Fig 18 - uploaded by A.M. Sodagar
Content may be subject to copyright.
Similar publications
Citations
... Mit zunehmender Integration von elektronischen Schaltungen und steigender Komplexität der Funktionalität sowie der Anwendung stieg auch der Wunsch einer externen Schnittstelle zur Kontrolle und Steuerung des Implantats. Um Infektionsrisiken zu vermeiden, kommt hierfür nur eine drahtlose Schnittstelle in Frage [17], die im Folgenden auch als Telemetrie 1 bezeichnet wird. ...
Metallische Gehäuse stellen eine große Herausforderung für die Schnittstelle von aktiven medizinischen Implantaten dar. Ihre elektrische Leitfähigkeit und die sich dadurch ergebenden Wirbelströme verhindern das Eindringen von hochfrequenten elektromagnetischen Wellen und Feldern. Aus diesem Grund werden die Antennen außerhalb des Gehäuses platziert. Niederfrequentere magnetische Felder dringen jedoch durch das metallische Gehäuse, wenn auch abgeschwächt. Damit kann eine induktive Kommunikation realisiert und so elektrische Durchführungen durch das ansonsten hermetisch dichte Gehäuse vermieden werden.
In dieser Arbeit wird die induktive Datenübertragung durch ein metallisches Gehäuse untersucht. Ein Modell wird entwickelt, das die Effekte des metallischen Gehäuses auf die Übertragung berücksichtigt. Hierzu werden in einem neuen Ansatz anhand von FEM Simulationen Korrekturfaktoren ermittelt. Diese Korrekturfaktoren können visualisiert und direkt auf die Auslegung der Antennenspulen angewendet werden. Im Gegensatz zu anderen Modellierungen werden nur frei zugängliche Software-Lösungen verwendet. Zudem werden die Feldverteilungen durch die im metallischen Gehäuse entstehenden Wirbelströme untersucht. Die unterschiedlichen Gehäuse- und Spulenparameter werden im Hinblick auf deren Einfluss auf das Übertragungsverhalten diskutiert, was in dieser Form bisher noch nicht veröffentlicht wurde. Das resultierende Modell kann auf unterschiedliche Ausführungen der metallischen Kapselung angepasst werden um damit die Grenzen und Einschränkungen unterschiedlicher metallischer Gehäuse-Materialien zu untersuchen.
Mit der Weiterentwicklung eines Transceivers, der mit 10 kBit/s bei 125 kHz Trägerfrequenz arbeitet, wird ein Übertragungsbaustein entwickelt, der mit herkömmlichen Mikrocontrollern verwendet werden kann. Der Transceiver wird in einem ASIC mit 32 Pin QFN-Gehäuse implementiert. Anschließend werden die Funktionalität überprüft und die elektrischen Eigenschaften im Hinblick auf Temperatur-, Spannungs- und Frequenz-Verhalten charakterisiert. Durch die geringe Stromaufnahme und die hohe Datenrate bei niedriger Trägerfrequenz eignet sich dieser Transceiver für Langzeitanwendungen in medizinischen Implantaten. Das Neue an dem Transceiver ist seine Einsatzfähigkeit für metallische Gehäuse, die wegen der schmalen Bandbreite mit \approx\unit[4]{kHz} eine effiziente Datenübertragung trotz hoher Dämpfung ermöglicht und darüber hinaus die frequenzabhängige Verzerrung der Impedanz- und Übertragungsparameter minimiert.
Anhand einer konkreten Anwendung für eine implantierbare steuerbare Infusionspumpe werden die gesamte Elektronik des Implantats sowie eines kleinen und ein großen Bediengerätes konzipiert, entwickelt, programmiert und erfolgreich in Betrieb genommen. Darin werden sowohl das induktive Übertragungsmodell als auch der Transceiver verwendet und somit deren Funktionalität und Einsatzfähigkeit demonstriert. Mithilfe dieser Entwicklung ist es möglich, über einen Abstand von 65 mm, die Dosierung eines Medikaments einzustellen und an den Tagesrhythmus der Patient*innen anzupassen sowie die Funktionalität des Implantats zu überprüfen. Aktuell gibt es auf dem Markt ein weiteres ähnliches Produkt, zu dem jedoch keine wissenschaftlichen Veröffentlichungen vorliegen. Diese Arbeit liefert damit einen wissenschaftlichen Beitrag für die Entwicklung langlebiger metallisch gekapselter Implantate mit induktiver Schnittstelle.
