實驗一報告
報告繳交期限: 3月19日(二)12:00
Report content (報告內容)
1. Complete three experiment reports (三份實驗紀錄表格檔案)
2. Complete additional questions
請合併成一個PDF檔案寄到助教的信箱([email protected]),主旨標明組別及實驗序。
mailto:[email protected]
行事曆
期中報告期中報告(Group) 題目:生醫工程相關皆可,例如:生理電信號原理、醫學影像等…
在決定題目之前請先跟助教討論,確定報告的題目範圍是否會太廣而無法負荷。
要求:每組報告時間約15分鐘,提問5分鐘(有提問者另外加分)。
註:期中報告結束的一個禮拜要給我們報帳發票。
實驗二:生理電信號量測電路 – 設計與實現
Introduction
根據實驗一選定的生理電信號繼續對這種信號作量測電路的設計
在操作實驗一的時候你發現什麼?
應該很順利都可以量到信號
是否跟文獻做過比較?
自行設計電路
不同的生理電信號其設計方式也會不同
利用NI ELVIS / Arduino + Android APP Invertor實現
Experiment Overview
Design circuit(s) for bio-signal detection
1. ECG
2. EMG
3. EEG
Digitize the detected waveform (ADC)
Transmit to the self-designed APP via bluetooth
APP: Waveform display oscilloscope
PART I
PART II
PART I:量測電路Circuit Design for Bio-Signal Detection
PARTI: Introduction
Characteristics of ECG, EMG, and EEG waveform
Based on the findings from experiment 1 and published
reports/journals
Examples: amplitude, center frequency and bandwidth
Design your own detection circuit(s)
Use NI ELVIS II to test the effectiveness of your circuit
Energy efficient circuit
Simplified Layout of Detection Circuit
Signal Inputs
(3 Leads)Pre-Amplification
Filter
(LPF / HPF /
NOTCH / BPF)
Post-Amplification
Circuitry
Signal Output
(0V – 5V)Voltage Level Shifter
ADC
Display
~µV
~mV
Noise Figure
如何達成最高的增益、最低的雜訊指數?
Noise Figure
Pre Amplifier
Lead II 三點ECG(正極、負極、接地)
OP放大器?
雙極訊號轉為單極訊號
差動放大器
Buffer
使前一級電路不受負載影響
R=∞
儀表放大器
差動放大器→儀表放大器(INA128)
在正負輸入端都加上unit gain buffer
非常低直流偏移、低漂移、低雜訊、非常高的開迴路增益、非常大的共模拒斥比、高輸入阻抗
市電
市電,又稱壁上電源、交流電、輸電網,為城市裡主要提供市民使用的電源
一般家庭用電為AC 100~125V 60Hz正弦波
該如何解決60Hz的訊號影響?
Notch filter
訊號頻率範圍
從頻譜以及文獻看訊號主要的頻帶在哪
設計適當的濾波器
高通濾波器(DC offset、低頻雜訊)
低通濾波器(高頻雜訊)
Notch filter(市電)
Low Pass Filter𝑉𝑜𝑢𝑡 − 𝑉𝑖𝑛
𝑅= −
𝑉𝑜𝑢𝑡
ൗ1 𝑠𝐶
𝑉𝑜𝑢𝑡1
𝑅+ 𝑠𝐶 =
𝑉𝑖𝑛𝑅
𝑉𝑜𝑢𝑡𝑉𝑖𝑛
=1
1 + 𝑠𝑅𝐶=
ൗ1 𝑅𝐶
𝑠 + ൗ1 𝑅𝐶
𝑓𝑐 =1
2𝜋𝑅𝐶
C = 0.33uF
R = 10k
Cut off frequency = 48Hz
Low Pass Filter
頻率響應
參考電路(二階低通濾波器)
Sallen-Key Lowpass filter
1
2𝜋𝑅𝐶𝐺𝑎𝑖𝑛 =
ൗ1 𝑅𝐶
𝑠 + ൗ1 𝑅𝐶
High Pass Filter𝑉𝑜𝑢𝑡 − 𝑉𝑖𝑛
ൗ1 𝑠𝐶
= −𝑉𝑜𝑢𝑡𝑅
𝑉𝑜𝑢𝑡1
𝑅+ 𝑠𝐶 = sC𝑉𝑖𝑛
𝑉𝑜𝑢𝑡𝑉𝑖𝑛
=𝑠𝑅𝐶
1 + 𝑠𝑅𝐶=
𝑠
𝑠 + ൗ1 𝑅𝐶
𝑓𝑐 =1
2𝜋𝑅𝐶
High Pass Filter
頻率響應
參考電路(二階低通濾波器) Sallen-Key highpass filter
1
2𝜋𝑅𝐶
𝐺𝑎𝑖𝑛 =𝑠
𝑠 + ൗ1 𝑅𝐶
Notch Filter
Twin-T notch
Center reject frequency
https://www.changpuak.ch/electronics/Active_Notch_Filt
er.php
https://www.changpuak.ch/electronics/Active_Notch_Filter.php
Notch Filter
Wien Bridge Notch Filter
𝑓𝑐 =1
2𝜋𝑅𝐶
Post Amplifier
基本OP放大器
non-inverting amplifier
Gain=1+R2/R1
Level Shifter
Arduino接收電壓範圍0~5V
不准送負的電壓進去Arduino
𝑉𝑜𝑢𝑡 = 𝑉+ 1 +
𝑅2
𝑅1
𝑉+ =𝑅3𝑉2
𝑅3 + 𝑅4+
𝑅4𝑉1
𝑅3 + 𝑅4
透過電阻與電源的分壓讓心電圖的訊號平移至0V以上
Analog to Digital Converter
如何將0~5V電壓轉換為數位訊號?
