Now showing 1 - 3 of 3
  • Some of the metrics are blocked by your 
    Item type:Publication,
    A multichannel neurostimulator with transcutaneous closed-loop power control and self-adaptive supply
    (2012-12-14)
    Xu, Hongcheng
    ;
    Noorsal, Emilia
    ;
    ;
    Becker, Joachim
    ;
    Ortmanns, Maurits
    This paper presents an integrated multichannel neurostimulator ASIC with improved power management efficiency. The stimulator features transcutaneous closed-loop power control that enables optimum power transfer in spite of the coupling variation as well as the variation in the stimulation threshold/current. A programmable adaptive supply in the high voltage (HV) domain is further proposed to minimize the power dissipation during the active stimulation mode in terms of stimulus current/electrode impedance inconsistencies. The stimulator prototype, including the power management, the digital control as well as a 16 channel stimulation frontend, is fabricated in AMS 0.35μm HV CMOS technology. In measurements, automatic supply voltage adaptation from 13.1V to 8V with running stimulations has been achieved, resulting in maximum power saving of 40% for the implantable circuit. © 2012 IEEE.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Multichannel Microstimulating SoC
    (2022-01-01)
    Noorsal, Emilia
    ;
    Xu, Hongcheng
    ;
    ;
    Ortmanns, Maurits
    In recent years, limited research was focused on designing a multichannel microstimulator that could demonstrate high flexibility in terms of pulse parameters, waveshapes, stimulation strategy, number of electrodes, high-voltage compliance, and variety of charge-balancing techniques to optimize the use of an implant chip for various implementations, changing operating conditions, or research on stimulation efficiency. The reason for this is that designing a highly flexible multichannel stimulator that could fulfill all the different neural applications while concurrently maintaining low power and area consumptions is not a trivial task. Normally, there is a trade-off between high flexibility and hardware complexity. For neural applications, including neuromuscular, cochlear implant, and deep brain stimulators, which require a small number of electrodes, high flexibility of waveform pattern at each stimulation site is not an issue. However, especially for a large number of electrodes, such as a retinal implant, having high flexibility in the waveform pattern is not easy to implement. Therefore, this chapter presents an overview of design and implementation of flexible multichannel microstimulator in system on chip (SoC). Firstly, the importance of having high flexibility in neural stimulator application and the trade-off between high flexibility and hardware complexity are discussed. Secondly, the state of the art of flexible waveform generation, charge-balancing techniques for safe stimulation, and power management requirements in multichannel microstimulators are reviewed. Thereafter, the examples of overall design architecture, stimulation protocols, flexible stimulation, and functionality for a multichannel epiretinal stimulator ASIC with 1024 electrodes are provided. In addition, an area- and power-efficient stimulator front-end circuit which covers the HV current driver, compliance monitor, and several types of charge-balancing techniques are further elucidated. Finally, a power management circuit with closed-loop power control and dynamic supply adaptation for multichannel epiretinal stimulator is explained in detail. A 16-channel epiretinal microstimulator has been developed and successfully tested in a 0.35 µm AMS HVCMOS technology.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Multistimulator backchannel communication link implemented for safety information and closed-loop power management
    (2014-03-30)
    Noorsal, Emilia
    ;
    ;
    Xu, Hongcheng
    ;
    Sukumaran, Deepti
    ;
    Ortmanns, Maurits
    This paper describes the importance of having a backchannel communication link between a microstimulator ASIC and an external control unit for complete safety closure and closed-loop power management. An example of the overall microstimulation system with backchannel communication link for an epiretinal implant is provided. Additionally, the backchannel operation and protocol between the implant chip and the external control unit are given. The flexible multichannel stimulator was implemented and successfully tested in a 0.35 μm AMS HVCMOS technology. A test measurement setup is developed to test the functionality of bidirectional communication between the fabricated stimulator ASIC and the external control unit. Conducted measurement results on erroneous data packet, non-accomplished charge balancing and supply voltage adaptation validate the functionality of the bidirectional communication system.