Microcalorimeter fabrication and new measurement methodology for thermal sensing in microfluidics

This work describes the integration of a Resistance Thermal Detector (RTD) microcalorimeter integrated into a 324 nL microfluidic channel. The sensor is fabricated in a clean room using photolithography and evaporation techniques, and it has a platinum serpentine with 60 windings. The RTDs undergo testing in the 30 to 45 °C temperature range, exhibiting great linearity and a sensitivity of 8.42 Ω/°C. Additionally, to perform the thermic measurement, we also provide a circuit architecture that ensures stability against external thermal fluctuations and the self-heating Joule effect. We showed that this measurement method allow us to achieve a precision of ±6.7·10⁻³ °C, compared to ±0.178 °C total fluctuations found by using the traditional 2-wire method.