3D-Printed Calorimetric Flow Sensor

This work shows the development and char-acterization of a fully 3D-printed thermal mass flow sensor, based on regular and carbon-doped thermoplastic polyurethane (TPU). Using multi material fused deposition modelling (FDM) 3D-printing, the sensor is based on one heater element and two resistive thermal sensors (sensor -heater - sensor configuration). The transduction is based on the temperature dependent resistance of carbon doped polymers. Characterisation of the conductive TPU shows a positive thermal coefficient of resistance (TCR) ranging between 0.002 ◦C−1 to 0.024 ◦C−1, whereas the sensor shows a responsivity of 20 mV ml−1 min−1 in the pseudo linear range for flows below 3 mL min−1 while using a power of 1 W and a temperature up 58 ◦C.