Implantable CMOS Biomedical Devices

The results of recent research on our implantable CMOS biomedical devices are reviewed. Topics include retinal prosthesis devices and deep-brain implantation devices for small animals. Fundamental device structures and characteristics as well as in vivo experiments are presented

고밀도 망막 자극을 위한 CMOS IC 와 3차원 전극의 통합 기술

본 논문에서는 고밀도 자극기를 구현하는 방법으로 3차원 전극을 CMOC (Complementary Metal–Oxide–Semiconductor) IC (Integrated Circuit) 에 집적하여 자극기를 제작하는 공정 방법을 제안한다. 고밀도 망막 자극기를 구현하기 위하여 기판에서 차지하는 면적 대비 조직과 접하는 표면적을 크게 할 수 있는 3차원 화살촉 전극이 적용되었고, CMOS IC 의 자극 패드에 Au/Sn 플립 칩 본딩으로 접합되었다. 3차원 화살촉 전극의 적용은 조직 전극간 계면 임피던스를 최소화하여 망막 신경 세포를 활성화시킬 수 있는 자극조건의 저전압화를 구현하는데 목적이 있다. 망막 하 이식이 가능하도록 CMP (Chemical Mechanical Planarization) 공정과 DRIE (Deep Reactive-Ion Etching) 공정을 통해 CMOS IC 두께를 약 50㎛ 로 박막화하였다. 제작된 전체 소자 두께는 폴리이미드, 페럴린 두께를 포함하여 약 80㎛ 이다. 추가적으로, 망막 이식 환경에서 장기간 안정적으로 동작할 수 있는 신뢰성 있는 자극기를 구현하고자 하였다. 장기간 전해질 환경에 노출시에 수분 흡수에 의한 전기적 누설 전류 발생을 예방하기 위하여 보호막 공정을 진행하였다. 폴리이미드로 주요한 자극기 공정을 진행한 이후 마지막 단계의 공정에서 수분 흡수가 적고 이식 환경에서 많이 사용되는 페럴린 C 가 소자 보호막으로 적용되었다. 추가적으로, 보호막 공정으로 3차원 화살촉 전극 전면에 페럴린이 증착된 상태에서 자극을 주는 화살촉 전극 부분만 보호막으로부터 개방시키는 공정을 진행하였다. 본 자극기에 적용된 Au/Sn 본딩의 기계적 특성 확인을 위해 접합 강도 평가가 이루어졌다. 그리고 Au/Sn 본딩 구조물이 자극기의 동작에 미치는 전기적 신호 전달 특성을 확인하기 위하여 전압 강하 및 고주파 신호 통과 특성이 평가되었다. 또한, 장기간 이식에 대한 수분 흡수 특성을 평가하고자 전해질 환경에서의 가속 환경에 노출한 후 누설 전류를 측정하여 안정적인 특성임을 확인했다. 위 평가를 통해 CMOS IC 와 3차원 전극 결합형 고밀도 망막 자극기가 물리적, 화학적, 전기적으로 안정된 특성을 가지고 있음을 확인하였다.In this study, a process of implementing a high-density retinal stimulator with integration of a three-dimensional electrode and complementary metal–oxide–semiconductor (CMOS) integrated circuit (IC) is proposed. For implementing the high-density retinal stimulator, three-dimensional arrowheaded electrode is applied to maximize surface area in contact with retinal tissue in a relatively small area of the substrate. Moreover, it is bonded to a stimulating electrode of CMOS IC using Au/Sn flip-chip bonding. Three-dimensional arrowheaded electrode is applied to implement low voltage stimulation through reduction of interface impedance between three-dimensional electrodes and retinal tissue. CMOS IC was thinned smaller than 50㎛ with Chemical Mechanical Planarization (CMP) and deep reactive-ion etching (DRIE) process for subretinal implant. The total thickness of the stimulator is approximately 80㎛ including polyimide and parylene thickness. In addition, a reliable stimulator is implemented for long-term stable operation in environment of retinal implant. As a passivation of stimulator, parylene C is deposited with entrie stimulator to prevent current leakage caused by moisture absorption. After the main process is performed with polyimide, parylene is applied for supplement of wafer absorption in the last process. In addition, the selective etching process was conducted to open the stimulating electrode from the entirely deposited parylene to an implantable stimulator. To confirm reliability of the operation of the stimulator, the evaluation of bonding strength is performed. And, measurement of voltage drop and high-frequency signal transmission is conducted for evaluating the electrical properties in stimulator operation. In addition, to evaluate a characteristic of the long-term water absorption, the acceleration experiments were conducted in electrolyte environment. Through these evaluations, the stimulator for high-density retinal stimulation with CMOS IC and three-dimensional arrowheaded electrode is confirmed that the stimulator has a physical, chemical and electrical stability for retinal stimulation.Chapter 1 １ 1.1 연구 배경 ２ 1.1.1 시각 인식 ２ 1.1.2 망막 질환 ４ 1.2 망막 보철 ６ 1.2.1 인공 망막 이식의 종류들 ６ 1.2.2 인공 망막 자극기의 요구 조건 ７ 1.3 고해상도 망막 자극기 １０ 1.3.1 고해상도 망막 자극기의 기술적 문제 １０ 1.3.2 고해상도 망막 자극기의 이전 연구 결과들 １６ 1.3.3 생체 소자 보호용 고분자 물질들 ２１ 1.3.4 자극 전극과 망막 조직간의 임피던스 모델 ２３ 1.3.5 서술 개요 ２８ Chapter 2 ３０ 2.1 시스템 구성 ３０ 2.1.1 연구 동기 ３０ 2.1.2 CMOS IC 와 고밀도 3차원 전극의 통합 구현 방안 ３２ 2.2 고밀도 망막 자극을 위한 CMOS IC 와 3차원 전극의 통합 기술 ３７ 2.2.1 3차원 화살촉 전극 설계 ３７ 2.2.2 CMOS IC 와 3차원 전극의 통합 설계 ３９ Chapter 3 ４０ 3.1 제작 공정 ４０ 3.1.1 고해상도 망막 자극용 3차원 전극 제작 ４０ 3.1.2 고해상도 망막 자극용 기판 공정 ４８ 3.1.3 플립 칩 본딩을 위한 CMOS IC 금속 증착 공정 ５３ 3.1.4 CMOS IC 와 3차원 화살촉 전극의 접합 공정 ５６ 3.1.5 자극기 보호막 공정 및 몸체 정의 ６６ 3.1.6 3차원 화살촉 전극 보호막 노출 공정 ６８ Chapter 4 ７１ 4.1 Au/Sn 플립 칩 본딩 기계적 강도 평가 ７１ 4.2 Au/Sn 본딩 소자의 전기적 신호 특성 평가 ７３ 4.3 자극기의 전기적 절연 특성 평가 ７８ Chapter 5 ８０ 5.1 향후 진행 사항 ８３ Bibliography ８８ Abstract ９９Docto

