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Real-Time Coagulopathy Measurement
Development Team
Trenton RochelleJustin Hemphill Ziming Qi
Overview● Coagulopathy of Trauma – A hypo-coagulable state
caused by trauma, resulting in increased bleeding or clotting, heightened resuscitation requirements, and a 4x increased rate of mortality.
● Car accidents, shootings, bad falls...
● To minimize mortality, coagulopathy must be assessed and addressed nearest to the time of injury and monitored throughout the course of care.
Problem with Current Solutions● Measurements can only be taken in a hospital/lab setting
● Can take up to an hour
● Seconds matter when treating a critically injured person
Aptitude’s Solution● Proprietary molecule that binds to receptors in a person’s
blood. Electrochemical signals produced by the molecular binding give coagulopathy measurement.
● Developed a handheld sensor analogous to a blood glucose meter
● 30 second test
Location Hospital/Lab Portable
Time ~ 1 hour < 2 minutes
Size Stationary Machines Handheld
User Doctor/Lab Technician First Responder
Current Solution Aptitude’s Solution
Alpha Prototype
Our New System
Main Product Requirements ● Handheld and field-ready during an emergency
● Blood within the sensor needs to be stable at various goal temperatures (15-60°C)○ Needed for different tests + future development
Goals
● Temperature control
● Integrate modules into a PCB
● Provide future feature expandability
● Device charging in-use
● Redesign enclosure
● Quick and reliable readings
Design Limitations
● No bluetooth
● Long battery life
● Handheld
● Work while charging
● Work with Android
Simplified Block Diagram
Core Modules
Central Processor
● SAMD21 Cortex-M0+● Low power 32-bit● 48MHz Clock● SPI/UART/USB + GPIO + PWM
Emstat Pico
● Highly compact potentiostat used for electrochemical measurements
● Provides coagulopathy measurement
Power System
Battery:● PKCELL Li-Po rechargeable battery● 3.7V● 2500mAh● 50mm x 50mm x 7mm● Use: Supply system power
Battery Controller:● PowerBoost 1000C● Boosts output to 5V● Battery level reading● Safely charges Li-Po Battery from USB● Charge + Use simultaneously.
Temperature Control
Peltier Module:● Heats + Cools the blood chip● 25mm x 12mm x 3mm● 6.0-9.0V operating voltage● 800mA draw● Voltage changes as temperature changes
● H-Bridge device alternates current
Temperature Readings
Surface Mount Thermistor (PT100):● Responsive thermal equilibrium● Thin Film
Digital Amplifier (MAX31865):● Read temperature every 100ms● 0.02℃ resolution● Connected to Thermistor
Thermistor atop Peltier
Side View
Peltier Control Function
1. Input: Temperature (℃)
1. Output: PWM Duty Cycle (0-100%)
1. Using two PID controller objects
i. One for heatingii. One for cooling
Proportional-Integral-Derivative (PID)● Control loop mechanism employs feedback● Continuously calculates an error value e(t) as the difference
between a desired setpoint y(t) and a measured process variable r(t)
● Applies a correction based on proportional, integral, and derivative terms
PID Tuning - Kp, Ki, KdTarget
Ampl
itude
Time
Heating PID - No Enclosure Results
Converges to +10℃ in around 7-8 seconds!
Cooling (more difficult)
Working against ambient temperatureCreated an enclosure for thermal isolation
Heat from bottom side diffuses into colder sideHigh temperature gradient reduces efficiency
Attached heat sinks
} ΔT = temperaturegradient
Enclosure Design
Enclosure Design
Heating Improvement
25°C to 37°C in 4 seconds (50%)
25°C to 60°C in20 seconds
4
Putting It All Together
PCB Revision 1
● 2-Layer● Single-sided● 45mm x 75mm
PCB Revision 2
● 4-Layer● Double-sided● 45mm x 63mm (12mm shorter)● Blood reading system included
TopBottom
Android Application
● Microprocessor-Android communication while also charging
● Microprocessor data can be changed in-app with JSON messages
○ {"mode":"set","modeType":"isTempControlling","modeData":[1]}
Developer Settings
Scanning App ● Scan Start
● Status Info
● Temperature
AcknowledgementsScott Ferguson, PhD, CEO and Founder, Aptitude Inc.
Radhey Patel, Electronics Engineer, Aptitude Inc.
Yoga Isukapalli, Professor and Capstone Chair, UCSB ECE.
Aditya Wadaskar, Teaching Assistant, UCSB ECE.
Kyle Douglas, Teaching Assistant, UCSB ECE.
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