INVESTIGATION 1

Overview

Nanosized objects are so small we cannot

measure them directly - the usual

instruments we use for measuring at the

macroscale (like rulers and balances) will

not work. So, we need to use indirect

ways of measuring – these methods are

as ingenious as they are varied. This

investigation looks at some of the ways of

measuring at the nanoscale.

In this investigation you will look at how to:

see microscopic objects using little

more than a laserpointer;

use a ruler to estimate the size of a

molecule;

use a laserpointer to calculate the

width of a hair;

investigate ways of describing the

nanoscale.

The activities are simple to do, but

endlessly challenging in their

interpretation.

Some mathematics is required.

Before you start?

1. Think about how you will record

your results for your final

presentation. Some of these

activities need to be done in a

darkroom. Others will take some

time to set up - so use of a

camera or video would be good

your presentations.

2. Whether you do all of the activities

or focus on a few is up to you.

Perhaps try a few favourites first.

Then as a group decide what you

want to focus on to further

investigate and present on.

3. Do not rush. Examine the method

beforehand and imagine yourself

doing each of the steps

beforehand.

4. Collect and assemble any

materials you will need in the one

place. Consult with your mentor.

5. Wear safety glasses while in the

Studio

Icebreaker: water-drop projectori

In this activity you will use a hand-held

laser pointer to view the organisms found

within a single water drop. The aim is in

part to show that we do not always need

expensive equipment and materials to do

interesting science. While there is nothing

particularly nano about this activity it is a

nice lead in to a later activity where we will

be using the laser pointer again.

Materials

1. Green laser pointer

2. 50-100 mL plastic syringe

3. 2 x retort stands

4. Dark room

5. Blank wall to project magnified

image

Method

1. Find a completely dark room.

Using the syringe, collect a sample

of water from a pond (one that

contains decaying plants is ideal).

Try to catch some very small

animals (0.2mm to 0.5 mm) that

move around in the water (in

general they will be found close to

the bottom of the pond).

2. Fix both the syringe and the laser

pointer into separate retort stands

so they imitate the arrangement in

the figure (which uses lego blocks)

3. To create a lens, carefully push the

syringe piston until a water drop

(about 2 mm in diameter) is formed

at the end of the nozzle.

4. Place the syringe holder on a table

about two meters away from a

screen or white wall.

5. Switch on the laser pointer and

adjust the beam to point exactly

through the middle of the water

drop and onto the screen.

6. With the right adjustment of the

laser, a bright spot extends in to a

large round image on the screen

about 2 m in diameter.

Figure 1: Water drop projector experimental setup. Substitute retort stands for the lego blocks.

Figure 2: Photograph of projected water flea image (Daphnia species). The actual size of the

projected image is about 1 x 1 m.

Main Investigation 1: Measuring the size of a molecule (oleic acid)1 Aim

To estimate the length of an oleic acid molecule. When Benjamin Franklin (1706-1790) was a passenger on large sailboats he learnt that cooking oil was often poured overboard. He observed the oil would spread out and calm the ocean waves. He conducted experiments on a pond and discovered that a small volume of oil created a very thin film with a very large area. When oleic acid (a type of oil) is dropped onto water it spreads out to form a film that is only one molecule thick. Ask your mentor:

1. What is the chemical formula and appearance of an oleic acid molecule?

2. Why does oleic acid spread out to be one molecule thick?

3. How can a lump of plasticine be used to model this activity?

If we know the volume of the drop, and the area of the oil film we can calculate the width of the oleic acid molecules. In this investigation we will drop a small volume of oleic acid onto the surface of a tray of water and analyse the thin film that results.

1 This version of a traditional oleic acid

activity by UMass Amherst.

Disposal

Oleic acid dilutions can be washed down the sink with water. Materials

1. oleic acid 2. ethanol 3. Lycopodium powder 4. Plastic cups (disposable) 5. Pipettes (disposable) 6. Shallow tray or basin

(50cm x 50 cm)

7. 2 x 25 mL Graduated cylinders 8. Beakers 9. 1 x 10 mL graduated cylinder 10. Paper towels

The Procedure Ask your mentor: How do we prepare the dilutions of oleic acid? How do we take the measurements?

Create a work space large enough for a circular tray, graduated cylinders, paper towels, plastic cups, a pipette and a ruler.

1. Put water in a circular tray to form a layer of water

2. You will be given a small amount of oleic acid in a small cup.

3. Also, a bottle of ethanol.

Make solution #1

1. Use a pipette or a 10 cm3 graduated cylinder to measure 1.0 cm3 of oleic acid

2. Put 1.0 cm3 of pure oleic acid into a 25 cm3 graduated cylinder

3. Add alcohol to the oleic acid in the 25 cm3 graduated cylinder until the total volume of solution #1 is 25 cm3

4. Transfer the solution back and forth between a cream plastic cup and the 25 cm3 graduated cylinder to mix the solution. In the last step of the mixing process, Solution #1 should be in the plastic cup.

