V i t a l i s

ECE 477 - Spring 2013

TEAM 13

Wireless Biometric Sensor

Team Members: Aakash LambaDi MoShantanu JoshiYi Shen

Design Review

ECE 477 Design ReviewTeam 13 – Fall 2013

Paste a photo of team members here, annotated with names of team members.

Shantanu Joshi /Aakash Lamba / Di Mo / Yi Shen

Outline

• Project overview• Project specific success criteria• Block diagram• Component Selection Rationale• Packaging Design• Schematic and theory of operation• PCB layout• Software design/development status• Project completion timeline• Questions

• Prototype of a portable wireless biometric sensor

• Battery-powered device with fuel gauge

• Mounted on the wrist

• Monitor pulse rate, SpO2 and skin temperature

• Transmit the information via Wi-Fi for remote web access

• NFC chip allows immediate access to patient data

• Accelerometer on the shoulder for fall detection

• Manual and automatic alarm system.

Project Overview

Project-Specific Success Criteria

• An ability to determine pulse and SpO2 readings from blood light absorption

• An ability to display the users vital statistics (pulse, SpO2 , skin temperature) on the LCD screen mounted on the device which is located on the patients wrist

• An ability to remotely monitor the users medical status from a web-site via secure login or authentication through an on-device NFC tag

• An ability to activate an alarm both manually (through an emergency button) and automatically  in response to anomalous readings of vitals

• An ability to detect if the user has suffered a fall and automatically raise an alarm

Block Diagram

Component Selection Rationale Microprocessor (1)

Critical Design Constraints• At least 2 UART outputs for WiFi

and LCD• One or more I2C and SPI (for

debugging) connections• Operable using internal oscillator

(8 MHz or more)• Low power consumption (< 20 mA

active)• Has a well established design tool

chain

Preferable Design Characteristics • Low pin count • Large amounts of internal

flash/SRAM

Component Selection Rationale Microprocessor (2)

ATmega1284 PIC32MX250F128DSupply Voltage 1.8-5.5 V 2.3-3.6 VActive current draw (8 MHz) 12 mA @ 5 V 10.5 mA @ 3.6 VI2C channels 1 2SPI 1 2UART 2 2Internal Oscillator 8 MHz 8 MHzPin count 44 44Memory 16k RAM/ 128k flash 32k RAM/ 128k flashIDE Atmel Studio MPLABAdditional Info Available in 40 pin PDIP built-in USBCost $7.22 $4.81

Component Selection Rationale Sensors/Modules (1)

General Requirements

• Small size • Low cost• Easy to use• 3.3 or 5.0 V• Well documented• Communication via UART or

I2C

Components

• Accelerometer• Temperature• OLED screen• Wi-Fi module• Light to frequency converter

Component Selection Rationale Sensors/Modules (2)

Accelerometer• Analog output• 3.3 V• Easily clipped on shoulder• 3 axis sensing• Low power (350 μA)

OLED Screen• UART communication• 5.0V• Extremely easy to program• Appropriate size for

embedded application

WiFly Module• Low power - 4 μA sleep and

38 mA active • UART communication• Built in HTML commands to

make POST request

Light to Frequency converter• Programmable sensitivity• Extremely small size• Operates in wide range of

temperature(-25°C to 75°C)

Packaging Design (1)

Packaging Constraints

• Portable - The device must be portable such that a patient may move around while carrying it. It should operate wirelessly so as to enable patient mobility.

• Light weight – The device must be light weight. Since the average weight of a smart phone is 120 g, we are targeting something on the order of 100-150g.

• Small – The device needs to be small since it needs to be mounted on to the users wrist. We are aiming to make the breadth less than 5 cm. The average wrist is approximately 4.7cm in diameter.

Packaging Design (2)

Philips IntelliVue MX40

• Hung around the neck in a transparent carrying pouch

• Touch screen UI• Sensor wires extend across patient’s

chest• Entire package (including pouch) is

relatively large and cumbersome.

ViSi Mobile health monitor

• Worn around the wrist; supported by a band

• Touch screen UI• Small and discrete.• Only respiration rate sensor is placed

on user’s chest• Aesthetically pleasing

Packaging Design (3)

Packaging Design (4)

Packaging Design (5)

Packaging Design (6)Summary:

Size and Weight (main device):

Height: 96 mm

Width: 50 mm

Depth: 10.1 mm

Weight (estimated): ~150 grams

 

Components external to device:

Pulse oximeter: Clipped on finger

Accelerometer: Clipped on to clothing near shoulder

Temperature sensor: Underneath the main device mounted on the band

  Power module: Attached to the bottom on the neoprene band

Packaging requirements:

