Eyelid movement sensor device

Danielle Perez & Shuki Eizner Boaz Blankrot & Leon Karabchevsky

Adi Hanuka

January 8th, 2013

Acknowledgments

Prof. Schächter Levi Mr. Eli ShoshanMr. Alex Kinko Mr. Stanislav Shapira

Contents

Overview

Physical part

Hardware

Software

What’s next?

1

2

3

4

5

Overview

Doctors: Monitoring neurologic diseases and eyelid disorders by analyzing eyelid movements.

Our Main Goal: Develop a device for monitoring eyelid motion, acquiring the eyelid movements and enabling analysis of the results.

Overview1

How it works?

Overview1

Basic ConceptPatient

Eyelid Movement Sensor

Doctor

Results of analysis PC Application

Overview1

USB cable

Collaboration

Overview1

Hardware part - Memory- Power- Schematics draws

Physical part- Magnetic field measurement - Algorithm

Software part- User experience- Integration- Robust

Portable system

Samples each eye separately

Evoked motion

Device’s output: position, velocity , frequency

Two operating modes: Real time - data stored on the computer

Offline - data stored on the device’s memory

User friendly interface Data analysis and presentation

Multiple tests for a single patient

Device Requirements

Overview1

Overview

Physical part

Hardware

Software

What’s next?

1

2

3

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Physical partGoals1. Measure the field of a tiny magnet attached to

the upper eyelid

2. Establish the voltages of 4 Hall probes located on the device

o The voltages are indicative to the motion of the magnet

3. Inverse algorithm that establishes the motion from the voltage measurements

Physical2

Computer

Glasses

Physical part

Sensors system

Sample&

processing

Data Base

Presentation &

analysisPhysical2

1

4

3

2

Hall probes

1 - Signal CharacterizationMagnetic field measurement

magnet

2 - Algorithm

Experiment

Physical2 4- Typical voltage measurements from 2 probes (V1,V3)

1- Artificial eyelid and magnet

2- Hall probes and circuit holder

3- Complete device

1 - Signal Characterization

Hall probe sensor

1. The strength of the magnet’s field varies with the distance

2. A voltage is applied to the sensor which returns a voltage that is linear with the strength of the magnetic field

3. If properly calibrated, the system’s voltage represents the distance between the magnet and the sensor

B=f(r)

V=g(r)

Physical2

V B

1 - Signal Characterization

Computer

Glasses

Physical part

Sensors system

Sample&

processing

Data Base

Presentation &

analysis

Physical2

1 - Signal CharacterizationMagnetic field measurement

magnet

2 - Algorithm

2 - Algorithm

V=g(r)V V V

VVVV

r=f(V)r r rr r r

y

x( )sX té ùê úë û

r

( )1X té ùê úë ûr

( )n̂ t1

4

3

2

y

xz

Physical2

The challenge

( )2X té ùê úë ûr

( )3X té ùê úë ûr

( )4X té ùê úë ûr

V3 B3

V1 B1

2 - Algorithm

0 2 4 6 8 10 12 14 16 18 20-0.5

0

0.5

1

1.5

2

2.5x 10

-5

t[sec]

Bx[

T]

Bx=f(t) for Rs=0.01m ,Phi=cos(wt)

Bx1Bx2Bx3Bx4

Simulation-Magnetic field in time

Physical2

B1

B3

2 - Algorithm

Physical2

Solution- Probe planeB1=f(r1,r3)B3=f(r1,r3)

r1=h(B1, B3)r3=h(B1, B3)

Once “r1 “ and “r3“ are determined, knowing “d” makes the location of the magnet a trivial geometric problem

2 - Algorithm

Simulation- Magnetic field vs. the distance

Physical2

0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04-1

0

1

2

3

4

5

6

7x 10

-4 Bx(r1)

r1[m]

Bx[

T]

r3=0.023 [m]

r3=0.033[m]

r3=0.04[m]

Overview

Physical part

Hardware

Software

What’s next?

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2

3

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USB cable

Hardware part

Overview1

Hardware part -Memory-Power- Schematics draws

hardware3

• Design and implementation of portable PCB with the following

capabilities:

The system can store the data in two non-volatile memories,

micro-SD and EEPROM.

Computer interface using a USB cable.

Alerts & Control (LEDS and switches).

Capable to measure each eye separately.

Powered by rechargeable battery

System Requirements

Design Flow

• Market survey • Schematics• Routing• PCB production• HW debug- software• Integration

hardware3

hardware3

Block Diagram

Overview

Physical part

Hardware

Software

What’s next?

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2

3

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The demand for an easy to use, fast to learn, robust & all-encompassing environment led to the development of:

Eyelid Pro, combined with the Eyelid Sensor Device embedded software, forms a complete and user-friendly solution for recording, analyzing and documenting patients’ eyelid movement.

USB

Software Overview

Software4

Eyelid Pro Eyelid Sensor Device embedded software

Main Concept• Portable, low-power plug & play system• Well- defined doctor-patient work flow

• Based on customer specifications, flowchart design

• Built-in operating assistant & user’s manual• Tool-tips, guided installation, fully documented design

• Utilized & fine-tuned for maximum performance and user experience

Software4

Eyelid Pro• End-to-end, flow-oriented design• Real-Time data acquisition• Simply accessible results database• Simultaneous multiple device support• Easily deployable platform• Powerful results viewer & analyzer• Integrated results comparison tool

Software4

Eyelid Pro• End-to-end, flow-oriented design

• High review rate• User error fail-safes• End case reference

Software4

Eyelid Pro• Real-Time data acquisition

• Incorporates the abilities of the results viewer with a real-time data link• Ability to store the session• Adjustable sample viewing window

• Simply accessible results database• Easily updatable patients record• Ignore\un-ignore session data

• Simultaneous multiple device support• Automatic device detection & user selection option

• Easily deployable platform• Just press “install”…

Software4

Eyelid Pro• Powerful results viewer & analyzer

• Annotation support• Session remarks• Advanced toolbar• Full screen view• Cursor positioning • Image export

Software4

Eyelid Pro• Integrated results comparison tool

• Visually compare date between different session & even different patients• Ability to adjust all axes simultaneously or separately

Software4

Eyelid Sensor Embedded SW• Easy to operate user-end controls

• On/Off/Sleep mode switch• Start/Stop sampling switch• Device is ‘foolproof’ – device operates only according to pre-defined workflow

• Integrated user notification system• Device state indication by 2 tri-color LEDs and buzzer

• High speed device-PC data streaming link using USB• Maximum throughput – 1.2MB/sec

Software4

Eyelid Sensor Embedded SW• Accurate multi-sensor data acquisition

• 8 sensor sampling at 400Hz effective rate each• x4 oversampling (1600Hz) for noise reduction• 80% data compression ratio

• High capacity micro-SD storage solution for long recording time• Data acquisition rate of 3.1KB/sec – or almost 3MB for a 15 minute session• Due to storage restrictions a microSD card is used to store information (up to 2GB

of storage)• When connected, the device is recognized as a disk-on-key drive, enabling:

robustness, speed, ease-of-use & future development

Software4

Overview

Physical part

Hardware

Software

What’s next?

1

2

3

4

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What’s next?5

What’s next?

1. Full integration of the system2. Adaption for clinical tests

Questions

?