Abstract

The experiment involved constructing a microphone from the materials given to us. Our group was supposed to make as sensitive microphone as possible. This laboratory was also intended to introduce the concept of “sensor” materials which can be made to act as electric sense organs. Our group has lost the competition, but even so by the end of the lab we understood how the microphone works and was able to construct it and test it using the Lab VIEW program.

Introduction

A real microphone consists of a diaphragm that is connected to a magnet. Sound waves vibrate the diaphragm and move the magnet in and out. The magnet is inside a coil of wire. When the magnet moves inside a coil of wire it produces a voltage signal through the wire.

Experimental Work

In order to build piezoelectric microphone successfully our group began by thinking of our initial idea for the design. We drew it to the best of our knowledge to get the best results. After that our group got all the necessary parts and began the construction. After a lot of thinking and arguing it was decided to use a small paper cup, aluminum foil, rubber band, scotch tape and of course piezoelectric film. As the parts were put together we made sure that as the sound goes into the microphone it would pick up all the sounds and produce clear result. Then our group made sure that it doesn’t fall apart and taped the piezoelectric film to the top of the aluminum foil and tied it together with a rubber band. And only then our group began testing. Our results were not so good, so we began to improve the design by changing the amount of layers of aluminum foil and by trying to cover the top of the paper cup with plastic. Each time our group tried to improve the microphone and tested it, the results were different.

Data and Observations

Our microphone was constructed using a small paper cup. It was thought by the members of our group that a small cup would help focus the sound in one place. Inside the cup our group has placed layers of aluminum foil, because we thought it would prevent the sound from leaving. At the bottom we made a hall for the piezoelectric film.
When our group was observing the printouts from the LABVIEW we looked at both Time Domain and Frequency Domain.
Our Time Domain wasn’t as high as others, but piezoelectric microphone worked fine and we competed with everyone else. Our Frequency Domain wasn’t high either and on the graph you can see two peaks instead of one.
Our group also made some observations about the audio. It was difficult to tell the frequency and very difficult to analyze how the microphone responds to certain sounds. It allows people to hear the clarity of a sound produced by a microphone. As far as visual observations, it allows us to analyze the wave the microphone produces. It isn’t useful in allowing people to determine how the microphone actually sounds.

Conclusion

In conclusion I’d like to say that this experiment has taught us not only how to build a piezoelectric microphone, but also about piezoelectric films that we knew nothing about before, and how we can use them in other places.
Piezoelectric means composed of crystalline material that when mechanical stress is applied an electric charge is produced. The molecules of crystalline material compress and expand and this causes a voltage to appear at the opposite ends of the film.
Some of the places where we might use piezoelectric microphone might be motion detectors, touch-sensitive pads or airbags deployment systems. I think it would be a great idea to use them in airbags deployment systems, because they would be able to tell how short or tall, large or small the person is and adjust the airbag accordingly. I believe this would prevent a lot of injuries.
1. Why can piezoelectric film be used as a sensor?
Piezoelectric film can be used a sensor because it is sensitive and picks up sounds very easily. If it is located at the right place and surrounded by the right environment it can pick up noises that are hard to hear and vibrate.
2. What difference would the size and shape of the material make?
The