... The necessary data is provided by this incoming wireless signal which is required for the generation of appropriate current pulses and power. Carrier frequencies used in the inductive links for the transfer of power should be kept below 15 MHz Ghovanloo 2007, 2009) [26,70]. Both sides of the link are required to be tuned to the same frequency for high efficiency (Sawan et al. 2005;Jow and Ghovanloo 2009) [26,71,72]. ...
... Carrier frequencies used in the inductive links for the transfer of power should be kept below 15 MHz Ghovanloo 2007, 2009) [26,70]. Both sides of the link are required to be tuned to the same frequency for high efficiency (Sawan et al. 2005;Jow and Ghovanloo 2009) [26,71,72]. There are many alternatives that provide power to the implant which include the use of implanted and external antenna or deriving power from the external environment. ...
... One of the sources in this area is the IEEE standard for safety levels (IEEE Std C95. [26]. For maximum transmission of power and information from the primary to secondary coil, the misalignments between these two coils must be within limits [10,11]. ...
... In Implantable Biomedical Microsystems (IBM), a wireless interface is used for transmission of power and data between the internal and external parts of the system (Figure 1). The most important issues in a wireless link for IBM are data transfer rate, power consumption, and chip area [1][2][3]. It is evident that in a forward data transfer, the maximum data rate is desired, especially in applications such as visual prostheses in which the implanted microsystem is in direct contact with the central neural system [4]. ...
... It is evident that in a forward data transfer, the maximum data rate is desired, especially in applications such as visual prostheses in which the implanted microsystem is in direct contact with the central neural system [4]. Furthermore, due to the power loss in the power-transmission circuitry and power dissipation in the tissue [5], the maximum frequency of the carrier signal for the IBMs is limited to a few tens of megahertz [1][2][3][4][5]. ...
... There have been proposed various modulation techniques for wireless data transfer [1,4,6]. Making comparisons between the various digital modulation schemes from different point of views, reveals that binary phase-shift keying (BPSK) structure is more appropriate in most IBMs [7][8][9][10][11][12][13]. Generally, this scheme provides proper insensitivity to amplitude noise, high data rate, and good power transfer efficiency. ...
A novel non-coherent, low-power, area-efficient binary phase-shift keying demodulator for wireless implantable biomedical microsystems is proposed. The received data and synchronized clock signal are detected using a delayed digitized format of the input signal. The proposed technique does not require any kind of oscillator circuit, and due to the synchronization of all circuit signals, the proposed demodulator can work in a wide range of biomedical data telemetry common frequencies in different process/temperature corners. The presented circuit has been designed and post-layout-simulated in a standard 0.18 μm CMOS technology and occupies 17 × 27 μm2 of active area. Post-layout simulation results indicate that with a 1.8 V power supply, power consumption of the designed circuit is 8.5 μW at a data rate of 20 Mbps. The presented demodulation scheme was also implemented on a proof-of-concept circuit board for verifying its functionality.
... [83,[103][104][105][106]). For the wireless transfer of data two different approaches can be taken: (1.) Data transfer via radio-frequency transmissions (e.g. [83,103,[107][108][109][110][111][112][113][114][115][116][117][118]). (2.) Data transfer via Infrared(IR)-transmissions: Since the skull and skin allows infra-red light to pass [119], it is possible to use IR technology to transmit data [120][121][122][123]. ...