8bits ADC
2^8=256 → 0~255
例如輸入電壓3V
255/5*3=153(DEC)=10011001(BIN)
Digital Signal
ADC (Analog-Digital-Convertor)
Nyquist sampling frequency
Quantization error
Offset error (LSB)
Digital filter:
MATLAB
Built-in functions: butter / besself / cheby1 / maxflat
Self-design: designfilt
Simplified Layout of Detection Circuit
Circuitry
Pre-Amplification
Filter
(LPF / HPF /
NOTCH / BPF)
Post-Amplification
Voltage Level Shifter
This detection circuit could be the
platform for building your term project
Goals
Accuracy
Regardless of the complexity of the detection circuit
Compare the detected signal with the results from exp.1
ECG: PR interval / QRS interval / ST intervals … etc.
EMG: Tonus measurement … etc.
與實驗一結果比較
量到的電信號波形穩定與否
Noise的情況又是如何?SNR?
商用儀器v.s.自行設計之電路
MOST IMPORTANT!
Goals
1. ECG、EMG必須透過電路設計出適當的濾波器
2. EEG可以藉由電腦設計出適當的濾波器
α: 8〜13Hz
β: 13〜40Hz
θ: 4~7Hz
δ: 0.5~4Hz
PART II:資料擷取與APP設計DAQ and APP for Bio-Signal Detection
Simplified Layout of Detection Circuit
Signal Inputs
(3 Leads)Pre-Amplification
Filter
(LPF / HPF /
NOTCH / BPF)
Post-Amplification
Circuitry
Signal Output
(0V – 5V)Voltage Level Shifter
ADC
Display
~µV
~mV
Analog Input
類比輸入
Manual Control
手動控制
Analog Outputs 類比輸出
Func. Generator 函數產生器
Var. Power Supply 可變電源Fix Power Supply & Ground
固定電源&接地
可變電源供應器〔-〕
可變電源供應器〔+〕
NI ELVISmx Instrument Launcher
NI ELVISmx Instrument Launcher
啟動
波形
頻率
振幅 Offset
NI ELVISmx Instrument Launcher
啟動
顯示
固定波形 紀錄
頻道
歸零
刻度
Time Base
NI ELVISmx Instrument Launcher
PARTI: Introduction
Analog signal Digital signal
Digital filter
Decrease the chance of signal distortion
System integration
User interface & display recorded signal
Bluetooth (BT) module
Android APP
Arduino Uno v3
(or any mcu eval. board)
HC-05
App Inventor 2
Arduino Uno
Microcontroller evaluation board
ATmega328 microcontroller
Clock: 16 MHz
14 Digital I/O
6 Analog inputs
10 bits ADC
Software serial function
https://www.arduino.cc/en/Main/ArduinoBoardUno
Arduino IDE
1. Import Library
2. Define Variables/Constants
1. Setup Pins
2. Initialize Functions
Do…… until power is turned off!
1. Read ADC output
2. Send ADC result via BT module
Arduino IDE
Tool
Please select the correct board and port
HC-05 Bluetooth Module
1. AT
2. AT+NAME?
3. AT+PSWD?
4. AT+UART = Baud Rate , 停止位元 , 同位(parity)位元
Enter AT Mode
1. KEY: HIGH (or)
2. Push Button Down
Before power up Bluetooth Module
App Inventor 2
You need to have a Google Account
URL: ai2.appinventor.mit.edu
http://ai2.appinventor.mit.edu/
App Inventor 2
http://ai2.appinventor.mit.edu/
App Inventor 2
http://ai2.appinventor.mit.edu/
App Inventor 2
http://ai2.appinventor.mit.edu/
Important !
Arduino CANNOT sample negative voltages.
Voltage range: Vref_- (i.e., GND) and Vref_+ (i.e., +5V, +3.3V
or external voltage)
What is your sampling frequency, and how is this defined
in Arduino’s code.
Syntax: references
Arduino http://arduino.cc/en/Reference/HomePage
App Inventor 2
http://appinventor.mit.edu/explore/library.html
Please download:
Arduino software: http://www.arduino.cc/en/Main/Software
Demo
Date: 9 April 2019 (12:20 – 14:00)
Circuit: ECG(30%), EMG(30%) and EEG (20%)
Display your recorded waveform on oscilloscope (ELVIS II)
Display your recorded waveform on your designed APP
(Arduino + App, 20%)
Grading
Accuracy of the bio-signal recorded
App v.s. Oscilloscope
Report
Date: 23 April 2019, 12am
Contents
Normal report format: Introduction, Method, Results,
Discussions, Conclusions
Design/Specification: circuits, Arduino program, App
Additional questions! (詳見生醫工程網頁)
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