Ozone Team Progress Log
Week of September 1, 2003:
Motorola Ozone Team members will be students
Scott Chao, Allison Douglas, and Kristin Lee, and mentor Markus Stutz.
We decided to do research on existing ozone sensors and how they work, and
on ozone and its effects. We wanted to learn about how ozone was formed, different
types of smog, and how it effected humans.
Week of September 8, 2003:
Our team presented the research we had done
on ozone and sensors to the class this week. This presentation can be found
here.
We had our first teleconference with our Mentor, Markus Stutz. We learned
that Motorola has been doing research on hazardous substances and creating
environmentally friendly devices and components, and in creating an ozone
detector Motorola is hoping to create an environmentally-focused device that
will add value to their products. Markus told us that Europeans are much more
environmentally aware than Americans are, so it seems more likely that there
would be a market for this type of device there. The team decided to do some
additional research to try to find out if anyone in the industry else has
a similar idea they are developing, and also to learn more about ozone sensors
and how they can be used for our project. Eventually we will look into improvement
possibilities for the sensor hardware (smaller size, higher reliability, lower
cost) as well as software possibilities for communication with a computer
and later for integration with a mobile phone.
Week of September 15, 2003:
This week one of our main objectives was to narrow
and define our design challenge. We decided that our design challenge would
be to get an ozone sensor to work with a computer, with potential for integrating
with a cell phone later. It is possible that the sensors we order will include
some type of software package to read the output of the component, but we
do not know yet if they will. Our mission statement can be found here.
We found an ozone sensor made by MicroChemical Systems that we are planning
on ordering and testing. We also are going to get some phones sent from Motorola
so we can learn about how cell phones work in order to know where the sensor
could possibly be integrated. We thought it would also be valuable to buy
some other types of sensors so that we could learn how sensors work in general.
The team also discussed doing some market research, either with paper surveys
or an online survey. We talked about doing research here on campus to see
if people would be willing to pay extra money for an ozone sensor on their
phone. For example, having a short form with a quick explanation of the harmful
effects of ozone and then asking if they would pay $10 more than they paid
for their current phone if the new phone had an ozone sensor on it. This is
not definite and will be discussed in more detail by the group later. We also
sent Markus a more detailed progress report, which can be found here.
Week of September 22, 2003:
We contacted three companies who manufacture ozone sensors: MicroChemical Systems, City Technology LTD., and Sensoric to get more information about prices and technical specifications of their devices. We got replies from MicroChemical and Sensoric- the MicroChemical sensors cost $200 for 10 units, and the Sensoric sensors cost $148 each. This week Markus ordered ten ozone sensors for us from MicroChemical Systems. We are going to be testing and evaluating the sensors to determine how they should be used with a cell phone and/or computer. Markus also reported that he sent us three cell phones: one with no battery, one with a battery, and one with a battery and a charger. These phones will be used by us to develop a more in-depth knowledge of how cell phones work, and also to help figure out where the ozone detector could be added. Two temperature sensors and two infrared light sensors were ordered from Mouser this week so we should be getting them sometime next week. We decided on some circuits to use for testing the sensors based on recommended circuits in the data sheets. These circuits can be found here.
Week of September 29, 2003:
We received the three cell phones from Markus this
week! We are going to get schematics for the one that is non-working so we
can take it apart and know which parts are which. We decided to order some
additional sensors from Sensoric, because they use a different type of technology
for their sensors than MicroChemical does. Markus is going to order three
and send them to us. We tested the temperature and light sensors in the lab
but did not get working results for the light sensors. We thought that the
light sensor circuit was possibly not working due to ambient light hitting
the sensor. Although it was an infrared sensor, some ambient light may have
had an effect on it. The temperature sensor was working but uncalibrated.
We did see a change in voltage when the temperature was raised or lowered.
Week of October 6, 2003:
We presented our results from testing the light and temperature sensors in
class and discussed improvements in our testing method. Click
here for our presentation. The team also made progress in the planning
of a market research survey and discussing using LabVIEW to create a display
for our circuits. We went back to the lab and tested our light sensors again,
this time using a box to cover the emitter and sensor so that it would block
any ambient light. We achieved better results this time but are still unsure
of how to calibrate our sensor.
During our conference call with Markus, we reviewed the types of ozone sensors
we will be receiving. Motorola has purchased for us 10 sensors from MicroChemical,
which are HMOS sensors that use an internal heater. The actual ozone sensing
chip is very small, but the packaging is large, which gives us potential for
a design integrating only the chip and therefore greatly reducing the size
of the addition to the cell phone. The other 3 sensors that were ordered are
from Sensoric. These sensors use less energy because they do not need heat
to measure the level of ozone, but rather uses an organic gel to determine
the ozone level. An interesting fact we learned from Markus is that 10 million
ozone sensors are sold worldwide per year, and projected potential for the
ozone phones is 1 million, which should greatly decrease the price of each
detector.
