Indium-Tin Indium-Tin Oxide SensorsOxide Sensors

Measuring Atmospheric OzoneMeasuring Atmospheric Ozone

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GeneralGeneral

• The primary goal of the ITO sensor project is to measure the concentration of Ozone (O3) as a function of altitude.

• The concentration of these gases will specify the current situation of ozone depletion.

• These measurements will be compared to past measurements made by other payloads.

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ScienceScience

• The measurement from the sensors depend greatly on temperature conditions, which must remain relatively constant (24 – 30 deg C).

• The obtained measurements are compared with various experiments showing the precise concentration of Ozone.

• Indium-Tin Oxide Sensors have been chosen for this flight.

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TechnicalTechnical

• The concentration of Ozone is calculated as the function of voltage produced across the sensor.

• As the resistance in the ITO sensor varies with the concentration of these gases, different voltages are produced with the same amount of input current in the circuit board.

• The Real Time Clock will be utilized as a counter and a timestamp will be printed for each measurement so that it can be related by time to altitude.

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System DesignSystem Design

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Electrical Design and Electrical Design and DevelopmentDevelopment

Sensors/Sensor InterfacingSensors/Sensor InterfacingControl ElectronicsControl Electronics

Power SupplyPower SupplyPower BudgetPower Budget

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Sensors/Sensor InterfacingSensors/Sensor Interfacing

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Control ElectronicsControl ElectronicsBalloonSATBalloonSAT

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Kapton HeaterKapton Heater

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Power SupplyPower Supply

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Power BudgetPower Budget

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Supply Component Current Drawn Suffi cient Power?10.5V

BalloonSat 53 mA YESITO 1 - 8 8 mA YESThermistor 0 - 0.3 mA YES

3VRTC < 1 micro amp YES

13.5VHeater 173 mA YES

Software DesignSoftware Design

Data Format and StorageData Format and Storage

Flight SoftwareFlight Software

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Data Format and StorageData Format and Storage

• EEPROM will store all data collected on flight

• EEPROM stores addresses for flight software

Byte # Data Stored0 Original Address1 Current Address

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Byte # Data Stored ADC ADC Channel1 - 8 ITOs 2 CH1 - CH8

9 THERM 1 CH110 HOUR N/A N/A11 MINUTE N/A N/A12 SECOND N/A N/A

Flight SoftwareFlight Software

• Read “original address” from EEPROM Address $0000

• Read RTC – 3 bytes

• Read all ITO sensors and Thermistor– 9 bytes

• Store all data from reading • Store current address in

EEPROM Address $0000• Repeat loop until current

address equals 8170– (current_address =

original_address)– LED flashes once per second

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Thermal DesignThermal Design

• ITO Sensors must maintain temperatures between 24 and 30 degrees Celsius

• Kapton Heater• Requires

approximately 1W

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Mechanical DesignMechanical Design•A hollow regular hexagonal A hollow regular hexagonal prismprism

•FOAMULAR Insulating FOAMULAR Insulating SheathingSheathing

External Design:External Design:•Each side of the base = 94 Each side of the base = 94 mmmm

•The height of the prism = 193 The height of the prism = 193 mmmm

•51mm X 49mm rectangular 51mm X 49mm rectangular hole for the ITO sensorhole for the ITO sensor

•The ITO sensor attached The ITO sensor attached from the inner walls; minimal from the inner walls; minimal area of the ITO sensor is area of the ITO sensor is exposedexposed

The external design of ITO sensor payload (in m) 17 of 25

Internal Design:

• Rectangular- shaped foam (thickness = 18 mm) bisects the internal payload in two– Heater Batteries,

Heater, ITO sensors, BalloonSat

– BalloonSat Batteries, Sensor Interfacing Board

• Kapton Heater attached to the back of the sensor with thermal paste

Internal Divider with BalloonSAT (in m)

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a) Side where ITO sensor is attached (in m)

b) Side where ITO sensor is attached with ITO sensor (in m)

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Weight Budget:

• Balloon payload should be less that 500 g

• Density of The FOAMULAR Insulating Sheathing = .029 g/ cm3

S.N.

Components Weight (gram) Clearance (g)

1. BalloonSAT 60 +/- 5

2. FOAMULAR Insulating Sheathing 110 +/- 20

3. Power Supply (Battery) 240 +/- 15

4. ITO sensor and PCB 70 +/- 5

5. Components for Sensor Interface 15* +/- 5

6.7.8.

Mass of cable for ITO sensorKapton Heater/ThermistorTape, Glue and other structure

15*10*10*

+/- 500

Total: 530.00 +/- 50

* Approximated within 0.1g 20 of 25

CalibrationsCalibrations

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CalibrationsCalibrations

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Ground SoftwareGround Software

• Save into text file

• Use Microsoft Excel

• Algorithms pre-programmed

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Risk ManagementRisk Management

User BacklashMalfunctioning of

ITO sensor

Cold Solder JointUnexpected

Weather

Software Malfunctioning

System Freezing

Bad Landing (Not on ground) Batteries DrainedHardware

Malfunctioning

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PROBABILITY

SEVERITY

Special ThanksSpecial Thanks

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