametric determination of the best time for fertilization

International audienceDuring intracytoplasmic sperm injection (ICSI) attempts, oocytes reaching metaphase II are microinjected. A morphological examination under a microscope is the usual method for determining oocyte maturity. The level of oocyte maturity is based on the meiotic status (Germinal Vesicle, metaphase I and metaphase II) of the oocytes with respect to their increasing maturity. In this letter, we summarize the studies conducted to analyze cytoplasm maturity using various microsystems and image processing. Optical microsystems are used to measure the transmission spectra and refractive index of the oocytes. We compared the transmission spectra measurements to the transmission electron microscopy results. Karhunen-Loeve transform is also used to evaluate the maturity of the oocytes. To summarize, optical analysis techniques are a minimally invasive technology allowing cytoplasm maturity to be assessed. Oocytes should not only be qualified in terms of GV, MI or MII, but also regarding their temporal evolution over the course of these maturation stages. The ultimate aim of this work is to describe the maturation of the oocytes by a trajectory in a multidimensional space and to determine when would be the best time for successful fertilization

Une recherche pluri-science et transdisciplinaire pour le développement de dispositifs intelligents en santé Biom’@x, CLIP et SmartTransfuser

International audienceDiagnostic and Medical Device B4B-Connection23-24 mars 2016, Besanço

Bi-directional translational research: how practical applications fuel fundamental research

International audienceTranslational research consists in translating fundamental research results as closely as possible to patients. Researchers or institutions sometimes underestimate these translational studies because it is thought that, although essential for setting up new investigation tools, they do not deepen fundamental knowledge.However, users face specific difficulties due to biological, physiological and clinical constraints. In other words, new questions and scientific obstacles arise when research is applied to the real world. In order to address these new challenges, reverse translational research is required. This paradigm consists in understanding difficulties faced when accounting for the above mentioned constraints, expressing them in terms of scientific theories and solving them by defining new prisms through which reality is perceived.Consequently, fundamental research is fueled by this renewed perception translational research induces.In this talk, we illustrate this principle with the development of what is, to the best of our knowledge, the first fluorescence based calibration free micro pH sensor. The expressed need was to continuously monitor some physiological pH related constants inside the human body. The main clinical constraint was therefore the use of the sensor in a calibration free manner. We show how fluorescence pH measurement had to be rethought and how a new physical-chemical understanding of acid-base reactions at the sensor’s surface had to be discovered to address this constraint.More generally and to open discussions on translational and reversed translational research, we present how we developed bi-directional research actions between practitioners and technology researchers in eastern France

Enhanced security in a coherence modulation system using optical path difference corruption

The security aspect of coherence modulation for telecommunication is discussed, We have recently demonstrated a simple technique for decoding the signal without any decoder interferometer, A secure alternative method based on the corruption of the interferometers optical path difference is now shown

Calibration free optical pH sensing using physico-chemical modeling of fluorescein grafted silica fibers

International audienceDual emission wavelengths fluorescent indicators like SNARF® allow measuring pH by calculating the ratio of the emitted fluorescence at two distinct wavelengths. This ratiometric technique is however not calibration free and molecule manufacturers advise users to perform a pre-calibration using the acidic and basic endpoints of titration respectively.pH sensing is based on the monitoring of the acid-base reaction which occurs in the indicator layer grafted at the end of an optical fiber. Calibration is required to account for degradation of the sensor probe due to aging or repetitive use and because the pKa of the acid-base reaction cannot be considered constant. pKa variations are due to several factors like temperature and/or ionic strength of the solution to be measured, structure and thickness of the indicator layer at the end of the fiber. Indeed, pKa can differ from almost 2 units between the value in a low concentration solution and the value in a dense layer close to a solid surface which is the case in fiber optic pH sensors. Furthermore, it is extremely difficult to fabricate pH sensitive fibers with a reproducibility high enough to control the pKa of the acid-base reaction in the sensing volume.In this conference, we show that modeling the fluorescence properties of ratiometric indicators existing in their 2 acidic and basic forms cannot be used to access calibration free pH sensing. We then explain how pH indicators exhibiting more complex prototropic equilibria can be used to compute not only the pH value but also the value of the pKa at the moment when measurements are performed. We present the complete mathematical modeling of the fluorescence properties of fluorescein and we explain how, from any fluorescence spectrum, it is possible to fit the values of both pH and pKa. This is, to the best of our knowledge, the first example of calibration free micro pH sensor.This project has received partial funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement No 754907

Translational research as a source of new visions: examples in technologies for health

International audience<span style="font-size: 11.0pt; mso-ascii-font-family: Calibri; mso-ascii-theme-font: minor-latin; mso-hansi-font-family: Calibri; mso-hansi-theme-font: minor-latin;" data-mce-style="font-size: 11.0pt; mso-ascii-font-family: Calibri; mso-ascii-theme-font: minor-latin; mso-hansi-font-family: Calibri; mso-hansi-theme-font: minor-latin;"&gtTranslational research consists in translating fundamental research results as closely as possible to patients. Researchers or institutions sometimes underestimate these translational studies because it is thought that, although essential for setting up new investigation tools, they do not deepen fundamental knowledge. However, users face specific difficulties due to biological, physiological and clinical constraints. In other words, new questions and scientific obstacles arise when research is applied to the real world. In order to address these new challenges, reverse translational research is required. This paradigm consists in understanding difficulties faced when accounting for the above mentioned constraints, expressing them in terms of scientific theories and solving them by defining new prisms through which reality is perceived. Consequently, fundamental research is fueled by this renewed perception translational research induces. In this talk, we illustrate this principle with the development of what is, to the best of our knowledge, the first fluorescence based calibration free micro pH sensor. The expressed need was to continuously monitor some physiological pH related constants inside the human body. The main clinical constraint was therefore the use of the sensor in a calibration free manner. We show how fluorescence pH measurement had to be rethought and how a new physical-chemical understanding of acid-base reactions at the sensor’s surface had to be discovered to address this constraint. More generally and to open discussions on translational and reversed translational research, we present how we developed bi-directional research actions between practitioners and technology</span&g

Security vulnerability in coherence modulation communication systems

A simple method for detecting a signal encoded by coherence modulation without the use of any decoder interferometer is demonstrated, The technique is based on wavelength filtering of the channelled spectrum in the transmission link, To overcome this vulnerability in the scheme, more secure coherence modulation arrangements are proposed

Calibration free and fluorescein based fiber optic pH sensor for clinical applications

International audienceThis communication describes how fluorescein grafted at the end of an optical fiber can be used for calibration free pH sensing in the range of physiological values. The method is based on a complete mathematical description of the fluorescence mechanisms of this pH indicator. The analysis of the shape of the fluorescence spectra allows computing values of both the pH and the pKa3. Doing this, it becomes possible to access calibration pH sensing using conventional optical fibers. This is, to the best of our knowledge, the first fiber optic calibration free pH sensor reported to date