Therapeutic Challenges to Retinitis Pigmentosa: From Neuroprotection to Gene Therapy

Syndromic retinitis pigmentosa (RP) is the result of several mutations expressed in rod photoreceptors, over 40 of which have so far been identified. Enormous efforts are being made to relate the advances in unraveling the patho-physiological mechanisms to therapeutic approaches in animal models, and eventually in clinical trials on humans. This review summarizes briefly the current clinical management of RP and focuses on the new exciting treatment possibilities. To date, there is no approved therapy able to stop the evolution of RP or restore vision. The current management includes an attempt at slowing down the degenerative process by vitamin supplementation, trying to treat ocular complications and to provide psychological support to blind patients. Novel therapeutic may be tailored dependant on the stage of the disease and can be divided in three groups. In the early stages, when there are surviving photoreceptors, the first approach would be to try to halt the degeneration by correction of the underlying biochemical abnormality in the visual cycle using gene therapy or pharmacological treatment. A second approach aims to cope with photoreceptor cell death using neurotrophic growth factors or anti-apoptotic factors, reducing the production of retino-toxic molecules, and limiting oxidative damage. In advanced stages, when there are few or no functional photoreceptors, strategies that may benefit include retinal transplantation, electronic retinal implants or a newly described optogenetic technique using a light-activated channel to genetically resensitize remnant cone-photoreceptor cells

An investigation of extraocular and intraocular wireless communication techniques on a retinal prosthesis system

