This document summarizes a capstone project to design a temperature logger for blood analyzer cartridges. The project aimed to modify existing cartridge PCBs to log temperatures during shipment and storage using a microcontroller, thermistor, and battery. The design was tested and found to accurately measure temperature within ±2°C while extending battery life to over 3 months. Testing confirmed the design could interface with existing blood analyzer instruments and read stored temperature measurements.

1. Capstone Project
Temperature Logger for Blood Analyzer Cartridge
Ciro Mazzola
Vladimir Pogorelov
Wai Tang
UMASS Lowell
Electrical and Computer Engineering
December 18, 2015

2. Introductions
■ Ciro Mazzola
■ BSEE ’15
■ Vladimir Pogorelov
■ BSEE ‘15
■ Wai Tang
■ BS EE & PHY ’15
■ Project Mentor: Paul McCormack, Dr. John Palma

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

4. Background
■ GEM 4000 Instrument
■ GEM 4000 Cartridge
■ Contains PCB with EEPROM storing information
■ Cartridge configuration, capacity, identifying information, etc.
■ Reagents

5. 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

6. 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

7. 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

8. 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

9. 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)

10. Schematic

11. 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)

12. Test Case Example

13. Test Case Example
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Voltage(V)
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Battery Discharge Curve through a 15k Resistor at ~8 oC
Energizer
Sony

14. 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

15. Demo (Arduino)