Recent progress in neuro-prosthetic technology gives rise to the hope that in the future blind people might regain some degree of visual perception. It was shown that electrically stimulating the brain can be used to produce simple visual impressions of light blobs (phosphenes). This technology, using electrodes placed on top of the visual cortex, was successfully used to give blind people some degree of visual impression of their surrounding. However, this perception is very far away from natural sight. For developing the next generation of visual prostheses, real-time closed-loop stimulators are required. Such a stimulator measures the actual neuronal activities and on this basis determines the required stimulation pattern. In addition, there is a desire to shrink the diameter of the applied electrodes and increase their spatial density. This leads to the challenge of designing a system that can produce arbitrary stimulation-patterns with up to ±70 V and with up to 25 mA while measuring neuronal signals with amplitudes in the order of mV. Furthermore, interruptions of the measurements during stimulation should be as short as possible and the system needs to scale to hundreds of electrodes. We discuss how such a system and especially its current pumps and input protection need to be designed and which problems arise. We condense our findings into an example design for which we provide all design files (boards, firmwares and software) as open-source. This is a first step in taking the existing open-sourcewww.open-ephys.org recording system and converting it into a closed-loop experimental setup for neuro-prosthetic research. Keywords: Neuro-prosthetics, Visual cortex prosthesis, Closed-loop experiments, Electrical stimulation, Neuro-implant, ECoG, Open Hardware
... One of the inseparable parts of the design of implantable biomedical microsystems (IBMs) is wireless data/power telemetry [1]. From among the various techniques proposed for power telemetry and bidirectional data exchange with IBMs, inductive links [2], capacitive links [3], and recently ultrasonic links [4] have shown promising results, each for a number of unique reasons. ...
This paper reports on the design, simulation, and test of an ultrasonic data telemetry link. A pulse-based data telemetry technique is suggested in this paper, which aims at the suppression of the residual tail of oscillations that naturally follows the response of an ultrasonic transducer to a rectangular pulse. This is made possible by the introduction of a line encoding scheme that suggests the use of an excitatory/inhibitory complex rather than a single excitatory pulse. Efficacy of the technique suggested in this paper was verified through modeling and testing a complete ultrasonic data telemetry link including the transmitting and receiving transducers, as well as the signal conditioning and data recovery blocks on the receiver side. According to the results for transducers with the resonance frequency of 1MHz and saline as the communication channel, a maximum bit rate of 350kbps was achieved.
... For the wireless transfer of data two different approaches can be taken: 1.) Data transfer via radio-frequency transmissions (e.g. [82,102,106,107,108,109,110,111,112,113,114,115,116,117]). 2.) Data transfer via Infrared(IR)-transmissions: Since the skull and skin allows infra-red light to pass [118], it is possible to use IR technology to transmit data [119,120,121,122]. ...
Recent progress in neuro-prosthetic technology gives rise to the hope that in the future blind people might regain some degree of visual perception. It was shown that electrically stimulating the brain can be used to produce simple visual impressions of light blobs (phosphenes). However, this perception is very far away from natural sight. For developing the next generation of visual prostheses, real-time closed-loop stimulators which measure the actual neuronal activities and on this basis determine the required stimulation pattern. This leads to the challenge to design a system that can produce arbitrary stimulation-patterns with up to ±70V and with up to 25mA while measuring neuronal signals with amplitudes in the order of mV. Furthermore, the interruption of the measurement by stimulation must be as short as possible and the system needs to scale to hundreds of electrodes. We discuss how such a system and especially its current pumps and input protection need to be designed and which problems arise. We condense our findings into an example design for which we provide all design files (boards, firmwares and software) as open-source. This is a first step in taking the existing open-source www.open-ephys.org recording system and converting it into a closed-loop experimental setup for neuro-prosthetic research.
... Concerning the individual components of such an implant [75,76,77] like e.g. bio-signal amplifiers [78,79,80], analog-to-digital converter [81,82,83], data processors [42,84], wireless data transfer sub-system [85,86,87,88,89,90,91,92,61], or energy harvesting [93,94] a large number of publications exist. ...