Retinitis Pigmentosa (RP) and Age-related Macular Degeneration (AMD) are two genetic ocular diseases that cause gradual visual impairments which will eventually lead to blindness as a result of damage in the retina. In the cases of people suffering from RP and AMD, it has been found out that 95% of the photoreceptors are damaged, while interestingly majority of the bipolar and ganglion cells that are responsible for the nerve stimulation remain intact. This is where a retinal prosthesis system comes into the picture. Retinal prosthesis is a prosthetic device that is aimed to assume the functionality of the damaged photoreceptors and produce stimulations to the bipolar and ganglion cells for a visual perception. Typically, a retinal prosthesis system comprises of two major components: an image capturing unit and an array of microelectrode. While a lot of studies have been conducted on each major component, the development of the wireless link between the two components has been mostly overlooked. It is clear that the two components are not physically connected and a data exchange is required between the two. This thesis aims to bridge the knowledge gap in this area by addressing the following research questions: “What is the most suitable frequency band for a wireless link in a retinal prosthesis system?” and “What kind of antenna would generate the most optimal performance under the constraints introduced by a retinal prosthesis system?

Towards Retinal Repair: Bioelectric Assessment of Retinal Pigment Epithelium in vitro and Electrode Materials for Retinal Implants

The aim of this thesis was to develop methods for future solutions to prevent eye diseases caused by the dysfunctions of retinal pigment epithelial (RPE) cells and to restore the vision of blind patients. On a cellular level, the degeneration of RPE cells is often the prime cause of eye diseases such as age-related macular degeneration and some forms of retinitis pigmentosa. RPE cell replacement therapy may provide new solutions for the prevention of eye diseases that lead to blindness. RPE cells differentiated from pluripotent stem cells provide a promising source for cell replacement therapy. However, the functionality of the differentiated cells is still not fully proven. One objective of this thesis was to provide solutions for testing the functionality of differentiated RPE cells. If blindness cannot be cured, artificial vision provided by retinal implant may be considered. The second objective of this thesis was to characterize the electrochemical properties of the different electrode materials used in retinal implants. The electrode materials used in retinal implants should be carefully considered in order to increase the resolution of the implant and to provide stable, safe, and biocompatible charge injection. All the methods used and developed in this thesis were based on bioelectrical phenomena. The electrochemical characterization of five different electrode materials used in retinal implants used electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. We considered the effect of electrode size and material on charge capacity and impedance. Atomic force microscopy (AFM) was used to study the surface properties of the studied electrodes. The testing of the materials was done using exactly the same measurement conditions and electrode producing methods to provide easily comparable data. In this thesis, the functionality of RPE cells differentiated from human embryonic stem cells (hESC-RPE) was studied with two different methods. EIS was used to compare the electrical properties between two different RPE cell lines (immortalized human RPE cell line (ARPE-19) and hESC-RPE). To our knowledge, EIS measurements of RPE cells have not been published before. EIS was also used to find out how the barrier properties of hESC-RPE cells differ when the cells are in different stages of maturity. In addition, we developed a method that could be used to study the functionality of hESC-RPE cells with in vitro electroretinography (ERG) measurements: Our hypothesis is that RPE cells enhance the ERG response of the mouse retina and enable longer culturing of the functional retina in vitro. Comparing the ERG responses of a mouse retina alone and of a mouse retina cultured together with hESC-RPE cells could reveal the functionality of hESC-RPE cells. The EIS measurements were in accordance with biological analyses. The hESC-RPE cells resembled morphologically mature RPE, and thus created high transepithelial resistance (TER) indicating high integrity and tight junction formation. The EIS measurements revealed that during the maturation the TER of the cell culture increases, peak phase diagram shifts to lower frequencies, and the capacitance of the epithelium increases. Permeability measurements verified that EIS measurements reveal the tight junction failures and integrity decrease caused by calcium chelation. With the developed setup we were able to measure ERG responses from both the co-culture of retina and RPE and the retina cultured alone. However, due to limited sample size and possibly due to short co-culture time in our culture setup as yet we were not able to prove the hypothesis by showing that RPE cells would enhance the ERG response of the retina in vitro. Both the retina cultured alone and the co-culture responded to light stimulus after one day of culturing. CV and EIS measurements of different electrodes showed that iridium-black (Ir-b) and platinum-black (Pt-b) electrodes were superior, i.e. they had higher charge injection capacity and lower impedance when compared to other tested materials (gold (Au), titaniumnitrate (TiN), titanium (Ti)). Based on our findings we can conclude that novel biocompatible electrode materials that have the potential to be used in implantation are available. In the same way as in this thesis, the electrochemical testing of electrode materials should be done using similar testing methods for every material to enable easy comparison of the results between different materials. At the moment, cell replacement therapy and the use of RPE cells is seriously considered as a choice for eye disease treatment. Our results suggest that EIS is useful when evaluating the overall maturity, integrity, and functionality of the RPE cell culture. In forthcoming cell transplantation therapies, EIS could provide a means to test the validity of stem cell-derived RPE non-invasively and aseptically before implantation. Our initial tests show that studies to test the ability of RPE cells to rescue the photoreceptors in a mouse model by testing ERG responses in vitro should be continued. Even though our results did not produce conclusive evidence, the co-culture of the retina and hESC-RPE cells may be a useful in vitro model for investigating the RPE cell replacement therapy and possible drug releasing materials for the retina

