L’électro-encéphalogramme (EEG) est un examen qui permet l’enregistrement de l’activité cérébrale et reste incontournable pour les diagnostics et pronostics des comas, le suivi des épilepsies et de ...la maturation du système nerveux central. Actuellement, la pénurie nationale de médecins neurophysiologistes ne permet plus l’accès aux soins pour tous. Il existe actuellement des solutions de transmission à distance des EEG, non informatisées pour 34 % d’entre elles. Après analyse des problèmes que rencontrent ces « plateformes », nous décrivons le projet SMART-EEG qui vise à résoudre quelques-uns des freins technologiques et à proposer une plateforme intégrée qui devrait permettre d’apporter des solutions techniques et pratiques innovantes aux soucis majeurs de la réalisation et de l’interprétation des examens d’EEG par télémédecine en France.
The electroencephalogram (EEG) is a test that allows recording of brain activity and is essential for diagnosis and prognosis of coma, monitoring of epilepsy and maturation of the central nervous system. Currently, the national shortage of neurophysiologist physicians no longer allows access to care for all. Currently, remote transmissions of EEG have been implemented in France; 34% of them are not computerized. After analyzing the problems faced by these “platforms”, we describe the SMART-EEG project aimed to provide technical solutions and innovative practices to the major concerns of the implementation and interpretation of EEG examinations via telemedicine in France.
Fibrosis represents an open issue for medium to long-term active implants, such as pacemakers, given that this biological medium surrounds the stimulation electrodes and can impact or modify the ...performances of the system. For this reason, Embedded Impedance Spectroscopy (EIS) techniques have been investigated these last years to sense the fibrosis. The following article introduces a new technique for EIS derived from multi-carrier digital communication methods. Due to its properties of flat spectrum and fast generation the Orthogonal-Frequency Division Multiplexing (OFDM) technique for EIS represents an efficient and a low foot-print alternative compared to the classical sweep frequency technique. This article focuses on this approach and also proposes a solution that reduces the effect of high crest factor typically found in OFDM systems. An embedded implementation is also presented. This designed prototype is used here to characterize the impedance spectrum of a pacemaker's electrode achieving an accuracy of 99% when measuring with 64 OFDM subcarriers and with a sampling frequency of 12 kHz.
Pulse oximetry is one of the most commonly employed monitoring modalities in critical care setting. Conventional pulse oximeters use two leds at different wavelengths and a photodiode to estimate ...blood oxygen saturation noninvasively, based in the difference of absorption coefficients between hemoglobin and deoxyhemoglobin. Nevertheless, factors such as low oxygen saturations or led wavelength displacement, modify differently the expected light absorbance for both LEDs. To address this issue, we propose a novel approach combining a single led and a Buried Quad Junction photodetector, i.e. a multispectral sensor. With this fundamental modification of the pulse oximetry principle, we reduce the modifying effects introduced by the aforementioned sources of inaccuracy by using a single led. Results from in vivo measurements, show that the three tests of the proposed system's precision falls within the commercial tolerance of 4% SpO2%.
This paper focuses on the study of fibrosis induced by an implanted medical device and explores the possibility of characterizing this process by in situ measurement of electrical impedance. The ...approach combines concurrent electrical and biological characterizations of fibrotic tissue, applied to electrodes implanted in an animal model. The methodology used is described. Initial results evidence the strong correlation between fibrotic tissue and electrical parameters. Identification of such electrical parameters will enable the establishment of a reliable monitoring method.
Wireless Implantable systems are of primary interest for the in situ chronic monitoring or regulation of physiological parameters. Nevertheless, the implantation of such devices leads to immune ...system responses including an abnormal cell proliferation in its immediate surroundings. Both functioning and performances can be altered. So, it is necessary to monitor the evolution of the fibrotic tissues to prevent the dysfunctions. ECIS technique is appropriate for that. In this article, we propose, as a first step, an embedded system based on this technique for continuous bio-impedance measurements and designed for an arrangement in a culture chamber. It features a wide frequency range analysis with a view to determining an electrical marker of the cell type as a function of the frequency response. A validation of the system, for measurements on human fibroblasts, shows a very good match with the usual Cole-Cole model with an average error of only 1.5% on a 8-days experiment performed in real conditions.
The electroencephalogram (EEG) is a test that allows recording of brain activity and is essential for diagnosis and prognosis of coma, monitoring of epilepsy and maturation of the central nervous ...system. Currently, the national shortage of neurophysiologist physicians no longer allows access to care for all. Currently, remote transmissions of EEG have been implemented in France; 34% of them are not computerized. After analyzing the problems faced by these “platforms”, we describe the SMART-EEG project aimed to provide technical solutions and innovative practices to the major concerns of the implementation and interpretation of EEG examinations via telemedicine in France.
This paper proposes an in-depth analysis of the tri-state inverter based digitally controlled oscillator. This oscillator topology has been reported in numerous publication, however its features ...remain poorly understood. In this study, we propose to focus on these lacks. We specifically addressed the oscillation period and the associated jitter as these quantities are the design key parameters. In this paper, we propose analytical expressions taking into consideration the design, the technology as well as the input code. These equations are suitable for hand calculations and have helped to establish a design methodology for rapid implementation. Two circuits have been designed in STMicroelectronics CMOS 65 nm process. The first one was evaluated through simulations. Then, the measurement results obtained with the second circuit manufactured within the same technology node are presented. Finally, the experimental data support the proposed theory.
Pulse oximetry is one of the most commonly employed monitoring modalities in critical care setting. Conventional pulse oximeters, use two leds and a photodiode to estimate the percentage of ...oxyhemoglobin and deoxyhemoglobin, assuming that those are the only light absorbers in the blood. Nevertheless, the presence of other types of dyshemoglobin may invalidate their calibration. In this study, we employed a Buried Quad Junction photodetector in order to estimate the oxygen saturation using simultaneously lit leds. More precisely, a proof-of-principle was shown for developing an oximeter capable of estimating up to four types of hemoglobin simultaneously with a single led. Results from in vivo measurements obtained with this setup show that we successfully isolated the information of our interest for oxygen saturation estimation. These results were compared with a commercial device yielding acceptable estimations with a mean error of 1.3% of the oxygen saturation estimation.
The following article introduces a wireless and portable system for Electrochemical Impedance Spectroscopy (EIS) sensing based on the Orthogonal Frequency-Division Modulation (OFDM). This technique ...is derived from multi-carrier digital communication methods and due to its properties of flat spectrum, fast generation and low-foot print memory, the OFDM technique for EIS seems to be a real alternative to traditional ones. The manufacture of the OFDM-EIS system is under the framework of the electrical sensing of fibrosis induced by medium to long-term active implants, given that the detection of fibrous tissues surrounding the electrode, that usually affect the operation of the implant, is an open research problem. Because of this, this article defines its performance on living cells under in-vitro experimentation where the proliferation of cells are matched with the results. Furthermore, traditional EIS techniques, such as frequency sweep and multi-sine are compared to OFDM-EIS.
This paper presents a versatile SAR ADC targeting the acquisition of signals in biomedical applications. The converter is implemented in a CMOS AMS 0.35µm technology and powered with 3.3V. Its output ...bit-width can be varied from 4 to 8 bits. The device includes built-in programmable clock generator and voltage reference circuit. The sampling rate can be tuned up to 100kS/s in the 8-bit mode and with a maximal input range of 2.5V. All these parameters can be independently adjusted. This is an unique fully-configurable converter. The simulation results are reported and positioned with respect to the most recent designs.
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