Make a more dilute solution # 2

1. Put 1.0 cm3 of Solution # 1 into a 25 cm3 graduated cylinder.

2. Add alcohol to the 1.0 cm3 of solution #1 until the total volume of the Solution #2 is 25 cm3.

3. Transfer the solution back and forth between a clean plastic cup and the 25 cm3 graduated cylinder to mix the solution. In the last step of the mixing process, the second oleic acid solution should be in the plastic cup.

Count the number of drops in 1.0 mL of

solution # 2

1. Use a plastic pipette and a 10 cm3 graduated cylinder to determine and record how many drops (N) are in 1.0 cm3 or solution #2

Make an oleic acid thin film

1. Use baby powder (or chalk dust, very finely ground pepper, etc.) to lightly cover the surface of the water in a large food tray.

2. Use a medicine dropper to drop one drop of solution 2 onto the centre of the surface of the water in the circular tray.

3. Allow a short time for the alcohol solvent to dissolve in the water. The remaining oleic acid will not dissolve in water and will spread across the surface of the water.

4. Use the ruler to determine the average diameter (in centimetres) of the circular layer of oleic acid. Record the average radius of the area.

Calculate the Depth (thickness) of the layer of oleic acid

1. Record the information for each step on an Oleic Acid Calculation Worksheet

Oleic Acid Thin Films Calculation Worksheet

1. Write a fraction that represents the volume of oleic acid in 1.0 cm3 of the first solution.

2. Change the fraction of oleic acid from step 1 to a decimal form

3. Calculate the volume of oleic acid in 1.0 cm3 of solution #2

4. Record the number of drops in 1.0 cm3 of solution #2

5. Determine the volume of oleic acid in one drop of the Solution#2

6. Record the average radius of the circular area of the thin film (in centimetres)

7. Calculate the area of the thin layer of oleic acid (in square centimetres)

8. Calculate the thickness (depth) of the thin layer of oleic acid (in centimetres)

9. Convert the thickness of the layer of oleic acid from centimetres to meters.

10. Record the thickness of the thin film in nanometers. Brainstorming List any ideas for varying or extending this activity

Main Investigation 2

Part A: Using a micrometer screw gauge

Your Goal A micrometer measures very small lengths very accurately in millimetres. In this

activity your goal is to measure the diameter of a hair using a micrometer. You will then

compare this to the diameter of the same hair using a laser pointer in the next activity.

Note: Micrometers are sensitive instruments and are easily damaged.

Mentor staff will explain how to zero, read and look after the instrument.

Materials and Equipment

1. Micrometer

2. Items to measure (coin, wire, paper tissue, hairs)

Method

1. Clean jaw faces before checking zero error

2. Check zero error (use ratchet knob only)

3. Place object to be measured between spindle and jaw and take 3 readings

4. Calculate the mean (DO NOT over tighten the main knob)

Note: Always leave the jaws open when packing away

Reading the scale

1. This micrometer reads 26.32 mm. Set your micrometer to 18.45mm.

2. What are the measurements on these micrometers?

3. Using a micrometer, measure the thickness of the following:

Item Size (mm)

A - thickness of a coin

B - width of wire (copper)

C - thickness of - paper tissue

- aluminium foil

D - Compare the width of 3 hairs

from different people. Is there a

measurable difference?

4. What is the smallest item you can measure with the micrometer?

5. What is the mean diameter of a human hair in micrometres?

Part B: Measuring diameter using laser diffraction

Materials

1. Red laser 2. Slide holders 3. Scissors 4. Sticky tape 5. 1 x meter rule 6. 1 x 30 cm ruler 7. whiteboard 8. whiteboard marker 9. calculator

Method and Results

1. Using scissors cut a single strand of

hair from your head, or get your partner to do it for you

2. Attach the hair vertically on the slide holder by sticking each end down with a piece of sticky tape. Ensure that the hair is taut by attaching one end first, pulling tight, and then attaching the other.

3. Tape the slide to the bracket in front of the laser.

4. Stand near the laser spot on the whiteboard. Get your partner to move the slide back and forth in front of the laser. When the hair crosses the laser beam, the spot will change into an elongated diffraction pattern, so keep your eye on it, and let your partner know when an optimal pattern has been achieved!

5. Using a ruler, measure the distance between any two adjacent bright spots in the pattern. If the distance from the hair to the screen is much larger than the spot separation on the whiteboard, then the hair diameter d is given by:

d ≈ Lλ/D where: D = average spot separation on the white board (cm) L = distance from hair to the whiteboard (cm) λ = laser wavelength (0.633μm).

6. Calculate the value of d in μm.

Extension ideas?

List your ideas for extending this activity here.