Implantable neuronal interfaces to the brain are an important keystone for future medical applications. However, entering this field of research is difficult since such an implant requires components from many different areas of technology. Since the complete avoidance of wires is important due to the risk of infections and other long-term problems, means for wireless transmitting data and energy are a necessity which adds to the requirements. In recent literature many high-tech components for such implants are presented with remarkable properties. However, these components are typically not freely available for your system. Every group needs to re-develop their own solution. This raises the question if it is possible to create a reusable design for an implant and its external base-station, such that it allows other groups to use it as a starting point. In this article we try to answer this question by presenting a design based exclusively on commercial off-the-shelf components and studying the properties of the resulting system. Following this idea, we present a fully wireless neuronal implant for simultaneously measuring electrocorticography signals at 128 locations from the surface of the brain. All design files are available as open source.
... In order to extract the useful components/information of the recorded neural signals, an analog, digital, or mixed-signal neural processing module (NPM) is usually envisioned on the implant [14][15][16][18][19]. Importance of the role of this module is more * These are the data sent to the implant to program it for proper operation in the desired mode. highlighted when the system is designed to record neuronal activities on multiple channels (i.e., tens to hundreds of channels) and transmit them to the outside world through a wireless link with limited bandwidth [33]. ...
... The wireless interface on the implant contains a power regulator and a data demodulator circuit for the retrieval of the received power and data, respectively. [24] Recently, capacitive links have been proposed as novel alternatives which offer several advantages over their traditional counterparts, i.e. the inductive links [ Figure 6b]. One of the most important advantages of the capacitive coupling approach is the high-pass nature of the link. ...
Millions of patients are either slowly losing their vision or are already blind due to retinal degenerative diseases such as retinitis pigmentosa (RP) and age‐related macular degeneration (AMD) or because of accidents or injuries. Employment of artificial means to treat extreme vision impairment has come closer to reality during the past few decades. Currently, many research groups work towards effective solutions to restore a rudimentary sense of vision to the blind. Aside from the efforts being put on replacing damaged parts of the retina by engineered living tissues or microfabricated photoreceptor arrays, implantable electronic microsystems, referred to as visual prostheses, are also sought as promising solutions to restore vision. From a functional point of view, visual prostheses receive image information from the outside world and deliver them to the natural visual system, enabling the subject to receive a meaningful perception of the image. This paper provides an overview of technical design aspects and clinical test results of visual prostheses, highlights past and recent progress in realizing chronic high‐resolution visual implants as well as some technical challenges confronted when trying to enhance the functional quality of such devices.
... The ASK modulation is considered as the simplest modulation used in near-field transcutaneous power systems. However, for more immunity against interference, noise reduction and high data rate (PSK) is used [88]. ...
With the development of communication technologies, the use of wireless systems in biomedical implanted devices has become very useful. Bio-implantable devices are electronic devices which are used for treatment and monitoring brain implants, pacemakers, cochlear implants, retinal implants and so on. The inductive coupling link is used to transmit power and data between the primary and secondary sides of the biomedical implanted system, in which efficient power amplifier is very much needed to ensure the best data transmission rates and low power losses. However, the efficiency of the implanted devices depends on the circuit design, controller, load variation, changes of radio frequency coil's mutual displacement and coupling coefficients. This paper provides a comprehensive survey on various power amplifier classes and their characteristics, efficiency and controller techniques that have been used in bio-implants. The automatic frequency controller used in biomedical implants such as gate drive switching control, closed loop power control, voltage controlled oscillator, capacitor control and microcontroller frequency control have been explained. Most of these techniques keep the resonance frequency stable in transcutaneous power transfer between the external coil and the coil implanted inside the body. Detailed information including carrier frequency, power efficiency, coils displacement, power consumption, supplied voltage and CMOS chip for the controllers techniques are investigated and summarized in the provided tables. From the rigorous review, it is observed that the existing automatic frequency controller technologies are more or less can capable of performing well in the implant devices; however, the systems are still not up to the mark. Accordingly, current challenges and problems of the typical automatic frequency controller techniques for power amplifiers are illustrated, with a brief suggestions and discussion section concerning the progress of implanted device research in the future. This review will hopefully lead to increasing efforts towards the development of low powered, highly efficient, high data rate and reliable automatic frequency controllers for implanted devices.
