Capstone ProjectTemperature Logger for Blood Analyzer Cartridge

Ciro MazzolaVladimir Pogorelov

Wai Tang

UMASS LowellElectrical and Computer Engineering

December 18, 2015

Introductions■ Ciro Mazzola

■ BSEE ’15■ Vladimir Pogorelov

■ BSEE ‘15■ Wai Tang

■ BS EE & PHY ’15■ Project Mentor: Paul McCormack, Dr. John Palma

Agenda■ Background■ Objectives■ Requirement Highlights■ Design Overview■ Software Overview■ Hardware Overview■ Testing■ Conclusions

Background■ GEM 4000 Instrument■ GEM 4000 Cartridge

■ Contains PCB with EEPROM storing information■ Cartridge configuration, capacity, identifying information, etc.

■ Reagents

Objectives■ Modify current GEM 4000 PCB to incorporate

temperature logging■ Log temperatures during shipment / storage of

the GEM 4000 cartridge■ Store the temperatures to be read upon insertion

of the cartridge into the instrument

Requirement Highlights■ Log temperatures below 10oC and above 40oC■ Store temperatures in non-volatile memory■ Interface with GEM4000 instrument■ Minimum battery life of 4 weeks (shipment +

storage)■ Cost less than $1/ea. at 100,000 unit buy

Design Overview■ Silicon Labs C8051F902 Microcontroller

■ Low-Power: 300 nA sleep mode current draw■ On-board DC-DC converter■ As low as 0.9-3.6V Supply■ On-board ADC

■ NTC Thermistor■ 1.5V Zinc Silver Oxide Battery, 27 mAh■ Same EEPROM as existing GEM 4000 PCB

(24LC08B)■ Same PCB dimensions as existing GEM 4000 PCB

Software Overview■ To be programmed

during fabrication; Activate once battery is inserted

■ I2C mode ■ Address 0x34■ On demand

■ Sensing mode■ Measure every 4 hours■ Save data and switch to

30 minutes for abnormal temperature

Hardware Overview■ Electrical & Mechanical design of PCB ■ Used Diptrace software for designing schematic

and PCB layout■ Sent Layout (Gerber) to PCB manufacturer■ Two versions:

■ Prototype: With programmer and through hole I2C & C2 headers for troubleshooting & programming. 5% tolerance thermistor (0805)

■ Production: Only IL header. 1% tolerance thermistor (0402)

Schematic

Testing■ Timing

■ Long sleep interval: 3 hours 24 minutes■ Time required for measurement: 216 ~ 423 ms

■ Accuracy■ Temperatures captured within ± 2 oC■ Data was not lost if battery was removed

■ Power Consumption■ Average current: 0.958 uA; Battery Cap: 27 mAh■ Projected lifetime: 111 weeks

■ Compatibility■ Can read EEPROM using exiting system (f = 400 kHz)■ Can read temperature using MCU and Arduino (f < 200

KHz)

Test Case Example

Test Case Example

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0.2

0.4

0.6

0.8

1

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Battery Discharge Curve through a 15k Resistor at ~8 oC

EnergizerSony

Time (hour)

Vol

tage

(V)

Conclusions■ Designed temperature logger to existing PCB■ Tested temperature accuracy within ±2 oC ■ Microcontroller + thermistor + Silver Oxide

battery ■ Measure ambient temperature every 4 hours;

30 minutes if temp. out of range■ Data can be read through I2C by calling slave

address 0x34■ Costs an additional $1.19 per unit at 100k

Demo (Arduino)