Artificial Eye Lesson Plan

The TEAK Project

Rochester Institute of Technology

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Artificial Eye

Partial support for this project was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement (CCLI) program under Award No. 0737462. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

TEAK Artificial Eye Lesson Plan

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ACTIVITY OVERVIEW

Artificial Eye Activity Overview Students completing the Artificial Eye kit will work in teams to build an electrical circuit capable of seeing and responding to infrared light. Students will adjust the sensitivity of their electrical circuits to detect different amounts of infrared light. Using analogies between the biological and electrical components of the eye, students will be shown how engineered devices can be created to mimic some human functions.

Activity Time Description

Introduction: Vision 10 min Students will see the parts of the human eye, as well as the engineered counterparts that perform similar functions in an artificial eye

Constructing a Model Artificial Eye 35-40 min Students will construct an artificial eye that will be able to see infrared light, using a breadboard and basic electrical components.

Learning Objectives By the end of this lesson, students should be able to…

• Explain that the eye is a receptor for human vision. • Explain that the eye sends visual images to the brain in the form of electrical pulses. • Recognize that engineers can simulate biological ideals with electrical circuitry to create devices such as

the artificial eye. • Associate the parts of the artificial eye system to corresponding parts of the human eye system.

NYS Learning Standards Standard 1: Engineering Design. Engineering design is a repetitive process involving modeling, optimization and finding the best solution within the given constraints that is used to develop technological and innovative solutions to technical problems.

• Activate devices • Recognize why an object or choice is not working properly • Recognize how a defective simple object or device might be fixed • Under supervision, manipulate components of a simple, malfunctioning device to improve its

performance Standard 5: Technology. Students will apply technological knowledge and skills to design, construct, use, and evaluate products and systems to satisfy human and environmental needs.

• Asemble, operate, and explain the operation of simple open-and closed-loop electrical, electronic, mechanical, and pneumatic systems • Describe how system control requires sensing information, processing it, and making changes.


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TABLE OF CONTENTS Instructor Preparation Guide .................................................................................................................................. 4!

Bioengineering Overview ....................................................................................................................................... 4!Human Sight Overview .......................................................................................................................................... 4!Simplified Definitions ............................................................................................................................................ 4!Engineering of Sight Overview .............................................................................................................................. 5!Functions of an Artificial Eye ................................................................................................................................ 5!Concepts in the Artificial Eye Kit .......................................................................................................................... 6!

Bioengineering Introduction .................................................................................................................................... 8!Background Information ......................................................................................................................................... 8!Bioengineering Background Group Discussion: 5 Minutes ................................................................................... 8!

Human Sight Introduction ....................................................................................................................................... 9!Background Information ......................................................................................................................................... 9!Simplified Definitions ............................................................................................................................................ 9!The Importance of Sight Group Discussion: 5 Minutes ......................................................................................... 9!

Engineering Sight Introduction ............................................................................................................................. 11!Background Information ....................................................................................................................................... 11!Engineering/Technical Aspects Group Discussion: 5 Minutes ............................................................................ 11!Learning Objectives .............................................................................................................................................. 12!Materials ............................................................................................................................................................... 12!Procedure .............................................................................................................................................................. 12!Concluding Discussion ......................................................................................................................................... 13!

Artificial Eye Activity Worksheet ......................................................................................................................... 14!Team Members: .................................................................................................................................................... 14!Data Tables: .......................................................................................................................................................... 14!Matching Chart: .................................................................................................................................................... 14!

Artificial Eye Activity Worksheet Answers ......................................................................................................... 15!Data Tables: .......................................................................................................................................................... 15!Matching Chart: .................................................................................................................................................... 15!

Activity Instructions ............................................................................................................................................... 16!List of Materials .................................................................................................................................................... 16!Building the Artificial Eye ................................................................................................................................... 16!

Artificial Eye Circuit Building Handout .............................................................................................................. 17!Biology Sheet ........................................................................................................................................................... 19!

Matching of Biological Equivalent Components ................................................................................................. 19!Engineering Sheet ................................................................................................................................................... 20!Image Sources ......................................................................................................................................................... 21!Extended Information/Resources .......................................................................................................................... 21!Revisions .................................................................................................................................................................. 22!

