INDIUM-TIN OXIDE SENSORS

Science ReportScience Report

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GENERAL• The primary goal of the ITO

sensor project is to measure the concentration of Ozone (O3) as a function of altitude.

• Ozone concentration will be measured with an Indium-Tin Oxide Sensor provided by Dr. Patel.

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

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SYSTEM DESIGN

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SENSORS/SENSOR INTERFACING

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CONTROL ELECTRONICSBALLOONSAT

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KAPTON HEATER

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DATA FORMAT AND STORAGE

• EEPROM will store all data collected on flight

• EEPROM stores addresses for flight software

Byte # Data Stored0 Original Address1 Current Address

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

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THERMAL DESIGN• ITO Sensors must maintain

temperatures between 24 and 30 degrees Celsius

• Kapton Heater

• Requires approximately 1W

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MECHANICAL DESIGN•A hollow regular A hollow regular hexagonal prismhexagonal prism

•FOAMULAR Insulating FOAMULAR Insulating SheathingSheathing

External Design:External Design:

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

•Foam Divider in center of Foam Divider in center of payload separates each payload separates each board and power supplyboard and power supply

The external design of ITO sensor payload (in m)

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CALIBRATIONS

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CALIBRATIONS

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ResultsIssues/Solutions

Future Work

FAILURE REPORT

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RESULTS• EEPROM read-out showed all values as either 0 or 255 including the

output of the thermistor control

• ITO Sensor must be functional because it reacted to post-flight Tesla Coil output (may not be calibrated properly).

• 4-Channel ADC must be functional because it is read properly and the proper I2COUT command is given to the EEPROM (this code worked in BR).

• 8-Channel ADC is functional when not connected to conditioning board (connected to arbitrary 1.5V input and produced proper output.

• Bad EEPROM?

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ISSUES/SOLUTIONS• EEPROM not working

• Blown during pre-flight work Monday

• Solution: New EEPROM

• Sensor calibrations are inaccurate

• Resistance of sensor at just above 0 ppm is approximately 850Ω (not 970Ω).

• Solution: Recalibrate sensors and modify conditioning board by using proper resistor values for actual ITO calibration in order to produce the proper amount of gain and offset

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FUTURE WORK• Once EEPROM and sensor issues are resolved, payload SHOULD be ready for

flight.• System testing will determine whether or not the payload IS ready for flight.• Future flight requires that payload lose approximately 75g.

• Payload box may be made with ½” foam instead of ¾”• ≈ 15 – 20g

• Power supply for heater may be reduced• ≈ 30 – 45g

• Reduce excess wire and ribbon cable• ≈ 15 - 20g

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