After the needle formation in the DRIE, a protective passivation layer of SiO2 was deposited on the microneedle device leaving the sensing area clean. In order to protect the sensing area from the passivation, AZ -1518 photoresist was spin-coated and baked with the same parameters as before and exposed to a UV light with a dose of 45mJ/cm 2 . The substrate was developed in AZ-726 developer for 1 minute and the microneedle was placed inside the PECVD for the deposition. (140 sccm N2O, 40 sccm 2% SiH4/Ar, 80°C, 95 mTorr, 30 W bias 200W ICP , 1h))