Signifies Group Discussion Signifies Activity


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INSTRUCTOR PREPARATION GUIDE

Bioengineering Overview Bioengineering is the application of science, mathematics and engineering principles to define and provide solutions to problems in the fields of biology and medicine. An example of a product created by bioengineers is the artificial eye.

Human Sight Overview The human eye is a complex organ. Its function can be broken down into three stages.

1. The first stage is the collection of light. At the front of the eye, a lens stretches or contracts to adjust the visual focal point. This allows an individual to focus on objects that are either far or close to the individual.

2. The second stage is the processing of visual light. At the back of the eye, there are two types of receptors called cones and rods. Cones help the individual to detect and distinguish different colors. The human eye has blue, green and red cones. Rods help the individual to detect and distinguish between light and dark.

3. The third stage is the process of stimulating the brain. After a receptor is stimulated, an electrical pulse is sent out through the optic nerve to the visual cortex of the brain. This is the area of the human brain where visual stimuli are processed.

Figure 1 - The Human Eye

Simplified Definitions Cones: Receptors in the eye that are stimulated by colors Rods: Receptors in the eye that are stimulated by different intensities of light Optic Nerve: A sensory nerve that allows the receptors in the eye to send electrical pulses to the brain Visual Cortex: The area of the brain that processes vision. This is located in the back region of the brain, the occipital lobe. If you fall on the back of the head and you see stars, it is because the visual cortex of the brain was stimulated by the shock of falling.


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Engineering of Sight Overview Individuals with visual problems could have damaged or defective lenses, receptors, or even optic nerves. Engineers and scientist have been studying how the human eye works and functions in hopes to find solutions for the visual impaired. Currently, bioengineers are working to develop a device called the artificial eye. The artificial eye is a device that can replace the second and last stages of the eye to allow the individual to process information and stimulate the brain.

Figure 2 – Artificial Eye Implants

Functions of an Artificial Eye 1. The first stage is the collection and focusing of light. If an individual has a problem with their lens, they

suffer from nearsightedness or farsightedness. • Nearsightedness – A condition in which an individual has difficulty viewing objects from a

distance. • Farsightedness – A condition in which an individual has difficulty viewing objects from a close

distance. Solutions to these problems include obtaining glasses, or contact lenses, or even laser vision surgery

2. The second stage is the processing of visual light. Engineers have thought of two ways to replace human

receptors • Camera – Engineers can attach a micro camera to a pair of glasses to easily allow an individual to

obtain vision. However, this attachment is noticeable to others and requires the transfer of large signals to the visual cortex. Thus, large bulky wiring is required to be sent from the glasses, through the human skull, and into the brain. Wireless transmission of these signals is currently being investigated.


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• Electrodes – Engineers have also devised a plan to implant electrodes into the human eye. These implants will contain millions of electrodes to stimulate different locations of human sight. The more electrodes that can be implemented, the sharper the image the artificial eye can send to the user. However this technology is not fully developed.

3. The third stage is the process of stimulating the brain. Stimulating the brain with electrical pulses is not a problem for engineers. The main problem for engineers is finding the right location of the brain to stimulate for images to appear accurately.

Concepts in the Artificial Eye Kit 1. The following kit is designed to operate with infrared light signals. Infrared light signals are safe and can

also be found in television remote controls. These signals are not visible to the human eye.

2. The following kit operates with an operational amplifier. This allows small readings to be amplified. In this circuit, the larger the resistance used, the larger the gain; in other words, the system becomes more sensitive.

3. To increase the distance of operation, a larger resistance is required to increase the gain or sensitivity to light.

4. Raising the resistance too high is similar to having no resistor at all, and will give an infinite gain. In this scenario, the output light will never turn off. (The artificial eye will not stop stimulating the brain.)

5. To simplify the circuit for students to build, the circuit does not operate at far distances. This kit should operate from within a foot.

6. The students are to find the optimal resistance so that the light operates at moderate distances and still turns off.


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The Artificial Eye Activity

Figure 3 – Artificial Eye Implant

DURATION 45-50 Minutes

CONCEPTS Bioengineering

Human Sight Systems Engineering Sight

Artificial Eye Activity


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BIOENGINEERING INTRODUCTION Background Information Bioengineering is the application of science, mathematics and engineering principles to define and provide solutions to problems in the fields of biology and medicine. An example of a product created by bioengineers is the artificial eye.

Bioengineering Background Group Discussion: 5 Minutes (Pose the following questions to the group and let the discussion flow naturally…try to give positive feedback to each child that contributes to the conversation.)