Réalisation d'une procédure de micro-assemblage d'un implant rétinien sans fil

La rétinite pigmentaire et la dégénérescence maculaire liée à l’âge sont des pathologies de l’oeil atteignant les cellules photoréceptrices de la rétine. À l’heure actuelle, il n’existe aucun traitement efficace pour éradiquer ces deux maladies. L’utilisation d’implants rétiniens, des dispositifs électroniques stimulant les cellules nerveuses, compte parmi les options pour pallier ce problème. L’implant rétinien présenté dans ce mémoire est encapsulé dans un boîtier en diamant contenant des électrodes de stimulations placées sur les cellules ganglionnaires de la rétine du patient. Un circuit intégré à application spécifique génère des patrons de courants afin de stimuler les cellules ganglionnaires par l’intermédiaire d’électrodes. Ce dispositif recevra son alimentation et ses données par un laser modulé en amplitude traversant la pupille du patient pour aller directement sur une cellule photovoltaïque et une photodiode située dans le boîtier en diamant. Un processeur vidéo capte et traite l’information provenant d’une caméra localisée sur une paire de lunettes portée par le patient en vue de générer les patrons de stimulation. Le but de ce projet de maîtrise est de développer une procédure de microassemblage réalisant cet implant rétinien sans fil avec les équipements de l’Institut Interdisciplinaire d’Innovation Technologique (3IT) et du Centre de Collaboration MiQro Innovation (C2MI). Étant limité par des contraintes mécaniques dues à la petite taille des échantillons, il ne sera pas possible d’utiliser les procédures standards d’assemblage de montage en surface de circuits imprimés. Il faudra donc développer une procédure unique d’assemblage pour la réalisation de ce projet de recherche incluant, notamment un substrat en diamant

Microsystème implantable dédié à la stimulation du cortex visuel

Notions fondamentales au sujet des stimulateurs implantables -- La stimulation électrique fonctionnelle -- Généralités au sujet des stimulateurs implantables -- Restitution de la vision par la stimulation électrique fonctionnelle -- Le système visuel biologique -- Principes et historique des implants visuels -- Considérations spécifiques aux implants intra-corticaux -- Travaux de pointe dans le domaine -- Dispositifs implantables -- Liens inductifs -- Composants externes -- Travaux du laboratoire de neurotechnologies polystim -- Conception et validation du dispositif implantable -- Architecture globale de l'implant -- Module de stimulation -- Module d'interface -- Implémentation et résultats expérimentaux -- Faisabilité d'une prothèse complète sur la base de l'implant proposé -- Conception et validatin du contrôleur externe -- Optimisation au niveau de la puissance dissipée -- Description du système externe -- Implémentation et validation -- Système d'expérimentation in-vivo -- Parotocoles d'expérimentation comportementale -- Description du système expérimental -- Fabrication du système expérimental

Neurostimulateur hautement intégré et nouvelle stratégie de stimulation pour améliorer la miction chez les paraplégiques

