Characterization of the actual heat distribution is done using a FLIR One Pro iOS thermal camera (FLIR Systems, Inc., Wilsonville, OR, USA). Thermal images of the heat distribution are made at the side of the substrate without the resistor, whereas different input powers are used to heat up the heater. Au reflects the infrared radiation of the environment directly, therefore an image with the resistor facing the camera would give a heat map of the surrounding and not of the real temperature of the heater. These measurements also gives a better insight of the heat distribution inside the reaction chamber. The images are processed using the FLIR postprocessing freeware. Results of these measurements are shown in Figure 11a,b. The results are in good agreement with the estimations in Table 1. The slight deviation between the values can be explained by the fact that the heated area in the calculations had an assumed value, the thermal camera measurements used 1.5 mm thick COC substrates without a water-filled chamber, the actual resistors have small parts wich have a double thickness due to the two used shadow masks, and rounding of the values used in the calculations.