Q: What do you think bio (biology) means?

• The study of life and a branch of the natural sciences that studies living organisms and how they interact with each other and their environment.

• The study of the environment. • The study of living organisms and living systems.

Q: What do you think engineering is? What do you think it means to be an engineer?

• A technical profession that applies skills in: o Math o Science o Technology o Materials o Structures

Discuss with the students what bioengineering is and the broad scope of areas that bioengineering includes. For this discussion, provide students with examples of bioengineer products and applications.

• Bioengineering applies engineering principles in the fields of medicine, biology, robotics, and any other living system.

• Examples of products that have been bioengineered are: o Artificial Hearts o Artificial Heart Valves o Stents o Catheters


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HUMAN SIGHT INTRODUCTION

Background Information The power of sight is one of the five senses humans have. Sight is processed by an impressive organ called the eye. The human eye can detect shades of light and shades of colors. When light reflects off an object, these shades of light and shades of colors are collected by our receptors in the eye. Receptors then send electrical pulses to the brain for processing via the optic nerve.

Simplified Definitions Cones: Receptors in the eye that are stimulated by colors Rods: Receptors in the eye that are stimulated by different intensities of light Optic Nerve: A sensory nerve that allows the receptors in the eye to send electrical pulses to the brain Visual Cortex: The area of the brain that processes vision. This is located in the back region of the brain, the occipital lobe. If you fall on the back of the head and you see stars, it is because the visual cortex of the brain was stimulated by the shock of falling.

The Importance of Sight Group Discussion: 5 Minutes (Pose the following questions to the group and let the discussion flow naturally…try to give positive feedback to each child that contributes to the conversation.)

Q: What are the five human senses?

• Seeing • Hearing • Tasting • Touching • Smelling


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Q: If you were to lose the sense of sight how would life be different? Give a few examples of some daily difficulties

• Having a hard time cooking • Having a hard time walking • Having a hard time being aware of their own surroundings

Hand out papers and pens to each student. With the students’ eyes opened, have them write their names on the piece of paper and draw their own hand (without sketching around their own hand). With the students’ eyes closed, have them write their names on the piece of paper and draw their own hand again. Ask the students if it was more difficult to write and draw with their eyes closed. Q: What kind of diet can help maintain healthy eyes?

• Eating carrots can help with keeping health vision • Carrots contain vitamin A – this is an essential vitamin for maintaining healthy vision • Vitamin A can also be found in milk, egg yolks, and cheese

Q: What is the difference between nearsightedness and farsightedness?

• Nearsightedness – Condition in which an individual has difficulties viewing objects from a distance. • Farsightedness – Condition in which an individual has difficulties viewing objects from a close distance.

Q: What are some animals with excellent vision?

• Eagles - eyesight about 3-4 times better than a human • Vultures - keen eyes for seeing far distances • Owls - excellent night vision


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ENGINEERING SIGHT INTRODUCTION

Background Information Engineers and scientist have been studying how the human eye works and functions in hopes of finding a solution for the visually impaired. Currently, bioengineers are working to develop a device called the artificial eye. The artificial eye is a device that allows the individual to receive and process light, and stimulate the brain.

Engineering/Technical Aspects Group Discussion: 5 Minutes (Pose the following questions to the group and let the discussion flow naturally…try to give positive feedback to each child that contributes to the conversation.)

Q: How can engineers replicate receptors in the eye?

• With the use of electrodes that respond to light signals • With the use of a camera

The human brain responds to and sends out electrical pulses. To communicate with the human brain, engineers construct devices that can send and receive electrical pulses. However the human brain is complex and differs from person to person. Can anyone think of some difficulties engineers must deal with?

• Engineers do not know the location in which to stimulate or receive signals to or from the brain • Implanting electrodes into the human eye • Designing electrical pulse for different individuals • Stimulating the brain to know the difference between light, dark, or different colors


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Learning Objectives By the end of this exercise, students should be able to…

• Describe and identify the biological equivalent of parts of the artificial eye kit • Describe and identify the engineering parts of the artificial eye kit • Create and use the data table to find optimal performances of a circuit

Materials 1. Infrared LED Flashlight 2. Photodiode LED (Black) 3. Red LED (Clear) 4. Yellow LED (Yellow) 5. Breadboard (Pre-wired) 6. IC Chip 7. 2 AAA Batteries

8. Battery Holder 9. Switch 10. Resistors (68Ω, 10 Ω, 100 Ω, 1k Ω, 1 M Ω) 11. Capacitor (1 pF) 12. Laminated Biology Sheet 13. Laminated Engineering Sheet

Procedure

1. Students should be working in teams, with two students per team. Assign roles for each member of a group: a Design Engineer and a Performance Engineer. Have the model eyeball demonstrated in front of class.

