Thermpack

Jason Torres

Inspiration: Thermpack is an MEng Capstone project to develop a device that will provide heating and cooling of skin between 10C and 40C for therapeutic applications related to exercise recovery.

Goal: To create the first version of the prototype that can control a Peltier device based on thermistor temperature readings for feedback and a PID loop for control.

Description: The board is powered by a 5V DC source supplied through screw terminals. The 5V is then stepped down to 3.3V with a regulator to power the ESP32-S2-SOLO microcontroller. The microcontroller reads temperature values from thermistors, controls LEDs for indication, and controls an H-Bridge IC to drive the current supplied to Peltier devices. There is also a Micro-B USB receptacle to communicate with the micro over serial.

Architecture block diagram of the prototype goals this semester and for the end of the school year.

EPS32-S2-SOLO microcontroller circuitry.

Completed layout with the thicker traces designed to carry 5A through the H-Bridge and the Peltier devices.

Pre-populated PCB.

Fully populated PCBA with the TEC and the thermistor leads hanging off of the edge of the board. These will then be bonded together to provide a closed feedback / driver loop.

Challenges During Assembly:

Suboptimal SMD soldering tools and techniques.
H-Bridge bring-up issues.
Initial microcontroller communication issues.

Future Work:

Add a USB-UART bridge to improve communication and bring-up.
Choose a simpler H-Bridge.
Add lithium-Ion battery supply.

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