An interdigitated capacitive structure whose fingers have branches across them is described in this article. By
changing the traditional interdigitated electrodes (IDE), the area where the sensor is defined can be reduced by a third,
while its capacitance and sensitivity are maintained. This enhancement with respect to the traditional one is obtained
thanks to the contribution to the capacitance not only in the finger length direction (unidimensional) but also in the finger
width dimension (2-D). In order to test the sensitivity enhancement of this device in comparison with the conventional
IDE, two version of this structure and the classical IDE have been manufactured by inkjet printing on flexible foil and
characterized as relative humidity (RH) sensor. For this purpose, a substrate whose electrical permittivity changes with
moisture content has been selected. Their capacitances have been measured as a function of RH in a wide range of
frequencies at different temperatures, obtaining comparable results as a function of the RH and temperature. However, in
the case of the sensor with closer branches, the response changes above 50%RH, showing a significantly higher sensitivity
due to the fact that electrodes are much closer than in the other structures. The accumulation of water molecules between
consecutive fingers occurs at lower values of moisture content than in the other layouts, resulting in higher capacitance
values due to the higher electrical permittivity of water.
«
An interdigitated capacitive structure whose fingers have branches across them is described in this article. By
changing the traditional interdigitated electrodes (IDE), the area where the sensor is defined can be reduced by a third,
while its capacitance and sensitivity are maintained. This enhancement with respect to the traditional one is obtained
thanks to the contribution to the capacitance not only in the finger length direction (unidimensional) but also in the finger
width dimension (...
»