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Nanowire pH Sensors Experiment - Student
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1.
Please identify the school where you performed the Nanowire pH Sensors laboratory:
(Required.)
2.
In what grade are you currently enrolled?
8th grade or younger
9th
10th
11th
12th
3.
After performing this hands-on activity, please rate how well you understand the following:
Not at all
A little
Mostly
Very
A sensor converts one signal (in the nanowire pH sensor example, the chemical signal of acidity) into another type of signal readable to a person (e.g. electricity that lights the LED)
Not at all
A little
Mostly
Very
The longer the conducting wire, the higher its resistance. The wider the conducting wire, the better it conducts (i.e. lower resistance).
Not at all
A little
Mostly
Very
Lower pH solutions have more available protons for acid/base reactions, favoring the protonation processes. If pH is high, the reverse is true.
Not at all
A little
Mostly
Very
Please respond to the following questions.
4.
The sensing element of the sensor (the black goo) is a dense aggregated mesh of nanowires made of a polymer called polyaniline. Because the diameter of each nanowire is small (<50nm), the sensing element of nanowires is significantly more sensitive to the chemical environment than a single indivisible polyaniline film of the same thickness. Why is this the case?
5.
When is resistance of the polyaniline nanowire higher, when exposed to acid or to base? Why is this so?
6.
Why do you have to wait for the polyaniline solution to dry before testing your sensor? Consider what happens if you connect the circuit when the polyaniline is still wet.
7.
The nanowire pH sensor can determine whether a solution is acidic or basic because the solution gives off chemical vapor that is detectable through the air. Provide two examples of instruments you know that can detect chemicals in the air (hint: one is never far from your eyes).
8.
Identify any concepts that you might have better understood after performing this activity:
None
Acid/base/pH
Resistance
Polymer
Sensors
Circuit
Other (please specify)
9.
On a scale from 1 to 4, where 1 means "not at all" and 4 means "very much", rate the following:
1
2
3
4
Did you find the science you learned in this activity interesting?
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2
3
4
Do you want to learn more about how to modify material properties?
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2
3
4
How well can you explain how to build a chemical sensor using nanomaterials to someone who doesn’t know (perhaps a younger sibling)?
1
2
3
4
