Organe artificiel

Résumé

vignette|Le cœur artificiel JARVIK 7. Un organe artificiel est un organe ou un tissu fabriqué par l'homme qui est implanté ou intégré dans un être humain - en interface avec un tissu vivant - pour remplacer un organe naturel. La fonction remplacée n'est pas forcément vitale, mais c'est souvent le cas. Par exemple, les os et les articulations de remplacement, tels que ceux trouvés dans les prothèses totales de hanche, peuvent également être considérés comme des organes artificiels. Par définition, il est implicite que l'appareil ne doit pas être attaché en permanence à une alimentation électrique fixe ou à d'autres ressources fixes telles que des filtres ou des unités de traitement chimique. Ainsi, un appareil de dialyse, tout en étant un appareil nécessaire à la survie en remplaçant presque complètement les fonctions d'un rein, n'est pas un organe artificiel. Objectif La construction et l'installation d'organes artificiels, un processus extrêmement coûteux au départ en rec

Source officielle

https://fr.wikipedia.org/wiki/Organe_artificiel

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Biomedical technologies in neuroprosthetics are made to restore or replace functions from the nervous system, as well as alleviate pathological conditions. Peripheral nerve interfaces use neuromodulatory techniques to inhibit pain or depression, prevent epileptic strokes, or connect amputee patients to an artificial limb. Man-made neural interfaces are, however, far from matching the complexity of the nerves, leaving patients with low-resolution interfaces. To engineer peripheral neuroprostheses, scientists and clinicians investigate neuromodulatory strategies using in vitro neuron culture, explanted nerves, in vivo and in silico experiments using simulation, patch-clamp or extracellular recordings, and neural classification/learning algorithms. However, the available models can not replicate the complex morphology of the nerves, thereby limiting the resolution and selective recording of axonal activity. While nerve fibers respond differently to a neuromodulation paradigm depending on their size and degree of myelination, studies often fail to deal with the whole variety of axon characteristics present in the body. Therefore, in this thesis, I developed a nerve-on-a-chip platform that uniquely integrates the following features: stimulation and recording of single myelinated nerve fibers, controlled single-fiber action potential propagation with respect to electrodes position, and signal amp- lification leading to recorded signals in the 20 - 300 ÎŒV range. Nerve fibers diameter can further be deduced from propagation velocity to include the effect of nerve heterogeneity and function in the implementation of neuromodulatory strategies. I first present a versatile nerve-on-a-chip platform, aiming at offering robust standards to eval- uate neuromodulation strategies and selectivity of neuroprostheses. In order to conduct rapid, high resolution and systematic recording of peripheral nerve activity, microchannel electrodes are used to achieve stimulation and recording of single myelinated nerve fibers ex vivo. I demonstrate the platform versatility through three case studies: (i) Optimising the design of microchannel regenerative implants to detect the velocity and direction of neural signal propagation. I implemented and experimentally validated a mathematical model predicting how the reliability of velocity calculation depends on the implant geometry and neural signal waveform. (ii) Demonstrating how heat-induced neuroinhibition upon P3HT:PCBM (blend polymer) illumination selectively and reversibly silenced thinner fibers, but did not affect larger fibers. (iii) To improve artificial sensory feedback, new patterns of electrical stimulation were investigated in silico. In this study, the platform is used to show that high frequency modulated stimulation elicits more biomimetic nerve activity. This novel nerve-on-a-chip platform enables rapid prototyping using standard microfabrication methods, simultaneous probing of myelinated fibers of various diameters, data library collection for computational modelling and multi-factorial analysis. Subsequently, I have applied the results from (i) to develop a microfabrication process of a microchannel regenerative implant, further exploiting the use of microchannel electrodes to improve neural interfaces. The nerve-on-a-chip platform is an efficient tool for designing and evaluating new implantable neuroprosthetic devices, using time and cost-efficient techniques. We foresee that this simple and broad

EPFL2019

Chargement

Stretchable metallization technologies for skin-like transducers

Hadrien Olivier Michaud

The skin is not only the largest human organ, capable of accomplishing distributed and multimodal sensing functions. Replicating the versatility of skin artificially is a significant challenge, not only in terms of signal processing but also in mechanics. Stretchable electronics are an approach designed to cover human and artificial limbs and provide wearable sensing capabilities: motion sensors distributed on the hand of neurologically impaired patients could help therapists quantify their abilities; prostheses equipped with multiple tactile sensors could enable amputees to naturally adjust their grasp force. Skin-like electronic systems have specific requirements: they must mechanically adapt to the deformations imposed by the body they equip with minimal impediment to its natural movements, while also providing sufficient electrical performance for sensor transduction and passing electrical signals and power. A metallization ensuring stable conductivity under large strains is a prerequisite to designing and assembling wearable circuits that are integrated with several types of sensors. In this work, two innovative metallization processes have been developed to enable scalable integration of multiple sensing modalities in stretchable circuits. First, stretchable micro-cracked gold (Au) thin films were interfaced with gallium indium eutectic (EGaIn) liquid metal wires. The Au films, thermally evaporated on silicone elastomer substrates, combined high sheet resistance (9 to 30 Ohm/sq) and high sensitivity to strain up to 50%. The EGaIn wires drawn using a micro-plotting setup had a low gauge factor (2) and a low sheet resistance (5 mOhm/sq). Second, a novel physical vapor deposition method to deposit of thin gallium-based biphasic (solid-liquid) films over large areas was achieved. The obtained conductors combined a low sheet resistance (0.5 Ohm/sq), a low gauge factor (~1 up to 80% strain), and a failure strain of more than 400%. They could be patterned down to 10 µm critical dimensions. Skin-like sensors for the hand were assembled using the two processes and their capabilities were demonstrated. Thin (0.5 mm) silicone strips integrating EGaIN wires and micro-cracked Au strain gauges were mounted on gloves to encode the position of a biomimetic robotic finger and a human finger. In combination with soft pressure sensors, they enabled precise grasp analysis over a limited range of motion. Then, biphasic films were micro-patterned on silicone to assemble 50 µm thin epidermal strain gauges. The strain gauges were attached on a user's finger and accurately encoded fine grasping tasks covering most of the human hand range of motion. The biphasic films were also used to power wireless MEMS pressure sensors integrated in a rubber scaffold. The device was mounted on a prosthetic hand to encode normal forces in the 0 N to 20 N range with excellent linearity. The epidermal strain sensors are currently being used to quantify the tremors of patients with Parkinson's disease. In the future, the unique properties of the biphasic films could enable advanced artificial skins integrating a high density of soft transducers and traditional high-performance circuits.

EPFL2017

Chargement

Do we want to share our lives and bodies with robots? A 2000 people survey

Kai Oliver Arras

For roughly two decades a new generation of robots, robotic prostheses and implantable devices is about to arise accompanied by great optimism that they will widely pervade our daily life in a near future. This paper presents the results from a survey on the question if people want to share their life and body with robots. The survey, carried out in connection with the Robotics exhibition at the Swiss National Exhibition Expo.02, counts over 2000 participants. The questionnaire covers issues on robotics in general, service and personal robots, robotic prostheses and artificial organs. While the results testify a positive attitude towards potential robotic co-workers, flat-mates or body part, they include a number of surprising answers. We find correlations in the data, discuss interpretations, speculate about the answers and cultural influences and finally conclude: Whom are we building robots for and what should they be like? To whom are we selling robots and how should we market them?

2005

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EPFL2019

Stretchable metallization technologies for skin-like transducers

Hadrien Olivier Michaud

EPFL2017