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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

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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.