2. Have the Design Engineer collect the necessary materials for the group. This student will follow the illustrated Activity Instruction sheet to construct the artificial eye onto the breadboard. Have the student build with the 1 kΩ resistor first. This resistor value will allow the circuit to operate at a fair distance.

3. While the Design Engineer is constructing the artificial eye kit, have the Performance Engineer test the infrared LED flashlight with the model eyeball in the front of the class.

4. Have the Performance Engineer test the circuit. This student will place different resistors onto the breadboard for testing. They will be testing the circuit for its maximum distance of the infrared LED Flashlight operating with their artificial eye kit. Each distance will be recorded in a data table under the Artificial Eye Activity Worksheet.

5. Have each group decide which resistor is best for the artificial eye. Then have both engineers work together to fill out the Matching Chart portion of the Artificial Eye Activity Worksheet.

Artificial)Eye)Activity)–25)Minutes)


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Concluding Discussion Have the class go over the Artificial Eye Activity Worksheet. Ask the students the following questions: Q: With what resistor value did the red LED stay constantly on? Q: With what resistor value did the circuit operate the furthest with the ability to turn off? Have the class take a poll of which resistor is best for the more optimal artificial eye circuit.

• The answer should be the 1 MΩ resistor

Q: Can anyone guess why a person might see stars when he/she falls down on their back side of their head? (Do not allow students to test this theory!)?

• A blow to the back of a person’s head stimulated the optical lobe which can cause a person to think he/she sees stars

Q: What are some problems with the artificial eye stimulating the brain? • Engineers and Scientists have a hard time stimulating the exact location of the brain

Q: What is another application of the artificial eye?

• Engineers can implant artificial eyes to robots

Tell the class some fun facts about the human eye:

1. A shark’s cornea is similar to that of a human’s and is sometimes used in eye surgery.

2. People generally read 25% slower from a computer screen than compared to reading from a piece of paper.

3. All babies are color blind when they are born.

End)Artificial)Eye)Activity)


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ARTIFICIAL EYE ACTIVITY WORKSHEET

Team Members: Design Engineer: _____________________________________ Performance Engineer: _____________________________________

Data Tables:

Testing the Artificial Eye Resistor Values Maximum Distance Still Working (inches)

10 Ω 100 Ω 1 kΩ 1MΩ

No resistor

Matching Chart: Match the following components from the Biological Human Eye column to the Engineered Artificial Eye column by drawing a line connecting between the items that match. (See Biology Sheet for additional assistance) Biological Human Eye

A. Eye B. Cones and Rods Receptors C. Optic Nerve D. Occipital Lobe (Back of Brain)

Engineered Artificial Eye 1. Infrared LED (Black LED) 2. Red LED 3. IC Chip 4. Wires


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ARTIFICIAL EYE ACTIVITY WORKSHEET ANSWERS

Data Tables:

Testing the Artificial Eye Resistor Values Maximum Distance Still Working (inches)

10 Ω 0 100 Ω ~1 1 kΩ ~4 1MΩ ~10

No resistor Never Turns Off

Matching Chart: Biological Human Eye

A. Eye B. Cones and Rods Receptors C. Optic Nerve D. Occipital Lobe (Back of Brain)

Engineered Artificial Eye 1. Infrared LED (Black LED) 2. Red LED 3. IC Chip 4. Wires

A=1 B=3 C=4 D=2


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ACTIVITY INSTRUCTIONS

List of Materials

Building the Artificial Eye 1. Check to see all materials listed above are available. (Note: The IC Chip is very delicate and will

be given out by the instructor)

2. Place the electrical components listed on the back into the breadboard slots indicated by the pictures. (Excluding the resistors)

3. Take the 1kΩ resistor and place it into slots D8 and A9 of the breadboard (orientation does not matter). To modify the performance of the Artificial Eye, this resistor value may be altered by the Performance Engineer.

a. 10Ω resistor (Color code Brown Black Red) b. 100Ω resistor (Color code Brown Black Orange) c. 1kΩ resistor (Color code Brown Black Yellow) d. 1MΩ resistor (Color code Brown Black Green) e. No resistor (Having no resistor equals infinite resistance)

4. Remove and set aside (do not lose) the pink stopper from the Infrared LED Flashlight. Using the

flashlight, test the maximum distance the circuit detects the infrared light and record the results on the worksheet.