Band material: Neoprene band with Velcro for securing onto wrist

Device packaging: Plastic casing

Schematic: Complete Design

Schematic: Section Breakdown

Microcontroller

Power and Battery Management

Sensors

External Interfaces

Power Supply Description

• Supply Voltage

– Lithium Polymer Outputs

3.7 Volts (Nominal)

– 3.3 Volts

• Microcontroller

• Sensors (SpO2,

temperature, accelerometer)

• Wi-Fi Module

– 5 Volts

• OLED

Schematic: Power SupplyCharger/Booster

Fuel Gauge

Headers

5V Step Up

Sensor DescriptionPush Button – (Emergency)

• Digital Inputs

Accelerometer (Analog)

• 3 Analog Inputs (3-axis)

Temperature (digital)

• I2C interface

Pulse Oximeter

• External Interrupt

(Frequency output from

photo-sensor)

• 2 Digital Outputs

o Regular Red LED

o Infrared LED

Schematic: Sensors

Pulse Oximeter

Temperature

Accelerometer

EmergencyPush Button

Wi-Fi and OLED Description• Communicates with microprocessor

via UART

• Wi-Fi also requires hardware flow

control through CTS/RTS

• OLED operates at 5V compared to

3.3V for everything else

• Wi-Fi and OLED both contain a on-

board processor

– Wi-Fi module implements handshaking,

parsing, and TCP stack creation

– OLED handles high-level graphics and

programmable updates

Schematic: Wi-Fi & OLEDWi-Fi Module

• UART

• TXD0: PD1

• RXD0: PD0

• CTS: PC6

• RTS: PC7

OLED

• UART

• TXD1: PD3

• RXD1: PD2

Wi-Fi

OLED

Microcontroller Description

• Does all on-device data acquisition and

processing

– Peak detection for pulse

– Look-up table for SPO2

– Acceleration processing for fall detection

– Temperature conversion

• Communicates to website through Wi-

Fi via UART interface

• Debugging and Programming using

standard 10-pin JTAG interface

JTAG

Headers To Power Board

SPI

ATmega1284

Schematic: MicrocontrollerI2C Bus

Decoupling Capacitors

PCB Layout: Overall PCB (3.8 x 3.25)Powe

r Boar

d

Main Board

PCB Layout: Top Copper

PCB Layout: Bottom Copper

PCB Layout: Silk Layer

Trace Size for 3.3 V, 5 V and GND is 0.032

PCB Layout: Power PCB (2.9 x 1.15)(GND Highlighted)

PCB Layout: Power PCB (2.9 x 1.15)

Power Conne

ct5 V Step

UpFuel

Gauge Charger/Booster

Decoupling Capacitors (C1,C2) for Power Traces

PCB Layout: Main PCB (3.25 x 2.8)(GND Highlighted)

Trace Size:3.3 V, 5 V and GND - 0.032Others – 0.012

Hole Size (Diameter):Power - 0.04330709Others – 0.02362205

PCB Layout: Main PCB (3.25 x 2.8)

Decoupling Capacitors for Micro:C3,C7,C9 (Size:0805)

9

7

86

10

4

5

3

Decoupling Capacitors for VCC(3.3V)/GND: C10Decoupling Capacitors for Accelerometer : C4Decoupling Capacitors for OLED : C5,C8Decoupling Capacitors for Wi-Fi : C6(Size:1210)

*All passive components are surface-mounted

PCB Layout: Main PCB (3.25 x 2.8)(Debugging Connectors Highlighted)

Power

SPI

RESET

JTAG

PCB Layout: Main PCB (3.25 x 2.8)(Sensor Connectors and Others Highlighted)

Accelerometer

BUTT

ON

Temperature Sensor

POW

ER

Wi-Fi

SPO2LED

OLED

Software Design• Web Application

– Node.js, Express,Jade,Stylus,MongoDB– Login, patient details and DB communication Done– Improve UI, plotting library and Wi-Fi communication To Do

• Embedded Software– UART up and running– Pulse oximeter processing finished.– ADC,I2C, OLED display, Wi-Fi configuration to be accomplished.

• Android application– Programming in eclipse SDK– Login screen, detecting and reading NFC tags Done– Once web site is hosted, will enable auto-login from the app using NFC

authentication

Project Completion Timeline• Week of 2/25:

– Focus on embedded software– Get the Accelerometer interfaced

with the micro.– Iron out flaws in PCB

• Week of 3/4:– Proof of parts– Continue with software

development• Week of 3/11:

– Host the website– Spring Break!!!

• Week of 3/18:– Begin populating the PCB– Finish building OLED display– Finish interfacing all sensors

• Week of 3/25:– Continue populating PCB– Get the Wi-Fi updating useful

information to the web-server– Enhance the UI for the web-app

• Week of 4/1:– Start testing– Arrive at stable version of SW

• Week of 4/8:– Debugging– Ethical and Environmental impact

• Week of 4/15:– Final tweaks– Prepare demo

Questi

ons?