RÉSUMÉ Une lésion de la moelle épinière est un problème dévastateur médicalement et socialement. Pour la population des États-Unis seulement, il y a près de 10 000 nouveaux cas chaque année. A cause des nombreux types de lésions possibles, divers degrés de dysfonctionnement du bas appareil urinaire peuvent en découler. Une lésion est dite complète lors d’une perte totale des fonctions sensorielles et motrices volontaires en dessous du niveau de la lésion. Une lésion incomplète implique que certaines activités sensorielles et/ou motrices soient encore présentes. Si la lésion se produit au dessus du cône médullaire, la vessie développera une hyperréflexie qui se manifeste par des contractions réflexes non-inhibées. Ces contractions peuvent être accompagnées d’une augmentation de l’activité du sphincter externe. Par conséquent, cela mène à un état d’obstruction fonctionnelle de la vessie, qui induit une forte pression intravésicale à chacune des contractions réflexes et qui peut potentiellement endommager le haut appareil urinaire. Dans ce contexte, la neurostimulation est l'une des techniques les plus prometteuses pour la réhabilitation de la vessie chez les patients ayant subi une lésion de la moelle épinière. Le seul neurostimulateur implantable commercialisé, ciblant l'amélioration de la miction et ayant obtenu des résultats satisfaisants, nécessite une rhizotomie (section de certains nerfs) afin de réduire la dyssynergie entre la vessie et le sphincter. Cependant, la rhizotomie est irréversible et peut abolir les réflexes sexuels, de défécation ainsi que les sensations sacrales si encore présents dans le cas de lésions incomplètes. Afin d'éviter la rhizotomie, nous proposons une nouvelle stratégie de stimulation multi-site appliquée aux racines sacrées, et basée sur le blocage de la conduction des nerfs à l'aide d'une stimulation à haute fréquence comme alternative à la rhizotomie. Cette approche permettrait une meilleure miction en augmentant sélectivement la contraction de la vessie et en diminuant la dyssynergie. Huit expériences en phase aigüe ont étés menées sur des chiens pour vérifier la réponse de la vessie et du sphincter urétral externe à la stratégie de stimulation proposée. Le blocage à haute-fréquence (1 kHz) combiné à la stimulation basse-fréquence (30 Hz), a augmenté la différence de pression intra-vésicale/intra-urétrale moyenne jusqu'à 53 cmH2O et a réduit la pression intra-urétrale moyenne jusqu'à hauteur de 86 % relativement au niveau de référence. Dans l’objectif de tester la stratégie de neurostimulation proposée avec des expériences animales en phase chronique, un dispositif de neurostimulation implantable est requis. Un prototype discret implémentant cette stratégie de stimulation a été réalisé en utilisant uniquement des composants discrets disponibles commercialement. Ce prototype est capable de générer des impulsions à une fréquence aussi basse que 18 Hz tout en générant simultanément une forme d’onde alternative à une fréquence aussi haute que 8.6 kHz, et ce sur de multiples canaux. Lorsque tous les étages de stimulation et leurs différentes sorties sont activés avec des fréquences d’impulsions (2 mA, 217 μs) et de sinusoïdes de 30 Hz et 1 kHz respectivement, la consommation de puissance totale est autour de 4.5 mA (rms). Avec 50 mW de puissance inductive disponible par exemple et 4.5 mA de consommation de courant, le régulateur haute-tension peut être réglé à 10 V permettant ainsi une stimulation de 2 mA avec une impédance nerf-électrode de 4.4 kΩ. Le nombre effectif de sorties activées et le maximum réalisable des paramètres de stimulation sont limités par l’énergie disponible fournie par le lien inductif et l’impédance des interfaces nerf-électrode. Cependant, une plus grande intégration du neurostimulateur devient de plus en plus nécessaire à des fins de miniaturisation, de réduction de consommation de puissance, et d’augmentation du nombre de canaux de stimulation. Comme première étape vers une intégration totale, nous présentons la conception d’un neurostimulateur hautement intégré et qui peut être assemblé sur un circuit imprimé de 21 mm de diamètre. Le prototype est basé sur trois circuits intégrés, dédiés et fabriqués en technologie CMOS haute-tension, ainsi qu’un FPGA miniature à faible puissance et disponible commercialement. En utilisant une approche basée sur un abaisseur de tension, où la tension induite est laissée libre jusqu’à 20 V, l’étage d’entrée de récupération de puissance inductive et de données est totalement intégré.----------ABSTRACT Spinal cord injury (SCI) is a devastating condition medically and socially. For the population of USA only, the incidence is around 10 000 new cases per year. SCI leads to different degrees of dysfunction of the lower urinary tract due to a large variety of possible lesions. With a complete lesion, there is a complete loss of sensory and motor control below the level of lesion. An incomplete lesion implies that some sensory and/or motor activity is still present. Most patients with suprasacral SCI suffer from detrusor over-activity (DO) and detrusor sphincter dyssynergia (DSD). DSD leads to high intravesical pressure, high residual urine, urinary tract infection, and deterioration of the upper urinary tract. In this context, neurostimulation is one of the most promising techniques for bladder rehabilitation in SCI patients. The only commercialized implantable neurostimulator aiming for improved micturition and having obtained satisfactory results requires rhizotomy to reduce DSD. However, rhizotomy is irreversible and may abolish sexual and defecation reflexes as well as sacral sensations, if still present in case of incomplete SCI. In order to avoid rhizotomy, we propose a new multisite stimulation strategy applied to sacral roots, and based on nerve conduction blockade using high-frequency stimulation as an alternative to rhizotomy. This approach would allow a better micturition by increasing bladder contraction selectively and decreasing dyssynergia. Eight acute dog experiments were carried out to verify the bladder and the external urethral sphincter responses to the proposed stimulation strategy. High-frequency blockade (1 kHz) combined with low-frequency stimulation (30 Hz) increased the average intravesical-intraurethral pressure difference up to 53 cmH2O and reduced the average intraurethral pressure with respect to baseline by up to 86 %. To test the proposed neurostimulation strategy during chronic animal experiments, an implantable neurostimulateur is required. A discrete prototype implementing the proposed stimulation strategy has been designed using commercially available discrete components. This prototype is capable of generating a low frequency pulse waveform as low as 18 Hz with a simultaneous high frequency alternating waveform as high as 8.6 kHz, and that over different and multiple channels