PART FUNCTION Infrared LED Flashlight Emits infrared light Photodiode LED (Black) Receives infrared light Red LED (Clear) Represents electrical pulse sent to the brain Yellow LED (Yellow) Indicates power is on Breadboard (Pre-wired) Platform for kit IC Chip (Given out by instructor) Processes electrical signals 2 AAA Batteries Provides power to the kit Battery Holder Incases the battery Switch (Already glued to Breadboard) Turns the kit on or off Resistors ( 10Ω, 100Ω, 1 kΩ, 1MΩ) Used for gain adjustments Capacitor - 1pF Assist in processing electrical signals


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ARTIFICIAL EYE CIRCUIT BUILDING HANDOUT Note: The Numeric and Alphas enclosed in boxes represent locations on the breadboard

1. Note: the orientation of the dot and notch in the IC chip indicate the top. Place the IC chip on the breadboard with the pins in the following orientation.

2. Place the battery pack onto the breadboard in the following orientation.

3. Place the Yellow LED onto the breadboard in the following orientation. Note: The straight wire on the LED goes to the Blue Line on the Breadboard, while the bent wire goes to position B30.

4. Locate the capacitor and place one of the prongs in B9 and the other in B10. Orientation does not matter

5. Place the Red LED, which is clear, onto the breadboard in the following orientation. Note: The straight wire on the LED goes to the Blue Line on the Breadboard, while the bent wire goes to position B30.

6. Place the Photodiode LED, which is black, onto the breadboard in the following orientation.

E8

E9

E10

E11

F8

F9

F10

F11

I 25 I 20

Blue Line B30

B9 B10

Blue Line A8 D5 G5




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7. Locate the Resistor (10Ω, 100Ω, 1K Ω, 1M Ω) and place one end into D8 and the other end into A9. The orientation does not matter.

10Ω

100Ω

1KΩ

1MΩ




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BIOLOGY SHEET Matching of Biological Equivalent Components

Answer the following questions below then use the answers to match the biological components of an eye to the electrical components of the Artificial Eye

Name the receptors that convert light signals into electrical signals.

What body part is used for receiving light signals?

How do electrical signals travel from the eye to the brain?

What region of the brain is stimulated by the visual electrical signals?

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ENGINEERING SHEET Answer the following questions below. Think about the similarities between the electrical components in the eye kit and the organs in the body.

What electrical component can be used for receiving infrared light?

Which component reacts when an electrical signal is received?

How does electricity travel between the components?

What electrical component can be used for processing signals?

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IMAGE SOURCES

[1] Schubert, E. F. Light-Emiting Diods. Cambridge University. JPEG file. http://www.ecse.rpi.edu/~schubert/Light-Emitting-Diodes-dot-org/chap16/F16-01%20Human%20eye.jpg

[2] The Bionic Man Wears Glasses. 2007. News as Cyberpunk. JPEG file. http://www.cyberpunkreview.com/news/bionic-eyechip3.jpg [3] Jen. MS Optic Nerve Attacks and Symptoms. 2008. MS Strength. JPEG file. http://www.msstrength.com/ms-optic-nerve-attacks-and-symptoms/ [4] Hecker, Miles. Light—Color & Human Vision. 2001. The Luminous Landscape. JPEG file. http://www.luminous-landscape.com/tutorials/color_and_vision.shtml

EXTENDED INFORMATION/RESOURCES

Rods and Cones http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html

Nearsighted and Farsighted http://www.everydayhealth.com/vision-center/the-eye-exam/nearsighted-farsighted.aspx

Bionic Eye Video http://www.youtube.com/watch?v=GZ0G9odShF4




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REVISIONS

Date Changes Made Changes Made By

3/26/2013 Updated formatting. Added table of contents and work cited page. Fixed grammar and syntax issues.

Todd Jackson

Artificial Eye Lesson Plan

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