Wearable Sensors

Final Presentation

05-10-04

Problem Background

Inferred Transmission (short range)

Bulky Design, hard to wear

20 Samples per second

MIT Research

Affective Wearable Computers

Goals and Objectives

To create a wearable device that reads

temperature, skin conductance, and blood

volume pulse and transmits data

wirelessly to a computer, where it will be

displayed in real time.

Expected Product Layout

Lapaic Wireless Transmitter

Blood Volume Pulse (BVP)

Galvanic Skin Conductor

Temperature

Sensors Team

Transmission Board Team

Software Team

Lapaic Wireless Receiver

Microcontroller

GUI

Team Overview

Sensors Team– Phillip Hay– Rosy Logioia – Gouri Shintri

Transmission / Microcontroller Board Team– Christina Hernandez– Clayton Smith– Adam Stevenson

Software Team– Daniel Bishop– Josh Handley

SensorsBVP Detection and Filtering

Temperature

BVP Subtraction and Offsetting

Galvanic Skin Conductance

Sensors (Design Specs)

Strengths• Compact• Wearable• Low power

Weaknesses• Poor quality board and parts• Sensitive signals• Inconsistent signals (BVP)

Transmission Board LayoutSchematic PCB Layout

Transmission Board (Design Specs)

Strengths• Size (1.8” square)• Potential wireless transceiver and

microcontroller on same board

Weaknesses• Wasted space where Chipcon was originally

soldered onto board• Separate transceiver / microcontroller boards

Software Overview

Divided into 2 programs that run concurrently:

Cygnal microcontroller

PC: The Wearable Sensor Display Utility (WeaSeL)

Connected through a USB Connection

Microcontroller Software

Microcontroller Code:

Interrupt Driven

Polls data from A/D converter every X seconds.

Transmits it to PC via USB using a custom packet protocol.

Used to connect the microcontroller to the computer

The device uses a simple FIFO interface

The high data speed rate coupled with a ~64k byte buffer on the computer, allows for our sensor technology to quickly send large amounts of data points to the computer for processing

The device is powered by the computer through the USB connection and therefore no additional power constraints are added to the project

MCU to Computer USB Connection

From:http://www.dlpdesign.com/usb/

Microcontroller / USB Connection(Design Specs)

Strengths• C-based IDE• Interrupt Driven

No wasted clock cycles Easier to maintain code

• USB High Data Rate Built in Buffering System Easy to integrate w/ .NET C# 1.1 Compliant

Weaknesses• Microcontroller clock somewhat erratic• ADC has some spill over

WeaSeL

Reads data from the USB port

“Real time” display of sensor readings, similar to oscilloscope

Can save readings to a file for future comparison

WeaSeL(Design Specs)

StrengthsEasy to visualize changes in data

User-friendly

WeaknessesUSB buffering may cause WeaSeL to lag or stall

Final Product LayoutBlood Volume Pulse (BVP)

Galvanic Skin Conductor

Temperature

Sensors Team

Software Team

Microcontroller

GUI

Lapaic Wireless Transmitter

Transmission / Microcontroller Board Team

Lapaic Wireless Receiver

Project Status

Due to lack of time and equipment, our team was not able to complete wireless transmission of data.

The transmission code is currently being reviewed by Laipac Corporation.

Project Integration

Sensor board hooked up to user and microcontroller

Microcontroller on evaluation board hooked up to USB

Team Management

IssuesSchedule ConflictsAreas of ExpertiseTime Management (other classes, work, graduation, etc)

Resolving the IssuesCommunicationDivision of WorkWeekly Team Meetings

Budget

USB Software $ 22.50

Lapaic Transmission $ 65.00

Transmission / Microcontroller Board Parts

$ 250.00

Board Fabrication Free

Sensor Board Parts $ 105.45

Fabrication of Sensor Boards $ 80.00

Total ~ $512.95

Engineering Standards and Safety

Easy to produce because of availability of parts

Product is for medical purposes

Product is powered by batteries at low voltage

Batteries must be disposed of properly to prevent environmental harm

Project Sponsors

This project was completed with the help of the Computer Science Department at Texas A&M University, especially Dr. Ricardo Gutierrez, Dr. Steve Liu, and Dr. Cote from the Biomedical Engineering Department. The project was financially sponsored by Applied Materials and the National Science Foundation.

Demonstration – Double-click to Play