The CNTs were used as received. The average dimension of the CNTs were 10 μm long with a axial diameter of 15 nm. To fabricate the screen print ink, the CNTs were dispersed in a ink formulation consisting of solvent, filler and dispersant. The solvent was ethanol, dispersant was SDS, binder was PVP and filler material to be the CNTs. The ink fabrication began with the dissolution of 8.0 wt% of SDS in ethanol under bubblefree stirring for 3h. Then the CNTs were added at a concentration at 5 wt% gradually duing a 1h sonication. Next, 20% binder was added to the solution with gentle stir for overnight. Screen printing was performed with a screen mask on top of the flat paper to define the electrodes and CNT sensor. After the CNT and silver ink printing, thermal annealing was conducted at 200C for 15 min to remove additives and let wax melt thoroughly to form the hydrophobic barriers.