Nanotechnology in Secondary Science Classroom: Modeling a Gas Sensor

NANOTECHNOLOGY IN SECONDARY SCIENCE CLASSROOM: MODELING A

GAS SENSOR

Elena Cox, Ph. D.,Curriculum & Instruction,

Texas A&M University, CommerceThe 7th Annual Texas STEM Conference

DallasFebruary 6, 2014

Introduction

Research Experience for Teachers (RET) program at Georgia Institute of Technology

Research team at Mechanical Engineering worked with developing and designing microelectromechanical gas sensors

Clean room

• Air

• Clothing

• Rules of behavior and safety

• Introduction to the latest equipment and advances in science and technology available in the area of nanotechnology.

Microelectronic Fabrication Micro gas sensors are fabricated on silicon

wafers which I saw there for the first time.

Microelectronic Fabrication

One thing is to see the pictures of computer chips in textbooks, and another thing is to actually to learn how to make them yourself.

Microelectronic Fabrication

The professor in charge of the research team has more than 200 patents and supervises a research group of graduate students, always found the time to introduce me to microelectronic fabrication and to teach me how to work with silicon wafers.

Basics of Photolithography

Most of the time during the Summer RET program was spent learning about and working with nano photolithography


As a part of research team, I was allowed to work in a clean room performing the following operations:

Spinning of photoresist:


Aligning the mask:


Developing photoresist:


The pattern quality check by using profilometer and a microscope:


Chemical and plasma etching


Cutting the wafer and glass bonding:


All this work was required to manufacture a gas chromatographic column less than 1/3 of an inch but 2 meters long.

Chemistry TEKs

(4) Science concepts. The student knows the characteristics of matter and can analyze the relationships between chemical and physical changes and properties. The student is expected to:(D) classify matter as pure substances or mixtures through investigation of their properties.

Gas Chromatograph: Separation of Mixtures

http://en.wikipedia.org/wiki/Gas_chromatography

Gas Chromatograph

Macro-scale Gas Chromatographic Column

Gas Chromatographer Video

Miniaturized Gas Chromatographic Column on Silicon Wafer

2 cm

SEM of a DRIE etched silicon microchannel of GC.

Noh et al., 2002

SEM images of a parylene-coated silicon microchannel.

Noh, 2004

Column geometry. Parylene column (middle) and parylene

column with heat diffuser (right)

Noh et al., 2002

Introducing Nanotechnology by Modeling the Gas Sensor

I could talk to students about the properties of atoms in more detail because I was working with structures on atomic level.

I was able to develop a lesson plan and conduct a lesson based on the knowledge I gained during RET on chromatography pertaining in a separation of mixtures unit.

Chromatography Concept and Chemistry TEK 4d

The chromatography lesson was presented at teacher conferences in Washington and San Francisco.

Modeling Gas Nano-Sensor at Texas A&M University: Project-Based Learning in STEM

classroom

CANDY CHROMATOGRAPHY: MODELING A GAS SENSOR

In your bag:• small bowl• coffee filters • droppers • Plate • 2 Clear drinking glasses filled with water• Drinking glass filled with salt water • Skittles, Gobstoppers, M&M's Ruler • Pencil• Food colors• Silica gel

Food Colors Separation

Put silica gel into one of the clear glasses filled with water. Wait for about 1 minute for crystals to absorb water.



Using dropper, put several drops of food color mixture on the silica gel after it increase in size.



Using dropper, put several drops of food color mixture on the silica gel after it increase in size.

Pour some water over the silica gel/the drops.

Food Color Separation

Food Color Separation

What do you observe? What food colors were mixed?

Food Color Chromatography

Take the unused tall clear glass filled with water covering the bottom of the glass.



Take a strip of filter paper. Roll it over the Q-tip



Take a strip of filter paper. Roll it over the Q-tip

Using a pencil and a ruler, draw the line about ¼” from the edge of the paper

Mark a dot where you will put your separation mixture with a pencil


Using a dropper, put one drop of a food color mixture on the dot on the filter paper


Carefully place the Q-tip with filter paper inside your glass with water.

Wait for the water to start rising on the filter paper.

Food Color Cromatography


What changes of your dot do you observe?

What colors do you think were mixed together? Can you tell the difference between colors?

Candy Chromatography Take out a dinner plate and lay one of

each color of Skittles, leaving a little space around each one.

Using a pipette or dropper, squeeze a little water onto each piece of candy to start dissolving the shell.

While you wait for the candy to dissolve, draw a pencil line about 2 cm from the bottom edge of the paper. Do not use pen, because the ink will run. This is your origin line.

When the water around the candy has turned color, squeeze the colored water into the pipette bulb.

Drop a few drops of colored water on the origin line on your filter paper. You may need to add several drops to ensure you have enough dye.

Repeat this with each color, leaving about 2 cm between each color

Let the filter paper dry completely.

Place filter paper in the glass with salt water so that it is standing up and the bottom is barely touching the surface of the salt solution.

You can tape the top of the filter paper to a pencil and hang it down into the solution if you have a hard time getting it to stay right at the surface.

Observe the salt water rising up the paper by capillary action until it is almost at the top.

Remove the paper from the glass and mark with a pencil where the solvent stopped.

Let the paper dry completely.

Repeat the experiment using M&M's, Gobstoppers or other dyed candy and compare like colors. Is the red dye the same in all of the candies, or do the colors run differently?

Nanotechnology in Secondary Science Classroom: Modeling a Gas Sensor

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