Method for fabrication of a sensor device , the sensor device being adapted for measuring a first parameter (P 1 ) of a test substance, preferably a humidity of the test substance, the method comprising the steps of: i) providing a substrate with a front side and a back side , the front and back sides each extending in an in-plane direction (x) and being located at a distance to one another in an out-of-plane direction (z); ii) depositing from the front side of the substrate a structured first protection layer ; iii) arranging on the front side of the substrate a stack of dielectric and conducting in-plane layers, the stack comprising: - a first electrode ; - a second electrode ; - a sacrificial layer ; wherein the first and second electrodes are arranged on the first protection layer and at a distance to one another in the in-plane direction (x), wherein the sacrificial layer is arranged without overlap with the first protection layer with respect to the in-plane direction (x) and between the first electrode and the second electrode with respect to the in-plane direction (x); and the stack further comprising: - a passivation layer that covers front sides of the first and second electrodes and the sacrificial layer , respectively; and iv) generating from the back side of the substrate , in a process step an opening , the opening extending through the substrate from its back side to its front side and the opening removing at least part of the sacrificial layer , thereby creating a sensing cavity extending between the first electrode and the second electrode , wherein the first protection layer protects the first and second electrodes from being removed during the process step iv). i) providing a substrate with a front side and a back side , the front and back sides each extending in an in-plane direction (x) and being located at a distance to one another in an out-of-plane direction (z); ii) depositing from the front side of the substrate a structured first protection layer ; iii) arranging on the front side of the substrate a stack of dielectric and conducting in-plane layers, the stack comprising: - a first electrode ; - a second electrode ; - a sacrificial layer ; wherein the first and second electrodes are arranged on the first protection layer and at a distance to one another in the in-plane direction (x), wherein the sacrificial layer is arranged without overlap with the first protection layer with respect to the in-plane direction (x) and between the first electrode and the second electrode with respect to the in-plane direction (x); and the stack further comprising: - a passivation layer that covers front sides of the first and second electrodes and the sacrificial layer , respectively; and - a first electrode ; - a second electrode ; - a sacrificial layer ; - a passivation layer that covers front sides of the first and second electrodes and the sacrificial layer , respectively; and iv) generating from the back side of the substrate , in a process step an opening , the opening extending through the substrate from its back side to its front side and the opening removing at least part of the sacrificial layer , thereby creating a sensing cavity extending between the first electrode and the second electrode , wherein the first protection layer protects the first and second electrodes from being removed during the process step iv). <EOS>