Week of October 13, 2003:
We are trying to find a contact at Duke either within the Pratt School of
Engineering or at the Nicholas School for the Environment who has experience
with ozone generation and detection. So far we have not found someone here,
but we are being referred to other professors and hope to find someone who
can help us in this area.
The team is also trying to learn more about cell phones and how they work
with the eventual goal of knowing where we could possibly integrate the ozone
detector into an already existing cell phone design. Markus has sent us schematics
and we are examining them and trying to figure them out.
Week of October 20, 2003:
The team planned on creating a simulation of the ozone sensor circuits using
Psched, and had contacted the companies to get information about what the
current and voltage behavior would be for the ozone sensors so we could simulate
them correctly. Later on in the week, Markus informed us that the ozone sensors
from both MicroChemical and Sensoric have been sent and should arrive sometime
early next week. We have contacted individuals from both companies and discussed
the optimal circuit design for utilizing their sensors. We have ideas for
circuit layouts and are planning on acquiring the required components and
building the circuits so they will be ready when the ozone sensors arrive.
This week we also created a survey to try and compile some market research
data. The survey first gives some background information on ozone and its
harmful effects. We also ask for regional location, age, and past cell phone
usage, then ask for how much they would be willing to pay for a cell phone
with an integrated ozone detector. Click
here to take our survey or to view the survey results.
The team decided to contact resources in the Triangle area to get more information
about the ozone alerts in the area and who measures them, how they are measured,
etc. We also are trying to find someone in the area that has an ozone generator
and/or expertise in the area of ozone generation.
Week of October 27 2003:
We are trying to locate an ozone generator or
some other way to collect ozone for testing our sensors. We discussed sources
of ozone generation, including water treatment using ozone and ozone generated
by photocopiers. The team is trying to find a resource at Duke or in the Triangle
area who may have some knowledge about ozone generation and/or detection,
but we have not been successful so far. We did some additional research on
ozone generators and presented the findings in class. Click
here to view the ozone generation presentation. We also researched different
types of wireless technologies and made an in-class presentation. Click
here for the wireless technology presentation.
We received all of the ozone sensors this week from Markus!!!! We are preparing
to test them, and we should be ready in about a week. We got a power supply
and a multimeter from Dr. Ybarra, and connected three of the MicroChemical
sensors to the power supply at 2V with a maximum current of 1.35 A. Our contact
at MicroChemical recommended that we power the sensors for a week before using
them to obtain best results. We have a 100k resistor as recommended by MicroChemical
Systems, and we are working on getting all of the necessary parts for the
Sensoric circuit. We were able to get some of the parts from the ECE department,
and have ordered the additional parts from DigiKey.
Dr. Ybarra informed us that he has a 15,000 volt transformer and a Jacob's
Ladder that will generate ozone. The 15,000 volts is
connected to two copper leads (the Jacob's Ladder) and the voltage difference
causes a current to arc between the two leads. This generates ozone by electrons
from the electric field between the two leads combining with O2
in the air, which creates 2O-. Each of these O- combines with an O2
to create O3, or ozone:
2e- + O2 -> 2O-
2O- + 2O2 ->2O3
For more information on high voltage ozone generation, click
here.
We needed some sort of enclosure to contain the generated
ozone and another enclosure to house the sensor circuit being tested. We wanted
the circuit in a different enclosure than the 15,000 volt transformer both
to serve as a safety precaution and to electrically isolate the sensor circuit
from the transformer. We made measurements of the transformer and Jacob's
Ladder as well as our breadboards so we would know what size to make our boxes.
We spent a couple hours at Home Depot and returned with several pieces of
plexiglass, some L-braces, a plastic hose, and clear caulk.
Week of November 3, 2003:
We picked up the transformer, Jacob's Ladder, and
tools for connecting the generator from Dr. Ybarra this week. He demonstrated
how to operate it in class and what precautions to take in order to ensure
our safety.
We put together the enclosures for the ozone generator and sensor circuits
this week. We had the BME shop drill some holes in the sides of the ozone
box and the circuit box to fit the plastic pipe connecting the two chambers,
and additional holes for the wires to pass through. Then we came back to our
"lab" (also known as Kristin's apartment) to assemble the boxes.
After a few hours of drilling, screwing, and caulking we had two 5-sided clear
plexiglass boxes, with tops to be added later. Our ozone generator chamber
is 16''x20''x36'', which is large enough to fit both the transformer and the
Jacob's Ladder. The circuit chamber is 12''x14''x4'', which is large enough
to fit both circuit boards if we want to test both circuits at the same time.
