Detecting chemicals, measuring strain with a pencil and paper

Detecting chemicals, measuring strain with a pencil and paper

Jan. 22, 2014 — Sometimes solving a problem doesn't require a high-tech solution. Sometimes, you have to look no farther than your desktop.

---

Share This:

Three students from Northwestern University's McCormick School of Engineering -- an undergraduate, a master's student, and their teaching assistant -- have proven that pencils and regular office paper can be used to create functional devices that can measure strain and detect hazardous chemical vapors.

A paper describing their findings, "Pencil Drawn Strain Gauges and Chemiresistors on Paper," was published January 22 in Scientific Reports, an open-access journal from the Nature Publishing Group.

The project originated in fall 2011 in McCormick's Introduction to Conducting Polymers course (MSE 337) during a discussion about the conductive properties of graphene, a one-atom thick layer of carbon that can be parsed from regular pencil lead. (A misnomer, pencil "lead" actually comprises graphite in a clay binder.)

"When you draw a line on a piece of paper, the graphite may shed numerous graphene sheets," said Jiaxing Huang, associate professor of materials science and engineering. "A student asked, 'Can we use that graphene for something?' That started an exploration of what pencil traces can do."

One team of students -- including lead authors Cheng-Wei Lin (MS materials science '13) and Zhibo Zhao (BS materials science '13) -- started by measuring the conductivity of a pencil trace on paper, then used the traces to create a rudimentary electrode. They learned that curling the paper in one direction increased the trace's conductivity by compressing the conductive graphene particles. Curling the paper in the other direction loosened the graphene network and decreased conductivity.

The students then turned to the traces of a bendable toy pencil. (These novelty pencils are flexible because the graphite is mixed not with clay, but with a polymer binder.) Again, conductivity could be increased and decreased by manipulating the paper, but the students found it also was affected by the presence of volatile chemical vapors, such as those from toxic industrial solvents.

When the chemical is present, the polymer binder absorbs the vapors and expands, pushing the graphene network apart and decreasing conductivity. The conductivity decreased the most in the presence of vapors that are more readily absorbed by the polymer binder.

These types of chemical sensor -- also called "chemiresistors" -- are key elements in "electronic noses" for detecting toxic chemical vapors. In creating chemiresistors, researchers often use more expensive materials, such as networks of carbon nanotubes or metal nanoparticles, and need to disperse them in polymer matrix to form a network.

"Now our students showed that this can be done simply with a pencil and paper -- and it works," Huang said. "This is a great example showing how curiosity leads to innovative work."

Other applications of the pencil-and-paper technology could be more unconventional. "It could help to inspire some new form of art," Huang said. "Perhaps one can make 'smart' and interactive drawings, in which the art itself is the circuitry and can respond to the environment."

Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.

Chip Inductors High Precision Resistors Industrial IC HARRIS IC Metal Can Packages Transistors LINEAR IC Chip Ferrite Beads Current Sensors Resistors ON Transistors Resistor Arrays TOSHIBA Diodes MURATA IC TI IC Diodes Inc Electronic News NXP Transistors AD IC Civil IC Other Parts IR transistor Rectifier Diodes Xilinx IC Fairchild Semiconductor Transistors Atmel IC INTERSIL IC PANASONIC Resistors Renesas parts IC Voltage Regulators Transistors MOTOROLA IC Resistor Networks YAGEO Resistors Schottky Diodes Microchip IC Chip Fuses ELPIDA IC NS IC Discrete Semiconductor Transistors DIODES Transistors Zener Diodes Texas Instruments(TI) IC
http://www.suvsystem.com/a/9552.aspx