實驗一報告 -...

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


High Pass Filter𝑉𝑜𝑢𝑡 − 𝑉𝑖𝑛

ൗ1 𝑠𝐶

= −𝑉𝑜𝑢𝑡𝑅

𝑉𝑜𝑢𝑡1

𝑅+ 𝑠𝐶 = sC𝑉𝑖𝑛

𝑉𝑜𝑢𝑡𝑉𝑖𝑛

=𝑠𝑅𝐶

1 + 𝑠𝑅𝐶=

𝑠


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


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


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


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


啟動

波形

頻率

振幅 Offset


啟動

顯示

固定波形紀錄

頻道

歸零

刻度

Time Base

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/

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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