Ultra-thin and flexible CMOS technology: ISFET-based microsystem for biomedical applications

A new paradigm of silicon technology is the ultra-thin chip (UTC) technology and the emerging applications. Very thin integrated circuits (ICs) with through-silicon vias (TSVs) will allow the stacking and interconnection of multiple dies in a compact format allowing a migration towards three-dimensional ICs (3D-ICs). Also, extremely thin and therefore mechanically bendable silicon chips in conjunction with the emerging thin-film and organic semiconductor technologies will enhance the performance and functionality of large-area flexible electronic systems. However, UTC technology requires special attention related to the circuit design, fabrication, dicing and handling of ultra-thin chips as they have different physical properties compared to their bulky counterparts. Also, transistors and other active devices on UTCs experiencing variable bending stresses will suffer from the piezoresistive effect of silicon substrate which results in a shift of their operating point and therefore, an additional aspect should be considered during circuit design. This thesis tries to address some of these challenges related to UTC technology by focusing initially on modelling of transistors on mechanically bendable Si-UTCs. The developed behavioural models are a combination of mathematical equations and extracted parameters from BSIM4 and BSIM6 modified by a set of equations describing the bending-induced stresses on silicon. The transistor models are written in Verilog-A and compiled in Cadence Virtuoso environment where they were simulated at different bending conditions. To complement this, the verification of these models through experimental results is also presented. Two chips were designed using a 180 nm CMOS technology. The first chip includes nMOS and pMOS transistors with fixed channel width and two different channel lengths and two different channel orientations (0° and 90°) with respect to the wafer crystal orientation. The second chip includes inverter logic gates with different transistor sizes and orientations, as in the previous chip. Both chips were thinned down to ∼20m using dicing-before-grinding (DBG) prior to electrical characterisation at different bending conditions. Furthermore, this thesis presents the first reported fully integrated CMOS-based ISFET microsystem on UTC technology. The design of the integrated CMOS-based ISFET chip with 512 integrated on-chip ISFET sensors along with their read-out and digitisation scheme is presented. The integrated circuits (ICs) are thinned down to ∼30m and the bulky, as well as thinned ICs, are electrically and electrochemically characterised. Also, the thesis presents the first reported mechanically bendable CMOS-based ISFET device demonstrating that mechanical deformation of the die can result in drift compensation through the exploitation of the piezoresistive nature of silicon. Finally, this thesis presents the studies towards the development of on-chip reference electrodes and biodegradable and ultra-thin biosensors for the detection of neurotransmitters such as dopamine and serotonin

Erstmaliger Gesamtentwurf und Realisierung der Systemintegration für das Künstliche Akkommodationssystem

Das Künstliche Akkommodationssystem ist ein Linsenimplantat zur Wiederherstellung der Akkommodationsfähigkeit, aufgebaut aus aktiv-optischem Element, Sensorik, Kommunikation und Energieversorgung. Zu den Aufgaben der Systemintegration gehören die Auswahl eines Schaltungsträgers sowie die Entwicklung einer langzeitstabilen Kapselung. Die wesentlichen Herausforderungen hierbei sind der anatomisch begrenzte Bauraum sowie die Aufrechterhaltung der Dichtigkeit