طراحی و شبیه‌سازی بخش کنترل‌کننده‌ی دیجیتال یک تراشه‌ی تحریک عصبی برای یک ایمپلنت مغزی

نویسندگان

1 کارشناسی ارشد مهندسی پزشکی، دانشکده‌ی مهندسی پزشکی، دانشگاه صنعتی امیرکبیر، تهران

2 استادیار، دانشکده‌ی مهندسی پزشکی، دانشگاه صنعتی امیرکبیر، تهران

10.22041/ijbme.2018.90981.1386

چکیده

در این مقاله، طراحی و شبیه­سازی یک کنترل کننده‌ی دیجیتال برای استفاده در یک سیستم تحریک الکتریکی قابل کاشت در مغز ارائه شده است. کنترل کننده‌ی دیجیتال ارائه شده در این مقاله، دارای قابلیت تولید پالس­های تحریک مربعی با امکان برنامه­ریزی مقادیر عرض پالس، دامنه‌ی پالس، تک فازی یا دو فازی بودن و تقدم فاز کاتدی بر آندی یا برعکس (در صورت دو­­­­­‌‌‌‌‌ فازی بودن آن) می‌باشد. هم‌چنین، در این سیستم امکان کنترل 16 سایت تحریک و تحریک 4 تا از آن‌ها به طور هم‌زمان فراهم شده است. عرض پالس­های تحریک، بین 4 میکروثانیه تا 4 میلی‌ثانیه و فاصله‌ی میان دو فاز، بین 4 تا 512 میکروثانیه قابل برنامه­ریزی است. هم‌چنین، دامنه‌ی پالس­ها می­تواند مقادیری بین 4 میکروآمپر تا 1 میلی‌آمپر را اختیار کند. کنترل هر 4 سایت از 16 سایت موجود، توسط یک واحد تحریک کننده‌ی محلی (LDC) صورت می­گیرد که داده­های خود را از واحد کنترل کننده‌ی سراسری (GDC) دریافت می­نماید. صحت عمل‌کرد کدهای VHDL مدار طراحی شده، ابتدا روی یک برد FPGA بررسی و سپس تراشه‌ی ASIC آن با تکنولوژی CMOS 18/0 میکرومتر جانمایی گشته است. ابعاد هر یک از بخش­های تحریک کننده‌ی محلی در تراشه‌ی طراحی شده برابر با 160/19 میکرومترمربع و ابعاد بخش تحریک کننده‌ی سراسری برابر با 246/4 میکرومترمربع می­باشد. هم‌چنین توان مصرفی بخش­های کنترل کننده­های محلی و سراسری به ترتیب برابر 12 و 2/8 میکرووات می‌باشد. به منظور سهولت در ارسال پارامترهای سیگنال­های تحریک توسط کاربر، یک واسط گرافیکی در محیط نرم‌افزار MATLAB طراحی شده است، که با ارسال متناوب دستور تولید پالس توسط آن، می­توان فرکانس پالس­ها و یا تعداد و فاصله‌ی آن‌ها را در یک قطار پالس تحریکی برنامه­ریزی کرد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Design and Simulation of the Digital Controller Block of a Neural Stimulation Chip for a Brain Implant

نویسندگان [English]

  • Farnaz Fahimi Hanzaee 1
  • Mohammad Mehdi Ahmadi 2
1 M.Sc, Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
2 Assistant Professor, Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
چکیده [English]

Nowadays, implantable electrical neural stimulation is extensively used to treat or alleviate certain brain-related health conditions, such as in deep brain stimulation (DBS) or in vagus nerve stimulation (VNS). In this paper, we present a digital controller block, designed for a neuroelectrical stimulator chip dedicated for a brain implant.The presented design is very power and area-efficient and provides a great flexibibity in programming the specifications of the stimulation pulses. The duration of each stimulation pulse can programmed to be from 4 µs to 4 ms, and the amplitude of each pulse could be from 4 µA to 1 mA. The stimulation pulses could be either monophasic or biphasic, In addition, in biphasic stimulation, the priority of the cathodic pulse over the anodic pulse, or vice versa, could be pragrammed. The interphase delay between the anodic and cathodic phases could be programmed to be between 4 µs and 512 µs. The controller controls 16 stimulation sites, four of which can be stimulated simoultaneualy. The 16 stimulation sites are divided into four groups, each of which is stimulated by a current-controlled stimulation circuit. Each stimulation circuit is controlled by a local digital controller (LDC), which receives its data from a global digital controller (GDC). The designed controller blocks have been implemented and tested on a Spartan-6 field-programmable gate array (FPGA) board, before being implemented as an application-specific integrated circuit (ASIC) layout. The ASIC circuit has been designed using 0.18-µm CMOS technology. Based on the layout, each LDC occupies an area of 19,160 µm2 and consumes 12 µW of power from a 1.8V supply. On the other hand, the GDC takes up an area of 4,246 µm2 and consumes 8.2 µW of power. We have also created a graphical user interface (GUI) to be able to program the stinulation chip.

کلیدواژه‌ها [English]

  • Neuroelectrical Stimulation
  • Digital Controller
  • Application-Specific Integrated Circuit (ASIC)
  • Field-Programmable Gate Array (FPGA)
  • Graphical User Interface (GUI)
  • Brain Implant

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