Part C: Explaining the nanoscale

How can you describe the nanoscale to someone for whom it is all new? How much is a

nano of anything? What does 1,000,000,000 look like as a number? Getting a sense of just

how small nanoscale objects are is not easy. People have, however, come up with many

inventive ideas, some of which can be found at the following websites:

mrsec.wisc.edu/Edetc/curriculum/index.html

pbskids.org/dragonflytv/show/whatsnano.html

The time it takes for one thousand million lollies to pass along a conveyer belt. The size of a

playing field that contains one billion blades of grass. These are all ways of representing

nano.

Can you come up with ways of your own?

Putting it all together

You have now explored a number of ways of indirectly measuring the size of small objects.

Many of these same methods can be used to calculate the size of nano-sized objects. If you

have not done so already, think of what you have discovered and look for ways of extending

the activities – you might, for example, look at new objects to measure using any of the

techniques we have used; or you might look for ways of improving these techniques.

You may have also investigated ways of describing the nanoscale and perhaps have also

come up with your own.

Further resources on the internet

The number of nanotechnology websites is huge. Many hours could be spent with

interesting, but possibly pointless searching when exploring around the expert

inquiry investigations. Following is a list of some of the better or more useful

websites you may like to visit. We have kept this list short to help give focus.

A good approach would be to start work on your expert inquiry first. Then, once you

are under way start to use these websites for additional information, activities and

presentation ideas. Websites are invariably aimed at different age groups and

different levels of expertise – everything from primary level through to expert level.

Keep that in mind while searching – quoting jargon from a technical manual with

have both yourself and those around you frustrated. But, at the same time it can be

worth looking at to challenge yourself. If you can’t understand it then no-one else will

– so move on. Meanwhile, primary activities can seem simplistic. However,

presenting things in simple terms is a challenge. When it comes to education,

primary instructors often lead the way.

While these websites are primarily from the UK and USA please keep in mind that

nanotechnology is truly a global activity including countries from all around the world.

Japan, Germany and the USA are the biggest participants in the field.

General Information

www.technyou.edu.au/resources This website has some useful nanotechnology

fact sheets.

www.understandingnano.com General information about nanotechnology and its

applications

www.nanowerk.com If you want to explore nanotechnology in general this is a

good starting point. Lots of links in lots of different directions.

www.nano.gov One of the more interesting general link websites out there with

some solid links

www.livescience.com/nanotechnology A good collection of nano related news

stories

www.nanotech-now.com Not a bad collection of web links

www.smalltimes.com Online nanotechnology magazine. Quite senior in tastes.

www.sciencecentral.com Information and videos on current nano research. Click

on technology for nano info.

www.nanooze.org/english/article_listing.html School-age magazine on

nanotechnology

www.nanohub.org/education/nanotechnology101 Would you like to get a taste

of University level studies? This site features university lectures on a wide range of

nano-related topics. Want the undergraduate lectures? Then visit the 101 lectures.

Ready to move up to graduate level? Then try the 501 series.

What is nanoscience and nanotechnology?

www.nanowerk.com/news/newsid=16048.php If you are a Stephen Fry fan and

can’t get enough, he has even turned his attention to nanotechnology. Aimed at the

younger middle-school student.

www.sciencemuseum.org.uk/antenna/nano Offers overview of some of the uses

of nanotechnology. Flash game available that looks at how properties of matter differ

on a nanoscale

www.ucsd.tv/getsmall Video gives a good introduction to nanotechnology with

high production values. Aimed squarely at middle-school students.

www7.nationalgeographic.com/ngm/0606/feature4/index.html National

Geographic article about nanotechnology entitled “Nano’s Big Future.” By Jennifer

Kahn.

Presentation ideas

www.nisenet.com This site features many ideas for presenting nanotechnology to

the public. The website is the result of multiple partnerships between science

museums and research organisations.

Pbskidsgo.org/dragonflytv This website has very high production values with

video content and activity ideas that cover everything from where’s nano?; to what’s

nano?; to butterfly wings; surface area; gecko feet etc. Written for younger middle-

school students it is nonetheless a great resource.

The following resources help give a perspective of the nanoscale:

www.mcrel.org/nanoleap/multimedia/Nanosize_me.swf

www.nanoreisen.de

www.micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

www.microcosm.web.cern.ch/microcosm/p10/english/welcome.html

Social and environmental impacts of nanotechnology

www.crnano.org The Centre for Responsible Nanotechnology (CRN) offers

Nanotechnology Basics: for students and other learners

Dictionaries online

http://www.m-w.com Merriam-Webster Dictionary online

http://www.oed.com Oxford English Dictionary Online

Video

Searching for video on nano-related topics? Then don’t forget:

video.google.com

www.youtube.com

www.metacafe.com

i From: Planisic, G, Water-Drop Projector. The Physics Teacher Vol 39, February 2001 pp 76-79