How peltier works
A peltier has two dissimilar conductors, causing one side of the peltier to be hot, while the other side to be cool. By allowing the cooler side of the peltier to cool the copper sheet, conduction and convection currents will cause the temperature of the air in the jacket to be reduced. Heat will be dissipated from the other side of the peltier using a DC fan and heat sink, such that heat would not be transferred to the cool side of the peltier and affect the cooling process.
How is the temperature of the peltier regulated
Temperature sensors will be attached to the hot and cool side of the peltier to monitor the heating and cooling process respectively. The temperature measured of the cool side of the peltier will be used as an input for Proportional Integral Derivative (PID) control. Should the temperature difference between the setpoint and the input be large, the current supplied to the peltier would be increased to enhance the cooling process. The PID coefficients will also be modified to optimise cooling. When the temperature of the input and setpoint is the same, current would be reduced to maintain the temperature of the peltier.
ESP32
Our ESP32 can perform together with our host MCU, reducing communication stack overhead on the main application processor. It can interface with other systems to provide Wi-Fi and Bluetooth functionality through its SPI / SDIO or I2C / UART interfaces.
Flex sensor
When the substrate is bent, the sensor produces a resistance output correlated to the bend radius—the smaller the radius, the higher the resistance value. This is used in our jacket as a posture correction mechanism, where the user is reminded to sit upright when the curvature of the back reaches the threshold.