We are planning on adding a hinged lid to the circuit box so we can easily
take the circuits in and out, and just using a plexiglass platform for the
bottom of the ozone box so we can put the transformer and Jacob's Ladder on
the platform and but the box over it. For a picture of the ozone generator
in the chamber, click
here. For a picture of the circuit chamber with the MicroChemical sensors
in it click
here.
Week of November 10, 2003:
This week we did our first testing of the ozone
sensors!! On Monday we ran the ozone generator for 20 minutes and measured
the voltage across the MicroChemical sensor at 30-second intervals. To see
our MicroChemical Systems circuit, click
here. We got results that were similar to what we wanted and expected,
which was very exciting since it was only our first try. We got an output
graph that was the same shape as the one on the data sheet, but because our
circuit was uncalibrated it didn't have the same values. To see our results,
click here.
Our search for an ozone detector in the area was unsuccessful, so we decided
to order an Eco Sensors portable ozone detector so that we will be able to
calibrate our circuits. We ordered the EZ-1X model, which has a range of 0-.14
ppm, because it is the most cost-effective solution for calibration. We received
the detector on Friday and immediately powered it up using the AC adapter,
because the instruction manual recommended a warm-up time of 24 hours if the
detector had not been used in a week or more. For specs on the EZ-1X ozone
detector, click
here.
Markus has suggested that we try to make a voltage to sound converter to change
the frequency and/or volume of the sound according to the level of ozone present.
Dr. Ybarra recommended two options: first, using a sound generator chip to
control volume and frequency by adjusting signals at two different pins; second,
using a VCO (voltage controlled oscillator) to convert a voltage level to
frequency. We will look into these options further and hopefully have a solution
by the end of next week.
Our current plan is to mainly focus on the MicroChemical sensor since we have
our circuit working and have gotten results using it. We are still planning
on testing the Sensoric sensor but have not yet gotten the circuit working.
We tested it on Thursday with the circuit we had assembled, but did not get
any change in voltage with a variation in the ozone level so we need to examine
our circuit and make some changes to get it working. Click
here to see our Sensoric circuit.
We did some additional testing on Saturday with the MicroChemical sensor circuit
and using the Eco Sensor detector to determine the ozone levels at the measured
voltage levels. We got the maximum level of ozone shown on the detector (.14
ppm) in 9.5 minutes of ozone generation. View our results here. To see a video
of ozone being generated, click
here.
We did some additional testing this week in order
to determine the calibration of our sensor. To view our results, click
here.
The team did some research on voltage converters and decided that our best
option would be to get an IC that converts voltage to frequency. We ordered
some samples of the LM331N converter from National Semiconductor which should
arrive next week. To view the VCO circuit diagram from the product data sheet,
click
here. Markus has sent us some cell phone speakers so we can connect them
to our sensor circuit and hopefully have it working for our final presentation!
We decided to also have a visual display, so that the user can have a display
with text describing what the ozone level is and what precautions to take.
We are going to create this using LabVIEW.
Week of November 24, 2003:
We received the speakers from Markus this week,
and are expecting to receive the voltage-frequency converters soon so we can
get those working. This week we did yet more testing to get more data for
calibration; click
here to see our results thus far. We have encountered an unexpected obstacle
in our testing: the temperature outside is lower than the operating temperature
range for the Eco Sensors detector. When we open the windows to diffuse the
ozone outside, the temperature inside is too low for the ozone detector to
work properly. We have found that to get around this we have to open the windows
and turn the fan on to expel the ozone, then close them to allow the air inside
to heat up. The copper leads and wires in our ozone generator are starting
to turn green as we have seen in copper roofs and the like. We are not sure
why this is happening but are planning on doing some research to find out.
We made a presentation on the MMOS sensor technology (the type of sensor used
by the MicroChemical Systems devices). To view the presentation, click
here.
We made some progress this week on our visual display using LabVIEW. The output
voltage will be read by a DAQ (Data Acquisition) Board and input into the
LabVIEW program, where it will be used to search the database we are going
to create using our calibration values. It will then find the ozone parts
per million value that correlates with the measured voltage level, and a new
window will pop up with the ozone warning level and describe the effects of
ozone at this level and the precautions to take.
Week of December 1, 2003:
We received the voltage-frequency converters
and required capacitors from National Semiconductor and Digikey. We changed
up some of the design on our website and added content that we felt would
be helpful. Also, we added a quick overview on the entire project which can
be accessed here.
We assembled the circuit for the voltage-to-frequency converter. The schematic
can be found here.
We successfully varied the frequency of the audible tone of the speaker by
increasing the input voltage from 0V to 5V, which is the range of the ozone
sensor output.
The LabVIEW code is complete and ready to run! This will enable us to have
a way to indicate the health risk levels by reading the sensor output voltage.
Click
here for a detailed explanation of the LabVIEW code.
We did a cost analysis of the total money spent this semester; to read the
analysis click
here.
