Temperature Sensor Development and Characterization.

A 100 kΩ Negative Temperature Coefficient (NTC) thermistor (NTCG064EF104FTBX, TDK Corporation) was placed on the back side of a fPCB (3 mm in diameter) and balanced using a wheat stone bridge configuration with 0201 components. The NTC was balanced with a 69 kΩ resistor to provide a reference voltage of 0.116 V. Voltages from the bridge were fed into a differential amplifier (ADA4505-1, Analog Devices) with gain set to 82.64× using 10 MΩ and 121 kΩ resistors. Characterization of the NTC thermistor was carried out using a proportional-integral-derivative (PID) controlled hot plate where the NTC and commercially available digital thermocouple (HT-9815, Hti-Xintai) were secured to the system. Temperature was increased in 0.5 °C increments and left for 2 min for the temperature to stabilize. The ADC readout was recorded, as well as the commercial thermistor readings and ADC values were converted to voltage. Results were collected and a calibration curve was developed.